Re: Topband: from Mac Reynolds, w9evi - Rellector post repeats
Ive been receiving duplicates for quite awhile Charlie, OK now. Carl KM1H - Original Message - From: Charlie Cunningham charlie-cunning...@nc.rr.com To: 'HAROLD SMITH JR' w0ri...@sbcglobal.net; w9...@aol.com; topband@contesting.com Sent: Sunday, February 23, 2014 10:03 AM Subject: Re: Topband: from Mac Reynolds, w9evi - Rellector post repeats Thanks, Harold! Well, I would have thought I'd see repeats here also. I think that what might have thrown Mac, was that there I have had a lengthy exchange, over several days, with Carl Braun, AG6X (and also W8JI, and KM1H) over the past few days regarding Carl's experiments and modifications of his 90' shunt-fed Skyneedle antenna. We often ping-ponged exchanges back and forth without changing the subject line in the e-mails, so if Mac didn't actually read them, they might have appeared to be repeats, And they have been NUMEROUS! Anyway, Carl has arrived at what appears to be a really good solution to his antenna design and I expect to see good results! Thanks for your update and input, Harold! Have a good day! 73, Charlie, K4OTV From: HAROLD SMITH JR [mailto:w0ri...@sbcglobal.net] Sent: Sunday, February 23, 2014 10:35 AM To: Charlie Cunningham; w9...@aol.com; topband@contesting.com Subject: Re: Topband: from Mac Reynolds, w9evi - Rellector post repeats Charlie, I have NEVER seen a repeat of your postings. 73 de Price W0RI near St Louis, MO Good morning, Mac Please let me know if you see further repeats of any of my posts to the reflector. No one else had told me about that, so I appreciate your letting me know. After your e-mail, I did restart my computer and did a malware scan. The malware scan did find one item that needed to be removed. I did remove that item and restarted the computer. Perhaps I need to do some further spyware scans and do a full in-depth virus scan. Haven't done that in a week or so. I don't see repeats of my own posts to the reflector, so I don't know what to think Please let me know if you see further repeats of my posts to the reflector. I'm sending this post to topband also as a test for repeats. Thanks and have a good day! 73, Charlie, K4OTV From: w9...@aol.com [mailto:w9...@aol.com] Sent: Saturday, February 22, 2014 12:29 PM To: charlie-cunning...@nc.rr.com Subject: from Mac Reynolds, w9evi Dear OM Cunningham - Something has gone wrong: Every time you send a message to Topband, I get a long list of repeats of your message. The last one, about some antenna thing, was repeated to me fifteen times! That about fills my inbox. The cause must be local to you because no other e=mail to Topband does that. Hope you cure ure it..73 de Mac. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4335 / Virus Database: 3705/7117 - Release Date: 02/22/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Shunt feeding the Skyneedle - new developments
The only benefit of getting it better would be a bit more 2:1 VSWR bandwidth to keep the amp happy but even then there is sometimes a gotcha when tuning an antenna. Carl KM1H Subject: Re: Topband: Shunt feeding the Skyneedle - new developments Well, you can do all that, Carl But if your series variable capacitor is not maxed out (fully meshed) if you can increase the capacitance enough to get to j0, you would be at 45 +j0 and on a 1.1:1 VSWR circle. No point int trying to do better than that!! Otherwise, just increase the series capacitance to bring that -j11 as close to j0 as possible and take that! You'd be so near perfect that there would be no real point in going further! Your time and efforts might be better spent working on your radial field! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Carl Braun Sent: Friday, February 21, 2014 8:46 PM To: Charlie Cunningham; 'Tom W8JI'; '160' Subject: Re: Topband: Shunt feeding the Skyneedle - new developments Thanks to all who replied Tom W8JI, your comments on the metallic panel and the static bleed choke make sense. I was so pleased with the FLAT SWR reading with the variable cap outside the panel but I guess I can live with the slight SWR. (Thanks Charlie K4OTV). I have a Nye Viking monster tuner but I hate to use it as my Henry amp seems to load strangely when I have it inline so I think I'll just live without it. Can I add some coax (coiled) to bring the X down on the -j11 reading? I did this with the old Telrex and brought the X right down and out of the pic. I'm sure Ill need much more than I would on 14MHz but I think I'd like to try anyway. I'm still going to drop the tower down and add two more gamma wires to create a cage and I still have the option of pulling the gamma wire(s) away from the tower another 8-10 inches to add a few more ohms to the equation. I'm having fun with the experiment. Right now I'm hearing the beginnings of the SSB contest with N7GP, WD5COV, W6YI with the big signals so far. XE is the only DX I've heard. Lots of stateside calling stateside Carl AG6X -Original Message- From: Charlie Cunningham [mailto:charlie-cunning...@nc.rr.com] Sent: Friday, February 21, 2014 5:21 PM To: 'Tom W8JI'; Carl Braun; '160' Subject: RE: Topband: Shunt feeding the Skyneedle - new developments Well, Carl I plotted your 45-j11 load on a Smith Chart (normalized to 50 ohms) and it's very near the origin on a 1.3:1 VSWR circle. Since you have a relatively short feedline of LMR-400, You should be able to just tune it out at the transmitter end of the line, and the LMR-400 line will be operating at such a very low SWR (around 1.3:1 that the excess loss from a 1.3:1 VSWR at 160 is completely trivial and negligible! It may not be completely intellectually satisfying to have -j11 of reactance at the load, but it should match easily and the antenna should work very well! Enjoy! Sounds like that Array solutions static bleed is not as high in impedance as we might wish! A large resistance might give you more satisfactory results! GL! Enjoy! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Friday, February 21, 2014 8:02 PM To: Carl Braun; '160' Subject: Re: Topband: Shunt feeding the Skyneedle - new developments Since then I've moved the variable capacitor inside the panel and mounted it to a ¾ think Plexiglas sheet mounted to the back plane with nylon bolts and washers. There is a 1 air gap between the Plexiglas and the backplane. I now have seen the 42+j0 ohms change to 45 - j11 ohms...that's the lowest reactance I can tune the capacitor for. Not really sure if its +j11 ohms or - j11 ohms but I assume if the reading was + j11 I could continue to tune it out with the capacitor but I cant. Does the capacitor not play well with a steel enclosure? Any enclosure will change things, especially a metallic enclosure. Just readjust the cap. The other strange situation I'm experiencing is when I connect my Array Solutions static bleed choke to the feed thru insulator at the outside of the panel to ground the resonant frequency jumps to 2.014 MHz at 25 +j0 ohms...remove it entirely and I'm back to my 45 - j11 ohms. The choke is completely unnecessary with a shunt feed tower. It won't help a thing, so leave it out. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4335 / Virus Database: 3705/7115 - Release Date: 02/21/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Coax issues
Chomp chomp, burp. Some critters travel under the snow and vegetation for their vitamins. Was that double female or burnt PL-259 an import? The coax dielectric shouldnt make any difference and maybe it wasnt sealed properly and water got in. Ive blown import junk enough times in the past to get rid of them all. Carl KM1H - Original Message - From: Gary Smith g...@ka1j.com To: Topband@contesting.com Sent: Wednesday, February 19, 2014 2:05 PM Subject: Re: Topband: Coax issues Resolution: Eat more rabbit. Thanks again for the pointer to the 259B being an answer. I now see it will do more than I knew, I didn't know about the advanced mode. So... Last night I disconnected the coax in to the distal coax switch, it was not connected in the shack but I read a dead short with the fluke. This morning I went out and disconnected the coax so I could make a reading on both ends of the coax to see how well they jived. Found the instigator of the problem that damned rabbit chewed mostly through the control cable to the coax switch. He must have bit into the voltage that stopped him. However, he had chewed through the cable and had severed 3-4 wires of the 6 involved in switching and this disconnected the coax from the antenna. I was trying for 3B9/OE4AAC on Rodriguez on 17 using the amp. Amazingly the amp didn't have any issue but that energy had to go somewhere. I reattached the control wires at the switch, went back to the shack and read 515 feet to fault and that multiplied by the VF of .66 = 334 feet. Not knowing the exact footage of the coax, I went to the distal end and remeasured from there and kept getting different distances but one thing was for sure, it was easier getting the zero readings at the shack end. I cut off the connector there still was a dead short in the coax so I cut away the roll of coax I used for a choke thinking it would be found there but no. I started the long grind of pulling up the coax from under the leaves snow came to something I'd forgotten about, I had run short of coax and needed to use a female/female jumper to add a length of coax to reach the switch box. I undid the sealant could smell the burn. The end going to the house was undamaged but the other end had fried at the connector. I'd forgotten that the last part was foam coax my long run used the hard plastic dielectric; it was the foam that melted shorted. All's well now with the coax and antennas, all read just where they should and I now have a vial of that Coyote urine under the switch to deter any more of those wascally wabbits. Thanks again for the replies. Gary KA1J --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4335 / Virus Database: 3705/7106 - Release Date: 02/19/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Palomar R-X Noise Bridge
- Original Message - From: Jim Brown j...@audiosystemsgroup.com To: 'TopBand' topband@contesting.com Sent: Saturday, February 15, 2014 12:15 AM Subject: Re: Topband: Palomar R-X Noise Bridge On 2/14/2014 7:00 PM, Charlie Cunningham wrote: All generally true, I expect, but I also believe that dielectric constant and dielectric losses also figure in and the lowest loss lines would be filled with air, dry nitrogen or evacuated. I expect those would likely be the lowest loss AND highest velocity factor cases. If you run the equations, you find that below about 1 GHz, the losses are all copper losses. Dielectric loss is a few percent of the total loss in the 500 MHz range. The benefit of a foam dielectric at HF and VHF is that it allows the center conductor to be larger for a given shield diameter. But the improvement in loss of a foam dielectric coax below 1 GHz is entirely due to the center conductor being larger. BTW -- the relevant equation is on each Times data sheet. 73, Jim K9YC Dielectric losses become evident at 2M with 1500W and at 432 400W of steady carrier will heat up even the best N connectors and RG-213. For that reason many are switching to the 7/16 DIN. Carl KM1H _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Palomar R-X Noise Bridge
Carl: I've read, at several places, that sleeve baluns are effective at VHF and above but not at HF frequencies..thoughts?? 72/73, Jim Rodenkirch --- former Tempest inspector for the U.S. Navy..ah...Tempest comcerns - the good 'ol days hi Hi! Oh, the fun we had almost living in a screen room in order to get a product past those inspectors!! The effect of shielding and ferrites has been permanently imprinted on my brain. I sometimes have to laugh when reading that some consider a sleeve balun/choke to be a recent invention! Maxwell sort of stumbled on it in later years with those tiny beads that seriously overheated with most amps. We started with the type that fit over RG-213 and went from there to custom made, the big donuts, and sheet products from pioneers such as Arnold. Carl KM1H From: charlie-cunning...@nc.rr.com To: k...@jeremy.mv.com; topband@contesting.com Date: Sat, 15 Feb 2014 11:39:14 -0500 Subject: Re: Topband: Palomar R-X Noise Bridge I'm a great believer in ferrite sleeve baluns, Carl! That's all that I use, and with a little work you can even connect two of them for 4:1 nalance. 73, Charlie, K4OTV -Original Message- From: Carl [mailto:k...@jeremy.mv.com] Sent: Saturday, February 15, 2014 11:05 AM To: Charlie Cunningham; 'TopBand' Subject: Re: Topband: Palomar R-X Noise Bridge The lowest loss cable I have here is 75 Ohm 1 General Cable Fused Disc; its under a differnt name these days. Mostly air with poly discs and used for the 200' runs for 10M, 2M, and 222 MHz. For the 160/80 inverted vee it is 450' of regular foamed 3/4 75 Ohm CATV hardline with a RG-11 jumper and plenty of ferrite to the feed point. Ive been using ferrite sleeve baluns since the mid 70's; I was introduced to them by the company I worked for who was building equipment for the joint CIA/DOD Tempest program. Carl KM1H - Original Message - From: Charlie Cunningham charlie-cunning...@nc.rr.com To: j...@audiosystemsgroup.com; 'TopBand' topband@contesting.com Sent: Friday, February 14, 2014 10:00 PM Subject: Re: Topband: Palomar R-X Noise Bridge All generally true, I expect, but I also believe that dielectric constant and dielectric losses also figure in and the lowest loss lines would be filled with air, dry nitrogen or evacuated. I expect those would likely be the lowest loss AND highest velocity factor cases. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Brown Sent: Friday, February 14, 2014 9:42 PM To: 'TopBand' Subject: Re: Topband: Palomar R-X Noise Bridge On 2/14/2014 2:17 PM, Carl wrote: Isnt that what lowest loss means? At least that was my intention. I must not have written clearly enough. I was not questioning the low loss, only that the high Vf was the way to get it. You DO get the low loss by going to larger coax, (like the 7/8-in hard line), but it's the fact that it's LARGER and has lower RF resistance, NOT the higher Vf. Think of it this way -- The higher Vf cable has less attenuation per ft because the higher Vf allows the center conductor to be larger. But a stub made with foam coax with Vf = 0.84 must be 27% longer than one with with a solid dielectric and Vf =.66. If those coaxes are the same diameter and of comparable quality, the stub attenuation and Q will be nearly the same. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3705/7095 - Release Date: 02/15/14 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3705/7095 - Release Date: 02/15/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Palomar R-X Noise Bridge
Absolutely and I had the pleasure of meeting him and hear him speak. Unfortunately his very public arguments with Warren Bruene in QEX and elsewhere over the Conjugate Match and then showing up on various forums to publicly push his last book as part of his legacy (which contains his final words on the subject with no further discussion) while the battle was still in progress was a bit dissapointing. Several tried to engage him in a discussion but he didnt want to be challenged and the subject was pulled out of respect for all the good he has done over his long career. Carl KM1H - Original Message - From: Charlie Cunningham charlie-cunning...@nc.rr.com To: 'Tom W8JI' w...@w8ji.com; 'Top Band Contesting' topband@contesting.com Sent: Saturday, February 15, 2014 4:35 PM Subject: Re: Topband: Palomar R-X Noise Bridge Walt surely did know his stuff and he published some great material!! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Saturday, February 15, 2014 4:31 PM To: Top Band Contesting Subject: Re: Topband: Palomar R-X Noise Bridge Maxwell sort of stumbled on it in later years with those tiny beads that seriously overheated with most amps. We started with the type that fit over RG-213 and went from there to custom made, the big donuts, and sheet products from pioneers such as Arnold. Walt Maxwell was not only a real nice guy, he knew his stuff. Walt was a senior antenna design engineer for RCA, including satellite antennas. It is outrageous to say Walt Maxwell sort of stumbled on something so simple, and that heating of beads relates to amplifiers. The heating is much more an issue of abnormal common mode impedances, rather than power levels. Walt's article, along with articles by Lewallen, accelerated use of common mode chokes and current baluns. They got us away from those silly voltage baluns people were using. People who don't understand how things work are the people who spend a lifetime sort of stumbling on things. Why, I remember when Walt patiently taught me how conductor losses dominated transmission line loss, and why that was important! :-) 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3705/7095 - Release Date: 02/15/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Power stayed on!
Looks like we dodged the bullet here also. Storms are unpredictable and go anywhere from right up the Hudson River valley to out to sea Watching the storm track it took a sharp right turn over LI, NY and then a NE tack past Boston and out to sea. About 8 of fluff which stopped about 4PM and likely some rain later tonight from the back side as the temps get into the 40's. We are still getting a few 25-30 mph gusts but not like earlier when it was pretty steady for several hours. I took one pass with the plowtruck at 430 so we can get in/out as needed and will do the cleanup tomorrow. Carl KM1H Subject: Re: Topband: Power stayed on! Genuinely sorry to hear of the unfortunate damage this storm has done to some of us. It takes so much effort to put things together in a way that we're happy with and mother nature can undo it in a heartbeat. Sandy did my damage with salt water submerging all my external antenna switching systems as well as the loss of my wire antennas which snapped from falling branches. This time I escaped damage, I hope those affected get their equipment back to shape as fast as possible. 73, Gary KA1J --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Shunt feeding the Skyneedle
Any idea how much top loading that 5 el 46' boom monster contributes? At a prior QTH in the 80's I had a 90' 25G toploaded with a 10-15-20M stack of PV-4 monobanders and about 18' of mast. The 20M boom was 40' and the tower resonated at 1620KHz if I remember. Sure worked great once I figured out that 60 radials werent so hot over sand and added a mesh extending 50' from the base. The gamma rod was the shield of 3/4 CATV coax about 2' from the tower and the best tap point was around 60' if I remember. Carl KM1H - Original Message - From: Carl Braun carl.br...@lairdtech.com To: '160' topband@contesting.com Cc: 'Tom W8JI' w...@w8ji.com Sent: Monday, February 03, 2014 11:17 AM Subject: Topband: Shunt feeding the Skyneedle Topbanders If you followed my post on 'In search of resonance' you'll see that I was struggling with feeding a 160m inverted L up close to my 90' Skyneedle. Tom W8JI suggested that I cut back the L to 129' but the same phenomenon was seen...that being the VERTICAL section of the inverted L was being completely suppressed by the Skyneedle. At 129' long the antenna resonated nicely on 8.2 MHz or so...indicating the vertical section was still suppressed and the top 29' was resonating. With this in mind I decided to run a shunt wire from the top to see where the antenna resonates. Here's what I found... The Skyneedle is 90' tall and has a 13' mast sticking out the top that mounts a Telrex 20M546 yagi on a 15m boom. The aluminum gamma arm was attached at the 90' level at 24 away from the tower and held in place by PVC standoffs. See attached photo if the reflector lets me post an attachment. The MFJ read 380 ohms at 1825 and the X is way off the scale. I inserted an EF Johnson 10-160pf air variable capacitor at the base...in series...and was able to tune the antenna to 60 ohms and the X=22. If I played with the cap there was a real sharp drop in reactance showing X=12. The air variable was about ¾ meshed. Here are the other resonant points... 15.8 MHz X=0 R=37 with pos and neg reactance on either side of X=0. This freq showed the sharpest dip of any of the three. Next was 10.6 MHz X=0 R=23 with pos and neg reactance on either side of X=0. The last real dip I saw was at 5.3 Mhz with X=0 R=10 No dips below these frequencies but as I stated earlier I tuned the MFJ 259 to 1825 and then played with the variable cap where I saw the big drop in impedance. (58-60 ohms at X=12 to 22. Here are my questions for the gurus... Do I attempt to match the antenna using a gamma match by tapping the Skyneedle at the 67' level to see how it reacts with regards to R and X? (Note - I cannot vary my gamma arm height as this is a tubular tower and there are few places to bolt on the gamma arm...90', 67', 46' and 25' with the latter being the crows nest platform). Or Can I leave the gamma arm at 90' and rely on an Omega match to tune the antenna? Carl _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3684/7058 - Release Date: 02/03/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Bad tower shunt capacitor
The 3 line sections will handle more (-; And as many BCB and other commercial stations are being dismantled it is available at scrap prices or less. I have several large rolls of 1 5/8 here for sale. Carl KM1H - Original Message - From: Herb Schoenbohm he...@vitelcom.net To: topband@contesting.com; TopBand List topband@contesting.com Sent: Wednesday, January 29, 2014 10:53 PM Subject: Re: Topband: Bad tower shunt capacitor Wouldn't 1 5/8 hardline make a better HV RF capacitor? Herb, KV4FZ On 1/29/2014 11:34 PM, HAROLD SMITH JR wrote: Jamie, The VSWR would change because the arc would change the impedance at the Arc point. From perhaps several hundred or thousand ohms to near Zero during the Arc.. 73, Price W0RI Thanks Steve: Not bad - I may try that ! :) The question in my mind was if there was an arc outside the caps, why would the SWR change ? Anyway, I may be missing something. I haven't been inside the cap box at the tower for many months so I'll get into it - may be something easy. 73, Jamie WB4YDL Sent from my iPad On Jan 29, 2014, at 7:11 PM, wb6r...@mac.com wrote: Have someone hit the key while you watch which one flashes over. Steve WB6RSE _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3684/7045 - Release Date: 01/30/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Submerging variable caps in oil as substituteforvacuum variables
The large Bird dummy loads use oil up into the low microwave region. Carl KM1H - Original Message - From: Tom W8JI w...@w8ji.com To: HAROLD SMITH JR w0ri...@sbcglobal.net; Shoppa, Tim tsho...@wmata.com; n...@contesting.com; topband@contesting.com Sent: Thursday, January 30, 2014 5:32 AM Subject: Re: Topband: Submerging variable caps in oil as substituteforvacuum variables Still I am intrigued by the thought of a remote tuning capacitor via hydraulic tubing :-). The capacitor plates could be as simple as two concentric cylinder conductors with appropriate spacers. I betcha crud collecting on the top of the oil would set voltage limit. I would be as concerned, or more concerned, with the dissipation factor of the oil at short wave frequencies. The thing that worries me is I cannot recall every seeing a single good high-Q oil-dielectric capacitor above power line and audio frequencies. As a matter of fact, many years ago I tried to use a surplus 20-40kV oil capacitor from Fair Radio as a plate blocking capacitor, and it overheated so badly it exploded. I looked for HF data on mineral oil as a dielectric and couldn't find anything. That would be my main concern. I guess I could stick mineral oil between the plates of a capacitor and see what happens to Q. _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3684/7045 - Release Date: 01/30/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Submerging variable caps in oil as substituteforvacuum variables
Very true but the RF is still in the oil dielectric from the coax connector to the hot end of the resistor. Carl KM1H - Original Message - From: Shoppa, Tim tsho...@wmata.com To: z...@jeremy.mv.com; w...@w8ji.com; w0ri...@sbcglobal.net; n...@contesting.com; topband@contesting.com Sent: Thursday, January 30, 2014 11:32 AM Subject: Re: Topband: Submerging variable caps in oil as substituteforvacuum variables That uses the thermal properties outside a resistor, not dielectric constant properties in a capacitor :-). Tim N3QE - Original Message - From: ZR [mailto:z...@jeremy.mv.com] Sent: Thursday, January 30, 2014 11:28 AM To: Tom W8JI w...@w8ji.com; HAROLD SMITH JR w0ri...@sbcglobal.net; Shoppa, Tim; n...@contesting.com n...@contesting.com; topband@contesting.com topband@contesting.com Subject: Re: Topband: Submerging variable caps in oil as substituteforvacuum variables The large Bird dummy loads use oil up into the low microwave region. Carl KM1H - Original Message - From: Tom W8JI w...@w8ji.com To: HAROLD SMITH JR w0ri...@sbcglobal.net; Shoppa, Tim tsho...@wmata.com; n...@contesting.com; topband@contesting.com Sent: Thursday, January 30, 2014 5:32 AM Subject: Re: Topband: Submerging variable caps in oil as substituteforvacuum variables Still I am intrigued by the thought of a remote tuning capacitor via hydraulic tubing :-). The capacitor plates could be as simple as two concentric cylinder conductors with appropriate spacers. I betcha crud collecting on the top of the oil would set voltage limit. I would be as concerned, or more concerned, with the dissipation factor of the oil at short wave frequencies. The thing that worries me is I cannot recall every seeing a single good high-Q oil-dielectric capacitor above power line and audio frequencies. As a matter of fact, many years ago I tried to use a surplus 20-40kV oil capacitor from Fair Radio as a plate blocking capacitor, and it overheated so badly it exploded. I looked for HF data on mineral oil as a dielectric and couldn't find anything. That would be my main concern. I guess I could stick mineral oil between the plates of a capacitor and see what happens to Q. _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3684/7045 - Release Date: 01/30/14 _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3684/7045 - Release Date: 01/30/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: FT5ZM
Some of my best Antarctic area contacts have been with a horizontal antenna and the very best had the apex at only 50' and the end at 3blew the pileup away with one call and was told later at Dayton I was at least 10dB above the 10 KHz+ of callers. Not bad for a fast installed antenna at the new home and 1200W. Ducting via NVIS? Carl KM1H - Original Message - From: Milt -- N5IA n...@zia-connection.com To: topband@contesting.com Sent: Monday, January 27, 2014 9:26 AM Subject: Topband: FT5ZM He was first discernable here at 1350. In the log at 1400. It is now 1422 and he is fading with my sunrise. The signals peaked at S3 on the Beverages for about 20 minutes, but was good copy on ALL 16 Beverages. This indicates a VERY HIGH arrival angle here near the Amsterdam antipode. He was good copy (S1) on a full wavelength horizontal loop just 10 feet AGL. He is now working northern Scandinavian station as well as NA west coast as he fades away. Still 449 at 1427. 73, and good luck to all. de Milt, N5IA - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3681/7035 - Release Date: 01/26/14 _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3681/7037 - Release Date: 01/27/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennasfor160???
