[Repeater-Builder] Narrowband Range -was- Seeking emergency system design help
This has always interested me, and I've never seen a good technical reason for a loss of range with narrow deviation and receivers, either. But somewhere one must exist. If it didn't, there'd be no reason not to take analog deviation down to say, 1 kc., or 0.1 kc., would there? And I don't think that knowing a repeater's tail signal strength doesn't change is an apples to apples comparison. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, MCH m...@... wrote: This makes no sense. On the same band, with the same power, and with the same modulation type (analog) there is no reason there should be any loss by lowering the deviation and narrowing the receiver. If there was a change, it is not due to making the bandwidth more narrow. Maybe the new equipment is not as 'robust' as the old equipment. (IOW, both were putting out 50W, but the new one has more energy off-frequency). Or, maybe your new equipment's receivers are not as sensitive as the old ones. A good test of apples-to-apples is to see if a repeater's tail is lower in signal strength than the modulated/repeated carrier, as you're comparing the same thing - a signal of lower deviation to one of higher deviation. You should notice no difference whatsoever. Joe M. Andrew Seybold wrote: Bill one of the losses if a County fire department system which has 6 simulcast repeaters( 150 MHz) operating on wide-band with about 85% coverage of the County, and we put in three new channels (after almost 2 years of coordination and finding the correct channels), we put them up using the same sights and same output (50 watts erp) and using the same antennasâthe new 3 channels under talk the existing wide-band systems by at least 30 percent. We are in the process of adding 2 new sites to make up the difference. I am glad that you did not have a problem but this is just one of several which I have had a problem with, and I have become a believer in lost coverage, I have yet to see a system that has not lost coverage, I am glad that you have. Andy *From:* Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] *On Behalf Of *Bill Smith *Sent:* Friday, August 27, 2010 5:58 PM *To:* Repeater-Builder@yahoogroups.com *Subject:* Re: [Repeater-Builder] Re: Seeking emergency system design help Andy, my comment was not directed at the professionals, such as yourself and others I know personally that are on this list. They were based on his stated requirement for a disaster recovery radio system. It's not something to do cheap or without expert guidance. People keep commenting on losing range with narrowband systems. A large UHF LTR system I installed and maintained lost no discernable range switching from 5 KHZ to 2.5 KHz. All else was the same. Same antenna system, same repeaters, same mobiles. They just pushed a button to bring them to the new talkgroups. Bill KB1MGH *From:* Andrew Seybold aseyb...@... *To:* Repeater-Builder@yahoogroups.com *Sent:* Fri, August 27, 2010 5:39:21 PM *Subject:* RE: [Repeater-Builder] Re: Seeking emergency system design help The FCC is re-thinking the move to 6.25 KHz based on the fact that narrow band systems (and I have done a few of them) lose about 30% of the existing coverage AND the NEW FCC believes that broadband is what it is all about in the futureâno matter that broadband cannot do simplex or any of the other stuff needed for LMR and public safety. And like a few others have said on hereâyou have to narrowband but are NOT required to move to digitalâP25 or anything else, I have just completed several systems which use analog and we have moved them from Wide to Narrow with no problemsâEXCEPT the coverage problems I mentioned. Andy W6AMS (and btw there are professional LMR folks and consultants who work with this stuff every day on this list, just because we are hams too does not mean that we are not in the business as well)
[Repeater-Builder] Re: Adding capacitors to lower electric bill
Very nice explanation of the issue. Just to clarify a point or two, industrial users benefit directly from PF correction of their plants largely because the utility supplier either: a. doesnt' penalize them for low PF, and/or b. credits them for PF above say .90. Payback for PF correction equipment for them is often very fast, maybe just a few months. The residential or light commercial user's PF is not tracked nor billed, so there is very little to gain money-wise by raising PF. Laryn K8TVZ
[Repeater-Builder] Re: Adding capacitors to lower electric bill
