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: Signal attenuation from foliage near 160m antenna
This subject has been discussed here plenty of times in the past, and the consensus has always been that trees and other foliage near a 160m antenna has a negligible effect on the transmitted signal. That's what I have believed for some time. This was discussed last month at http://www.eham.net/ehamforum/smf/index.php?topic=90638.0 . This article by Carl Luetzelschwab K9LA appeared in the March/April 2006 NCJ titled Low Band Antennas and Trees. LINK: http://k9la.us/Low_Band_Antennas_and_Trees.pdf . Look at the chart and discussion there. It flies in the face of previous observations by a lot of intelligent Topbanders. I'm not at all saying that I agree with this. But it certainly does seem that after the leaves came out and the weeds grew around my 160m inverted-L, my signal on the Reverse Beacon Network is nowhere near what is was in the early spring. I doubt that it has anything to do with the tall weeds under my elevated radials or the oak leaves near the inverted-L. But never mind all that; what do you gentlemen think about this article? I don't know what to think. 73, Mike Mike, from what Ive read on here from many intelligent topbanders, and also commented on in the past, is that trees definitely have an effect on vertical antennas. I'll certainly have to agree with the other Carl. Other forums have had similar agreement. Ive no 160M experience with them. Someone with the time can research the US Army experiments in the 50's that was published in either CQ or QST, I forget which and dont have the time today to search. It was done at Ft Monmouth in NJ and also in the Canal Zone. To repeat my own experience it was in the early 80's. I started out with a 6 wire 12 diameter cage vertical for 80 hung from a branch of a pine tree about 1-2' away from the trunk. Even with 64 on ground radials performance was dismal. Moving it out to about 8' and I could work DX without having to wait until I was the only one calling. The resonance point also changed. There were only 2 trees in the back yard, both pines, and the other was very cooperative with a branch a quarter wave away so another cage was hung at the same distance. This was phased with the other using coax and relays for 2 cardiod and a broadside figure 8 pattern and was competitive in pileups. I then used the array as half waves on 40 in a pair of figure 8's but was never satisfied and felt the trees were absorbing considerable RF. A 4el 40M KLM at 120' soon took care of that problem. In retrospect I have to believe the trees were still affecting 80 to some degree. The only test equipment I had at the time was a Bird 43, a noise bridge, and a borrowed Knight T-150 as I was not about to haul a 100+ lb CE-100V back and forth from the basement. Carl KM1H _ Topband Reflector
Topband: Blame it on global warming
According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999.html _ Topband Reflector
Topband: tree losses
Rudy Severns wrote: 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? Here are several data points on this subject. Recording the relative readings on the dBµ and S/N displays of a Tecsun PL-310 tuned to a 790 kHz directional station about 52 miles east of me, radiating about 1 kW in my direction: Location dBµS/N (dB) (Tecsun 4-1/2 ft AGL) Area clear for 50 ft around32 15 Pin oak tree, 3' diameter trunk, 42 24 east side against trunk Ditto, but west side of trunk 34 14 Gnd Wire of 50' utility pole48 24 (Tecsun 9 ft AGL) Gnd Wire of 50' utility pole50 24 The field improvement when the rx is held against the east side of the trunk is completely gone when the receiver is moved to the east about 15 feet. So the effects are quite localized. These locations were all within 100' of each other. _ Topband Reflector
Topband: trees and antennas
My QTH in central Delaware is about 12 acres with most of it a young forest of loblolly pines, oak and maple that top out around 80-90 feet tall. Prior to 1978 or so most of this was cleared farmland. In 1998 I erected a 100-foot tower that became the (series-fed) driven element for a 160-meter K3LR-style parasitic array. This tower was amidst a grove of about a dozen or so loblolly pines that at the time were about 40 feet tall. Since then they have grown to around 60-70 feet. I did make a change in the tower top-loading a few years ago that required changing the matching at the feedpoint, but other than that change I have not found any need to readjust the matching over time that I would think would be needed if there was any interaction with the trees. This antenna (3 elements to the SE/SW/NW and 4 elements to the NE) has seemed competitive with other arrays on the band at inland locations. My new 4-el bs/ef tx array for ne/sw on 160 also is built in the forest and performs well (as expected slightly more gain than the parasitic array to the NE). These elements are only 73 feet tall and below the treetops in that area. They are each different distances from the closest trees yet I didn't see any significant variation in resonance of the antennas. One possible tree-antenna interaction I have seen is with copper ground rods. In at least two cases where I used a large loblolly pine as an end support for a Beverage antenna and drove in a 5-foot copper pipe for a ground rod next to the tree, the tree later died. Loblolly pines have a deep tap root, and copper is known to kill vegetation, so I've since started using galvanized steel for ground rods when they need to be near these trees. 73/Jon AA1K _ Topband Reflector
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
Re: Topband: Blame it on global warming