It shouldnt be too hard for some to install a wire mesh of plastic coated rabbit fencing below the antenna, after a few months the grass will grow well past it allowing mowing. I did a variation at another home in the 80's when 60+ on ground radials didnt perform as expected using a 100' shunt fed tower with stacked monobanders. Adding four 4' x 50' mesh strips over the radials and connecting into them made a huge difference. Carl KM1H - Original Message - From: Guy Olinger K2AV olin...@bellsouth.net To: Charlie Cunningham charlie-cunning...@nc.rr.com Cc: Mike Waters mikew...@gmail.com; topband List topband@contesting.com Sent: Tuesday, January 21, 2014 11:32 PM Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennasfor160??? On Tue, Jan 21, 2014 at 10:40 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Be careful not to extrapolate very specifically qualified broadcast experience into ham radio. Originally FCC spec radials still make the close foreground earth appear VERY conductive, which is NOT an advantage one will have putting up two or four radials over plain old dirt, unless one is talking about midwest USA 30 millisiemen super dirt. I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. A ham is talking about two or four raised over plain dirt. Two or four over ugly North Carolina 2 millisiemen will be down, though one will need comparison RBN plots watching an entire 160 contest to see it. It's not so far down though that you won't work happy DX with it, but there is a power loss. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3681/7024 - Release Date: 01/22/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Buffaloed by a bias tee
That gives only a 509 Ohm reactance at 1800 Pete. Going to an oft suggested 100uH raises that to 1131 which is possibly sufficient. I use 220uH for a 2488 XL simply because I have a bunch from a hamfest and they work fine for me in similar service. Carl KM1H - Original Message - From: Pete Smith N4ZR n...@contesting.com To: topband reflector Topband@contesting.com Sent: Wednesday, January 22, 2014 3:32 PM Subject: Topband: Buffaloed by a bias tee I'm still wrestling with the bias tee for my 1-of-8 remote beverage switch. If I use a cliplead to connect a 270-ohm dummy load, bypassing the relay, and connect an MFJ-259B to the receiver port on the controller, the impedance looks completely reasonable - with a 3:1 binocular transformer, 89 ohms R and X=5, measured by the MFJ. However, as soon as I connect a 12V regulated supply to the bias tee - one of the little radio shack variable wallwarts - the measured R drops to 5 ohms and the X goes up to 19. My history major's diagnosis is inadequate isolation between the DC supply and the RFline, but why? The series RF choke in the DC line is 7 turns on a ferrite core, measures 45 uH at 2 MHZ, and the bypass capacitor is a 0.01 uF disk, on thesupply side of the choke. Theseries cap between the Antenna and the RX jacks on the controller is a .1 uF disk (it was what I had). I do not yet have a safety choke between the RX side and ground, but will add one before I deploy it, if I can ever figure out what's going on. I'd really appreciate some ideas of what to try. Thanks in advance! -- 73, Pete N4ZR Check out the Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com. For spots, please go to your favorite ARC V6 or VE7CC DX cluster node. _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3681/7024 - Release Date: 01/22/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: DX-100 adventure - progress
Ive been using a 6AH6 in the VFO and regulating the screen and plate with a 120V 5W zener and suitable dropping resistor and a 47uF 'lytic with a .01disc. Grid drive is still sufficient for 100W+ on 10M with full audio after those mods are also done. A 6AH6 is also the better tube in the VF-1, Johnson 122, Globe Champs and others using a 6AU6. The change to choke input on the LV goes back decades since the original way was too much LV for some circuits for long reliability. I use a scope to get ripple down in all circuits to where I like it since most of my customers use them on AM but it shouls also help on CW. I did make a few contacts in the Stew using a 1939 Meissner Signal Shifter at 7W and a 1934 National FB-XA receiver. Carl KM1H - Original Message - From: Charlie Cunningham charlie-cunning...@nc.rr.com To: 'Bill Cromwell' wrcromw...@gmail.com Cc: 'top Band' topband@contesting.com Sent: Saturday, December 21, 2013 12:21 AM Subject: Re: Topband: DX-100 adventure - progress Hi, Bill! That's great! You're good to go with the elecrolytics, then! BTW - as for the chirp on the signal - the DX-100 VFO and voltage regulator was pretty much what they sold separately as the VF-1 vfo. The DX-40 had a socket to power it, but I never could get rid of the chirp, until I built a separate PS for the VFO. The OA2 gas tube just wasn't stiff enough to eliminate the chirp. You might be able to eliminate most of the chirp by replacing the gas tube with a Zener Diode. By the time you get up ro a 100 volts with the Zener, it's really avalanche breakdown and has a pretty stiff knee. Might improve your chirp! Have Fun! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Bill Cromwell Sent: Friday, December 20, 2013 11:12 PM To: Charlie Cunningham Cc: 'top Band' Subject: Re: Topband: DX-100 adventure - progress On 12/20/2013 11:00 PM, Charlie Cunningham wrote: BTW, Biii - tip/suggestion - for those series-connected electrolytics you probably should put a pair of equal value resistors - one across each series capacitor, as the leakage currents will not be equal in each capacitor in each series string and the DC voltage won't divide equally across each capacitor unless you put individual bleeder or swamping resistors across each cap in the series pair to equalize the DC across each capacitor in the series! I'll be interested to see how it turns out! I never had a DX-100 Benton Harbor Kilowatt! I did have a DX-40 for a while, but no 160 on that one, though! I do have an EF Johnson Navigator in pretty good condition that needs to have all of its electrolytics replaced because of their age. I does have 160 (and 11 meters also!). Good luck and Merry Christmas! 73, Charlie, K4OTV Hi Charlie, In the DX-100 there is already a big honking pair of bleeder resistors so that the bleeder is divided with one half across each half of the series pair. I think that's what you meant. The DX-100 originally had two caps rated at 450 volts in series and the bleeder set up that way. 73, Bill KU8H _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6938 - Release Date: 12/20/13 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: BOG antenna
Interesting timing Bruce! Last week I had noticed my NW/SE 2 wire Beverage acting funny, poor F/B in particular along with it being noisy. It turned out to be the ground rod clamp had loosened, the screws doing the clamping and holding the #12 wire were completely rusted. This rod had been in the ground about 23 years and had been used on a different single wire Beverage. In addition the rod was actually quite loose and the clamping itself rather corroded. Ive alternated over the years between soldering to the rod or clamping purely due to having one on hand or having to make a 15 mile round trip to HD. In this case the 2nd rod is soldered. The rod is a utility grade with no rust anywhere and with the clamp wire brushed, and SS hardware performance is as expected. Carl KM1H - Original Message - From: Bruce k...@myfairpoint.net To: topband@contesting.com Sent: Monday, November 18, 2013 12:59 PM Subject: Topband: BOG antenna My South-East 160 foot BOG antenna lost its reasonably wide band width. Suspected and replaced the termination resistor resulted in the same symptoms. Checked the BOG wire for a possible break and it was also OK. Connected a resistor across the BOG transformer, antenna side, and it was good. It was getting to be a head scratcher. Finally an ohmmeter check to the ground rod connection showed a high resistance. Cleaned the ground rod connection area, tightened the clamp, and soldered it. The BOG antenna is now working well again. Like most of us, when the width goes bad we look at the far end termination, but in the case surprisingly it was at the near end. I am not giving other details for naysayer discussion purposes. Posting this information only to possibly help others. 73 Bruce-K1FZ www.qsl.net/k1fz/beveragenotes.html _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3222/6346 - Release Date: 11/18/13 _ Topband Reflector
Re: Topband: NOISE CANCELLERS
Here is Toms review on the MFJ-1025 along with his modifications to improve it. After doing the mods and using it extensively Im totally happy with it used only on Beverages and BOG's and have no BCB problems. http://www.w8ji.com/mfj-1025_1026.htm The $330 I saved over the NCC-1 was better spent on other station needs. Carl KM1H - Original Message - From: Jon Zaimes AA1K j...@verizon.net To: Marcelo Chrispin marc...@ultracyber.com.br; topband@contesting.com Sent: Saturday, November 16, 2013 10:16 AM Subject: Re: Topband: NOISE CANCELLERS DX Engineering NCC-1 tops both. 73/Jon AA1K On 11/16/2013 8:49 AM, Marcelo Chrispin wrote: Good morning, Dears TopBanders I need some opinions, What is the best acquisition between Timewave ANC-4 or MFJ-1025? Thanks for help me! 73s Marcelo Chrispin - PY5MC _ Topband Reflector _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3222/6339 - Release Date: 11/15/13 _ Topband Reflector
Re: Topband: Homebrew capacitors
In the late 60's I made a coaxial capacitor from a length of RG-17 to supply most of the C for a 40M Bobtail. A little too big to fold and the losses were not even worth thinking about. On 160 with a decent coax what would be the effect of a little loss besides a little heat ? Carl KM1H - Original Message - From: Richard Karlquist rich...@karlquist.com To: topband@contesting.com Sent: Sunday, September 29, 2013 10:12 PM Subject: Re: Topband: Homebrew capacitors On 09/29/2013 07:42 PM, Jim GM wrote: Could have saved more money with a Piece of RF-9913 or RG8 coax cable about 25pF per foot plenty voltage rating. Only thing can some one please help me on this, do I connect the center conductor on one end of the cable and use the shield on the other end? Or just use the center conductor and shield on one end, while the other end are floating not used and not tied together? Neither. Instead fold the coax and connect to both ends in parallel. IOW, connect the center conductors in parallel and the shields in parallel. This will greatly reduce the loss due to the resistance of the conductors. Constructing a capacitor out of coax is a suboptimal topology, but folding it and connecting the ends in parallel at least mitigates the loss. Rick N6RK _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3222/6211 - Release Date: 09/30/13 _ Topband Reflector
Re: Topband: 5/8 wavelength vertical is mo bettathan shorterversions??
I would think a 5/8 would be good for the various 160 contests where a lot of contacts are short distances and the extended groundwave plus some power at 40 degrees could be useful. Wth 3 antennas, a 1/4 wave, a 5/8 or 1/2 wave and a horizontal cloud warmer or for DX ducting, would cover all bases. OTOH a 1/4 wave only a few hundred feet away could null some of the signal. Carl KM1H - Original Message - From: Charlie Cunningham charlie-cunning...@nc.rr.com To: 'Mike Waters' mikew...@gmail.com; 'topband' topband@contesting.com Sent: Thursday, September 26, 2013 11:11 AM Subject: Re: Topband: 5/8 wavelength vertical is mo bettathan shorterversions?? Quite a bit of the radiation from 5/8 wave verticals is at relatively high elevation angles - above 40 degrees elevation. (Perhaps useful for VHF mobiles that need to hit mountain top or hill-top repeaters) Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Thursday, September 26, 2013 10:53 AM To: topband Subject: Re: Topband: 5/8 wavelength vertical is mo betta than shorterversions?? A lot of hams on 160m have been similarly shocked. :-) 73, Mike www.w0btu.com On Thu, Sep 26, 2013 at 9:37 AM, Niko Cimbur ac...@yahoo.com wrote: We were shocked to find that the existing 1/4 wl performed better than the much taller [5/8 wave] Vertical. _ Topband Reflector _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3222/6200 - Release Date: 09/26/13 _ Topband Reflector
Re: Topband: WD1A wire
The last reel I bought was 2.5km for $40 plus about $20 shipping from Ohio about 3-4 years ago on Fleabay. It was listed strangely but I forget how; I believe I searched for military wire or something similar. I see some speculators peddling it at .10/ft Carl KM1H - Original Message - From: Larry Molitor w7...@yahoo.com To: topband@contesting.com Sent: Wednesday, August 28, 2013 3:32 PM Subject: Topband: WD1A wire Anyone know of a good source for WD1A field phone wire these days? Best I've found so far runs abut 60 bux shipped to WA for a 0.5 km spool. Thanks, Larry - W7IUV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3211/6115 - Release Date: 08/28/13 _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
It pretty much boils down to what frequencies you want to cover. To cover down to the 600M band and below use more turns and to go up to 30 or 20M the 2-3T at 50-75 Ohms does well. I use a VNA and 73-202 transformers to tweak what I want and the effect of interwinding capacitance can also be seen. Im also installing a few new reversibles for LF using more turns. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: James Rodenkirch rodenkirch_...@msn.com; topband topband@contesting.com Sent: Thursday, August 22, 2013 11:21 AM Subject: Re: Topband: Two 2:1 transformers to choose from!! P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on the low-Z primary for binocular cores. It might work, but there are other turns ratios you might try. Here is a list of turns ratios for those cores I made: http://www.w0btu.com/Binocular_core_turns_ratios.pdf If you get a 500 Server Error message, contact me directly and I'll e-mail it to you. 73, Mike www.w0btu.com On Wed, Aug 21, 2013 at 3:49 PM, James Rodenkirch rodenkirch_...@msn.comwrote: I received enuff info and thoughts to know I'll utilize the 5:7 winding version. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3211/6097 - Release Date: 08/21/13 _ Topband Reflector
Re: Topband: RX antenna transformer winding (pure resistancetransformation issues)
- Original Message - From: Tom W8JI w...@w8ji.com To: topband topband@contesting.com Sent: Tuesday, August 20, 2013 4:00 PM Subject: Re: Topband: RX antenna transformer winding (pure resistancetransformation issues) SNIP Unless you have a system with pretty high common mode impedances, winding spacing means nothing. ** Contrary to what you have stated elsewhere The primary reason I (and DXE) isolate windings with Teflon tubes is to reduce lighting damage, and to greatly reduce assembly damage. If the system has pretty high common mode impedances there might be some small advantage in pushing windings apart, but the primary-secondary capacitance is never going to be important in Beverages or other low or modest common mode impedance antennas. Balancing a small loop might be an issue. ** Common mode is an overworked response for perceived ailments. I took your low capacitance suggestions a step further after carefully measuring C and frequency response for maintaining high directivity and F/B. Many Topband operators use their Beverages above 2 MHz. I started using Teflon sleeves in windings because I ran out of small Teflon wire wrap wire I was using. Without Teflon on the wires, and with normal mag wire, the enamel was easily scratched. Not only that, lightning would punch through from enamel to core, or from wire to wire. ** Telon is easily nicked, the type of wire used in modern vehicles is very robust but with the sleeves plain ole magnet wire works well and allows even smaller winding bundles. Since I was more interested in performance rather than production problems I took the time to evaluate a large number of variations. Carl KM1H _ Topband Reflector
Re: Topband: Effect of trees
Its been shown on here and elsewhere, by many and many times, that once beyond a modest radial field the field strength goes up marginally to the classic 128. Ive stressed many times that a mesh screen out from the base 50' or so for 160 does more for the signal than going from 32-64 or 64 to 128 radials. It also stabilizes the all important maximum current area so that climate doesnt have much effect. Carl KM1H - Original Message - From: Robert Kavanagh 73rjk...@sympatico.ca To: topband@contesting.com Sent: Tuesday, August 06, 2013 1:32 PM Subject: Topband: Effect of trees But, Carl, there may be other variables changing in the system, for example, the amount of moisture in the ground. So it's not a controlled experiment. Bob VE3OSZ Every autumn (when the fluid is leaving the trees) and every spring (when the fluid is coming up again) I have to go out and adjust the phasing in my 2 el phased vertical for 160m. So some kind of effect does high trees have on the antenna. 73 SM6CPY _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6055 - Release Date: 08/06/13 _ Topband Reflector
Re: Topband: tree losses
I cant think of anyone claiming a tree is resonant on any particular frequency but that doesnt mean it cant be used as an antenna. Anyone disagreeing with that should discuss it with the military who have been loading trees for decades for emergency communications; in the 3-8MHz range if I remember and going back as far as the 50's. Read the old CQ and QST's. On another note I spent most of today outside doing tree trimming and other sweaty exercises. I noted that my best producing Bartlett pear tree was dead at the top and also a bit down on one side. Now it may be just coincidence but the 80M sloper passes about 5' from the farthest out branches and the end is exactly at the same height as the tree top. This antenna is used at the vintage gear bench and also on the one for amp repairs where Ive been hitting it rather hard this year with AM with serious carrier power; the most recent being an Alpha 77SX. I also remember wilting the top of a sugar maple about 20 years ago with 1200W on 6M to a 6/6 yagi array. After I moved the antenna to another tower the tree recovered the following year. Another coincidence? Carl KM1H - Original Message - From: Rudy Severns rseve...@gmail.com To: Topband topband@contesting.com Sent: Sunday, August 04, 2013 5:39 PM Subject: Topband: tree losses Tom's correct, the issue is not resonance but rather what, if anything, happens when you have a so-so conductor/insulator (a tree) in the near-field and/or further out. Do the losses matter? Performing a definitive set of experiments would be a serious undertaking. I've fiddled around a bit but not much more than the tree conductivity work mentioned earlier. At this point I'm an agnostic: we really don't have good data. There are a number of Vietnam era papers on trees as antennas and propagation through jungle but most of that was at frequencies well above 160m. Here's a challenge for experimenters that'll keep you busy and out of the bars. 73, Rudy N6LF _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6051 - Release Date: 08/04/13 _ Topband Reflector
Re: Topband: tree losses
Jim, it seems to be a difficult subject for those who want to make a huge case out of taking measurements as if this was a scientific undertaking requiring a decade of reviews, papers, and the usual academia way of wasting time. For the rest of us ancedotal evidence is often sufficient...if the tree or parts of it died coincidental with installing an antenna or increasing ERP then that is good enough IMO. Others can hire an arborist and a passle of investigators from the County Extension who just might take you to court along with a screaming horde of tree huggers demanding your scalp (-; Foliage induced attenuation without obvious damage is another subject all together. That will vary by the tree, climate, phase of the moon and when the dog last peed on it. And like the perennial discussion on groundseveryone has an opinion and different circumstances. Carl KM1H - Original Message - From: jim rogers jd...@bellsouth.net To: ZR z...@jeremy.mv.com Cc: Topband topband@contesting.com; Rudy Severns rseve...@gmail.com Sent: Monday, August 05, 2013 9:03 AM Subject: Re: Topband: tree losses Carl et al, Interesting, my 80M full size (66') sloper comes within about 5 ft of a dogwood tree and it is dying. The sloped is fed 8' AGL with 2 full size elevated radials and about 500w and the dogwood is dying from that height(8') to the top of the tree at about 15'. Unfortunately for me, my XYL pointed this out to me - not good. The sloper has been in that position for about 1 year, before that the tree was doing fine. Coincidence? Jim N4DU On 8/4/13 9:42 PM, ZR wrote: I cant think of anyone claiming a tree is resonant on any particular frequency but that doesnt mean it cant be used as an antenna. Anyone disagreeing with that should discuss it with the military who have been loading trees for decades for emergency communications; in the 3-8MHz range if I remember and going back as far as the 50's. Read the old CQ and QST's. On another note I spent most of today outside doing tree trimming and other sweaty exercises. I noted that my best producing Bartlett pear tree was dead at the top and also a bit down on one side. Now it may be just coincidence but the 80M sloper passes about 5' from the farthest out branches and the end is exactly at the same height as the tree top. This antenna is used at the vintage gear bench and also on the one for amp repairs where Ive been hitting it rather hard this year with AM with serious carrier power; the most recent being an Alpha 77SX. I also remember wilting the top of a sugar maple about 20 years ago with 1200W on 6M to a 6/6 yagi array. After I moved the antenna to another tower the tree recovered the following year. Another coincidence? Carl KM1H - Original Message - From: Rudy Severns rseve...@gmail.com To: Topband topband@contesting.com Sent: Sunday, August 04, 2013 5:39 PM Subject: Topband: tree losses Tom's correct, the issue is not resonance but rather what, if anything, happens when you have a so-so conductor/insulator (a tree) in the near-field and/or further out. Do the losses matter? Performing a definitive set of experiments would be a serious undertaking. I've fiddled around a bit but not much more than the tree conductivity work mentioned earlier. At this point I'm an agnostic: we really don't have good data. There are a number of Vietnam era papers on trees as antennas and propagation through jungle but most of that was at frequencies well above 160m. Here's a challenge for experimenters that'll keep you busy and out of the bars. 73, Rudy N6LF _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6051 - Release Date: 08/04/13 _ Topband Reflector _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6052 - Release Date: 08/05/13 _ Topband Reflector
Re: Topband: Radial wire in bulk
Check at the metal recyclers; Teflon insulated wire brings little money as scrap and is rather common where there is high tech and military contractors. Regular tinned copper and stranded PVC insulated is also common and around here magnet wire as used in motor shops is hard to find in any quantity on a regular basis. Sometimes Fleabay is good when shipped from close by. I got all my military telephone Beverage wire real cheap since its listing description was misleading, $25 for 2.5km was hard to take! Hamfests have always been good hunting during a poor economy. Carl - Original Message - From: AA8R - Notebook a...@aol.com To: topband@contesting.com Sent: Friday, July 26, 2013 9:33 AM Subject: Topband: Radial wire in bulk Hi all, Can anyone suggest a good online resource to purchase wire in bulk? I am in the process of laying down a radial system for a 160m Inverted L. Randy, AA8R _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6027 - Release Date: 07/28/13 _ Topband Reflector
Re: Topband: 160M Rhombics
When I was floating around in the Med for the USN in the early 60's, the bases I visited were all using rhombics pointed at DC mounted on 80-120' wooden poles. These consistently outperformed a 20M 6 el Telrex at similar heights at the ham station into the same area. The arguments were going on strong even way back then and hams often had times they could use the rhombics and run tests with buddies at the ham station a mile or so away. The sites I regularly stopped at were Rota, Rhodes, just S of Athens, and Libya. For the guy who has the land and wants to own 20-10M in one or two directions for his daily chats, a rhombic will cost a lot less than a rotating tower with stacked yagis for each band. Also consider what seems like a very narrow beamwidth at the antenna can cover a lot of the planet by the time it reaches its antipode. With 2 rhombics and some relays to switch termination points a mighty potent signal can cover a lot in 4 directions. This is no more space than a decent Beverage farm. A rhombic isnt very practical on the lower bands for most hams as that link shows but for 20-10 it can be very effective. Carl KM1H If we want an antenna just for looks, might as well make it all out of a non-conductor such as plastic rope. :-) Seriously, Tom is right. Take time to study his rhombic page. However, as one wise man once told me, Time spent doing something you enjoy is not wasted time. Putting up a rhombic might also be a good learning experience. But you better make sure that you aim it right where you need it. 73, Mike www.w0btu.com On Fri, Jul 26, 2013 at 12:33 PM, Jeff Blaine j...@ac0c.com wrote: Why? The same reason guys put up quads. They LOOK very cool! Imagine standing on one end of the rhombic and saying well, you can't see the end of the antenna without the binoculars - but it's out that-way somewhere. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6022 - Release Date: 07/26/13 _ Topband Reflector
Re: Topband: 160M Rhombics
It still boils down to location and propagation. Nobody is King all the time and some hams have real jobs that keep them away during some important openings. Charlie had a very modest and average location and was near the top of DXCC even before he put up a yagi. Maybe one of those places rumored to exist where the magic lines of force happens. Dean, as N6BV/1, also modeled my QTH for the original TA program that was part of the K6STI AO/YO package. You might want to check it out. I make no particular claims but contest results during the stations active days as well as the ease I worked DX on any band support Deans analysis. He started the program to see why I consistently beat him during the many times our paths crossed. He was on another hilltop about 15 miles away and we were LOS. I felt it was my homebrew stacked monobanders versus his 4 high stack of TH-7's but he showed it was the location. Contesting became boring and the stacks were scaled down to single antennas and I get on when I feel like it and no longer driven. BTW, I worked W3CRA Thursday on 40M AM, it is now the Collins Radio Association often on daily with W3ST operating. Carl KM1H - Original Message - From: Bill Tippett btipp...@alum.mit.edu To: topband@contesting.com Sent: Saturday, July 27, 2013 6:23 AM Subject: Re: Topband: 160M Rhombics W0BTU: For whatever reason, there's what seems to be a lot of hype about W6AM's rhombics. Such as: The W6AM station was legendary around the world. Don could beat you in a pileup for some obscure African station no matter what band, and even if you were on the east coast. And him in Southern California. Don was #1 on ARRL's DXCC Honor Roll, and you didn't argue. No matter where you were, no matter what you were running, Don had beaten you in a pileup. More than once. Beat anyone on the east coast to Europe from California every time? I'm sorry, but a rhombic is just not that good, even if you DO have one pointed at every direction of the compass as W6AM did. Absolutely a lot hype, as you stated. The real King of the Hill in those days was Frank Lucas W3CRA: Gus Browning, W4BPD wrote (from Ahoy Aldabra! article in February 1964 CQ Magazine): After staying up for the long path opening to the U. S. which was 4:00 AM local time, I intended sleeping on a small bunk at the rear of the boat. After lying down for a while and wondering about the 5-9 plus 20 db signal that signs W3CRA when all the others on the band are S7, I came to the conclusion that Frank must have the world's best QTH. When the band is dead he's always S7 and when the W-boys are S7 Frank is always over S9. This just isn't once in a while, it's an every day occurrence. Frank did this with a single 3 element homebrew Yagi but his secret was location, location, location; as this webpage explains. http://users.vnet.net/btippett/w3cra.htm W6AM at the top of the Honor Roll? More hype. Charlie Mellen W1FH in Boston ran a simple 3 element Yagi and had 311/337 (current/cumulative including deleted) when W6AM was at 307/332 in November 1964. Here's the *complete* DXCC Honor Roll listing: http://users.vnet.net/btippett/dxcc_honor_roll.htm W6AM may have closed the gap for current entitiess in later years but W1FH was one of very few to work W6ODD/CR8 from Damao/Diu in 1948, which W6AM missed. W1FH was the first post-war DXCC holder and W3CRA was the first pre-war DXCC holder. Frank apparently quit submitting cards for the post-war award but he was very much King of the Hill signal-wise as W4BPD verified above. http://oldqslcards.com/W1FH.pdf http://hamgallery.com/qsl/deleted/Damao_Diu/w6odd.htm Just to keep this from being totally off-topic, note the many Topband DXers at the bottom of the DXCC page above. 73, Bill W4ZV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6024 - Release Date: 07/26/13 _ Topband Reflector
Re: Topband: Lightning QRN season?