--- In Repeater-Builder@yahoogroups.com, Gary Schafer gascha...@... wrote: The other thing involved if you are going to do power factor correction is that it needs to be done on EACH motor or inductive device. That's the best way, and we did do that, but it can be useful to float some amount of capacitance across the line. We did this where I worked. We had five primary substations that we owned, with their (obviously) inductive transformers, plus enough random loads going on and off all night. Our PF maybe have been above 1.0 at times, but we didn't worry about it. Our billed PF was always above .90, so we earned a nice $100-150 credit to our monthly bill. Trying to sell power factor correction to home owners and small business' is a scam. You save nothing on your bill! Yep! 73 Gary K4FMX Laryn K8TVZ
[Repeater-Builder] Re: Intermod Calculation
--- In Repeater-Builder@yahoogroups.com, Tim Sawyer tisaw...@... wrote: Basically, there is one controller for both the 929.0375 and the 157.74 transmitters. They also have two other transmitters on 929.6375 and 931.6625. Are the 929.0375 and 929.6375 transmitters at the same site as your repeater? I'm seeing 600 kc. difference there... Laryn K8TVZ
[Repeater-Builder] Re: Coax length, etc. GE Z-Matcher
--- In Repeater-Builder@yahoogroups.com, Jeff DePolo j...@... wrote: c) Although not explictly described in GE's tuning procedures, significant improvement in efficiency can be obtained with proper tuning of the Z-matcher. Tuning for 50+j0 at the input to the Z-matcher is NOT necessarily the RIGHT match! Right, GE's instructions on tuning the Z-Matcher in their base stations are not correct. Instructions should instead describe a procedure that reduces current draw of the amplifier while simultaneously maintaining or increasing the output power. d) To charge more. I'm half-joking on this; I can't say I've statistically seen more or less failures on M2 PA's with or without the Z-matcher, so I'll give this answer half a smiley: .-, If the failures you've seen are in amps with Z-Matchers that were tuned following GE's Z-Matcher instructions, that *could* explain why you've given half a smiley... :-) Laryn K8TVZ
[Repeater-Builder] Re: OT:QRZ.com
Just tried it... no login or password required for me. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, Don Kupferschmidt dkupf...@... wrote: Hi all. Has anyone used QRZ.com recently to look at a call sign and was challenged for a login and a password? I tried to look up a callsign for verification of an address, but was unable to go any further until I emailed their admin for a current login and password. Once I got it, I was able to use their site. Anyone know why this is happening? Don, KD9PT
[Repeater-Builder] Re: voting receivers
Here's a start... http://www.repeater-builder.com/tech-info/votingcomparators.html http://www.repeater-builder.com/tech-info/remotereceivers.html Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, Jed Barton j...@... wrote: Hey guys, Alright, i've just been giving the responsibility of being the head contact for a commercial repeater, and pretty much in charge of it. It's a damn good machine, a quantar. The one thing i'm not the best at is voting receivers. They only have 2 of them. Here are a few questions, how are they usually connected, i take it there isn't a lot to it, but just trying to learn more about voting receivers. Thanks, Jed
[Repeater-Builder] RC850 Aux DTMF Decoder Question
Hi all, we have an 850 v3.8 with the CIB. I connected DTMF1 to the control receiver audio input and mapped DTMF1 to the control receiver with programming commands. It accepts commands via the control receiver just fine. But while commands are being entered via the control receiver when the repeater is in use, the repeated audio mutes for the duration of each DTMF digit. This disrupts the in-progress QSO. Is there a fix for this? Thanks! Laryn K8TVZ
[Repeater-Builder] Re: Pager Interference Revisited
At the risk of mentioning something that's been mentioned and/or checked by you before... I believe you said that linking to the sites is not terrestrial RF but wireline and satellite. Be sure that there isn't some RF linking that's been fogotten by someone not very familiar with the entire system. I've seen 72 mc. link transmitters transmit spurs just like any defective transmitter can. The way this spur wanders around sure sounds like a dirty transmitter. Puzzling thing is that you've said that the bearings to the spurs while DFing wander all over the place. I would doubt there's more than one spur generator, so, point is, make sure your DFing person is an experienced Foxhunter and knows how to handle multipath, one of the biggest *spoilers* for any Foxhunter. You said you sat near one of the sites but the interfering signal was weak, or non-existent. Have you done the same at the other two sites? Good luck finding this beast! Laryn K8TVZ