Scientwists are trying to prove that it is all human fault, causing global (warming) climate change. The reality is that we are getting just about all energy from the sun. We know about the sunspot cycles. Low sunspot activity (less energy from sun) causes (iono)atmosphere to shrink, the layer's height decreases. Iono-atmosphere gets more dense, producing more extreme weather and changes in HF propagation patterns, we know so well. If gaseous envelope shrinks, of course it shows as decreasing temperatures on the outside. (Thermodynamics) Sun has huge fluctuations in its furnace and Algores can do nothing about it (besides scheming taxes). Blaming humans to cause climate change is like having Obama pee in the ocean and cause global flooding. Yuri, K3BU.us www.MVmanor.com http://www.MVmanor.com On Mon, Aug 05, 2013 at 06:25 AM, N7DF wrote: According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999.html _ Topband Reflector _ Topband Reflector
Topband: tree losses
Another way of looking at it: There is loss in vegetation that goes up as the frequency goes up. At low frequencies, in a seconds time, only a small amount of wavelengths pass through a given bit of vegetation. As the frequency goes up to UHF, and into gigahertz range, for a given second, many many more wavelengths pass through. Each pass contributing heat to this (slightly re-radiating) dummy load. They give the gigahertz range, a name of ionization waves, but this post is trying for an alternate way of looking at it. Microwave oven= hot dummy load= Lunch. ( ; - )) 73 Bruce-K1FZ - 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 6:03 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 _ Topband Reflector
Re: Topband: Blame it on global warming
This is the original research paper: http://www.physics.otago.ac.nz/space/Silber_etal_2013_as_accpeted.pdf Global warming is an indisputable fact, the cause is subject to much debate. Please, lets keep politics off of this reflector, science and politics don't mix well. 73 Frank W3LPL - Original Message - From: Yuri Blanarovich k...@optimum.net To: N7DF n...@yahoo.com Cc: topband@contesting.com topband@contesting.com topband@contesting.com Sent: Monday, August 5, 2013 2:55:20 PM Subject: Re: Topband: Blame it on global warming Scientwists are trying to prove that it is all human fault, causing global (warming) climate change. The reality is that we are getting just about all energy from the sun. We know about the sunspot cycles. Low sunspot activity (less energy from sun) causes (iono)atmosphere to shrink, the layer's height decreases. Iono-atmosphere gets more dense, producing more extreme weather and changes in HF propagation patterns, we know so well. If gaseous envelope shrinks, of course it shows as decreasing temperatures on the outside. (Thermodynamics) Sun has huge fluctuations in its furnace and Algores can do nothing about it (besides scheming taxes). Blaming humans to cause climate change is like having Obama pee in the ocean and cause global flooding. Yuri, K3BU.us www.MVmanor.com http://www.MVmanor.com On Mon, Aug 05, 2013 at 06:25 AM, N7DF wrote: According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999.html _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: Blame it on global warming
Global warming is an indisputable fact, Global warming is a very disputable fact and certainly bad science. While average temperatures are certainly higher than during the great ice ages they are still much lower (as are CO2 levels) than during eras in which much of the earth's surface was heavily forested. The mere presence of large oil and coal deposits in arid and frozen areas shows that neither of those climate extremes are permanent. Please spare us the defense of political science. 73, ... Joe, W4TV On 8/5/2013 10:31 AM, donov...@starpower.net wrote: This is the original research paper: http://www.physics.otago.ac.nz/space/Silber_etal_2013_as_accpeted.pdf Global warming is an indisputable fact, the cause is subject to much debate. Please, lets keep politics off of this reflector, science and politics don't mix well. 73 Frank W3LPL - Original Message - From: Yuri Blanarovich k...@optimum.net To: N7DF n...@yahoo.com Cc: topband@contesting.com topband@contesting.com topband@contesting.com Sent: Monday, August 5, 2013 2:55:20 PM Subject: Re: Topband: Blame it on global warming Scientwists are trying to prove that it is all human fault, causing global (warming) climate change. The reality is that we are getting just about all energy from the sun. We know about the sunspot cycles. Low sunspot activity (less energy from sun) causes (iono)atmosphere to shrink, the layer's height decreases. Iono-atmosphere gets more dense, producing more extreme weather and changes in HF propagation patterns, we know so well. If gaseous envelope shrinks, of course it shows as decreasing temperatures on the outside. (Thermodynamics) Sun has huge fluctuations in its furnace and Algores can do nothing about it (besides scheming taxes). Blaming humans to cause climate change is like having Obama pee in the ocean and cause global flooding. Yuri, K3BU.us www.MVmanor.com http://www.MVmanor.com On Mon, Aug 05, 2013 at 06:25 AM, N7DF wrote: According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999.html _ Topband Reflector _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