I would think that with optimized F/R for your Beverages that at least one path would be somewhat quiet. I was on 160 AM for a few hours last eve and QSO's out to 300-450 miles was good copy with stations at the 100W level at both ends. Northern Maine, Buffalo, WPA, and others were worked with the 1949 Viking I at 100W and also 1949 era HQ-129X with the 180' high inverted V. Reports using the vertical were weaker and with a lot of deep QSB except for the stations out to 50 miles or so. With a good part of SA being to the S/SE from here Ive heard the occassional LU, PY, etc on CW while keeping enough of the SW and W T storm static at bay. Cranking in the selectivity further improves the SNR. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Tuesday, July 23, 2013 10:03 PM Subject: Re: Topband: Lightning QRN season? I appreciate the replies and insight. Let me add some details I should have included in my original question. What I really wanted to know was, When do you think that QRN might let up a little, to the point when we might expect to have a relatively quiet night here and there? So far, we have gone many weeks with not one single evening of quiet, making DX --and most good stations on the east and west coast-- all but impossible to hear over the lightning crashes. Beverages _at both ends of the path_ helps, but that's not often the situation lately. I haven't listened on 160 every night, but ever since sometime in May (I forget exactly) I have been daily checking the Intellicast real-time lightning map at www.intellicast.com/Storm/Severe/Lightning.aspx . And there has not been a single evening on 160 since then when there was not a lot of lightning over the continental USA. I did manage to have some SSB ragchews late last night with some very strong stations in the Midwest, but the QRN never dropped below S9 even though the lightning was some distance away. 73, Mike www.w0btu.com On 7/23/2013 12:26 AM, Mike Waters wrote: Anyone have a guesstimate as to when the QRN will begin letting up a little on 160? _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3204/6014 - Release Date: 07/23/13 _ Topband Reflector
Re: Topband: Topband Inv-L Joy
On a side note WD-1A conductors are a copper/cadmium alloy; whatever that means in RF resistance. Fine for a Beverage but what is the loss? Carl KM1H - Original Message - From: Gary Smith g...@ka1j.com To: topband@contesting.com Sent: Thursday, July 25, 2013 1:22 AM Subject: Re: Topband: Topband Inv-L Joy Had a more difficult time getting the antenna up there this time. The first spud snapped away from the fishing line in the dense thicket I was unable to find where it landed. Had to make another the mosquitos were so thick they posted a LUAU sign on my forehead. Till I get something better I retrieved my WD-1A military field phone wire that was left out in the marsh as my old beverage wire. and after a comedy of errors I finally got the antenna up. I was earlier getting a SWR of 1.1 on 160 before and now am getting 1.1 on 1.74365 MHZ 1.74365mhz R=51 X= 6,7,8 swr 1.1 At the desired frequency to match the antenna I've aimed for 1.8MHZ here's the information I was able to get at my desired frequency: 1.8025 mhZ Coax loss 6.3db C=4193 XC=21 L=1.970 X1=21 r=41 x=21 swr 1.6 So this is what the antenna is giving me at this moment. I need to get back down and add the broken wire to the radial bed and I should also trim some length to bring my values to 1.1 at 1.025MHz. Given the info above from the MFJ 259B any idea how much I might nibble off and more, is there anything in this info that tells me I should look to do anything differently? Hopefully the coax loss will be mitigated by a friend bringing me 350' of hardline. Can't wait! Thanks, Gary KA1J _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3209/6019 - Release Date: 07/25/13 _ Topband Reflector
Re: Topband: Desktop Power Supply Brand/Noise Question
On 7/21/2013 8:49 AM, Tom W8JI wrote: I can't understand why throwing some ferrite beads at a problem, or changing the supply, are the only two solutions. Many times, if not most times, a few .01 uF line voltage rated bypass capacitors are significantly better than a sting of cores, or a winding through cores. Yes, IF the problem is differential-mode coupling to the power line. But often it is NOT -- Bypass capacitors will cure common mode also, because common mode cannot be generated without differential mode someplace in the system between two points. In virtually every situation, the power supply is in a metal box. The trash is between the power line leads, and also between those leads and the case. This is the nature of switching supplies, because they tie a chopper with squarewaves across the power mains, and the system is not well balanced. As a general rule the stuff exiting the dc side is much less problematic. If it is problematic, it needs cleaned up. Bypassing to the cabinet, groundplane, or case fixes or greatly assists in fixing it, too. If a line is properly bypassed to the case, the system can't produce much common mode or differential mode on that particular line. In the rarer case, where two or more lines are involved, they all must be suitably bypassed. The same things that work for lightning protection work for RFI issues, and vice versa. Payback for doing things right, rather than just tossing beads at wires, is much wider than the initial target. 73 Tom I certainly agree about not throwing ferrite at problem without understanding why. My introduction to serious line and computer noise was after moving here in 89 and I remembred a QST article by DeMaw a few years earlier where he introduced a differential mode noise filter using ferrite rods and caps in a pi filter. The line was noisy and I had just put my Commodore 64 out to pasture to be replaced on the new fangled DX Packet Cluster by a 386-33 PC with 12 monochrome monitor. It was soon also used for various DOS RF and other programs, Windoze 3.1 and a long learning curve. I built DeMaws circuit in a couple of outlet strips and used them for the PC and the TS-940's which were all on seperate circuits. Most of the noise was gone and using toroids on the keyboard and monitor cables took care of the rest. This was before ferrites were included from the factory. About 2-3 years ago when I took an interest in the LF frequencies I realized that DeMaws circuit wasnt effective down there and rebuilt the filters into 2 stage affairs with a 100KHz cutoff. There are now 6 PC's in the house and each got its own filter as well as the modern and boatanchor operating desks. A new level of quiet appeared as if by magic by attacking the differential noise first. Any remaining annoyances were locally radiated coming in via various antennas (including portable radio loopsticks and whips) which was eliminated by a lot of large 43 and then 31 toroids on power cords, router cables and some feedlines. With a couple of Beverages moved another 600-700' away back in the woods and feeding a new switch box and its own 1/2 CATV hardline run back to the house, even neighbors noise is mostly tolerable with noneso faron any good DX frequencies. Carl KM1H _ Topband Reflector
Re: Topband: My Turn For a Brain Pick - Sanity Check
On 6/12/2013 3:34 PM, Tom W8JI wrote: I can't think of a reason to pick 90 degrees as a target value, unless it is a system designed to protect something on groundwave that happens to be straight in line with the elements. I agree. For me, the primary design objectives are maximizing forward gain, beamwidth, and gain bandwidth. I don't care about F/B. 73, Jim K9YC Ditto as Ive already mentioned as F/R isnt useful to me since I have several receiving antennas. Gain variation with reasonable lengths of coax are miniscule and its not being wasted in a hybrid either. Carl KM1H All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: BOG antenna
Same here for about 3-4 years now with the first one I tested. OTOH its down quite a bit on the real low angle signals. Experimenting with a 2 wire and maybe some phasing. Carl KM1H Noticed many storms have caused rain static on every ham antenna except my BOG. The BOG was very quiet and hearing stations in its normal manner.. I did hear a slight trace of something in there, one time when the noise was screaming on other antennas. Another local 160 meter DXer reported similar reception on his BOG. Wonder how many others have observed the same? Thanks in advance, 73 Bruce-K1FZ www.qsl.net/k1fz/bogantennanotes/index.html All good topband ops know how to put up a beverage at night. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3199/5902 - Release Date: 06/11/13 All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Shunt fed tower plus Marconi vertical phasing on 160and80?
It is more cookie cutter to use series fed quarter wave elements with current feed (95% of people still do that wrong), but if you have a little patience and don't mind experimentation, you could certainly make it work. I phased dissimilar elements many times over the years, with the grossest mismatch a T phased against a shunt fed tower. All it takes is parts and patience. :-) 73 Tom Since it is very hard to lose gain with any halfway decent 2 vertical system and many also use directive receiving antennas there is no real need to build the best phasing network. In those cases a basic coax phasing network works as well as spending gobs of money and/or dumping power in a dummy load. Carl KM1H All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Magnetic Loops
Your forgetting that the front end is still broadband and wide open and being blasted into intermod many times. These days not everyone is blessed by the latest gigabuck rig which still is wide open until it hits the roofing filter which wouldnt be there if there werent problems. My first experience was with a modified R4C in the early 80's which at least had a front end tuneable preselector. Ive since used it with the various xcvrs here and easily hear the difference plus it can be tuned either side of the wanted signal. Does wonders for BCB rejection also. Carl KM1H Actually a properly designed purpose built loop can offer a reduction in noise from the high Q selectivity offered. That would only be true if the receiver system noise bandwidth was wider than the loop's bandwidth. If you had a SkyBuddy with 30 kHz noise BW and put a 5 kHz wide loop in front, then you would have a noise BW limited by the loop. The only way antenna BW reduces noise is if the receiver is overloading from out-of-band signals, or the receiver's ulitmate selectivity is wider than the loop antenna. While an SX99 or something that terrible might benefit with a high Q loop, even an SX101 would not. All good topband ops know how to put up a beverage at night. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3184/5862 - Release Date: 05/27/13 All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Thanks!
Are you now claiming that the thousands of bead choke baluns in use for decades at HF and 6M dont work? I suspect that those who have been happy with the results in mimizing feedline radiation would heartily disagree Carl KM1H - Original Message - From: Jim Brown j...@audiosystemsgroup.com To: topband@contesting.com Sent: Tuesday, May 21, 2013 11:58 AM Subject: Re: Topband: Thanks! On 5/18/2013 10:35 AM, Charlie Cunningham wrote: If you get the larger beads/tubes thatwill fit over RG-213 etc. you can make excellent 1:1 current baluns by slipping them over the cable before putting the connector on. These are not excellent 1:1 current baluns below about 75 MHz. Below that range, they are a lousy common mode choke, because they are inductive. Inductive chokes resonate with a line that is capacitive, so they actually increase the current. A line shorter than a quarter wave is capacitive; so is a line between a half wave and 3/4 wave. And so on. That's why we want a choke that is highly resistive -- the resistive component always reduces common mode current, which is the objective of a common mode choke (the so-called current balun.) There's an extensive discussion of this in my RFI tutorial, and also in the Coax Chokes power point (which is a pdf). On my website. k9yc.com/publish.htm 73, Jim K9YC All good topband ops know how to put up a beverage at night. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3162/5843 - Release Date: 05/21/13 All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Thanks!