[Repeater-Builder] Re: Dual receivers on one antenna for RX only site-cable length
In all of the discussion on cable lengths between a T and cavities to split to receivers, I'm wondering if the loop length inside of each cavity is to be included in cable lengths. It seems it always is included when calculating cavity interconnect cables on a duplexer, for example, but has not been mentioned in this thread. If loop length IS to be included, what is the assumed velocity factor of a cavity loop? Laryn K8TVZ
[Repeater-Builder] Re: Interference
--- In Repeater-Builder@yahoogroups.com, Leroy A. M. Baptiste leroybapti...@... wrote: When you key up the repeater, and you release, the repeater is held open (Sometimes) What do you mean by held open? Is the interference opening/keeping open the squelch of the repeater receiver, or are you hearing it with the squelch closed during the TX tail? , and you can hear the interference coming in. Is the interference audio relatively clean/undistorted, or loud, raspy, distorted? Is the interference always there, or quite intermittent? Laryn K8TVZ
[Repeater-Builder] Re: Interference
Leroy, perhaps you answered my questions from earlier today and I missed your answers. If you answered I apologize. So here they are again. --- In Repeater-Builder@yahoogroups.com, Leroy A. M. Baptiste leroybaptiste@ wrote: When you key up the repeater, and you release, the repeater is held open (Sometimes) What do you mean by held open? Is the interference opening/keeping open the squelch of the repeater receiver, or are you hearing it with the squelch closed during the TX tail? , and you can hear the interference coming in. Is the interference audio relatively clean/undistorted, or loud, raspy, distorted? Is the interference always there, or quite intermittent? Laryn K8TVZ
[Repeater-Builder] Re: Interference
--- In Repeater-Builder@yahoogroups.com, Leroy A. M. Baptiste leroybapti...@... wrote: Hi Laryn, no I did not get a chance to answer your questions, but here goes. The interference is holding the squelch open on the repeater receiver sometimes, which by extension holds the transmitter on, or cycles it, based on the interference into the receiver. OK, this tells me that the interference is indeed getting into the receiver, not RF getting into the controller, or some other audio stages, for example. The interference audio is not clean, it is distorted, the interference is not always there when you key up. This sounds like it is the wideband (75 kc. deviation) FM signal getting into the receiver. Audio at that deviation will be VERY distorted, if heard at all. That's because it's so wide that there's little energy within your receiver's IF bandwidth much of the time. Like I mentioned before, turning the FM transmitter off cures the problem. Hope that helps, and many thanks for your help. I haven't done any math on your numbers. There are several ways that the FM station's signal may be mixing somewhere with your transmitter, or even a third carrier may be involved in the mix. Locally, we have stations on 89.3 and 89.9, both mixing with our repeater output, to produce an intermod signal on our input. Like your symptoms, the signal was intermittent. Because two FM stations were involved, we had no noticeable interference until BOTH stations were transmitting very low, or no, audio. Such as spaces between words etc. Anything near normal deviation levels on either station would instantly close the receiver squelch and the problem was gone, for practical purposes. I found where the mixing was occurring with the aid of a spectrum analyzer, fed with a hand held beam. Guy wire turnbuckle weave wires were causing the mixing. I insulated them and problem is gone. Hope this helps. Good luck. Laryn K8TVZ
[Repeater-Builder] Re: Fw: FCC RO Involving the Amateur 70cm Band
Anyone have a real link to this? Those of us on the Web do not get attachments... Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, George Henry ka3...@... wrote: Re: the waiver request by ReconRobotics for 420 - 450 MHz operation. Hams get the shaft again... George, KA3HSW / WQGJ413
[Repeater-Builder] Re: LOOONG audio runs
A friend of mine full-time broadcast engineering told me he can detect zero crosstalk between pairs within the same CAT 5 cable at line level. As you suspect, balance is very important. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, JOHN MACKEY jmac...@... wrote: Using balanced audio in a broadcast environment, I have on rare occasions experienced issues with cross-talk between long runs of un-shielded balanced audio lines. (inductive pickup??) I always wondered if the wires were truly balanced when that happened. I prefer to used shielded balanced wiring for long runs.