I hope all of us can keep the topic at least somewhat scientific, logical, or rational, and less subjective, blind faith, or outright off-the-wall.. 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. I've wanted to catch logging operations around here and make field strength measurements before and after trees are removed. Unfortunately I've always been busy at the wrong times to click with tree removal, or the weather has been a factor. It wouldn't do much good to measure FS if one reading is in rain, and the other is in dry weather, unless a few unchanged path readings were taken to normalize the system. My general thought was to read absolute signal levels between TX antennas here and a remote fixed antenna on the other side of tree removal, with another reference point outside the removal area as a standard. But then, even if we know that, I always wonder what good it does. Foliage hundreds of feet. let alone miles away, is out of our control. As for trees being antennas, that would be a simple experiment. One could simply try to load the tree, however that might be accomplished, and compare the signal level with the same size loading system (properly rematched) without the tree. Several reruns with different trees could give a baseline. I think the reason that has never been done is most people who understand losses and radiation also understand the few feet of wire in the matching system is probably the major radiator in the system, so there is very little interest in proving the obvious. Most of us already understand an insulated copper wire thrown over a tree is a far better antenna than the tree could ever be, and that removing the tree actually INCREASES field strength. The logical conclusion is the tree is much more a dissipative load than an antenna. After all, if a tree was even a marginally effective LF or HF radiator, we would increases in field strength from reflections rather than just absorption. At some higher frequency there are measureable echoes, but they pale compared to the incident wave. Remember the moon, as horrible a conductor as it is, still has useful reflections when the illumination is over a wide surface area. In the real world, it often isn't a case of if something is or isn't, like a toggle switch being on or off. It is often a case of how much it is or isn't. Some things that are way over in the isn't meaningful column get publicity as being is, just because they are not perfectly zero or infinite. 73 Tom _ Topband Reflector
Re: Topband: The Beverage Antenna Handbook
On 2013-08-05, at 10:45 AM, Bob Cutter wrote: I have an excellent copy of this 1977 classic by Victor A. Misek, W1WCR. $25.00 shipped in the US. Contact me off list. Hi Bob, It's a very good book, bar none, but Vic's insistence upon running a ground-mounted parallel ground wire beneath the Beverage antenna itself runs counter to the theory that a poorly conducting soil at he base of the antenna is the very key to the design's success (hence the reportedly poor performance of Beverages erected at the sea shore). The parallel ground wire would effectively negate the resistance of the earth below the Beverage, in Vic's designs... I'm surprised that more Hams haven't made this same observation. I believe it was Tom (W8JI) who first noted this to me several years ago, and it made sense at the time...indeed, still does, to-day. ~73~ de Eddy VE3CUI - VE3XZ _ Topband Reflector
Re: Topband: Blame it on global warming
It's very disputable...but I agree politics should be kept off the reflector. 73, Greg-N4CC On Monday, August 5, 2013 10:31 AM, donov...@starpower.net wrote: This is the original research paper: http://www.physics.otago.ac.nz/space/Silber_etal_2013_as_accpeted.pdf Global warming is an indisputable fact, the cause is subject to much debate. Please, lets keep politics off of this reflector, science and politics don't mix well. 73 Frank W3LPL - Original Message - From: Yuri Blanarovich k...@optimum.net To: N7DF n...@yahoo.com Cc: topband@contesting.com topband@contesting.com topband@contesting.com Sent: Monday, August 5, 2013 2:55:20 PM Subject: Re: Topband: Blame it on global warming Scientwists are trying to prove that it is all human fault, causing global (warming) climate change. The reality is that we are getting just about all energy from the sun. We know about the sunspot cycles. Low sunspot activity (less energy from sun) causes (iono)atmosphere to shrink, the layer's height decreases. Iono-atmosphere gets more dense, producing more extreme weather and changes in HF propagation patterns, we know so well. If gaseous envelope shrinks, of course it shows as decreasing temperatures on the outside. (Thermodynamics) Sun has huge fluctuations in its furnace and Algores can do nothing about it (besides scheming taxes). Blaming humans to cause climate change is like having Obama pee in the ocean and cause global flooding. Yuri, K3BU.us www.MVmanor.com http://www.MVmanor.com On Mon, Aug 05, 2013 at 06:25 AM, N7DF wrote: According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999 .html _ Topband Reflector _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: Blame it on global warming
Doom/boom politics aside, it seems to be interesting data to examine nonetheless. I'll not dare knock propagation research, so long as it's carried out within good radioscience. Agreed that the claim of T driving H(ionosphere) is a bit strange... at least it's the first time I've seen such a claim. Yuri's explanation of heliosphereic/magnetic matters falls in line with everything I've studied. Shame there's not a link to the actual paper -- I've tried searching elsewhere to no avail. 73, - Josh / KF4YLM On 8/5/2013 9:55 AM, Yuri Blanarovich wrote: Scientwists are trying to prove that it is all human fault, causing global (warming) climate change. The reality is that we are getting just about all energy from the sun. We know about the sunspot cycles. Low sunspot activity (less energy from sun) causes (iono)atmosphere to shrink, the layer's height decreases. Iono-atmosphere gets more dense, producing more extreme weather and changes in HF propagation patterns, we know so well. If gaseous envelope shrinks, of course it shows as decreasing temperatures on the outside. (Thermodynamics) Sun has huge fluctuations in its furnace and Algores can do nothing about it (besides scheming taxes). Blaming humans to cause climate change is like having Obama pee in the ocean and cause global flooding. Yuri, K3BU.us www.MVmanor.com http://www.MVmanor.com On Mon, Aug 05, 2013 at 06:25 AM, N7DF wrote: According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999.html _ Topband Reflector _ Topband Reflector _ Topband Reflector