On 5/21/2013 1:18 PM, ZR wrote: Are you now claiming that the thousands of bead choke baluns in use for decades at HF and 6M dont work? I have published extensively on this, first in 2005 in a peer reviewed AES paper, and later in my RFI tutorial. All of this work is on my website. W1HIS published his work on this in 2006. A few years ago, an engineering supervisor at CIA sent me work from an US Army research group prepared in the 70s reaching the same conclusions as I had. And literature searches for my AES paper found references (in a European ferrite manufacturer's applications notes) to the importance of resistance in chokes as far back as the 50s. You didnt answer the question and anybody can write papers and create a website with a lot of readily available data plus new items that isnt open to peer review. Ive also mentioned to you and others several times over the years of my actual involvement with the CIA/DOD Tempest program. There were contributors nationwide, companies and individuals, that all created the results that you appear to have discovered later. I suspect that those who have been happy with the results in mimizing feedline radiation would heartily disagree Many people believe many things that are not true. That is a typical response to criticism or simply asking a question. It serves no useful purpose altho it is rather common on Topband. Many false beliefs are based on a grain of truth. The generalized assumption in ham literature has been that 500 ohms choking Z is sufficient to prevent pattern distortion caused by feedline radiation, but W1HIS showed that increasing choking Z to the range of 5,000 ohms can significantly reduce receive noise. More nonsense as well over 1000 Ohms, was recognized by the late 70's among the serious contesters. While this is Topband, ferrite use isnt limited to it and you show broadband graphs. My own Mosely TA-33 kits did wonders to stop feedline radiation and were soon popular with Hy Gain, KLM and others. When I saw his paper, I immediately tried multi-turn chokes on an antenna that was picking up a lot of noise. The choke reduced the noise by nearly 10 dB. Since I published my work, hundreds of hams have told me they have had similar results. I thought it was you or maybe Tom that belittled that paper 73, Jim K9YC In any case 43 mix large beads and 2.4 toroids did well until 31 came along and it still has its benefits. Has anyone asked Fair-Rite about producing the 2.4 and large beads in 73 mix? The following older paper with update should be read by all considering the authors 35 year involvement with Fair-Rite. Dont be surprised if some of the data and text is already familiar.. http://www.incompliancemag.com/index.php?option=com_contentview=articleid=739:using-ferrites-to-suppress-emicatid=26:designItemid=130 Carl KM1H Topband operators do not require adult beverages, just wire ones. All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: 160 and 80 meter QRN prediction
Now you have to use it up the band on AM where there are still plenty of 833's in use. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Sunday, May 12, 2013 10:44 PM Subject: Re: Topband: 160 and 80 meter QRN prediction Well, mine's not much to look at. I sort of designed it as I was building it, using junk parts that I had on hand. And there's things I should have done differently. A short explanation is at http://www.w0btu.com/833C_linear_amplifier.html . There's no complete schematic. It's not completed yet. I'm just having fun using it as is right now. And we're certainly looking forward to the 160 DX season! http://www.w0btu.com/files/misc/833C_linear_amplifier/?C=M;O=D has other photos from different stages of building it. 73, Mike www.w0btu.com On Sun, May 12, 2013 at 9:21 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: Wow!! That takes me back! Haven't seen an 833 amp since I was young!! Charlie, K4OTV All good topband ops know how to put up a beverage at night. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3162/5818 - Release Date: 05/12/13 All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Problem with compression F connectors on Quad RG-6
Im another who has been using the RF Industries tool for well over 20 years for both 50 Ohm and mostly CATV or Belden RG-11 foam. No failures or funny things happening. Carl KM1H Mike, Here's a link to an article on crimp UHF connectors with suppliers. It's from 2008 so the prices may have changed: http://www.eham.net/articles/19257 Today, you can get a crimp tool from a number of suppliers ranging from the low $30s and up. I have been using RF Industries UHF Crimp connectors with RG213 and LMR400 for years with excellent results. Make sure you have the correct connector for the coax you are using. I always solder the center conductor in the connector rather than crimping it. No more connector problems, no shorts or melted dielectric, etc. and much faster and easier to get it right. W3LPL and others have mentioned many times that the extra cost of the connectors is small compared to the cost of the entire installation and is worth it to reduce or eliminate a common point of failure. Les W2LK On 5/8/2013 6:16 PM, Michael Tope wrote: On 5/7/2013 7:55 PM, Tom W8JI wrote: LMR400 or any cable, in sensitive applications, requires a solid bond to the shield that carries the vast majority of return current. In the case of almost all cables on HF and higher, that is the innermost foil. Of course it is different at audio or lower frequencies. One common connector problem comes from not forcing the woven shield tight against the foil at the connector, or having the foil or woven shield tarnish or corrode. The path to the inside of the foil is out on the braid to an eventual contact point, then back on the outside of the foil to the foil edge. At the edge current can go inside. This is like adding 2X the length of the path to the connection point in overall shield connection path length. (Current can also get in across the edge of a longitudinal seam, if the seam's overlap is insulated. The problem with that is the seam can kill UHF performance.) If you solder to the shield of LMR400, and put it on a network analyzer and measure the stub characteristics, many times (not always) it will move around as the cable is flexed. This is because the soldering heat contracts the dielectric, releasing pressure between the braid overlay and the foil. Now you have a crummy connection that changes electrical length of the connection to the real shield. Even if you do things right, once the foil and braid develop an oxide layer the connection goes away. This can work its way out for several feet of cable length, really messing up a cable. This will not show with a single shield. Cables with foil have to be installed and treated correctly. The more layers you add, the more careful we must be. Since the extra layers are pretty much meaningless, the best practice is to avoid them. Use a good shield against the center and connect to it at the connector. Tom, I'll have to admit that I haven't given this much thought, but what you are saying about the foil to braid contact makes perfect sense. I do recall one friend who is a rabid VHF/UHF repeater builder complaining that LMR-400 has issues with IMD. Perhaps this is why. Can you recommend a source for a good LMR-400 crimp connectors and the corresponding installation tools? To date I've been soldering PL-259s on all the LMR-400 I've used as if it were regular single shield RG8. I haven't had any hard failures, but clearly there is some risk to doing this depending on the application. In fact I do recall some phantom inter-station QRM that would come and go when we had an SO2R setup running at W6UE some years back. Some of the coax used in that setup was LMR-400 with soldered PL-259s. 73, Mike W4EF. All good topband ops know how to put up a beverage at night. _ Topband Reflector All good topband ops know how to put up a beverage at night. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3162/5810 - Release Date: 05/09/13 All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Wall warts
On 2013-05-08, at 10:40 AM, John Harden, D.M.D. wrote: I am not offended at all relative to the fine whiskey deal. To begin with I'm too busy to worry about trivia such as that. I agree, John---there's nothing at all wrong with a fine whiskey, anyway...! If that's not some PC kop's thing, then he / she should mentally superimpose the words ...re-constituted septic sludge in place of whiskey, then get on with his / her life...such as it is. ~73~ de Eddy VE3CUI - VE3XZ After listening to some of the 160M operating antics it must be a common beverage for some Im far from PC but dont think having whisky lauded is a good thing especially for newcomers to see. Anyway Im glad it is gone. Carl KM1H All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: fine whiskey is a daylight beverage
How about replacing it with nothing! I find the current one offensive and dont think any forced signature is warranted. Carl KM1H - Original Message - From: Rick Stealey rstea...@hotmail.com To: topband@contesting.com Sent: Tuesday, May 07, 2013 10:55 AM Subject: Topband: fine whiskey is a daylight beverage fine whiskey is a daylight beverage is appended to the end of each posting. At first I thought it was the personal signature file of the individual poster but it is on everyone's posting. It was kind of cute the first time I saw it But ok, I get the point. How about replacing it with (could rotate messages periodically) - Big antennas work better DX is better after midnight More watts equals more S/N QRP is for 10 meters or my favorite ... Rick K2XT All good topband ops know fine whiskey is a daylight beverage. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3162/5805 - Release Date: 05/07/13 All good topband ops know fine whiskey is a daylight beverage. _ Topband Reflector
Re: Topband: Wall warts
- Original Message - I dont care for forced signatures...period. Just more useless bandwidth to be erased when replying so as to not aggravate you with untrimmed messages. Carl The fine whiskey signature has been there for a long time. I am surprised this has become an issue. It was suggested by one of the members of this list and I thought it was funny and appropriate and not the least bit offensive., I have changed it now to something that uses many of the same words - but hopefully is not the least bit offensive to anyone. Tree On Tue, May 7, 2013 at 12:17 PM, Wes Attaway (N5WA) wesatta...@bellsouth.net wrote: This has nothing to do with wall warts. I am just testing to see where that fine whiskey signature is coming from. - Wes Attaway (N5WA) --- 1138 Waters Edge Circle, Shreveport, LA 71106 318-797-4972 (Office) - 318-393-3289 (Cell) Computer Consulting and Forensics -- EnCase Certified Examiner --- All good topband ops know how to put up a beverage at night. _ Topband Reflector All good topband ops know how to put up a beverage at night. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3162/5805 - Release Date: 05/07/13 All good topband ops know how to put up a beverage at night. _ Topband Reflector
Re: Topband: Problem with compression F connectors on Quad RG-6
How about folding the shields back a little? I think that's a superior way of doing it as opposed to cutting them all flush with the jacket. Be careful doing that or using any non-approved assembly method, or using improper connectors. Many cables (I'm not sure exactly what percentage, but I saw a lot of them) aluminize mylar to form the foil shield. You can usually see the mylar on close inspection, it often is blue or a blue tint. This insulates one side of the foil. The shield that must have the best integrity at connectors is the shield just outside to the center conductor. Nearly all shield current in on the inside of that shield. If you do not get a good solid connection to the INSIDE wall of that shield, the cable will have all sorts of issues. It doesn't matter how solid outside shield connections are, because the innermost surface of the innermost shield does all of the real work. The inner wall connection can be, and usually is, by conduction across the cut end of the shield. Say the inner shield is mylar on the dielectric side, or bonded to the dielectric. The bare outside contacts the braid with pressure. The current just travels across the cut end edge (a very short path) to the inside of the inner shield. If you do something to miss that good solid end connection to the inner foil edge, like folding a mylar shield over so blue side is out, the connection is by stray coupling over what can be a pretty long length of cable, adding many feet to the shield connection path.Or you might have no connection at all. I generally avoid quad shield, because the extra layers are unnecessary and can often cause connection problems. This is especially true outside with lightning and age. I asked a question here some months ago about whether or not that should be done or not on my flooded quad-shield F-6 (the CATV alum. shield version of RG-6) that I use for my Beverages and to feed my inverted-L. Some people said absolutely not! and others said absolutely they should!. People do all sorts of strange things with shields. With copper braid, aluminum braid, or solid aluminum foil (not aluminized mylar) you can do almost anything at HF and get away with it. I see people fold the shield back over RG-8 and screw the connector over it! Just because it works in some cases, that doesn't mean it is a good idea. One cable that is really misused is LMR400. If you solder to the braid on LMR400, you set yourself up for shield connection problems. This is because the inner foil, and that is the real shield, often moves away from the braid and makes a sloppy connection. Sometimes wiggling the cable will make the electrical length of the cable change, and shield integrity is all over the place, when the cable is soldered. This generally won't hurt with dipoles, but it can with critical applications. Crimps actually make a better connection. Since folding them back is the only way of being sure that the braids are all making contact with the shell of the F connector, I now fold the shields back a little in my snap-and-seal F connectors. How can that hurt anything? I think it's a better way to do it. I would always use the correct connector, and install the connectors the way the connector and cable manufacturer say. They usually know more about their products than we do. :-) It is a bad idea to improve installation instructions without understanding the product in precise detail. How many people do you think understand the issue caused by overlaying a foil shield with braid, and soldering to the braid? 73 Tom CATV installers use almost 100% quad shield in order to keep the signals inside and not cause interfering leakage (egress); FCC specs are adamant about that. These specs go back to the 70's. In more recent years the cable also must keep local RFI (ingress) out. For topband Id suspect that the foil thickness is so thin that some skin depth currents are on the outside. The foil is BONDED to the foam dielectric and is not supposed to be folded back; I dont know where that misinformation originated. Id suggest actually reading the connector manufacturers and major installation professionals cable prep instructions and all the ones Ive seen specifically states to NOT fold back that foil. For QS the outer braid is folded back, the next layer is the outer foil and that is removed, and then the inner braid is folded back. The inner foil goes thru the connector tube and both braids go between the outer and inner tubes. Carl KM1H All good topband ops know fine whiskey is a daylight beverage. _ Topband Reflector
Re: Topband: RG-6 coax
- Original Message - From: Jim Brown j...@audiosystemsgroup.com To: topband@contesting.com Sent: Wednesday, April 10, 2013 12:49 PM Subject: Re: Topband: RG-6 coax On 4/9/2013 9:19 PM, donov...@starpower.net wrote: CCS RG-6 may be a problem for powering some remote devices such as preamps or relays through the cable because CCS RG-6 has significantly more DC resistance than SC RG-6. If you can find a proper (that is, complete) technical data sheet for whatever coax you are considering, it will include values for the DC resistance of the center conductor and the shield. Likewise, a proper technical data sheet for a remote device should include the DC current and the minimum voltage needed at the remote device for it to work reliably. Having this data, and the length of the coax, it's a simple matter to predict whether the cable resistance will be a problem. It's important to remember that the center conductor is not the only issue -- MOST RG6 coax is designed for use at VHF and UHF by cable TV systems, and their shields are optimized for use at those frequencies. The foil + braid shields of these cables tend to be relatively thin, so their DC resistance tends to be fairly high. I don't worry a lot about RF loss in RX antennas for topband and 80/40M, but I do worry about shield resistance, because high shield resistance (at the frequency of interest) degrades shielding. ALL CATV coax is designed for performance down to 5MHz as data, signaling and other narrow band applications operate below the TV channels. Many towns and cities have all their computers linked, traffic control, alarms and more on cable these days. The only real test of a cable is to terminate it at its characteristic impedance, insert a swept high level signal and then walk it with a sniffer such as CATV field crews use. Terminating and listening on a receiver is acceptable if all you are interested in is a narrow range of fairly low signal strengths. Carl KM1H All good topband ops know fine whiskey is a daylight beverage. _ Topband Reflector
Re: Topband: ALUMINUM
I use CATV hardline everywhere here and have had some left over bare coils on the ground for the 24 years Ive been here. Except for staining from leaves, etc it is still fine appearing. The ground is mostly leaves, twigs and pine needles. The bare cable CATV runs in this town have been up even longer and Ive been told by installers the operational life is expected to be 25 years or longer, unless it is subject to physical damage of course which is SOP from storms. Carl KM1H - Original Message - From: Hardy Landskov n...@cox.net To: Bob Kirkeby wb0...@gmail.com; Mike Greenway k...@bellsouth.net Cc: TOPBAND TOPBAND@contesting.com Sent: Friday, March 08, 2013 2:24 PM Subject: Re: Topband: ALUMINUM Bob, I had the same experience. I was using bare 75 ohm TV hardline as a matching section on my 160 Delta loop and it was partially buried. But after 2 years, the outer jacket was almost gone when I had to dig it up. My soil is just regular sandy dirt. So my advice to anyone that wants to bury aluminum cable or wire is make sure it is insulated or jacketed. 73 Hardy N7RT Phoenix - Original Message - From: Bob Kirkeby wb0...@gmail.com To: Mike Greenway k...@bellsouth.net Cc: TOPBAND TOPBAND@contesting.com Sent: Thursday, March 07, 2013 10:24 AM Subject: Re: Topband: ALUMINUM I have used solid #10 aluminum as radials buried 6 in alkaline soil. It became badly corroded in 2 years; nearly disintegrated in spots. Not saying it wouldn't be fine in other soils. 73 Bob WBØDSF On Wed, Mar 6, 2013 at 6:31 PM, Mike Greenway k...@bellsouth.net wrote: From some feedback on the aluminum coated steel, I am thinking about trying some regular aluminum, 14 gauge. Anyone got a downside to this? Price, weight, conductivity are good and little if any stretch. I will use aluminum screws and nuts on the end terminations with No Ox. 73 Mike K4PI _ Topband Reflector _ Topband Reflector _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5659 - Release Date: 03/09/13 _ Topband Reflector
Re: Topband: Elevated Radials EPILOGUE
ON4UN's series of books have always had way too many individual assumptions and we all know what happens then. Those books offer a place to start and then apply your own unique soil and local conditions and change as needed. Carl KM1H - Original Message - From: Buck wh7dx wh...@hawaii.rr.com To: topband@contesting.com Sent: Wednesday, March 06, 2013 3:42 PM Subject: Re: Topband: Elevated Radials EPILOGUE There is some good stuff in ON4UN Low Band Book - Chapter 9-10 on Elevated Radials. He suggests that an elevated system would be even better above ground versus on the ground in poor conditions. References 0.1 wave height or less. For 160m that could be 50 feet down. In Section 2.2.7 K3LC says that there is no point in raising radials any higher than 6 meters on 160 or 3 meters on 80 meters. Such a height would be between 0.2db of what can be achieved with 64 buried radials... N7CL says they need to be higher The perfect on ground system might be 50-100 1/4 wave ground radials... In 2.1.2 he warns of trusting modeling because of outside factors. 9-12 Figure 9-18 (modeling) regarding 160m gain using 1/4 wave is interesting over average ground. If you wanted max. it suggests using 120 - 80meter radials. But the difference between 120 (1.5 dbi gain) and going with 32 (1.0 dbi gain) would make one wonder if it was really worth it for another 1-2 miles of wire.. work? 0.5 dbi gain? The Conclusion in 9-14 is interesting.. basically saying.. Take the example of an 80-meter vertical over average ground: going from a lousy eight 20-meter long radials to 120 radials would only buy you 1.4db of gain, which is less than what I think it is in reality. In very good ground that difference wold be only 0.7 db! 2.1.3.2 - From these almost 70-year old studies, we can conclude that 60 quarter-wave long radials is a cost effective optimal solution for amateur purposes. K3NA's work in 2.3.1.3 talks about using 1/16 wave radials.. not going beyond 48.. but that doesn't match up with N6BV's work several years prior. In 2.2 Elevated Radial and beyond it's gets really interesting and less conclusive? The Conclusion States - If you want to play it extra safe, and if you have the tower height, get the radials up as high as possible and add a few more. Use a ground screen if you have it. It all is very logical. Get away from the lossy ground or hide the lossy ground with a dense screen using many radials. No free lunch!. This was one book and it goes on. All of this sounds like a great episode for Ham Radio Myth Busters... 73, Bryan WH7DX [CONFIDENTIALITY AND PRIVACY NOTICE] Information transmitted by this email is proprietary to Mr. Mrs. B and is intended for use only by the individual or entity to which it is addressed, or where ever the hell it ends up, and will almost certainly contain information that will offend a large portion of the population, which isn't our concern. If you are not the intended lucky recipient, or it appears that this mail has been forwarded to you without the proper authority of the Wizard of Email or Al Gore, you are notified that any thought, use, or consumption of this email is entirely your choice. In such case, Bon AppetitNote: A $.02 Internet Tax was charged for receiving this email and all funds were given to some family somewhere in America or the U.N Have a nice day. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5652 - Release Date: 03/06/13 _ Topband Reflector
Re: Topband: Elevated Radials
Since the radial field for any height vertical has equal importance the only way to get 1/4 wave efficiency is to have zero RF loss in the loading coil and matching network. Cryogenics anyone? There is no magic wire minimalist radial or counterpoise that accomplishes that. All they provide is some improvement over a poor on ground radial attempt; I wont call it a radial system. Carl KM1H - Original Message - From: Rick Karlquist rich...@karlquist.com To: topband@contesting.com Sent: Tuesday, March 05, 2013 8:42 PM Subject: Re: Topband: Elevated Radials One of the problems with discussing this topic is that nearly all studies of radials deal with 1/4 wave verticals. Most ham stations including mine don't have the luxury of a height of 130 feet. There are many cases where some novel grounding scheme is touted as just as good as 120 radials and indeed it may be for the 1/4 wave height case. What is scarce is advice for the owner of a short vertical as to what to do about grounding. What grounding scheme would it take to make the proverbial 43 foot vertical play as good as a 130 foot vertical? Whatever that scheme is, we know that it will have very narrow bandwidth. This is a good litmus test to separate short vertical installations worthy of additional testing from low efficiency ones. Of course, narrow bandwidth is merely necessary, but not sufficient, to prove high efficiency. The advantage of the bandwidth criterion is that it is easily and unambiguously measured, as opposed to field strength. The bandwidth should ideally be determined by measuring the antenna drive impedance directly, rather than looking at it through a matching network. A matching network will to a greater or lesser extent decrease the bandwidth of the antenna. Alternately, the matching network can be modeled to remove its effect on bandwidth. I think it is less likely that you can be fooled by a bandwidth measurement than you can with base impedance measurements. Rick N6RK _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5652 - Release Date: 03/06/13 _ Topband Reflector
Re: Topband: Elevated Radials
Hi Guys, Forgive me, please, if I'm re-hashing a bit of the ...same-old, same-old here, but I am really curious as to any real world experiences that might be out there in the matter of elevated radials, vs. those that are simply laid atop the ground... My arthritic knees here are making the chore of rolling, unrolling, my seasonal 24-radials-per-L-element radials (I have THREE of them here!) just that, i.e. a VERY painful chore...and barring the possibility of there being a new bionic knee replacement(s) in my future, pray tell me: (A) Is it true that a couple of elevated radials are just as effective as the optimum amount of buried ones...? ** Define a couple. As Ive said on here umpteem times everyones soil/ground conditions are different. Im on a hilltop with solid granite no more than 2' down and mostly less than that, a couple defined as 2 wouldnt fly here very well. (B) What is the ideal number of elevated radials that one should use...? ** When your antenna analyzer shows no change; in my case it was somewhere between 16 and 32 as I simply doubled them and there was no change in 2:1 bandwidth or the impedance display. (C) How many elevated radials are just enough...? ** Same as B unless you dont mind seasonal changes or have great soil. I probably could have done OK with 8 but I believe my success was by paying attention to the details and not throwing away an unknown amount of power be it some fraction of a dB or not. Watching the bandwidth narrow is an eye opener. (D) How high should these radials be...? ** So you can drive a fire truck or 18 wheeler under them if necessary otherwise 10-12' as a minimum. (E) Would it be a requirement that I raise the feedpoints of my L's to the same height as the elevated radials, or can I simply leave the bases where they are now (at ground level) simply slant the radials upward with no effect upon performance...? ** Dont know. On mine I started at 10' and slanted to about 15' at a 45 degree angle as per Christman and then ran thru branches in the 15-20' range. (F) Is it OK to bend the elevated radials to fit property allotments...? ** I did, the West antenna was about 60' from the property line. (G) What is the desirable length of an elevated radial...? ** Resonant if only 2-4. Mine are approximately 130' of #16 insulated copper but since they all go thru branches that lowers the resonance; I didnt bother measuring it. Ive seen some suggest tying all the ends together into one big loop but havent seen any model to indicate it helps. (H) Should any existing connections to real earth at the base of the L's (i.e. a ground pipe) be completed severed with a system of elevated radials...? ** Yes. It helps to have a close in ground screen but not connected. For lightning you can connect them and a couple of rods after the ferrite isolation choke but be sure you have sufficient isolation to not affect the antenna. This morning I happened to work a NJ station with elevated radials that almost pegged the S-meter on my 751A---the short distance between us notwithstanding, obviously something was working very well for him there! Thanks in advance my vy ~73!~ de Eddy VE3CUI - VE3XZ ** Ive been an elevated fan since 1990, sure beats running on the ground plus a screen and still not knowing if it really works as good as it could as I had prior to that about 5 miles away and 500' lower. Carl KM1H _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5638 - Release Date: 02/28/13 _ Topband Reflector
Re: Topband: Elevated Radials
Elevated radials avoid a collection of lossy mistakes that one finds in less than optimal buried/on ground radials. If a full size radial system is done properly, dense, uniform all around, you will not be able to tell the difference. If there were huge efficiency issues with buried radials never seen with elevated, you would be seeing elevated radials at AM BC stations all over the place. 24 radials on the ground is not optimal unless you are over midwest USA flat-land black super-dirt. 73, Guy. Ahh, but the BCB folks have been using elevated radials mostly in rebuilds of failed buried systems as new station construction is at a minimumthere aint no more room unless they get rid of one sideband or run real QRP at night high up the band. One of the locals here runs 2.5W at night but being in a salt water marsh they do cover their assigned in town area well. Carl KM1H _ Topband Reflector
Re: Topband: Broadband dipoles
The March QST has a broadband dipole feature article. Carl KM1H - Original Message - From: Tom Boucher t...@telemetry.demon.co.uk To: 160 reflector topband@contesting.com Sent: Tuesday, February 26, 2013 8:42 AM Subject: Topband: Broadband dipoles It's the reference to termination resistors in the SPX data sheet that bothers me. Tom G3OLB K1FZ wrote: The antenna in a simpler single dipole configuration has the wire ends tied with a perimeter wire to give very wide frequency banding. For a modern version of the old T-top see. http://www.spx.com/en/tci/pd-613t-and-f-broadband-dipole-antennas/ _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5634 - Release Date: 02/26/13 _ Topband Reflector
Re: Topband: Fifty low power sealed SPDT RF relays for five bucks!