[Repeater-Builder] Re: LOOONG audio runs
Shielding is not usually necessary for line level balanced pair audio on CAT 5 or any good twisted pair. CAT 5 is often used in broadcast audio work. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, skipp025 skipp...@... wrote: Joe k1ike_mail@ wrote: I wonder if CAT 6 would be better than CAT5 due to the difference in twist? Joe A number of different items in the specifications would be worth examining... like how much C per foot and I don't believe CAT network cables are shielded.
[Repeater-Builder] Re: Can the 4th harmonic of 1250 AM keep UHF repeaters locked up?
I agree with Bob. Mixing could also occur down at the guy anchor area, where cables are woven through the turnbuckles. Had it happen here... Laryn K8TVZ The cause of your interference problem is not RX overload. It is as others have suggested: a mix occurring somewhere in the near field of the antenna. Pads may eventually mask the real source of the problem, once you've added enough to drop the signal below your RX's noise floor, but you'll end up with a deaf repeater. How far away were the separate TX RX antennas when you tried that? I'd think if they were far enough apart that you would lose the mix. OTOH if a tower joint is the source of the mix (likely since a lot of length is required to couple in the AM BC station), it might be all over the tower. A similar problem was partially cured here by spraying some conductive paint into all the tower joints. Each time it was done the interference would disappear for a few months, then return. Bob NO6B
[Repeater-Builder] Re: Need DB4048 Duplexer Info
Thanx Paul, who responded directly, Randy, and Skipp. That puts me onto some things to check. So far the harness looks to be correct, with proper length jumpers made of RG9/B. I looked at all of the loops and they are also in good shape and correct size. Next I'll check each cavity individually on their respective notch frequencies. And maybe I should check all elements of the harness with a megger to find lightning damage/carbon tracks. Yeah, 1 watt and desense so bad it's not worth measuring -- something rather serious... Laryn K8TVZ
[Repeater-Builder] Need DB4048 Duplexer Info
Hi all I'm working on a 1 mc. split repeater using this duplexer. Transmitter is a VHF Engineering; output is 1 watt. I'm using a Mastr II receiver with no preamp. Interconnect cables are RG142. The old VHF Engineering receiver developed problems not worth fixing, so everything is on the bench for the new receiver and re-tuning. Desense was always an issue with this repeater, with 1-3db pretty normal. So I decided to re-tune the duplexer. I used a signal generator and receiver. All ports were either terminated in 50 ohms or had a 10db pad in series with the generator and receiver during tuning for minimum signal through the respective halves. It seems to tune well and predictably. However, I'm getting 20db+ of desense with the duplexer operating into a known good dummy load. I can reduce the desense considerably by *winging it* and tuning the cavities while the repeater is operating. (Maybe that's the way I should tune it...!) So something isn't right. I'm not totally convinced that this duplexer wasn't played with at some point, so it is possible that cables in the harness were mixed up. There is no labeling or other info on the duplexer, since the metal box that it was in when new is gone along with the nameplate. So it is not clear which side is which, and I may have been trying to use it reversed (although I don't think so). I believe that this duplexer was originally ordered for 2M, but I could be wrong, which could account for some troubles. So where would I find info on harness cable lengths so I can check them? Or if someone has one of these working on 2M and is willing to make some measurements that would be awesome. And which half of the duplexer is for the high and low frequencies? Laryn K8TVZ
[Repeater-Builder] Re: Battery system for portable repeater (non solar)
--- In Repeater-Builder@yahoogroups.com, tahrens301 tahr...@... wrote: Just not sure about leaving a trickle charger going all the time. (bad previous experiences) We'll want to know... What were your bad previous experiences regarding trickle charging? Then we can give you better answers. Laryn K8TVZ
[Repeater-Builder] Re: Battery system for portable repeater (non solar)
--- In Repeater-Builder@yahoogroups.com, tahrens301 tahr...@... wrote: Hi Larry... Batteries that ended up with no electrolyte - it had all boiled off. Not good for battery life, for sure. We've had numerous 'battery maintenance' systems on our trucks over the years which have resulted in the batteries having a shortened life. All were touted as 'will not overcharge, etc'. Obviously, they did overcharge. Were these consumer grade battery maintenance systems? If so, that could explain some things. A good, proper, float charger will apply the proper float VOLTAGE, not some often arbitrary trickle charge CURRENT of x value, or carry a will not overcharge statement. My point is that an ordinary cranking or trolling deep-cycle battery need not boil out under prolonged maintenance charging. I've kept trolling-type deep-cycle batteries on a float voltage of 13.6, +/- .05 volts for 7-8 years, at which point their capacity was not useful anymore. I simply checked the electrolyte every few weeks, added a bit of distilled water, and never had a problem. The exact float voltage is the key. Find out what the battery manufacturer recommends. In any case, 13.6 +/- .05 volts won't be far off. Hope this helps. Laryn K8TVZ
[Repeater-Builder] Re: Side mount to wooden utility pole?