Topband: The Beverage Antenna Handbook
I have an excellent copy of this 1977 classic by Victor A. Misek, W1WCR. $25.00 shipped in the US. Contact me off list. 73, Bob KIØG _ Topband Reflector
Re: Topband: Blame it on global warming
Please If I want a discussion on global warming, I'll sign on to the Huff Post. This site is for topband info. Bill K4XS/KH7XS _ Topband Reflector
Re: Topband: Blame it on global warming
Well said, Bill. 73/jeff/ac0c www.ac0c.com alpha-charlie-zero-charlie -Original Message- From: cqtestk...@aol.com Sent: Monday, August 05, 2013 10:03 AM To: topband@contesting.com Subject: Re: Topband: Blame it on global warming Please If I want a discussion on global warming, I'll sign on to the Huff Post. This site is for topband info. Bill K4XS/KH7XS _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
I found this and at least it makes a good old read. http://www.rexresearch.com/squier/squier.htm regards, Raoul ZS1REC From: Tom W8JI w...@w8ji.com To: Topband topband@contesting.com Sent: Monday, August 5, 2013 4:53 PM Subject: Re: Topband: tree losses I hope all of us can keep the topic at least somewhat scientific, logical, or rational, and less subjective, blind faith, or outright off-the-wall.. _ Topband Reflector
Re: Topband: Blame it on global warming
This discussion involves current scientific research of the D and E layers of the ionosphere that are within the thermosphere and parts of the mesophere. The D and E layers profoundly impact Topband propagation. 73 Frank W3LPL - Original Message - From: Jeff Blaine j...@ac0c.com To: cqtestk...@aol.com, topband@contesting.com Sent: Monday, August 5, 2013 5:10:59 PM Subject: Re: Topband: Blame it on global warming Well said, Bill. 73/jeff/ac0c www.ac0c.com alpha-charlie-zero-charlie -Original Message- From: cqtestk...@aol.com Sent: Monday, August 05, 2013 10:03 AM To: topband@contesting.com Subject: Re: Topband: Blame it on global warming Please If I want a discussion on global warming, I'll sign on to the Huff Post. This site is for topband info. Bill K4XS/KH7XS _ Topband Reflector _ Topband Reflector _ Topband Reflector
Topband: Beverage Handbook sold
_ Topband Reflector
Topband: best core material?
I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector
Re: Topband: best core material?
Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector
Re: Topband: tree losses
Bingo! Just because the military does (or did) something with antennas doesn't means it's good for us all to repeat. There was a discussion some time back that a Beverage must make a good transmitting antenna, because the military does it somewhere. I can vouch for the fact that while we can indeed transmit on a Beverage and make contacts with it, a vertical with a few radials makes a *much *better TX antenna. 73, Mike www.w0btu.com On Mon, Aug 5, 2013 at 9:53 AM, Tom W8JI w...@w8ji.com wrote: ... the few feet of wire in the matching system is probably the major radiator in the system ... Most of us already understand an insulated copper wire thrown over a tree is a far better antenna than the tree could ever be, and that removing the tree actually INCREASES field strength. The logical conclusion is the tree is much more a dissipative load than an antenna. After all, if a tree was even a marginally effective LF or HF radiator, we would increases in field strength from reflections rather than just absorption. _ Topband Reflector
Re: Topband: best core material?
If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Hi, Jim Yes, I gathered that it was a receiving loop. I built one a few years ago and used 73 mat'l for the transformer because it's what I had. Worked quite well. It was also a delta-shaped Kaz antenna like what John, ON4UN, did for F00AAA. My turns ratio was not quite as high as yours. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
I found this and at least it makes a good old read. http://www.rexresearch.com/squier/squier.htm This is how things get started! once something is in print, no matter how wrong or unsubstantiated, it lives forever. Look at this statement: It will puzzle the amateur as it has puzzled the experts, how a tree, which is certainly well grounded, can also be an insulated aerial. The method of getting the disturbances in potential from treetop to instrument is so simple as to be almost laughable. One climbs a tree to two-thirds of its height, drives a nail a couple of inches into the tree, hangs a wire therefrom, and attaches the wire to the receiving apparatus as if it were a regular lead-in from a lofty copper or aluminum aerial. Apparently some of the etheric disturbances passing from treetop to ground through the tree are diverted through the wire --- and the thermionic tube most efficiently does the rest. In about 100 years, we should reasonably believe there would be logically conducted experiments with documentation showing trees make reasonable antennas. We should also expect that trees would, by now, be universally hailed as useful antennas. The article even claims it makes no difference if the tree antenna is in a thick woods, something we know cannot be true, and that simply disconnecting the wire from the tree causes the set to go dead, something else we know is untrue. It also claims a 40 ft wire cannot work on multiple frequencies, which I suppose people who like magic 43 foot verticals would disagree with. Instead we have only reports and measurements that trees cause increased loss, and all those multiband single length antennas. :) 73 Tom _ Topband Reflector
Re: Topband: best core material?