I bought a similar deal from them about 3 years ago, great for Beverage and other switching and no failures or intermittents yet. Carl KM1H - Original Message - From: donov...@starpower.net To: topband@contesting.com Sent: Tuesday, February 12, 2013 1:58 AM Subject: Topband: Fifty low power sealed SPDT RF relays for five bucks! The web site is a little confusing about the quantity, but the deal is for fifty (50) sealed SPDT low power RF relays http://www.goldmine-elec-products.com/prodinfo.asp?number=G16510B gold contacts 24 volt 8 milliampere coil, ideal for remote powering through thin wires 10 watt RF rating 14 pin DIP package for printed circuit board mounting 70 DB isolation between contacts below 900 MHz 1.2:1 VSWR below 900 MHz I recently purchased these, and I did indeed receive fifty relays for five bucks. Thats three hundred dollars worth of sealed low power RF relays for $5.00 plus shipping The deal ends today, 12 February. 73 Frank W3LPL _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2639/5599 - Release Date: 02/12/13 _ Topband Reflector
Re: Topband: alternative to vacuum variables
- Original Message - From: Tom W8JI w...@w8ji.com To: topband@contesting.com Sent: Friday, January 25, 2013 1:00 PM Subject: Re: Topband: alternative to vacuum variables Yes, there is a great solution, I'm using it for almost 10 years. The issue with capacitors in 160m is the dielectric an most capacitors get hot and change the capacitance. I used 19 x 62 pFNPO 3KV capacitor to get 1200pF. Never had a failure. Just keep them apart , don't let two capacitor touch This is an age old problem highlighted with amplifiers. The problem with higher value ceramic doorknob capacitors is temperature coefficient, not so much the heat. It is impossible to find NP0 (negative positive zero) in a thick dielectric ceramic. Typically the transmitting doorknob cap has to be less than 100pF to get an NP0. A 200 pF 5 or 7.5 kV was typically measured in the N1000-2000 range, more often than not worse than advertised. 170 pF 5 kV's of better selection could get into the N150-300 range. Most of the reason I used to parallel multiple transmitting doorknobs was to keep the temperature coefficient reasonable, not for heat. Multi-layer transmitting chip ceramics and some disk capacitors are available in NP0 or the equivalent. Mica capacitors are generally very stable, so the old surplus WWII screw terminal block micas work pretty well and are often just a few bucks. We should remember coaxial cables are transmission lines. Because of that, they have pronounced standing waves. With any significant electrical length in degrees the capacitance will NOT be what we calculate for capacitance per foot. At just a few degrees they deviate from calculated because they start to have significant open stub effect. This also results in higher voltage at the open end than we have applied across the feed end. With longer stubs (even though we might imagine them capacitors) the voltage step up can be significant. This was a problem in more than one amateur antenna using coax to make cheap capacitors, the Unihat vertical being one of them that comes to mind. There are many cheap alternatives, but there are few cheap universally good alternatives except perhaps a multitude of lower value temperature stable caps in parallel, or mica or air insulated caps. 73 Tom A problem with old TX micas is leakage as they have deteriorated with age. Ive had to toss about half of mine since they wont even pass at 1000V from one of my vintage cap testers. Id still have resevations about the remainder in HV RF situations. Carl KM1H _ Topband Reflector
Re: Topband: Measured RG-6 Loss: Solid Copper vs. Copper Clad center conductor
Commscope, Times and what ever else quality distributors such as Tessco carry are what I suggest. Also see about buying from the local CATV installation contractors. Carl KM1H I have been watching this thread with interest, I am preparing to put up a receive array and it will have to be some distance from the shack. Is there a brand of RG-6 that someone has tried that is recommended? Or some idea of a good name to look for. Shipping to Molokai is more than 1000ft of coax costs, so need to make the right choice the first time. Not sure at this point of exact feedline length but will be more than 1000 ft. I see commscope RG-6 burial type orange on Ebay, anyone tested that and is commscope decent material?I will have to bury it due to mongoose chewing on most anything laying on the ground, they chewed through teflon coated wires for beverages that laid on the ground overnite before getting erected. Thanks 73 Merv K9FD/KH6 Several topbanders asked if I would measure the DC resistance of the solid copper and copper clad steel center conductors of the RG-6 coax for which I published the RF loss measurements. I also measured the quad-shield DC resistance, both cables measured the same. Here are my measurement results: Solid copper: 0.6 ohms per 100 feet Copper clad steel: 1.9 ohms per 100 feet Quad shield:0.3 ohms per 100 feet It appears that copper clad steel RG-6 is a good choice for remote powered preamps and relays except for very long cable runs. When using a remotely powered device its extremely important to prevent even the slightest moisture entry. RG-6 compression connectors are NOT waterproofed at the threaded end of the connector, additional waterproofing is absolutely essential. The Thomas Betts NS500 Nut Seal costs only a few cents and it very effectively waterproofs the connector threads. http://www.ebay.com/itm/NEW-LRC-AUGAT-THOMAS-BETTS-NS-500-NUT-SEAL-50-LOT-/160703026841 The inside of the connector should be stuffed with STUF Di-Electric Filler to prevent moisture accumulation from condensation. The finished connection should first be wrapped with electrical tape, then a final layer of waterproofing should be applied such as Coax-Seal moldable tape. 73 Frank W3LPL Original message Date: Wed, 23 Jan 2013 17:58:31 -0500 (EST) From: donov...@starpower.net Subject: Measured RG-6 Loss: Solid Copper vs. Copper Clad center conductor To: topband@contesting.com Today I measured the difference in loss (dB per 100 ft) between solid copper (SC) center conductor RG-6 vs. copper clad steel (CCS) Quad-Core RG-6 coaxial cable. The difference is not significant until cable lengths exceed 350 feet. You can see the affect of the steel core at 7 MHz and below in this table. The cables were manufactured by two different companies, but the relative measurements should be valid. Solid Copper Cable length in Freq Copper Cladfeet for a 1 dB MHzLossLossloss difference 1.80.3 0.6 350 3.50.4 0.6 500 7.00.6 0.8 500 10 0.7 0.85 650 14 0.750.9 650 21 0.9 1.0 1000 28 1.0 1.1 1000 73 Frank W3LPL _ Topband Reflector _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2639/5556 - Release Date: 01/25/13 _ Topband Reflector
Re: Topband: alternative to vacuum variables
Pete, I used a big 300pf breadslicer with somewhere in the 7.5 to 9KV range ( I forget the spacing, it was a vintage Johnson) and a couple of 857 size ceramic caps for my Omega at a prior QTH. Smaller spacing and lighter duty fixed caps didnt survive the 1200W of my own amp but the rebuild was tested with a customers Alpha 77DX and it held together fine. This was in the mid 80's and it was all housed in a plywood box. The other cap was a standard smaller spacing, dont remember the value but its still partially together out in a storage trailer and I can measure it. I seem to remember it was an even older 1000pf Cardwell. Carl KM1H - Original Message - From: Pete Smith N4ZR n...@contesting.com To: topband@contesting.com Sent: Thursday, January 24, 2013 2:33 PM Subject: Topband: alternative to vacuum variables One of the reasons I have mot gone to high power on 160 is the cost of capacitors for my omega match - at least $300. Anyone know of any workable alternative? I remember someone writing about using coiled-up RG-8, RG-213 or maybe Teflon coax. Where can I find more information? -- 73, Pete N4ZR Check out the Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com. For spots, please go to your favorite ARC V6 or VE7CC DX cluster node. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2639/5554 - Release Date: 01/24/13 _ Topband Reflector
Re: Topband: Help with RFI
Im running shielded CAT 5e from the router up in the office to the basement and none of the rigs bothered it but I did have to use a single 31 core at the router outputs to eliminate its noise; the 6 CAT5e cables are grouped together thru the toroid, and another at the DC input. The cable modem that feeds it was also very noisy and even outputting on the RG6. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Saturday, January 12, 2013 10:38 PM Subject: Re: Topband: Help with RFI I wrap a few turns of the CAT 5 Ethernet cable coming into the back of my shack PC around a few stacked 2.4 diameter #31 ferrite cores. Works for me. 73, Mike www.w0btu.com On Sat, Jan 12, 2013 at 4:48 PM, W7KW w7kw.te...@gmail.com wrote: I am having a problem with RF getting into my Ethernet cables. Anyone have any recommendations for a clamp-on filter that would help remove 1.8 MHz RF? _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2638/5530 - Release Date: 01/13/13 _ Topband Reflector
Re: Topband: Heater Choke Value
Typical reactance rule of thumb is 5 to 10X the input impedance of the tube(s). In some cases it is much less and the 160M input network is modified to compensate. #18 or 20 enamel wire would be suitable for 4A and be a lot easier to wind than 12 and require a lot less ferrite. Carl KM1H Mike(W5UC) Kathy (K5MWH) Sent: Wednesday, January 09, 2013 4:37 PM To: topband@contesting.com Subject: Topband: Heater Choke Value Hello Fellow Topbanders: I have just started the process of converting a MLA-2500 amplifier from it's original 8875 tubes to Gi-7b tubes. Current;y I can run only abut 400 watts on Topband, (not from the MLA=2500, I have no tubes for it) The conversion requires a RF Choke in the filament lines. I have searched the Handbook, and looked at several schematics with no luck. Please, can someone out there advise the value of reactance required for this effort. Most construction articles recommend #12 wire, which in this case, appears to be significant over kill, as the heater current is only 4 amps total. Thanks 73, Mike, W5UC _ Topband Reflector
Re: Topband: 160 shunt fed tower update
- Original Message - From: Steve London n2ica...@gmail.com To: Topband topband@contesting.com Sent: Friday, January 11, 2013 4:12 PM Subject: Topband: 160 shunt fed tower update When we last left this adventure, I was shunt feeding my 110' tower on 160, which supports a multitude of yagis and wires. Unfortunately, I was coupling so much energy into the 80 meter wire array that the 80 meter baluns were heating up. There were a number of interesting and useful suggestions on this reflector. As an experiment, I disconnected all of the feedlines going from the 80 meter switching/tuning box at the top of the tower to the individual elements of the 80 meter antennas. The 80 meter wires were still in place, just not connected to the tuning/switching box. That solved the balun heating problem, and greatly changed the shunt feed point and spacing needed for 50 + jX at the tower base feedpoint. I left it that way for several weeks, while I evaluated how well the shunt fed tower actually worked. Based on comments from topband readers and performance in the Stew Perry, I was satisfied it was working effectively. The next step was to build an insulated bracket to support the 80 meter switching/tuning box to keep all of the 80 meter coax lines electrically insulated from the tower. No torroids. No grounding of the 80 meter feedline to the tower. I was hoping this would keep the 80 meter array RF isolated from the shunt fed tower. No such luck. The shunt feed needed significant adjustment. There is significant coupling, despite having no DC connection. The good condx to EU most evenings this past week have been very frustrating as I struggled to work easy stations that were no problem to work in the past with the old sloping dipole. I have to conclude that the coupling is having a detrimental effect. Yes, I could experiment with torroids, etc., but my conclusion after reading comments here is that nothing is guaranteed to fix the 80 meter coupling problem, short of removing all the 80 meter wires. Back to the drawing board. Maybe a dedicated 160 tower is in the works. Hope to work some of you in the NAQP. Listen for the weak signal from New Mexico ! 73, Steve, N2IC I dont know what you are using for 80M Steve and why all the feeds, etc are located at the top of the tower. In the 80's I had a 100' Rohn 25 with a stack of yagis and shunt fed on 160 which worked well once I went to 4' x 50' galvanized 2x4 rabbit fencing running from the base as spokes and with lots of interconnecting wires between the sections. Then I worked on improving my 80M signal with an inverted vee, 3 switched slopers and a delta loop. The vee feed was taped to the tower, the sloper feeds came to ground where the relay box was, and the delta loop was about 6' from the tower and the feed went to ground level. I believe the loop was in place with the slopers for awhile but not certain; I think I tried using it as a reflector. About 60' and 125' away were 80M phased verticals. Nothing affected 160M tuning or performance that I remember and if so the tuning was very minimal. That Omega match shunt feed worked great in all directions. The delta loop was the final choice for 80 and its horizontal signal complimented the verticals when needed. I moved before I could try a reversible 2 el loop. Carl KM1H _ Topband Reflector
Re: Topband: A 160 Meter antenne puzzle
Is the 4x4 pressure treated? Or from a local sawmill and uncured? Both will have an effect. Carl KM1H - Original Message - From: Glenn Biggerstaff ww4...@gmail.com To: topband@contesting.com Sent: Monday, January 07, 2013 9:30 PM Subject: Topband: A 160 Meter antenne puzzle Hi everybody and happy new year . I have what I think is an interesting antenna riddle . I have some receive antenna verticals (4) that are selected by relays in pair and the pair is fed back to the shack to a phasing boxing .Each antenna is AL tubing about 30 feet tall, base loaded with an inductor and a resistor very much like ON4UN has for his 4 square receive array .There is a 1 to 1 balun between the antenna and the feed line . The tubing is insulated with an eight inch length of pvc pipe from the 4x4 that supports it .The overlap between the tubing and the 4x4 is about eight inches as well . I was doing some testing today and discovered that touching the 4x4 at the top caused the swr to increase from about 1.2 to 1 to 1.7 to 1 . The lower on the 4x4 I touch the less the effect . I am only moving my finger a fraction of an inch and my hand not at all when this happens .The feed lines are disconnected when this is going on .There is no dc continuity between the antenna and any mounting hardware or th e post .I disconnected the base loading and put the analyzer on it and it is resonant at about 8 mhz and touching the post causes no change with this setup . There are eight 30 foot radials laying on the ground and a 2 inch wide copper strap about 3 foot long in the hole that the 4x4 is in . What is going on here and should I make an effort to limit the coupling between the 4x4 and the antenna? 73 , Glenn WW4B _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2637/5518 - Release Date: 01/08/13 _ Topband Reflector
Re: Topband: Power Line Noise Detecting
I use an old CATV RF sniffer that was $10 at a hamfest, they got replaced whenever the systems added more bandwidth and are used by the techs to certify a new build or later to do leakage tests. Tuneable, AM/FM detectors and an analog meter. Mine goes to 400 MHz and has found every problem Ive encountered. Carl KM1H - Original Message - From: THOMAS M GREENWAY k...@bellsouth.net To: topband@contesting.com Sent: Friday, January 04, 2013 3:57 PM Subject: Topband: Power Line Noise Detecting Good job up to the last step. After getting where I think I have the pole with the VHF TRF receiver I use a Ultrasonic detector that was shown in QST by W1TRC. It will enable you to 100 % verify the problem is on the pole you suspect. You can actually hear the arc if it is in line of site of the mic. I had been fooled a couple of times using the VHF antenna thinking I had the right pole and the Ultrasonic found it was actually an adjacent pole. The power company also use these but a much more expensive model. The W1TRC can be built for under $100. There could possibly be a condition where the arc is internal to the transformer or on top of an item where the mic can't hear it but so far it has worked 100 % for me over many years. 73 Mike K4PI ___ Stew Perry Topband Distance Challenge coming on December 29th. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2637/5510 - Release Date: 01/04/13 ___ Stew Perry Topband Distance Challenge coming on December 29th.
Re: Topband: Trees (not the N6TR kind)
Subject: Topband: Trees (not the N6TR kind) Pine trees taller than 100 feet could be an issue, since they could be near resonance and lossy - a sad combination when within a wavelength or so of vertically polarized antennas. If your trees are 50 footers, they would probably not be of concern on 160m, but could be on 80m. For horizontally polarized antennas, the trees aren't a problem. Years ago, when some fellow proposed that trees would radiate because they were fractals, I measured the RF resistivity of freshly-cut pine trees. I firmly attached copper or aluminum plates to a thick one foot long trunk section, and measured resistance. These were wet, freshly-cut, sappy, pines. Pines are acidic and very wet inside, so they should reasonably be at the top of tree conductivity. I can't recall the exact RF resistivity, but I'm pretty sure it was either high hundreds or low thousands of ohms per foot for a one foot diameter log. I do know the number was significant. Resonance, significant absorption, or radiation would be impossible with that much resistivity per foot. Given a choice, I probably wouldn't have a high voltage area in close proximity or contact with a tree. I doubt a few trees would produce noticeable loss, and they certainly could not be by any stretch of the imagination resonant with such high resistivity per linear foot. 73 Tom My own experience was with a live 70+ foot pine tree on 80M some 30 years ago which I have recounted here before. I started off with a 6 wire 12 diameter cage vertical suspend from a branch about 12 from the trunk and 60 1/4 wave radials on the ground. Resonance was well below the band, not very pronounced, and signals on RX were severely attenuated. Back up the tree and I moved it to 3' out and reasonace came up in frequency but TX results were very poor. Climb again and I managed to get it maybe 8-10' out and at that point I could work DX much easier than with an inverted vee about 60' away. Resonance around 3650 was at 59' and the VSWR pattern was as published. The next step was a duplicate hanging from another tree, Mother nature was good to me since these were the only trees in the back yard that were in the lawn area and I didnt want to go way back and do some series chain saw work. The ARRL CW DX contest that season resulted in the #2 single band 80 US score and right behind John, W1FV, the perennial winner. I actually beat him in multipliers and he later told me he thought I had won. That experience proved to me without a doubt that pine trees at least made good RF absorbers. With other pine trees being over 100' away it wasnt like those phased verticals were in the middle of the deep woods. They also worked reasonably well on 40 as half waves but not competitive for pileups or contests. I dont know if it was trees or radiation angle but I soon went with a yagi for 40. K1VR later tried a standard 40M 4 square and wasnt impressed and also went to a yagi. Carl KM1H ___ Stew Perry Topband Distance Challenge coming on December 29th.
Re: Topband: Fw: Short Bogs
If youre building a Beverage/BOG as the thread title indicates, resonance does not matter, it is a nonresonant slow wave antenna. For a resonant antenna up in the air and used for transmitting the insulation adds 3-5% to the electrical length. Carl KM1H - Original Message - From: Bruce k...@myfairpoint.net To: topband@contesting.com Sent: Sunday, December 30, 2012 1:15 PM Subject: Topband: Fw: Short Bogs . If we want to make an antenna electrically longer through cable velocity factor, it can't be done by the insulation slowing the wave inside the shield. 73 Tom In my experience, external insulation (through synthetic covering or frost) lowers the resonant frequency of wire antennas of a given length and height above ground. For example, I typically use 453/F as a starter length for insulated wire dipoles...it's higher for bare wire of the same AWG diameter. It may not be due to velocity factor (not sure of the reason), but it is observable and repeatable. 73, Gary NL7Y I also have had insulated wires of the same AWG diameter resonate lower in frequency than bare ones of the same length. Think we need multiple people experiment: Put up an antenna with covered wire. Measure the frequency, then cut the insulation away (of this same piece), and re-measure the frequency. If we get different results from different people, then we can start looking at the insulation. Is it economy grade made for 60 cycles (600 volts), or is it the good stuff ??? 1. If it is low grade insulation with resistance at 1.8, 3.5 MHZ, then it may be making the wire appear to be fatter. If true, then that would be valid reason. 2. If the insulation is high quality at HF radio frequencies, and IF the frequency changes, then we need to look further 73 Bruce-K1FZ www.qsl.net/k1fz/ ___ Stew Perry Topband Distance Challenge coming on December 29th. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2637/5497 - Release Date: 12/30/12 ___ Stew Perry Topband Distance Challenge coming on December 29th.
Re: Topband: Inverted L question
- Original Message - From: Tom W8JI w...@w8ji.com To: Herb Krumich wa2...@yahoo.com; topband@contesting.com Sent: Wednesday, December 26, 2012 3:08 PM Subject: Re: Topband: Inverted L question I am right now using an inverted L which is spaced about 4 feet away from my tower. The vertical leg is about 85 feet. I only have 6 radials at the present time Now here is the question The horizontal leg is about 50 feet and goes to my back yard. Since the trees are not that high, it probably slopes down to 40 feet at the far end The horizontal wire faces west.. Would it help me to face that wire to the south for east west signals on transmit. I am hearing very well with a 550 foot beverage. At a prior QTH I had a 100' tower with a Christmas tree of HB 4 el wide spaced yagis for 10-15-20M and a 4 el KLM 40M on another tower about 60' away. The 100' tower was shunt fed on 160. Several months after the KLM was installed the VSWR went haywire and I used a coax balun until moving several years later. Never considered the possibility of another antenna causing the problem BUT KLM also suggested later to connect the parasitic elements to the boom with aluminum strap. In the 60's I had baluns burn out twice on a TH6 and finally went with a coil of coax. A 6 el 6M yagi was about 4' above it and fed with the legal limit. Coincidence? Both were similar construction I believe. Carl KM1H ___ Stew Perry Topband Distance Challenge coming on December 29th.
Re: Topband: Ground mounted 1/2 and 1/4 wave verticals (was GAP) - A Hoot! - A Dream?
I worked in one for several years testing my designs but this was at 2.4 and 5.6GHz. Long before that it was as a range tech for a defense contractor designing/building/installing military EME arrays of yagis as well as troposcatter antennas used during Vietnam. Sometimes the same yagi designs were used, just in different configurations. It was all about measurement, measurement, measurement as the slightest inconsistency had to be examined, reasoned why, and solved. Over and over and over. Carl Carl KM1H - Original Message - From: Charlie Cunningham charlie-cunning...@nc.rr.com To: 'DAVID CUTHBERT' telegraph...@gmail.com; 'ZR' z...@jeremy.mv.com Cc: 'Donald Chester' k4...@hotmail.com; topband@contesting.com Sent: Monday, December 17, 2012 6:31 PM Subject: RE: Topband: Ground mounted 1/2 and 1/4 wave verticals (was GAP) - A Hoot! - A Dream? Wouldn't it be something if we had a fully instrumented spherical anechoic chamber large to enclose a 160 m vertical, or inverted L or TEE and their radial systems - and then we could answer some of these challenginq questions by MEASUREMENT? !!! :-) Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of DAVID CUTHBERT Sent: Monday, December 17, 2012 5:23 PM To: ZR Cc: Donald Chester; topband@contesting.com Subject: Re: Topband: Ground mounted 1/2 and 1/4 wave verticals (was GAP) Carl, What we do in the near-field to control ground loss affects the far-field signal equally at all elevations. Therefore there is no need to measure far-field field strength at more than one elevation. We have control of the near-field and anything we do in that region shows up as a change in input impedance. Dave WX7G On Dec 17, 2012 3:08 PM, DAVID CUTHBERT telegraph...@gmail.com wrote: Carl. I quantified ground loss in the near field. Now it's your turn. Numbers please, not adjectives or hand waving. Dave WX7G On Dec 17, 2012 2:59 PM, ZR z...@jeremy.mv.com wrote: Because youre still stuck in neutral and are measuring/calculating nothing of interest. The loss is determined at various elevation angles at a sufficient distance by field strength. Get a helicopter. Carl KM1H - Original Message - From: DAVID CUTHBERT telegraph...@gmail.com To: Donald Chester k4...@hotmail.com Cc: topband@contesting.com Sent: Monday, December 17, 2012 1:53 PM Subject: Re: Topband: GAP Vertical Question Where is the 40-60% claimed ground loss? I get 4%. On Dec 17, 2012 6:12 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: *Half wavelength vertical ground loss* Let's see if we can quantify the conduction losses of a 1.8 MHz half wavelength vertical connected to average earth via a ground rod. This paper by N6LF shows one skin depth at 1.8 MHz to be 6 meters. http://www.antennasbyn6lf.com/**files/ground_skin_depth_and_** wavelength.pdfhttp://www.antennasbyn6lf.com/files/ground_skin_dept h_and_wavelength.pdf Let's assume the current magnitude in the ground mirrors that of the antenna. Driving the antenna at the base such that the current at the antenna center is 1 amp, the ground current 40 meters away from the antenna is 1 amp. The 1 amp of ground current passes through a section of earth having an effective depth of of 6 meters. For a 1 meter radial length and 40 meters from the antenna the section has dimensions of 1 meter X 6 meters X 250 meters (250 meters is the circumference). Given a resistivity of 200 ohms/meter the resistance of this section is 200/(6 X 250) = 0.13 ohms. The loss in this section is 0.13 watts. Using NEC we see with the base current set to give 1 amp at the antenna center the power into the antenna is 100 watts. Closer to the base of the antenna the effective ground resistance increases due to the smaller circumference. Closer to the antenna the current decreases. Roughly Integrating the ground loss from the base to the 80 meters away gives a total ground loss of 4 watts. The no-radial ground loss is 5 watts and the antenna gain is reduced by 10LOG(100/96) = 0.2 dB from the full radial case. How about ground loss due to the induced E-field in the ground? I believe this is accounted for in the previous calculation. I ran a NEC simulation to explore this. The two cases were a 266' vertical fed against thirty 3' radials and thirty 133' radials. The radials are 0.05' above medium ground. The NEC Average Gain was compared for the two cases and showed a difference of 0.06 dB. Dave WX7G On Sun, Dec 16, 2012 at 6:42 PM, Donald Chester k4...@hotmail.com wrote: Then, why do broadcast stations that use vertical towers at approximately a half wavelength, purchase valuable real estate and spend thousands of dollars for the copper to install from 120 to 240 or more radials, each usually a half wave or more in length? See G. H. Brown: Ground Systems as a Factor in Antenna Efficiency, IRE Proceedings, June 1937 p. 753. Brown demonstrated that the distribution
Re: Topband: GAP Vertical Question
I can think of NO earthly reason,that makes ANY electromagnetic sense to me, as antenna engineer fo placing a radial system under the end of a vertical 1/2 wave antenna - earth-worms not withstanding! ** Another case of not understanding the antenna or the purpose and handling of its current maximum. Some antenna engineer. Given that a half wave vertical has a base impedance of over 1000 ohms and a single ground rod in dirt is 100 ohms at most not a single radial is needed to obtain close to 100% radiation efficiency. Dave WX7G ** Its not the base that is the problem. The current has to be dealt with no matter where it is located on the vertical conductor or its electrical length. For want of a better word its image has to be a perfect conductor for the antenna system as a whole to be 100% efficient. It is also the current and its efficiency that determine the power radiated at the lowest angles. Excessive losses and that 10db becomes a simple glaring in your face reality. Carl KM1H - Original Message - From: Donald Chester k4...@hotmail.com To: topband@contesting.com Sent: Sunday, December 16, 2012 8:42 PM Subject: Re: Topband: GAP Vertical Question Then, why do broadcast stations that use vertical towers at approximately a half wavelength, purchase valuable real estate and spend thousands of dollars for the copper to install from 120 to 240 or more radials, each usually a half wave or more in length? See G. H. Brown: Ground Systems as a Factor in Antenna Efficiency, IRE Proceedings, June 1937 p. 753. Brown demonstrated that the distribution of earth currents and ground losses is such that the region of maximum current and loss occurs at a distance of about 0.35 wavelengths from the base of a ground mounted half wave vertical antenna, which was verified experimentally. There is zero loss at the base of the antenna itself, since there is no base current because the antenna a fed at a current node. An rf ammeter inserted in the ground lead, as well as one inserted in in the antenna lead attached to the insulated base of the radiator will read zero. The ground losses occur farther out from the base of the antenna. Low effective earth resistance provided by a good ground system is ABSOLUTELY NECESSARY for vertical antennas of ANY height if one expects good radiation efficiency. The claim that no ground system is needed for a half wave vertical is nothing more than a long-standing popular misconception. This topic prompted me to dig out and review an anecdote I recall reading in my decades-old copy of CQ magazine's Vertical Antenna Handbook, by USNR Capt. Paul H. Lee, K6TS (1974). He reported receiving mail from a ham who had made the discovery that he could tune and operate a half wave vertical without a ground system, feeding it by a parallel tuned tank circuit whose lower end is grounded. Since an rf ammeter in the ground lead showed no current, he could dispense with the ground system and its loss. He suggested to the Capt. that he should discover the new world of half verticals with no ground system. Quoting from the text (p. 84): The correspondent's claim... is true ONLY IF HE IS CONTENT TO THROW AWAY FROM 40 TO 80 PER CENT OF HIS RADIATED POWER IN THE FORM OF EARTH LOSSES. (the correspondent) stated, 'The ZL's call ME, when I use my half wave vertical!' This is not surprising, in view of the fact that the half wave's vertical pattern has a lower main lobe angle than a quarter wave would have... However, he would hit the ZL's even harder if he would put in a ground system. Of course, the half wave vertical is not dependent on a ground plane, however lossy or efficient, for the condition of RESONANCE, since it is resonant in itself because of its half wave length. However, IT IS DEPENDENT ON A GROUND PLANE FOR ITS EFFICIENCY OF RADIATION, as is any vertical antenna...' Don k4kyv Given that a half wave vertical has a base impedance of over 1000 ohms and a single ground rod in dirt is 100 ohms at most not a single radial is needed to obtain close to 100% radiation efficiency. Dave WX7G And this statement is based on what? Publications, measurements, modeling? I have built a number of 1/2 wave verticals without radials and compared them to 1/4 wave verticals with radials. They are indistinguishable in performance and certainly do not exhibit substantial ground losses AFAIK... Rick N6RK I can think of NO earthly reason,that makes ANY electromagnetic sense to me, as antenna engineer fo placing a radial system under the end of a vertical 1/2 wave antenna - earth-worms not withstanding! It's CURRENT that warms the earthworms! NOT electric field intensity! ...the ground system does NOT act as a shield from the lossy earth nor protect the earth-worms! There is absolutely NO reason to require a radial system under a 1/2 wave vertical antenna. Such an antenna will operate just fine on its
Re: Topband: Elevated Radials Questions
The only place Ive found tuned elevated radials being discussed so much is on ham forums. A bit over 20 years ago I installed a slanted wire 1/4 wave vertical for 160 coming off the top guy wire of a 160' tower and about 10' out. Started with 4 radials of roughly 130', trimmed the radiator for best match with zero reactance and measured the 2:1 bandwidth. Added 4 more radials and the BW narrowed, added 8 more and it narrowed a bit more. Added another 16 and no change in BW so I assume the sweet spot is somewhere in the 20's at this location and the radials starting at 12' and slowly sloping to 20' and then thru tree branches. Just the way they were placed likely precludes any chance of resonance. That antenna worked so well I added another, and used nothing but coax phasing lines to switch directions or fire a figure 8 broadside. Cheap, simple and effective unless you like throwing away money for a mailorder solution. YMMV depending on ground effects and surrounding objects. OTOH I believe people spend way too much time analyzing and relying on some questionable answers and too little time doing some basic construction work and testing. Carl KM1H - Original Message - From: Grant Saviers gran...@pacbell.net To: Dennis W0JX w...@yahoo.com Cc: topband@contesting.com Sent: Thursday, December 13, 2012 5:27 PM Subject: Re: Topband: Elevated Radials Questions Thanks for the comments and pointers. The land around the antenna is mixed grass and forested islands so on the ground radials would be partially buried and partially on the surface. Digging through the trees and clearing the brush is not something I want to do. Also, based on prior experience with verticals on metal roofs, I'm a real fan of elevated radials. I am relying on the credibility of the N6LF QEX series for how well/not well elevated radials will work (Mar - June 2012). I realize this work was all analysis with EZNEC PRO, but it seems to be the similar to results of others I've read. Googling K5IU elevated radials I did find the 2008 N6LF article which has the experimental data as well. His analysis shows there isn't much difference in losses with more than 4 radials between 0.15 and 0.27 wavelengths long. I've heard conventional wisdom is to tune radials for resonance, but the analysis for 4 or more radials elevated than a couple of feet seems to indicate it is a lot of work for little benefit. I also found the 2005 thread tuning elevated radials on this reflector quite informative. One thing that stands out is that I may be better off with more than 7 shorter than 130' radials. Grant KZ1W On 12/13/2012 12:06 PM, Dennis W0JX wrote: Grant, you should consider putting in an additional 23 radials and put the radial system on or in the ground. This will eliminate any possible detuning by the big metal building and interaction with the RX 4 square. You said that your vertical T will go up to 85 feet. However, by elevating the radials 10 feet, your effective vertical distance is 75 feet which will allow you to shorten the top hat wires a bit. As an alternate, you could put down 1/8 wavelength radials on the ground but more of them and have a good system too. If you must go with an elevated radial system, I recommend that you read the articles by Dick Weber, K5IU, who strongly advocated elevated radials shorter or longer than 1/4 wavelength. If shorter, then the radials are loaded with a small coil. If longer, then they are tuned out with a capacitor. W5UN uses shortened elevated radials on his 160 meter 4 square with great results. They are about 70% of a quarter-wave in length. 73, Dennis W0JX/8 Milan OH ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2634/5457 - Release Date: 12/13/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: Re: : antenna question ...this is not going todieqiuite yet....................
And one should never rely on a single source of information unless it has been well vetted. That is something that wont happen on Antennex but there are enough qualified people on Eham and here to seperate truth and fiction. Carl KM1H - Original Message - From: Bill Aycock billayc...@centurytel.net To: topband@contesting.com; mike l dormann w7...@juno.com Sent: Monday, December 10, 2012 9:50 PM Subject: Re: Topband: Fw: Re: : antenna question ...this is not going todieqiuite yet Mike-- Often, quoting eHam is repeating nonsense. Sorry, but it is so, and this is a good example. Any Ham that relies on published Velocity factor data, without verification, gets errors, and (frequently) blames it on something else. Start over; read some texts or handbooks; Think; read stuff from people like W8JI (and people he disagrees with). Reading eHam is like reading Antennex; There may be something good there, but how can you tell? It's not checked by anyone qualified. Bill--W4BSG -Original Message- From: mike l dormann Sent: Monday, December 10, 2012 2:46 PM To: topband@contesting.com Subject: Topband: Fw: Re: : antenna question ...this is not going to dieqiuite yet if I may quote eHam. Dale Hunt: The velocity of typical cheap TV twinlead is usually in the range of 0.8 to 0.85 (and can vary along a single role.) This is important if you are creating a quarter wave matching stub, but not for the overall length of a folded dipole antenna. Use the standard single- wire dipole formulas and it should work fine. One variation I have seen is to connect a short jumper wire across the twinlead a short distance in from each end of the folded dipole. The idea is that, while the overall antenna length is not corrected for the velocity factor, each half of the antenna is effectively a quarter-wave stub which does need the correction. The shorting bar is put on each side about 85% of the way out from the center. This may improve the SWR somewhat in a 300 ohm system, but if you are using a tuner to match 50 ohms to 300 ohms, then you won't seem any noticable improvement. (The tuner setting will compensate for any slight mismatch due to the velocity factor.) I guess if one was to use a balan of some sort to have the end to the transmitter be 50 ohms, this could of of some importance mike w7dra Woman is 53 But Looks 25 Mom reveals 1 simple wrinkle trick that has angered doctors... http://thirdpartyoffers.juno.com/TGL3141/50c64a7b534c04a7b6da2st04vuc ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5449 - Release Date: 12/10/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Not so Boring report
I used to work EU on 6-10M crossband in those days since very few had authorization. Ireland was one that did and quite a few were on. My rig was a HB 6AG7, 6V6, 829B crystal controlled with PP 6L6 modulators into an ARRL HB 4 el yagi just above the 3el HB 10M which was above a HB 15M at about 20' high. 6BQ7, 6J6 converter to a 20M IF was also HB. On 10M it was a Viking I, HQ-129X. I lived out on LI, NY back then, in Nassau County. Fun days about 8 years before I met Stu Perry when I was at National and he convinced me to try 160 after Id moved to 8 acres in NH. Carl KM1H - Original Message - From: Guy Olinger K2AV olin...@bellsouth.net To: n...@arrl.net Cc: topband@contesting.com Sent: Saturday, December 08, 2012 5:08 PM Subject: Re: Topband: Not so Boring report Alas, will I never see the likes of 1957-58 ever again for working EU on 6M using an end-fed window screen for an antenna? On the other hand, now that I have a couple really good trees to support 160m TX antenna, maybe I don't care. So conflicted... 73, Guy. On Sat, Dec 8, 2012 at 4:50 PM, Steve London n2ica...@gmail.com wrote: On 12/08/2012 12:52 PM, Tree wrote: It's very unusual to work the morning opening during a sunspot maximum. A solar flux of 97 is not what I would call a solar maximum. More like a bump in the new Mayan Minimum. Who knows what will happen on December 21 :) . Don't forget that in previous sunspot maximum's, we would go 3 or more years when the flux would never fall below 100 for even a day. This is good news for topbands enthusiasts, unless the Mayan prophecy 73, Steve, N2IC __**_ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5446 - Release Date: 12/08/12 ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
It just goes to show that what looks good on paper in theory does not mean it HAS to be the same in the real world. There is nothing to prevent 2 signals a continent away and with different antennas from taking completely different paths when one is at either sunset or sunrise. There hasnt been a book written yet to explain it all. On a different note there was no way anyone would have believed that it was possible to work JA on 6M at the bottom of the cycle from New England yet several of us made the trip starting a few years ago. Experts are still arguing about that mechanism while on here one stands on a platform (not you Carl) and expects everything said to be believed without question. Carl KM1H - Original Message - From: Carl Clawson clawso...@gmail.com To: topband topband@contesting.com Sent: Tuesday, December 04, 2012 6:22 PM Subject: Re: Topband: one-way propagation Yes, a good point that I neglected. This entirely circumvents my yammerings about reciprocity. Reciprocity is a characteristic of a single pair of ports in a network. Introducing separate receive antennas can surely cause a one way effect. Consider what happens when I hook up a dummy load as a Rx antenna ... 73 and thanks for listening, Carl WS7L I've often thought that some one-way propagation is simply due to the differences in antennas. For example, two stations with the same power, ambient noise level, etc. are receiving on Beverages pointed at each other, but their TX antennas have different takeoff angles and/or patterns. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5436 - Release Date: 12/04/12 ___ Topband reflector - topband@contesting.com
Re: Topband: F fitting adaptors
- Original Message - From: Tom W8JI w...@w8ji.com To: Bruce k...@myfairpoint.net; topband@contesting.com Sent: Tuesday, December 04, 2012 6:24 AM Subject: Re: Topband: F fitting adaptors When using a Ameritron remote antenna switch with SO-239 fittings, does anyone know a supplier for female F fitting to PL-259 adaptor ? Thanks, 73 Bruce-K1FZ Bruce, IMO, you have the wrong switch. A transmitting type high-power switch is a terrible device for receiving. The larger the relays (has a general rule) the greater the problem, and it has nothing to do with sealed (enclosed) or unsealed (open) relays. High current relays are very problematic when only used at low power. The problem surrounds the large contact area and lack of wetting currents, and no significant voltage and current ever being applied to burn through any film on the contact. There are hundreds of papers by relay manufacturers or others detailing this problem, and it even occurs with brand new sealed or enclosed relays. The only high power relays immune to this issue are vacuum type relays. I think you are heading for long term problems with adaptors and a transmitting switch. 73 Tom While Ive experienced vacuum relays having a problem on receive a reversal of the coil wires took care of it, that was obviously a magnetising issue as has been mentioned often over the years. OTOH the pair of Ameritron RCS-4's Id used for up to 20+ years never had an intermittent problem or lightning induced damage (a benefit of a big relay) they had somewhat poor isolation due to the daisy chain sequencing design and PC board layout and were replaced by a HB unit using sealed microwave relays. Now they wll probably blow from lightning even with the protection included. I would think the Ameritron RCS-10 would be an ideal solution for a multiple Beverage installation as the cost is reasonable considering the alternatives. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Having operated in Western and Central Europe a few times over the years on 160-40M from average to better stations Ive observed something else. With the typical 5-7 hour time difference the East Coast hears EU well before sunset in the winter and its hard to impossible to attract a QSO. This is the prime evening time in EU where activity is highest adding to the across the band din making weak signals poor copy. Also there is band sharing with commercial and other stations that drops down considerably as the evening progresses. Some of those signals are wide with TX generated noise. As it approaches EU bed time the consumer noise generators are shut off, more hams are in bed and the bands seem to open to NA. A good part of EU is also under the auroral curtain at times which adds to the band noise and signal attenuation. Whatever real or imagined propagation anomalies exist just add to the problem. The only cures I know of are running a remote TX a lot closer to EU; or a tube with handles and a 10dB+ boost over 1500W such as he who is often complaining about others comments on here. Carl KM1H - Original Message - From: k...@frontier.com To: topband@contesting.com Sent: Monday, December 03, 2012 1:09 PM Subject: Topband: one-way propagation Jim K9YC asked about other possible mechanisms besides atmospheric noise to account for one-way propagation on 160-Meters. For the record, I also believe atmospheric noise (and even man-made noise as experienced by the PT0S ops) is a big player in these observations. By the way, I also would like to extend a big THANK YOU to the PT0S ops, especially for their topband effort. One-way proapgation was an interesting topic in the AM broadcast industry in the 1970s (I do not know if it still is). The issue was tied to allocation of frequencies and the difference in loss depending on whether it was an east-to-west path or a west-to-east path. John C. Wang of the FCC measured signal strengths of 18 MF broadcasting stations (540 – 1630 KHz) at 4 receiving sites throughout the continental US to compare the measurements to the CCIR model. Subsequent analysis of this data by Douglass D. Crombie of the Institute for Telecommunication Sciences in Boulder found that for paths between 200 km and 3000 km, the east-to-west path loss is some 9 dB greater than in the west-to-east direction. Further analysis shows this is highest for frequencies above 830 KHz. The data did not show any such difference on north-to-south paths and south-to-north paths. The second-to-last sentence in the previous paragraph suggests that the ionosphere, being immersed in the Earth's magnetic field, is anisotropic – in other words, the ionosphere looks different for RF going east-to-west versus west-to-east. But if you run ray traces with Proplab Pro (it includes the effects of the magnetic field and electron-neutral collisions) for both directions, you will see no significant difference – at least I have not for my runs). We have to watch it here, though – the model of the ionosphere in Proplab Pro is a monthly median model (as it is in all of our propagation prediction programs) – so it does not capture the day-to-day variability, which may be involved in these observations. So I believe there is a possibility that there are other mechanisms at play to give us one-way propagation. Unfortunately, as far as I am aware, we do not understand them. Carl K9LA ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5434 - Release Date: 12/03/12 ___ Topband reflector - topband@contesting.com
Re: Topband: QRP/Poor antenna stations ARRL160
I made roughly 40-50 sporadic contacts using a 1939 Meissner VFO at 5-6W and
a 1934 National FB-XA, didnt even log them. Nothing spectacular since I
wasnt interested in staying up past 10PM (-; Antenna was the inverted vee
at 180'; it was too early for the vertical based on a few A:B listenings.
The Beverages with a BCB filter helped the very basic mixer (no RF stage)
front end considerably.
Carl
KM1H
- Original Message -
From: DAVID CUTHBERT telegraph...@gmail.com
To: Bill Stewart cw...@embarqmail.com
Cc: topband@contesting.com; jon jones n...@hotmail.com
Sent: Monday, December 03, 2012 4:19 PM
Subject: Re: Topband: QRP/Poor antenna stations ARRL160
N6VW reports driving 5 watts into his apartment plumbing against the AC
system ground and making a couples dozen QSOs in the 'test.
Dave WX7G
On Dec 3, 2012 9:19 AM, Bill Stewart cw...@embarqmail.com wrote:
Jon,
Good job with a minimal setup.
I worked ten stations using my homebrew 1924 4-coil Meissner osc,
using a C-301A tube ('24 vintage) at about 4 watts input (maybe 1.5 out).
The antenna was a 160m off ctr fed hertz, now called a windom, at 35ft.
Most of the stns I worked were in PA, TN and FL. Hope to be squeaking
this
w/e in an AWA event. Great fun.
73 de Bill K4JYS (NC)
- Original Message -
While not running QRP, my antenna in the ARRL 160 was loading up the rain
gutter on ourone story rental duplex in Lawrence, KS. Maximum height is
about 10 feet above ground, a marginalTop Band antenaa at best. I set up
to
hand out some contacts in the contest. Oddly, it loaded easilywith a MFJ
tuner. N0TT, N0NI, W0SD, AA1K and about 80 other stations heard me,
most
on first or second call Saturday night. Best DXwas probably KA6BIM/7 in
Oregon. Good ops and patient with the weak signal crowd. I found it
easier
to work stations after mid-night as many of the big ops were hungry for
QSOs. Butseveral stations were not worked who kept calling CQ over and
over
with almost no time listening...
- N0JK
Some harder than others. W0SD gave my QRP signal a real good try early
in the evening, but couldn't get the exchange. I'll certainly try again
tonight. N0TT and N0NI heard me almost right away, but it took some
repeats to get in their logs. They were my best DX last night. I worked
several NM stations, but WD5COV, even when on his 20 over S9 west-facing
TX antenna, never gave me so much as a QRZ for the several dozen times I
called, and had his auto CQ set for a very short recycle time.