BTW, Jim I assume that 18:1 is the impedance ratio, and the turns ratio is of the order of 4:1 or so Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: Blame it on global warming
This discussion involves current scientific research of the D and E layers of the ionosphere that are within the thermosphere and parts of the mesophere. The D and E layers profoundly impact Topband propagation. I think the problem is the completely off-topic political rants started, instead of serious, logical, rational, discussions or debate about the technical content of the article. _ Topband Reflector
Re: Topband: best core material?
When I did mine, I had used up all my binocular cores that were large enough, so I taped two tubular cores together side-by-side to make a binocular core. A little more room to wind, and maybe a little less inter-winding capacitance? 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Yes to both, Charlie - a friend of mine has a calculator to figure the exact turns ratio BUT, at a web site I found for this antenna (used during an FO0 dxpedition) the ratio was defined as 8 turns in the primary, 28 turns in the secondary (for 75 ohm cable so for 50 ohms it'll be something else but still fairly close to your mentioned 4:1 ratio) From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Date: Mon, 5 Aug 2013 14:24:05 -0400 Subject: Re: Topband: best core material? BTW, Jim I assume that 18:1 is the impedance ratio, and the turns ratio is of the order of 4:1 or so Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
Hi Tim, Here's how I did it. http://www.w0btu.com/Beverage_antennas.html#transmitting_on_a_Beverage I left the termination resistor off, and it still had a 5 dB F/B ratio. I also connected the two wires at each end and added a few extra radials. It surprised me how well it worked on 75 meters and up. It was fun to try, but I wouldn't recommend trying to win any contests with it. :-) 73, Mike On Mon, Aug 5, 2013 at 1:06 PM, Shoppa, Tim tsho...@wmata.com wrote: Every time I accidentally transmit into my receive antennas, I burn out the matching transformers and/or termination resistors in short order! I would guess the military termination resistors are quite a bit beefier :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Monday, August 05, 2013 2:04 PM To: Tom W8JI; topband Subject: Re: Topband: tree losses Bingo! Just because the military does (or did) something with antennas doesn't means it's good for us all to repeat. There was a discussion some time back that a Beverage must make a good transmitting antenna, because the military does it somewhere. I can vouch for the fact that while we can indeed transmit on a Beverage and make contacts with it, a vertical with a few radials makes a *much *better TX antenna. _ Topband Reflector
Re: Topband: best core material?
You'll notice in my original response I was trying to determine if this is only for receiving or if you were planning on transmitting with this transformer too :). FT-140 is pretty huge for a receive antenna transformer and winding just a few turns of skinny wire through it would look particularly odd. Binocular cores will have better coupling and less leakage than toroidal cores. Toroidal cores might be preferable if you had to wind so many turns that it wouldn't be possible to fit through the binocular holes (admittedly the hole in a toroid is much bigger than the holes in a binocular core :)!) Tim N3QE From: James Rodenkirch [mailto:rodenkirch_...@msn.com] Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: RE: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.commailto:tsho...@wmata.com To: rodenkirch_...@msn.commailto:rodenkirch_...@msn.com; ma...@isp.camailto:ma...@isp.ca; topband@contesting.commailto:topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.commailto:topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.camailto:ma...@isp.ca To: rodenkirch_...@msn.commailto:rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.commailto:rodenkirch_...@msn.com To: topband@contesting.commailto:topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.comhttp://www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.comhttp://www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Thanks to all that replied - VERY informative information as well as anecdotal evidence the small delta loop receive antenna works well AND at a lower height, which I was thinking of doing but not sure if that mod would alter the antenna's efficacy all that much! Suggestion that I use a binocular core understood and I will go that route - a friend of mine will wind the binoc core for me (have severe neuropathy and can't handle small stuff like that at all!). Great group of participants here - thank you for the advice/suggestions! 72, Jim Rodenkirch K9JWV --- Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Hi, Jim Well, seems that I may have borrowed the 40X10 dimensions from somewhere. Interesting thing, is, if you are into modeling things with EZNEC, as I am, you can play with the dimensions quite a bit. The gain goes down as the loop area is reduced, placing more demand on the preamp. My 40X10 loop did really well with an old AMECO tunable tube preamp. No, my loop was not as tall as Johns but worked really well. I had Dacron ropes on the ends, so I could re-orient it like leading a cow ! Would like to have built one rotatable, but dont think Im going to have that opportunity. Sure you can use a larger core, especially if you use 73 material. The two tubular cores that I used were almost ¼ in ID X 0.45 OD. I just taped them together to make a binocular core. They were what I had available -73 matl. I understand about neuropathy! I have it pretty bad in my right hand and some in my right leg. We recently found some lesions on my cervical spinal cord. Really scary bad news!! Enjoy the loop! 73, Charlie, K4OTV From: James Rodenkirch [mailto:rodenkirch_...