If you're going to work weak signals, both sides of the QSO need
patience, operating skill, and good ears. There are FAR too many
alligators on the band. Doing the math, 20dB down from 1.5 kW is 15
watts, and a 5W signal would be S8. If your noise level is S8, IMO, you
have no business running 1.5kW! - K9YC
___
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-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1427 / Virus Database: 2634/5434 - Release Date: 12/03/12
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Re: Topband: F fitting adaptors
Ive been using those adapters since the 80's when they first showed up and all were imports I believe. Used outdoors they dont all weather well externally but have made reliable connections even when on the old RCS-4 for 20+ years and shielded from direct percipitation. Some appear pitted as in old pot metal! The only problems Ive had were from tightening too tight with pliers that the outer shell popped loose. Another was on RG-6 feeding an 80M sloper at up to1200W for many years with no problem... it was a temporary antenna with no tape on the connectors that survived about 13 years until the cheap store bought center insulator/balun fell apart thanks to plain old steel eyebolts. Carl KM1H - Original Message - From: Bruce k...@myfairpoint.net To: topband@contesting.com Sent: Monday, December 03, 2012 10:24 PM Subject: Topband: F fitting adaptors When using a Ameritron remote antenna switch with SO-239 fittings, does anyone know a supplier for female F fitting to PL-259 adaptor ? Thanks, 73 Bruce-K1FZ ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5434 - Release Date: 12/03/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
Mike, Im pretty sure a group buy would convince the manufacturer to sell them. Supposedly an Ebay seller has an exclusive but since our use is non competitive to his SWL and cave dweller ham customers it could be negotiated. The large diameter steel ones work well but rust away in 15-18 months in this area of acid rain and salt water fogs. Using spray cans of Rustoleum, etc would be time consuming and likely needing periodic touchups. Plus the steel further slows down the incoming wave so it might not be possible to build an effective 1 wavelength + version. I had 5 stretched over about 175' and calculated a Vp of .57 but it sure worked gangbusters for those LP sunset signals over Africa. For many I was the only US station working them and the almost total lack of even EU QRM was a huge advantage. Switching to a 750' regular Beverage pointing right down the Med heard only a EU din; I'll let you estimate the F/S rejection of the Slinky. Using a high frequency local BCB station right off the back the null was at 1250-1300 Ohms using a 2K pot and replaced with 3 x 3900 Ohm 2W carbon resistors. Id guesstimate the general F/B to be over 20dB on 160. My feeling is that performance could not be duplicated by various other loading methods. If somebody wants to make real world comparisons it might be beneficial. Carl KM1H - Original Message - From: Mike Waters To: ZR ; topband Sent: Saturday, December 01, 2012 2:41 PM Subject: Re: Topband: Beverages 2 basic questions Please let us know how that works, Carl. I'd love to experiment with a Slinky. If brass Slinkys aren't available anymore, then we could wind one from some #14 or #12 solid copper wire using a long piece of plastic pipe as a form. Close-wind it first, then stretch it to the desired (?) pitch. 73, Mike www.w0btu.com On Sat, Dec 1, 2012 at 9:52 AM, ZR z...@jeremy.mv.com wrote: Next year Im planning to try a couple of Slinky Beverages again in order to get a 2-3 wave electrical equivalent for particular paths and narrow the beamwidth No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5430 - Release Date: 12/01/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
The same holds with loaded element yagis. Gain decreases due to RF losses but directivity is the same using the same boom length and number of elements as a full size version. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Saturday, December 01, 2012 2:47 PM Subject: Re: Topband: Beverages 2 basic questions It does? http://www.w8ji.com/slinky_and_loaded_beverages.htm Maybe Tom and Carl are both in on this conspiracy. ;-) 73, Mike www.w0btu.com On Sat, Dec 1, 2012 at 1:34 PM, Bob Eldridge eldri...@direct.ca wrote: You know very well that only the physical length matters for narrowing the lobe. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5430 - Release Date: 12/01/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
- Original Message - From: Eduardo Araujo er_ara...@yahoo.com To: topband@contesting.com Sent: Sunday, December 02, 2012 12:48 AM Subject: Topband: Beverages 2 basic questions Many thanks Dean, Carl, Mike, Joel and the rest of you who shared your opinions about why so many, probably I missed the point that 3 or 4 db in directivity loss because of deeps is much more important that I figured out and that could make a difference in a QSO or not. Keep in mind that without considering a very few stations, being in LU land I am really far away from all highly ham populated zones About my second question.. no takers ?? I repeat it here again just in case I modified the text of the second test for more clarity Is there a meaninfull or simple way to determine if at my location is worth to go from 600 to 900 feet? Ive no idea what the propagation data for signal arrival angles are for Argentina of if they even exist. To say its similar for US to AF as it is for LU to EU as an example would be guesswork. My suggestion would be to install a longer one and make A:B comparisons. Since a Beverage is non resonant distance seperation doent have to be extreme, 30-50' should be fine. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
- Original Message - From: Tom W8JI w...@w8ji.com To: topband topband@contesting.com Sent: Sunday, December 02, 2012 12:46 PM Subject: Re: Topband: Beverages 2 basic questions resistors. Id guesstimate the general F/B to be over 20dB on 160. My feeling is that performance could not be duplicated by various other loading methods. If somebody wants to make real world comparisons it might be beneficial. I looked at slinkys when I lived in Conyers. None of this is magical or difficult, nor are antenna slinkys or helical loads special. ** After I brought Slinkys up on the forums and on 160 in the late 80's and 90's. Your comments then were just what I expected. The behavior is the same as a series of lumped inductors spaced fractional wavelengths along the antenna. ** Maybe on paper which is why Ive asked others to make the real world comparisons. I find it hard to believe that a wire being randomly interrupted by a lossy lumped inductance plus capacitance can privide identical results. There is a certain optimum phase shift along an antenna's length. There are many ways to accomplish that, and if the resulting current distribution and phase is the same the results will also be exactly the same. ** Nothing beats a helice for a loading device for a steadily progressing phase shift. No guesswork needed. It even worked for high gain UHF transmitting antennas. Sometimes, like with long antennas fired away from the feedpoint, we don't want that delay. We actually might need a phase advance. ** Thats not related to the subject under discussion. The only thing magical about slinkys is how they can go down steps without feet, and without holding on to the banister! I never have figured that out. ** No magic involved in how they work as an antenna or as a toy, the toy part has been thoroughly explained ages ago. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
In addition not all signals come via the direct Great Circle bearings for SP or LP, at least here in NH which is at a fairly high latitude. Having an extra direction or more such as over Africa for skewed paths has helped add a new one or an extra contest multiplier several times. Next year Im planning to try a couple of Slinky Beverages again in order to get a 2-3 wave electrical equivalent for particular paths and narrow the beamwidth to get rid of EU noise. Carl KM1H - Original Message - From: Joel Harrison w...@w5zn.org To: Eduardo Araujo er_ara...@yahoo.com Cc: topband@contesting.com Sent: Saturday, December 01, 2012 9:15 AM Subject: Re: Topband: Beverages 2 basic questions Eduardo - your arrangement should work well, especially if you place the main lobe into areas of interest and the nulls are into regions of no activity (or noise sources). It is a good general setup. Everyone may have their own specific reason for utilizing multiple Beverages, but mine is very simple. I have nine Beverages that are targeted to specific areas for specific reasons; End fire Bev's on Europe, one to JA, one to the Caribbean, one S-SW for LP/skewed Gray Line to the far east, and so forth. The reason is while a Beverage in a general direction will work well, in contest times or times when you are trying to pull a very weak DX station out of the noise that extra 1 dB in pattern improvement from the Beverage being aimed at a very specific area may make the difference between a completed Q or a failed one (of course the noise reduction from other directions is key). Others may have varying reasons that are just as valid. Your setup should work well, especially after you install it and begin comparing signals and making future improvements. My arrangement works well for me here in Arkansas but is the result of 20 years of tweaking, rebuilding, reconfiguring, and comparing different RX antenna arrangements and your efforts will allow you to analyze how things perform at your QTH. GL. 73 Joel W5ZN On Fri, Nov 30, 2012 at 1:46 PM, Eduardo Araujo er_ara...@yahoo.com wrote: Dear Topbanders, I am planning my next move with the beverages and I would like to hear your opinions about 2 areas. Looking at the pattern response for beverages in for example ON4UN book, I found that If I install 4 x 600 feet or 5 x 900 feet beverages, I should cover 360 degress with deeps of no more than 3 or 4 db respect the main lobe. Taking into account that most people will not work extra without any benefit my first question is: 1 - Why many DXers and contester install 10 or 12 direction beverages ?? What am I seriously missing with my simple analysis? 2 - Is there a meaninfull or simple way to determine if at my location is worth to go from 600 to 900 feet? I did some measurements a) I injected a signal into the beverage and using a current probe, I meassure signal strength in an Smeter.(I replaced the mA with the input of a transceive) Variation was about 10db from begining to end of 900 feet. Curiously the 600 feet one gave aprox same result but I recognize S meter granularity was not good. b) I disconnected termination resistance and the signal stregth with or without it was 8db. 900 feet Bev gives about 20db F/B in broacast band Many thanks in advance to all ___ Topband reflector - topband@contesting.com -- 73 Joel W5ZN www.w5zn.org ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5430 - Release Date: 12/01/12 ___ Topband reflector - topband@contesting.com
Re: Topband: November 30-December 2 -- ARRL 160 Meter Contest
- Original Message - From: Tree t...@kkn.net To: Eddy Swynar deswy...@xplornet.ca Cc: TopBand List topband@contesting.com; he...@vitelcom.net Sent: Friday, November 30, 2012 9:32 AM Subject: Re: Topband: November 30-December 2 -- ARRL 160 Meter Contest On Fri, Nov 30, 2012 at 6:07 AM, Eddy Swynar deswy...@xplornet.ca wrote: At that time, I established a dialogue with one of the committee members who was situated in western Canada: as I recall, Frank had success in expressing his concerns to him, but I don't recall the outcome of your efforts. Did you, in fact, make a connection to the CAC through that particular window of opportunity...? CAC members have a fairly limited role in situations like this. They are only called in to advise on specific questions that are handed down from HQ. They then go off and collect data on those questions. Think of them as survey coordinators who collect data from members of their division and roll that up into a report that goes back to HQ. The ARRL160 isn't everyone's cup of tea. It does however have a fairly long history as being an event that gets people in the USA and Canada fired up and on topband.. It is sort of like the ARRL Sweepstakes - but only on 160 meters. DX QSOs are allowed - but it isn't an international contest really. It is a very boring contest from Zone 21 for example. If we engineered all contests to be perfect from one perspective - all contest would end up being the same. I don't think it is that bad of a deal that we have three different 160 meter contests that are all different - and you can decide which ones are the ones you want to participate in. If you feel there is something missing from this equation - I invite you to sponsor a 4th one and then see if people vote with their feet and participate in the event. 73 Tree N6TR I look at it as only a WAS contest and like to see how many times I can complete it at different power levels. Operating is strictly search and pounce. Still havent done it at 5W and doubt I ever will from out here in NH. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: High noise with Rx antennae
So what does your car radio say to you set to a quiet spot at the top of the AM band? Have you eliminated your own property by killing all power and run the K3 on a battery? Carl KM1H - Original Message - From: Gary Smith g...@ka1j.com To: Topband@contesting.com Sent: Thursday, November 29, 2012 1:03 PM Subject: Re: Topband: High noise with Rx antennae yes it is, although the quietest directions are to the N, NE NW which would make those directions the worst if it were the rail lines. I'm finding that the Rx triangle has more noise than the 160 Inv-V and that doesn't make sense to me yet. I don't use a pre on the low bands sometimes use an attenuator. Gary KA1J Is that rail line electrified? Carl KM1H - Original Message - From: Gary Smith g...@ka1j.com To: topband@contesting.com Sent: Thursday, November 29, 2012 11:52 AM Subject: Topband: High noise with Rx antennae I'm hearing a lot of noise with my triangle array. I was hearing it close to the house so I relocated 100' away albeit 10-15 feet lower. Unfortunately I can not put it in a clearing and there are trees around it, I cut down several that were within 10' of the elements. I am using flooded coax and the snap on terminals. I replaced all the terminals but this did not change the problem. I am getting directivity and to the south along the road I hear an increased background noise where home electronics may be a source of noise. What I hear sounds like electrical noise, nothing digital sounding but moving the antenna didn't help much. By necessity, the transmit antenna is 75' away and some of the 130' radials on the ground run fairly close to the Rx array. I find the inv-l to be sometimes less noisy but the triangle will often pick up a signal the vertical does not (albeit with greater background noise). I'm using a K3 with sub Rx and the AF control is rarely turned more than 15 degrees. Playing with Rf levels, AGC, noise blanker, noise reduction seems to help overall and Sometimes I run with no AGC at times too but it doesn't deal with the high background noise. I'm wondering if shortening the elements would have a positive effect on reducing the noise level? Here is a view of the QTH. My house is the last one, at the end of the road next to the rail line. I am sandwiched between two state parks. Other than Amtrak being beside the house and the people on the road south of me, there is no other house or signal generation within a mile. http://tinyurl.com/cy7zv7h Thanks for any suggestions. Gary KA1J ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5426 - Release Date: 11/29/12 ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5426 - Release Date: 11/29/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Detuning shunt fed towers
Ive never had a quality UHF arc even with a 5:1 VSWR of either sign at 1200-1500W. Never tried an import. Carl KM1H - Original Message - From: DAVID CUTHBERT telegraph...@gmail.com To: John Harden, D.M.D. jh...@bellsouth.net Cc: topband@contesting.com Sent: Thursday, November 29, 2012 1:30 PM Subject: Re: Topband: Detuning shunt fed towers A UHF connector won't flash over at 1500 watts if the VSWR is low. Dave WX7G On Nov 29, 2012 9:04 AM, John Harden, D.M.D. jh...@bellsouth.net wrote: I have a 100 ft 45G, shunt fed tower with stacked monobanders for 80 -10 meters. This includes a 24 ft mast with 12 feet out the tower top. I do not even worry about detuning it. The shunt (4 wire) cage only goes up to 30 feet due to monobanders down to about 35 feet. It requires a 2000 pfd vacuum variable in series and a 1000 pfd vacuum variable to ground (Omega match) to resonate the system. The series capacitor is motor driven by a 1 RPM, 12 VDC motor. The SWR remains flat over the band measured at the match and in the shack. I have right at 40 radials on ground. At this point the curve becomes asymptotic.. With an Amphenol Type HN connector there is never any flashover. SO-239's did not cut it. Type N is even worse. My Hi-Z 4-8 PRO RX antenna is over 100 feet away and there appears to be little interaction. If you do the math there should be interaction but there is so little real interaction that I simply disregard it The guys at Hi-Z will tell you there is very little difference between the 4-8 PRO and the 8 el array that is in a 200 ft diameter circle. They have both up. The decrease in beam width between the two is inconsequential to me I can now hear about anything that is on compared to others in my area, and can work it quickly if I can hear it. The Hi-Z array is that good The waters of the sea have parted for me on top band. 73, John, W4NU K4JAG (1959 to 1998) __**_ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5426 - Release Date: 11/29/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Beverage on Ground
- Original Message - From: Ashton Lee ashton.r@hotmail.com To: topband@contesting.com Sent: Thursday, November 29, 2012 1:20 PM Subject: Topband: Beverage on Ground No, I didn't spill my beer. But I am having very good experience with the roughly 300 foot Beverage on Ground that I just put in at my house. It is fed through a 300 ohm transformer and runs in the only direction where I can get a 300 foot run. It is made of insulated #14 wire and unterminated, as I would prefer a more omnidirectional pattern since I can have only the one compromise receive antenna. Also I couldn't get a ground rod in to experiment with. In Western Colorado we aren't all that big on soil… but we sure have great rocks. ** I also live on a rocky hilltop as opposed to a CO mountain and currently have 3 500' BOG's in place mainly for 160 and to minimize neighbor noises. I also have 5 two wire reversible regular Beverages of 500-750' wandering thru the woods. So far the BOG out receives both a K9AY I had up briefly (which, of necessity, was probably too close to my transmitting antenna) and a tuned loop I tried. ** That is no surprise. Now I want to put up a similar antenna on the remote hilltop where I have a cabin and contest site-lite. That location is ideal for transmitting antennas since it is on the absolute top of a mountain with cliffs down to the North and East of the property, and steep hillside to the South and West. But it makes running Beverages a bit of a trick. I also have 200 elk running around so it isn't easy to install wires above ground. This whole place is on rocks dusty soil where getting any sort of grounding requires a jack hammer. So I want to install one or two BOG's there as well. Which prompts several questions: 1) Should I again use insulated wire or can I use the cheap electric fence wire I can get at our ranch coop? ** Absolutely. There is enough low ground cover here that the BOG's are actually a few inches above the forest top soil which is only a few inches thick and the bony sand another foot or two to solid rock. That slight elevation seems to make a difference since they work decently to 40M; no preamps. 2) How do I get enough signal to noise without getting excessively directional. Is there anything like an optimal length for a less directional BOG? ** Each location will be different, experiment until you find a sweet spot. 3) My first experimental BOG works much better on 160 than 80. Is there anything unusual about that or that I should do differently? ** Likely the ground coupled losses have caused 80M to be electrically too long due to the reduced velocity factor. Mine seem to be sharper than an elevated Beverage on 80 and while 40M is down it is very useable. 4) I have essentially no local noise in either my regular home or at the cabin. So I am mostly concerned with suppressing atmospheric noise. Any implications for that in my design. ** Ive all sorts of noises so just try to maximize F/R rejection and or local noise pickup off the front. Havent tried a 2 wire BOG yet. I know that both my current and my contemplated antennas are sub-optimal. But a lot of what you have to do on 160 is less than optimal if you live anywhere but a large farm. The first test antenna is working so much better than receiving on my transmit antenna that I think sub-optimal antennas, of a reasonable quality, can work pretty well for me. ** The best thing to do is read a wide range of whats published on here and elsewhere. Dont get caught in the trap where a small few are always complaining about what others do and report. Someone on high conductivity pasture land doesnt have the experience to say what happens on a rock pilecomments are only guesswork. According to them I shouldnt be able to hear or work anything (-; but Ive never had the luxury of anything except the worst possible New Hampshire soil. Incidentally for anyone experimenting with BOGs I am using an old MFJ active antenna tuner on the antenna I just built. It serves as a preselector and possibly a preamp it would seem. It gives me better performance than sending the antenna directly into the rig. One always suspects that if an MFJ product works OK there could be something else which would work a lot better. But early days so far. So far the BOG really cuts down on the noise while giving me enough signal. ** Just keep experimenting until YOU ARE satisfied. I even tried a Johnson KW Matchbox 30 years ago on a Beverage for 40/80M; didnt have a 160M TX antenna or amp capability then. After all the help I got yesterday with one antenna question I was prompted to ask another. KQ0C Ash ** This site is a great resource. Carl KM1H ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5426 -
Re: Topband: 2 wire beverage question
Sounds like a problem many would love to have! When you say they work best at 1-3' how exactly do you mean and what are the antenna details? Getting more info on what others use is always good. Carl KM1H - Original Message - From: Richard (Rick) Karlquist rich...@karlquist.com To: Mike Waters mikew...@gmail.com Cc: topband topband@contesting.com Sent: Thursday, November 29, 2012 6:06 PM Subject: Re: Topband: 2 wire beverage question On 11/29/2012 8:14 AM, Mike Waters wrote: Rick, Why don't you just mount them on permanent posts (or trees) 10' high? That's what I and many others do. That ought to let you mow around them without taking them down. My support posts are 100' apart. Thanks for the suggestions, but... First, I have found that Beverages work better at 1 to 3 feet off the ground than at 10 feet. Second, while mowing around the posts is better than having to go around the whole wire, it is still too much of a hassle. I am using a brushhog, not a zero turn radius mower. After mowing, I would have to use the weed whacker around the posts. Third, I am planning to disc the area next year, so I would have to take out the posts. The beverages are basically in a treeless area. 73 Rick N6RK ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5426 - Release Date: 11/29/12 ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
- Original Message - From: Tom W8JI w...@w8ji.com To: topband@contesting.com Sent: Wednesday, November 28, 2012 10:49 AM Subject: Re: Topband: 2 wire beverage question ON4UN states in his book that the wires for a 2 wire reversible beverage must be installed side by side, but also may be placed one above the other with satisfactory results. Did someone try this? How satisfactory is satisfactory? There is no difference at all. If the feed system is right, and the line is properly constructed, it would all work virtually the same. It does not matter if one wire is above the other, or if they are side-by-side. Absolutely the best construction method would be a twisted or transposed line, twisted or transposed at fractions of a wavelength, but even using the best twisted or transposed installation it would be difficult to tell from an untwisted line if the conductor was very close spaced (a few inches or less). What does make a difference is the wire used, and how the line behaves as a transmission line. I would not use telephone, insulated wire twisted pair, or field phone wire, because they are very poor transmission lines that are lossy and heavily affected by water. ** Ive noticed no difference in any weather using field phone wire which happens to be in wide use by many very competitive contesters and lowband DXers. With 5 2 wire reversibles here and 750' of 1/2 feedline there is no need for a preamp. The galvanized thin fence wire you often champion is also lossy. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
Subject: Re: Topband: 2 wire beverage question ** Ive noticed no difference in any weather using field phone wire which happens to be in wide use by many very competitive contesters and lowband DXers. With 5 2 wire reversibles here and 750' of 1/2 feedline there is no need for a preamp. I'm talking about: 1.) impedance change 2.) reactance caused by loss Since the impedance presented at the far end of the antenna (in termination mode) varies with weather and is reactive (with high and variable dielectric losses), termination can be unreliable. I think you worry too much about minor things, even the much more expensive 450 Ohm window line is affected by rain. Spend more time establishing good ground connections and less worrying about rain. Maybe that's why you think I have a remote receiver :-) ? ** Ive no idea what that is supposed to mean? The galvanized thin fence wire you often champion is also lossy. That's an apples and oranges comparison. First, I don't champion galvanized wire. That aside, there is nothing wrong with using it in normal Beverages of reasonable length. ** You have suggested its use many times. It is not terminating the system for F/B, and the termination impedance and loss does not vary with weather. ** So now you have modified your stance by saying not to use it for a 2 wire Beverage? I wonder what the loss of steel fence wire and WD-10A is per 100' at 160M?. At $40 for a new 2.5km reel of WD-10A Im not about to let a little rain bother me even if it did upset things a bit which I doubt is enough to be noticable anyway. Carl KM1H Carl KM1H ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2629/5424 - Release Date: 11/28/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Where to ground the Beverage feedline?