@msn.com] Sent: Monday, August 05, 2013 2:53 PM To: Charlie Cunningham Subject: RE: Topband: best core material? Importance: High I was going with the standard dimensions mentioned in the ON4UN book, Charlie - 18' high, 28' wide at the baseBUT I really wanted to reduce the height so your dimensions work far more better for me. OK - I'm convinced on using binocular but that BN-73-202 core sure looks small! Is there a slightly larger one I could use (I have a sever case of neuropathy so handling small thing is next to impossible! The XYL won't even let me wash dishes 'cuz she's afraid I'll mishandle that stuff!) If I'm winding a 4:1 turns ratio for a toroid I assume I do the same for a binocular, just use less turnsi.e., instead of 28 to 8 for a toroid, 8 to 2 for a binocular??? From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 14:45:12 -0400 BTW, Jim I think you will be pleased with that loop! Mine was 40' long X 10' high and it was an excellent receive antenna for 160, 80, 40 and 30 m. If you model it in EZNEC, you will find that the impedances and cardioid patterns stay fairly constant as you go higher in frequency, but the gain goes up with increasing frequency. It helped me to hear and work Kazakhstan on 80m, when I couldn't copy on the 80m GP. It opened lots of additional paths on 160 as well. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:29 PM To: Charlie Cunningham; 'BY THE LAKE'; topband@contesting.com Subject: Re: Topband: best core material? Yes to both, Charlie - a friend of mine has a calculator to figure the exact turns ratio BUT, at a web site I found for this antenna (used during an FO0 dxpedition) the ratio was defined as 8 turns in the primary, 28 turns in the secondary (for 75 ohm cable so for 50 ohms it'll be something else but still fairly close to your mentioned 4:1 ratio) From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Date: Mon, 5 Aug 2013 14:24:05 -0400 Subject: Re: Topband: best core material? BTW, Jim I assume that 18:1 is the impedance ratio, and the turns ratio is of the order of 4:1 or so Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an
Re: Topband: best core material?
By the way, Jim. My loop was only about 3' high on the bottom 40' run and about 13' at the apex. Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 3:23 PM To: topband@contesting.com Subject: Re: Topband: best core material? Thanks to all that replied - VERY informative information as well as anecdotal evidence the small delta loop receive antenna works well AND at a lower height, which I was thinking of doing but not sure if that mod would alter the antenna's efficacy all that much! Suggestion that I use a binocular core understood and I will go that route - a friend of mine will wind the binoc core for me (have severe neuropathy and can't handle small stuff like that at all!). Great group of participants here - thank you for the advice/suggestions! 72, Jim Rodenkirch K9JWV --- Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
If you plan to use the antenna on 160m you'll need 73 material. 43 works 3.8 up. Regards JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Yes, JC - ordering 73 material binocular cores today! From: n...@comcast.net To: rodenkirch_...@msn.com; tsho...@wmata.com; ma...@isp.ca; topband@contesting.com Date: Mon, 5 Aug 2013 15:49:37 -0400 Subject: Re: Topband: best core material? If you plan to use the antenna on 160m you'll need 73 material. 43 works 3.8 up. Regards JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
It depends on what the measure of much better is. .. For many years US special forces have used field expedient long wire HF antennas close to the ground (i.e., Beverage antennas) pointed at the net control station to reduce the probability of being intercepted by opposing forces and to improve jam resistance and signal to noise ratio. 73 Frank W3LPL - Original Message - From: Mike Waters mikew...@gmail.com To: Tom W8JI w...@w8ji.com, topband topband@contesting.com Sent: Monday, August 5, 2013 7:04:16 PM Subject: Re: Topband: tree losses Bingo! Just because the military does (or did) something with antennas doesn't means it's good for us all to repeat. There was a discussion some time back that a Beverage must make a good transmitting antenna, because the military does it somewhere. I can vouch for the fact that while we can indeed transmit on a Beverage and make contacts with it, a vertical with a few radials makes a *much *better TX antenna. 73, Mike www.w0btu.com On Mon, Aug 5, 2013 at 9:53 AM, Tom W8JI w...@w8ji.com wrote: ... the few feet of wire in the matching system is probably the major radiator in the system ... Most of us already understand an insulated copper wire thrown over a tree is a far better antenna than the tree could ever be, and that removing the tree actually INCREASES field strength. The logical conclusion is the tree is much more a dissipative load than an antenna. After all, if a tree was even a marginally effective LF or HF radiator, we would increases in field strength from reflections rather than just absorption. _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
That's what we need, real data. Expand the experiment and see what we can learn. While I feel that our data on the subject is pretty thin and I'm not about to make any pronouncements I'm still quite happy that at my new QTH the trees are many hundreds of feet away. I would also go out of my way to keep the HV points of an antenna as far as practical away from a tree. No data, just a sense of caution. 73, Rudy N6LF _ Topband Reflector