As Ive mentioned here many times I started by removing noise sources around the house as well as at a few cooperative neighbors. That involved Mix 33 1/2 x 7.5 rods and 43, 75 and 77 mix 2.4 toroids. Ive been doing this for decades at 2 homes and long before most of the current crop of noise suspects were even on the market. That work continues and I can get up and personal with a battery radio to each part I suppress as well as listen right at the AC panel. The main feedline is 750' of 1/2 CATV hardline thats been in place since late 1989 and is checked a few times a year with a 75 Ohm CATV load at the far end. It is always dead quiet with just a single 4' ground rod driven at an angle about 30' from the switching hub and then another about 100' the house where it goes elevated over the lawn and down into the house using RG-6 quad shield for the final 25' into and inside the house. The switch is a RCS-8 with 750' of elevated unshielded control wires with a big 31 toroid about every 100' since its in a narrow strip about 30' wide between the N/S Beverage and the ends of elevated radials for 80 and 160. It was fine without them on the ground but not at 6.5' tacked to trees where RF triggered relays at times and seemed to couple noise into the Beverage. At almost $7 a pop from Mouser it was a pricy educationbut the 1000' reel of wire was free maybe 20 years ago. Amidon prices are a rip off. Another relay hub is fed with twin runs of elevated RG-6 quad from two more 2 wire bi directionals and about 250' and 200' of coax. No ferrites at all on any feedline and the 73-202 transformers are using the dual sleeves (4 per core) Ive also championed here to provide minimal coupling C. All Beverages have their own antenna ground rod and radials at both ends as well as a rod before the relay boxes for the last 2 mentioned. Some Beverages at the rear relay box start only 10-30' from it so Ive used only 2 4' rods about 8' apart at the box for all 8 feeds. All unselected feeds just float, no resistors used but doesnt seem to hurt anything; relays likely have enough isolation and there is no daisy chaining thru multiple relays as did the old RCS-4 Carl KM1H - Original Message - From: Herb Schoenbohm he...@vitelcom.net To: j...@audiosystemsgroup.com Cc: topband@contesting.com Sent: Tuesday, November 20, 2012 12:00 PM Subject: Re: Topband: Where to ground the Beverage feedline? Only if this before buying all those expensive 3' Type 31 Ferrite Rings I could have saved some money. I though that having many 250-350 foot lengths of RG-6 feedlines running all over the radial system (ROG's or radials on the ground) as well as having nearby 80 and 40 meter verticals that during some contests where I am operating on 160 and a guest is operating via remote control on 80 and 40, that trapping as much RF from the Receive Only coax shields made sense. on some Beverages I would get a de-sense making copy of weak signals very problematic. So I installed 12 turns on a 3 inch ferrite on both sides of a common ground bus and several ground rods outside and about 20 feet from the shack. I also have inline a KD9SV band pass filter with the Beverage bank output and now it is possible to co-exist with other operators on higher bands running full power. Maybe getting a higher quality flooded coax meant for direct burial would have been a better way to go but this is not convenient with the low cost of cable TV RG-6 even here. The coax shield at the feed transformer on both the single wire and reversible Beverages is not grounded, only the Beverage side secondary has a ground connection. So now I am not sure if I have really been wasting time this way. f it helps the debate I plan to take a very noisy Chinese switching supply running from a car battery and an 800 watt inverter and lay it running on several RG6 runs coming back to the shack at about 200 feet away while checking the difference in noise reduction. I thought that these toroid rings, although expensive, would buy me so isolation from cable induce noise, whatever the source. Winding some turns through these toroids of the AC power cable on the wife's entertainment center as made all IX vanish in the living room. But if it was wrong to buy all these type 31 ferrite rings, keep you eyes on e-Bay soon. Herb, KV4FZ On 11/20/2012 12:44 AM, Jim Brown wrote: On 11/19/2012 12:25 PM, Tom W8JI wrote: If the feedline is bonded to the same ground on both sides of the choke, any choke would do no good at all. It would be shorted. I was not suggesting the same ground electrode, rather widely spaced electrodes. 73, Jim K9YC ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version:
Re: Topband: Toroidal common mode choke
- Original Message - From: Jim Brown j...@audiosystemsgroup.com To: topband@contesting.com Sent: Saturday, November 17, 2012 1:12 PM Subject: Re: Topband: Toroidal common mode choke On 11/17/2012 9:12 AM, Bill Conwell (home) wrote: I've seen articles that studied the optimum number of turns for air-core chokes, but don't recall seeing any for toroidal chokes. Can anyone offer a pointer (or empirical data) that might guide me. (20 turns?) See http://audiosystemsgroup.com/RFI-Ham.pdf which includes both measured data for many choke configurations and core materials, and specific recommendations for winding transmitting chokes for the ham bands. For 160M, Fair-Rite #31 material is the weapon of choice, and 16 turns of a pair of #12 enameled wire (connected a parallel wire transmission line) makes a very effective choke for 160M and 80M, with Zo on the order of 50 ohms. #12 THHN works as well on 160M and 80M, and has bandwidth good to at least 20M, with Zo of about 100 ohms. If that level of mismatch concerns you, remember that it's only a few feet of line, less than 1/200 of a wavelength at 1.8 MHz. 73, Jim K9YC The question was for RG-58. Have you made tests using that and published it? Also the difference between Mix 31 and 43 is not great and was used for decades successfully before 31 was introduced. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Vertical Array Over Uneven Ground
- Original Message - From: N1BUG p...@n1bug.com To: ZR z...@jeremy.mv.com Cc: topband@contesting.com Sent: Thursday, November 15, 2012 6:58 PM Subject: Re: Topband: Vertical Array Over Uneven Ground I suspect most Americans are more comfortable with our own measuring system plus our ham bands where antenna formulas are still published in feet and inches. I suspect most (or at least many) Americans are resistant to change and unwilling to give anything different than what they are used to a fair try before dismissing it. When I don't have to deal too extensively with materials made to specific sizes for the U.S. market, I do much of my measuring and work using the metric system. Why? Because once I got used to it, I find it much easier to work with. My notes on projects going back over 20 years usually give dimensions in metric (eg. plate line dimensions for a VHF amplifier in millimeters). I have grown somewhat weary of converting to another system just so that other Americans won't grumble about my choice of units. I may stop that practice. If other Americans don't understand the measurements and can't be bothered to do the conversion, they probably don't really want/need the information. Paul I guess you never heard When in Rome, etc. If those from other countries want to partake on Topband my feeling is they can do the conversion on their end or they dont really want the information. When I join a European forum or look for info on one of their websites it is I who then do the conversion.without complaining. I can work well in metric, I just choose not to when I dont have to. I have no problem using thousandths, or any decimal version, of an inch for any VHF to microwave application, (or all automotive engine and driveline building) my Starrett and other Made In The USA precision measuring instruments work fine, thank you. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Covered /bare antennn wire
From my own exhaustive research and many lab experiments with HV corona discharge, it seems to me that at least some of this could be eliminated by either: 1. Eliminating all the sharp points 2. Properly covering all the sharp points with suitable insulation such as heat shrink or vinyl caps. You just might have nailed it Mike, congratulations. In order to keep the vibration damping ropes in place the yagi element ends have Caplugs and/or a couple of wraps of Scotch 88, I did not do that with the KLM 40M which finally was removed to be fodder for a HB 2/2 Cushcraft/Leeson clone. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Covered /bare antennn wire
The T Match tuner is what sits in the house Price. The T Match feed on the antenna is completely different, is grounded to the boom on the all metal design and is no more prone to P-static than any other feed system. My own yagis use a T Match from 28 to 432 MHz and work very well and without the pattern skewing of the gamma match. Carl KM1H Carl KM1H - Original Message - From: HAROLD SMITH JR w0ri...@sbcglobal.net To: Tom W8JI w...@w8ji.com; John Langdon jlang...@outer.net; Bruce k...@myfairpoint.net; topband@contesting.com Sent: Friday, November 16, 2012 4:42 PM Subject: Re: Topband: Covered /bare antennn wire Very true Tom, I am using on 20 meters a Telrex 20M546. The Telrex uses a T network. The T bars are very close to the driven element and longer than normal. They use no series capacitors. Or should I say condensers as they were called when Mike Arcelino designed the Telrexs. 73 Price W0RI The only noise caused by an element charging is a pop or arc as the element moves closer to air potential, until the voltage is high enough to break down some insulation path to earth. This is a huge problem with T network antenna tuners that feed big antennas without a ground leak path. The antenna trickle charges the output capacitor (with microamperes of current) until the cap flashes over. This sudden rings the tank with high voltage, and that blows the diodes in the directional coupler detector. We certainly do not want things to charge to the point something flashes over and is damaged, but a ground leak does not reduce p-static (corona) noise. A ground leak does not reduce the chance of a lightning strike, either. Neither do those tower whiskers (NASA has extensively tested that). 73 Tom ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5398 - Release Date: 11/16/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Vertical Array Over Uneven Ground
Not that Ive noticed. I suspect most Americans are more comfortable with our own measuring system plus our ham bands where antenna formulas are still published in feet and inches. Carl KM1H - Original Message - From: Pete Smith N4ZR n...@contesting.com To: topband@contesting.com Sent: Thursday, November 15, 2012 6:14 AM Subject: Re: Topband: Vertical Array Over Uneven Ground CU on the 525 foot band, Carl? Seriously, I suspect that the reason why many of us work in meters when modeling is simply that some of the most useful software products default to that. 73, Pete N4ZR Check out the Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com. For spots, please go to your favorite ARC V6 or VE7CC DX cluster node. On 11/14/2012 3:48 PM, ZR wrote: I cant find the button to convert that metric stuff to good old USA measurements when posted from this country(-: Subject: Re: Topband: Vertical Array Over Uneven Ground I never found a way to model an an antenna over anything but flat, level ground. Not in EZNEC+ 5.0, anyway. 73, Mike www.w0btu.com On Tue, Nov 13, 2012 at 7:41 PM, Ken Claerbout k...@verizon.net wrote: Has anyone modeled or have experience with a transmit vertical array, say a 4-square, over uneven ground? By uneven I mean a variance of up to 2 - 3 meters over the footprint of the array elements. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5394 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5396 - Release Date: 11/15/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Limiters - not T/R Relays
Ive made several contacts up to about 2500 miles (West from NH) running 100W into a single 750' #12 copperweld Beverage up about 8' using a FT114-43 autotransformer back in the 80's at a prior home. These were mostly on CW during contests; the terminator was a 600 Ohm 100W NI resistor and the #24 transformer wire still looked as new. Carl KM1H - Original Message - From: Rick Karlquist rich...@karlquist.com To: Brian Moran bria...@yahoo.com Cc: topband@contesting.com Sent: Thursday, November 15, 2012 3:16 PM Subject: Re: Topband: Limiters - not T/R Relays Brian Moran wrote: Some sort of saturable transformer design, like http://www.arraysolutions.com/Products/as_rxfep.htm ? What is interesting about this is that it uses T1-6 transformers, which I have been using and recommending for years for RX antenna use. I have repeatedly been told that these are no good because they will saturate at too low of a level and cause intermods, etc. The design cited is an existence proof that these transformers will work just fine in most situations. I'm only 6 miles from a 50 kW AM BC station and I have never had any trouble with T1-6 transformers generating spurs. I will note that the T1-6 has an especially large core, so it may be that the T1-1, for example, is not up to the job. FWIW, I accidentally transmitted into a beverage using a T1-6 transformer with 100 watts, and it did not burn out the transformer. Rick N6RK ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5396 - Release Date: 11/15/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Covered /bare antennn wire
Subject: Re: Topband: Covered /bare antennn wire As you have said it is difficult to get a A-B test unless instant switching or direct observation is available. The purpose of my test was to see if p-static was caused by individual charged particles as they hit the wire, or some other mechanism like corona discharge into the charged air or charged cloud of particles. My thought was if it was charged particles each making noise, the pitch or frequency distribution would be at the rate of particle contact, and that insulation should mute the effect by slowing rise time of charge transfer from particles to the wire. Clearly the noise was all from corona at sharp points. This also agrees with the effects people with multiple antennas see, or even two-way antenna on tall buildings or towers. The highest and most protruding antenna has the first and worse noise. Grounded elements, fiberglass housings, and other tricks make no difference at all. The only thing that matters is streamers from the exact point of corona leakage. We saw this when a repeater moved from side mount on a tower to a building roof peak. The fiberglass Station Master was swapped for a grounded folded dipole antenna, and both were equally useless in bad weather. The only thing that improved p-static noise was using an antenna well below the height of other sticks on the roof, but that didn't work out because of severe pattern nulls. We could raise the antenna and watch the noise increase, and at the same time actually hear the same sizzling acoustically through our ears and see it at night from antenna tips. Everyone with stacked monoband identical Yagis sees this on the top antenna. The top antenna is always terrible in inclement weather, even though the same precipitation strikes all antennas equally and the antennas are all on the same tower. This all, since it all always agrees, clearly means the noise has nothing to do with static drain or insulated or bare conductors. It is all about where the highest voltage gradient to space around the antenna is, and how easy that point can leak (generate corona). I was hoping for a test something like, side by side identical wires, one insulated, and one un-insulated with voltage measuring devices at the ends. Also separated enough not to get Beverage coupling, and using real stormy weather measuring. Over the insulation breakdown voltage, one would expect them to be equal anyway. Leakage current to earth was identical in my spray tests. It has nothing to do with insulation breakdown. It is more like the effect of a charged plastic comb. The charge obviously distributed right through the insulation. I suppose if the insulation was really thick the charge migration would be pretty slow, but charging of the wire is not what makes the noise we are concerned with. The noise comes from corona. I've had insulated wire Beverages and bare wire Beverages since the 1960's or 1970's, often at the same time as mixtures of wire. Neither is any quieter for me for local storm static. My bare wire Beverages here are dead quiet even while Yagi's are useless in foul weather, unless the Beverage points at the towers or are near tall trees. 73 Tom ___ Topband reflector - topband@contesting.com Before I moved here in 89 I had a KLM 4el 40M yagi at 120' that was very noisy during blowing snow and less in the rain. All elements were insulated from the boom. When I moved here (same town, 500' higher) the tower was initally 160'. I grounded the reflector and director centers to the boom using wide AL strap per KLM's suggestion. The dual driven elements then had low inductance heavy wire, very low DC resistance, chokes added (my own idea based upon what the USN did for receiver static) to each phasing line at the feed end and to the boom. There was nothing above it most of the time and those were a short experiment with a 20' boom 4el 10M (too high based upon 2 contests compared to the switchable 4 high stack) and a 34' boom 6el 6M (about 6 months) during the tail end of a sun spot cycle that did wonders on weak F2 openings. Another thing I did with that KLM at the new QTH was to toss their 4:1 voltage balun (it started acting up just before I moved) and build one from a 1/2 wave of coax and then added a big coax choke at the feed connector. All the changes were done at the same time so Ive no idea if any particular step did the trick or if it was cumulative. No more P-static as shown in the 40M scores in various all band contests. The 4 stacked 20M monobanders on the same tower below the 40 were silent as were the 10 and 15M stacks on other towers that had various VHF/UHF long yagis above them. Ive no idea if they helped or not. I would suggest trying various methods on 160 or other bands as the jury is still out on what works, when, where, and how. Carl KM1H
Re: Topband: Covered /bare antennn wire
Subject: Re: Topband: Covered /bare antennn wire Tom, Thank you for your research and information. You have me convinced My much lower BOG Beverage has a better signal to noise than my taller Beverages in storm events. This aligns to your research. 73 Bruce-K1FZ That has nothing to do with the P-static itself. The BOG is coupled closely to ground and the elevation angle signal lobe increases. I use elevated and BOG Beverages and see no correlation to P-static but the BOG's have much less local neighborhood crud which is vertically polarized; they always have a better SNR but do not hear the long haul pee weak DX at all most of the time. Both have their purpose in any weather. OTOH all my runs are thru deep woods and not wide open fields so maybe that is a factor. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Vertical Array Over Uneven Ground
I cant find the button to convert that metric stuff to good old USA measurements when posted from this country(-: Subject: Re: Topband: Vertical Array Over Uneven Ground I never found a way to model an an antenna over anything but flat, level ground. Not in EZNEC+ 5.0, anyway. 73, Mike www.w0btu.com On Tue, Nov 13, 2012 at 7:41 PM, Ken Claerbout k...@verizon.net wrote: Has anyone modeled or have experience with a transmit vertical array, say a 4-square, over uneven ground? By uneven I mean a variance of up to 2 - 3 meters over the footprint of the array elements. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5394 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
How do we know what it has with no schematic available? It could be $1-2 worth of parts. I recommend that nobody buy anything from DXE that does not support an at home repair. Carl KM1H - Original Message - From: Tom W8JI w...@w8ji.com To: Buck wh7dx wh...@hawaii.rr.com; topband@contesting.com Sent: Wednesday, November 14, 2012 8:07 AM Subject: Re: Topband: TX/ RX Antenna Switching By the way Buck, there is more to this than some people will tell you. The DXE switch uses a unique RF limiter that kicks in hard at about 23 dBm. Below that level there is no intermod at all!! It will not deteriorate the receiver, like normal cheap back-to-back diode systems. If you need a receiver limiter and do not want to hurt receiver dynamic range on modern receivers, it takes far more circuitry than cheap back-to-back diodes. 73 Tom ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5394 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: 8877 Tube
The only problem with pushing an 8877 or the 3CPX to or over the 4KV limit is that it enhances the chance of instability. Carl KM1H - Original Message - From: Paul Christensen w...@arrl.net To: topband@contesting.com Sent: Wednesday, November 14, 2012 7:23 PM Subject: Re: Topband: 8877 Tube Bob, A non-issue. Many of us have been running 8877s with Ep of 4KV. For example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the specified limit of 4KV. Some owners have been converting their 8877 amps over to the 3CPX1500A7 which has a much higher rated Ep since it was designed for pulsed service. Unless someone has access to a supply of pulse-rated tubes, I think it's waste of time unless the plate supply voltage is also increased. Paul, W9AC - Original Message - From: Chortek, Robert L robert.chor...@berliner.com To: topband@contesting.com Sent: Wednesday, November 14, 2012 6:56 PM Subject: Topband: 8877 Tube Wonder if someone can help with a technical question with the amp I use on 160 meters. The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. Any help would be appreciated. 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5395 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: 8877 Tube
The 5.5V is a ploy to get higher emission at the expense of operational life. It still has an 8877 filament. Eimac has been doing similar since WW2 with pulse versions of various tubes. Carl KM1H - Original Message - From: HAROLD SMITH JR w0ri...@sbcglobal.net To: Paul Christensen w...@arrl.net; topband@contesting.com Sent: Wednesday, November 14, 2012 8:10 PM Subject: Re: Topband: 8877 Tube Bob and Paul, The 8877 has a 5 volt filament. The 3CPX1500A7 has a 5.5 volt filament. Many have been running the 8877 and 3CPX1500A7 with a Peter Dahl transformer at over 4kV and they work fine. Eimac says that the filament should be 5.0 volts +- 5% or 4.75 to 5.25 volts. This should be measured with a True RMS voltmeter. A friend had high line voltage and his actual filament voltage was 5.5 volts. He had lost several tubes with an open filament. After he lowered the voltage to 5.0 volts he has not lost a tube. He used a Varistor in the secondary to each tube. The 77SX has 2 filament windings. Price W0RI Bob, A non-issue. Many of us have been running 8877s with Ep of 4KV. For example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the specified limit of 4KV. Some owners have been converting their 8877 amps over to the 3CPX1500A7 which has a much higher rated Ep since it was designed for pulsed service. Unless someone has access to a supply of pulse-rated tubes, I think it's waste of time unless the plate supply voltage is also increased. Paul, W9AC - Original Message - From: Chortek, Robert L robert.chor...@berliner.com To: topband@contesting.com Sent: Wednesday, November 14, 2012 6:56 PM Subject: Topband: 8877 Tube Wonder if someone can help with a technical question with the amp I use on 160 meters. The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. Any help would be appreciated. 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5395 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Outing The Scofflaws...
What gets me is the one who has a fantastic antenna farm but still has to resort to a tube with handles when he doesnt get thru right away with the store bought amp. The signal increase is dramatic and he is a regular on the forum. Carl KM1H It's like the guys we know who operate illegal power. Several of them are well known contesters, and some are well known 160 guys. Others are packet cheaters in contests. No one ever confronts these guys, at least directly...including me. I was once accused of using illegal power in contests, through a third party while I was out in KH6...untrue. However, the guy who made the accusation never came to me about it. Unless you are in the guy's shack while he's doing whatever offense it is, you never can know for sure if he is doing it. Result, it's hard to get in the guys face about it. Bill K4XS/KH7XS In a message dated 11/12/2012 4:37:05 P.M. Coordinated Universal Tim, p...@n1bug.com writes: This post may get moderated, but I will try it anyway. I question how many good operators would have the... [ahem] courage to out the offenders. As I say this I am thinking of one particular individual whose operating standards are consistently deplorable. This was often the topic of discussion on the DX chat sites until the individual in question joined the room. To my knowledge no one has ever said one word to him about his operating. He was simply welcomed with open arms. Honestly there is so much that goes on these days it makes me wonder if I really want to be a DXer any more. It is all too common to see remarks like this: I thought I heard him send two letters of my call so I sent a report. I will check the online log and see if I'm there. By my standards and what my elmer taught me, that is not a QSO even if he is in the log. I certainly would not count it. That's all I'm going to say on the subject of poor operating. 73, Paul N1BUG ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5390 - Release Date: 11/12/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Antenna analysers in close proximity to BC station.
MFJ sells a filter for that but I dont know how well it works around serious BCB RF; 10KW at the high end of the band in 2 directions in about 7-8 miles doesnt bother my unfiltered 259B nor do the FM and UHF TV sites about 2 miles away. Carl KM1H - Original Message - From: Chris G3SVL ch...@g3svl.com To: Tom Boucher t...@telemetry.demon.co.uk; 160 reflector topband@contesting.com Sent: Friday, November 02, 2012 6:42 PM Subject: Re: Topband: Antenna analysers in close proximity to BC station. At 21:21 02/11/2012, Tom Boucher wrote: .. but how to use the antenna analyser in the presence of a high BC station field. Anyone any ideas? Hi Tom, I have 2.4KW of MW BC transmitter 300m from the base of my 160m antenna, so I know the problem. I've found an ICE BC filter to be pretty good - but I've only ever used it to tweak a matching system, not to take absolute readings. I've used a loaned N8LP LP100A and that worked fine - but of course that's an entirely different measurement system. 73 Chris, G3SVL ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5369 - Release Date: 11/02/12 ___ Topband reflector - topband@contesting.com
Re: Topband: dipole height
I believe the original query was about transmitting effectiveness which is where the 15M and 60M heights of the original poster were suggested. Carl KM1H - Original Message - From: Tom W8JI w...@w8ji.com To: 'topband' topband@contesting.com Sent: Tuesday, October 30, 2012 7:18 PM Subject: Re: Topband: dipole height RDF is the key point to improve signal noise, not gain. Vertical or low dipole has very or none directivity, so low RDF or directivity does not improve signal noise. In general, this is the case, but it is not always true. Since I started using RDF, let me explain what it really is. RDF is really just directivity. I used RDF so people would stop using gain, because gain has little value for receiving. For example, if I place two Beverages side-by-side 1/4 wave apart there is almost no pattern change. Gain increases 3 dB, but certainly not receiving ability!!! As long as the noise is evenly distributed in all directions, or if dominate noise would be randomly distributed in all directions at different times, RDF works great as a guideline. If dominant noise comes from the SAME direction and polarization as the desired signal, nothing will help. Anything that nulls the noise also nulls the signal. If dominant noise comes from a null direction, the difference between gain in the desired signal direction to null of the noise will set the performance. For example, with a thunderstorm off the rear, F/R is most important. If noise is unevenly distributed, then it becomes very complex. Most people out in a rural area are probably in a situation where whatever QRM or noise bothers them, comes from random, differing, directions. Some people in congested areas have significant noise from one direction, and they need a deeper null in that specific direction. Going for exceptionally high F/R is meaningless unless there is somewhat-consistent strong QRM from the rear. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5363 - Release Date: 10/30/12 ___ Topband reflector - topband@contesting.com