Topband: transmitting beverages
In ancient times I was an A-team radio operator. We tried many experiments including the very low long wire. It worked but the range was very limited. 73, Rudy N6LF _ Topband Reflector
Topband: Blame D-Layer effectiveness on the seasons
Thanks for the link! There's a ton of good stuff in this paper for the 137kHz experimenter, or anyone else who is concerned about the D-Layer. 73, - Josh / KF4YLM On 8/5/2013 10:31 AM, donov...@starpower.net wrote: This is the original research paper: http://www.physics.otago.ac.nz/space/Silber_etal_2013_as_accpeted.pdf Global warming is an indisputable fact, the cause is subject to much debate. Please, lets keep politics off of this reflector, science and politics don't mix well. 73 Frank W3LPL - Original Message - From: Yuri Blanarovich k...@optimum.net To: N7DF n...@yahoo.com Cc: topband@contesting.com topband@contesting.com topband@contesting.com Sent: Monday, August 5, 2013 2:55:20 PM Subject: Re: Topband: Blame it on global warming Scientwists are trying to prove that it is all human fault, causing global (warming) climate change. The reality is that we are getting just about all energy from the sun. We know about the sunspot cycles. Low sunspot activity (less energy from sun) causes (iono)atmosphere to shrink, the layer's height decreases. Iono-atmosphere gets more dense, producing more extreme weather and changes in HF propagation patterns, we know so well. If gaseous envelope shrinks, of course it shows as decreasing temperatures on the outside. (Thermodynamics) Sun has huge fluctuations in its furnace and Algores can do nothing about it (besides scheming taxes). Blaming humans to cause climate change is like having Obama pee in the ocean and cause global flooding. Yuri, K3BU.us www.MVmanor.com http://www.MVmanor.com On Mon, Aug 05, 2013 at 06:25 AM, N7DF wrote: According to this study low frequency propagation is affected by atmospheric temperature changes http://www.terradaily.com/reports/Radio_Waves_Carry_News_of_Climate_Change_999.html _ Topband Reflector _ Topband Reflector _ Topband Reflector _ 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: 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. Carl, There isn't any reason to turn everything into something it clearly is not, so you probably just don't understand what I am saying. We ALL (or nearly nearly all) agree trees have an effect. But just having an effect, all by itself, isn't very useful information to any of us for anything. I don't think many rational adults would disagree with the idea it would be nice to have some reasonable idea how significant the effect is, or how much worry it is. Few of us like to worry about insignificant things, and anyone with any reasonable curiousity generally want to know how much. How much horsepower does a car have, how many years of smoking does it take to harm us, how high can the SWR be before it causes a problem, how many radials do we need, and how big a worry is that tree. Those all seem like logical, reasonable, questions that many people would enjoy having actual answers, rather than It has an effect. I read it somewhere. Next topic. 73, Tom _ Topband Reflector
Re: Topband: tree losses
Hi, For me the effect the trees have is purely academic. I live in the northern Michigan forests. I am surrounded and even protected by the trees. My antennas are *in* the trees. I'm sure the trees have some effect. There is nothing I can do but operate anyway. If the tree studies find that radio is impossible in the presence of trees I suppose I'll have to find a different hobby. Meanwhile I'll keep on keeping on. 73, Bill KU8H _ Topband Reflector
Re: Topband: tree losses
Bingo! Just because the military does (or did) something with antennas doesn't means it's good for us all to repeat. While Beverage antennas for transmitting are indeed one example, two more good examples are: 1.) that silly Maxcom antenna tuner sold from Florida, the thing that had the chopped up pieces of circuit board inside 2.) stainless steel terminated folded dipoles The problem with stuff like that is no one had actually quantified the loss, and even if they had, no one probably cared about signal levels. Just as long as they made contacts and the SWR looked OK, it was all working. The same type of thing is what sells those magical CB rings and the little dipole parasitic elements (about a foot long) that go on CB mobile antennas. Anecdotal evidence is that it all works, just like healing rocks and deer whistles for cars. :)It all has an effect that people feel or find useful, so it all works at some level. 73 Tom _ Topband Reflector
Re: Topband: tree losses
Tom and all, After spending 25 years in the military (Navy specifically), I can say, with a fair amount of authority, that the antennas used by them are often used for much different purposes than what people on this forum use them for. he he he. Never would a scenario arise where 1.8mhz DX would be of any interest whatsoever to a guy in the field. He/she is most likely trying to make contact with someone less than 200 miles away (and usually MUCH closer than that, like over the next hill, but not within range of a vhf/uhf signal). Antenna efficiency is often sacrificed for stealth. again, for extremely obvious reasons. Long distance HF and MF comms are rarely of any concern these days, whereas it is almost everything to us amateur radio ops. The T2FD antenna is one example of a purpose built antenna whose intention was ALWAYS short range comms (NVIS). It does what the military wanted it to do and then some. Same with almost every antenna in the military's RF arsenal. This is especially true today where high gain antennas, and dx type distances, are almost exclusively devoted to vhf, uhf, shf satellites. Satcom is (and has been for a fairly long time) ubiquitous in the military, as most of you probably already know. Now, having said that, I used some absolutely dynamite antennas on HF while underway. Simple antennas, like a horizontal end-fed that was roughly 60 feet long and stood about 70 feet out of the water. sea water. Had a practically infinite tuning range and could handle all the power that I could feed it for phone patches and amtor (when we started using it). Needless to say, in a situation where your horizontal (or vertical) is over salt water, in the clear (no houses, trees or anything else to block the RF), and about 70 to 80 feet above that water is darned near a perfect reflective surface for a horizontal ANYTHING, right? Anyway, unless you want to talk about the military's advances in NVIS, which it has done in spades, you are barking up the wrong antenna source. If you are wanting to do short range, NVIS, comms then DO take a look at military antenna designs. they work and they work well for that purpose, in particular. There ARE antenna designs used by the military for backup long range HF purposes, but they are mainly the same designs we all use for that purpose.. efficient vertical radiators (think verticals over a SHIP's deck as a groundplane, surrounded by salt water) or large log periodic beams that are mounted at the top (or nearly so) of the highest mast on the ship, etc, etc, etc. Again, those are really obvious and nothing new to us. So that is my two cents. keep in mind what the military wants its HF to do and those much maligned military antennas are all of a sudden almost perfect for their intended purpose. :) :) Seven-thirds, Mike AB7ZU Kuhi no ka lima, hele no ka maka On Aug 5, 2013, at 18:51, Tom W8JI w...@w8ji.com wrote: Bingo! Just because the military does (or did) something with antennas doesn't means it's good for us all to repeat. While Beverage antennas for transmitting are indeed one example, two more good examples are: 1.) that silly Maxcom antenna tuner sold from Florida, the thing that had the chopped up pieces of circuit board inside 2.) stainless steel terminated folded dipoles The problem with stuff like that is no one had actually quantified the loss, and even if they had, no one probably cared about signal levels. Just as long as they made contacts and the SWR looked OK, it was all working. The same type of thing is what sells those magical CB rings and the little dipole parasitic elements (about a foot long) that go on CB mobile antennas. Anecdotal evidence is that it all works, just like healing rocks and deer whistles for cars. :)It all has an effect that people feel or find useful, so it all works at some level. 73 Tom _ Topband Reflector _ Topband Reflector
Re: Topband: tree losses
On Mon, Aug 5, 2013 at 2:54 PM, ZR z...@jeremy.mv.com wrote: Youre unfairly throwing a huge spin on it Mike. Am I? Okay. Sorry. :-) If the military or a government agency does it, it could be an experiment or a purpose built project where the alternatives werent adequate or too expensive. Nothing at all wrong with an experiment. But ONE of the things I was thinking of (but didn't mention) was a publication by the military (about transmitting on a Beverage) that clearly showed it wasn't anything of the kind. I can't find it right now. Perhaps they did use multiple Beverages, and perhaps what they did was the right thing for what they needed. But is it for us 160m operators? I think not. An array of phased Beverages has a very narrow azimuth lobe and a controllable elevation lobe plus a high F/R. You phase enough of them and you have actual gain in +dB over a wide bandwidth for point to point communications. Not easy to do with a vertical. I agree. Is that what you used when you transmitted on a Beverage? But I think most of us don't have phased Beverages. I assumed that everyone would understand that I was talking about a single Beverage that the majority use on Topband (like my 580' ones). But the real point of the original post was the phenomenon of increasing foliage attenuation at 160 meters (more so that 80m, 40m, etc.) and later, using trees as radiators (which I think is ridiculous). It is similar with tree antennas. The military does it for a reason and it works for that specific purpose. Yet you will always have someone spinning that all around on here for whatever reasons. I thought that my point was that the major radiator is the WIRE going to the tree, and NOT the tree itself. Thats the problem with web sites that are not peer reviewed and misinformation is repeated forever if the author wont admit to an errorsome never will. Understand now? What I understand is that valid measurements need to be made. But as you said, nothing wrong with sharing anecdotal info (which was the basis for my original post). It's interesting about the dying foliage near an antenna, but (of course) that doesn't mean we can expect to use a tree as an antenna. Maybe I need to stop writing such short posts, and describe everything in detail, and include every possible scenario when I make a statement. :-) 73, Mike www.w0btu.com _ Topband Reflector
Topband: The solar magnetic field is about to flip, signalling the mid point of solar cycle 24
http://www.youtube.com/watch?v=34gNgaME86Y _ Topband Reflector