--- In Repeater-Builder@yahoogroups.com, DCFluX dcf...@... wrote: Back in the day I mounted a Ringo to the botom of a pole So THAT'S why they don't work so well... Laryn K8TVZ
[Repeater-Builder] Re: Low Voltage Disconnect and Very Remote Site Operation
--- In Repeater-Builder@yahoogroups.com, skipp025 skipp...@... wrote: Hi Laryn, larynl2 larynl@ wrote: So Skipp, you're getting away with using a cranking battery because you never discharge below, maybe, 90%? Laryn K8TVZ getting away with? Yeah perhaps that was a little flippant... Conventional wisdom would have a deep cycle battery for service such as yours. I get the cost-effective part. The truck battery perhaps has thicker plates than an ordinary auto battery, and so can tolerate the many discharges to ~80% that you impose onto it...? Laryn K8TVZ
[Repeater-Builder] Re: newbie looking for info
Well, this isn't a book necessarily, but there is a huge amount of info here: http://www.repeater-builder.com/ Plus we all are here for the rest of the questions... Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, tetrault mdtetra...@... wrote: Where would I find a book or list of items I would need to build a repeater. Is there a list of parts and rules etc? I didn't see anything appropriate in the files section. Tnx, Mark AA1OV
[Repeater-Builder] Re: FS: *NEW* UHF Motorola Micor repeater on Ham band
--- In Repeater-Builder@yahoogroups.com, larryjspamme...@... lar...@... wrote: What's the ebay I assume you mean the Ebay link. It was in the initial posted message of the thread... http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=140372635542ssPageName=ADME:B:SS:US:1123#ht_500wt_1145 Laryn K8TVZ
[Repeater-Builder] Re: Mastr II mods and parts
I totally agree with that Bob. I believe the dissimilar metal *thing* has far less to do with generating noise and PIM, than the simple fact that we have separate wires and elements constructing the shield that have very bad electrical connections with each other. Aluminum is known to always form a non-conducting oxide on it when exposed to air. Non-silver plated copper braid wires can have the same problem, though not quite as readily if kept dry. In any case, there are thousands of potential diode mixers per foot of cable. I too, use only silver-plated braid or solid copper such as Superflex. I'll never forget the piece of RG213 that I once had feeding a repeater antenna that easily generated noise when taken in hand and flexed. I say all the good luck to those that successfully use 9913 and similar cables in duplex service. I'll use cables that are virtually certain to *not* generate duplex noise in my installations. Laryn K8TVZ BTW, they don't need to be dissemilar metals. I once confirmed a 100% copper braided RG-213 jumper as a PIM source. I only use silver-plated braided coax beyond the duplexer from now on. Bob NO6B
[Repeater-Builder] Re: Mastr II mods and parts
For connection between duplexer and radios I like 1/4 Superflex, but RG400 or RG142 is also great. To a duplex antenna for short runs those same cables could be used, keeping loss figures in mind. Otherwise appropriately sized Heliax or equivalent cables should be used. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, Michael H. Cox michaelh...@... wrote: What cable do you guys recommend? Thanks,
[Repeater-Builder] Re: Dropping the Autopatch--Keep 911
Thanx to all who responded to this thread. We have some excellent ideas to chew on. Laryn K8TVZ
[Repeater-Builder] Dropping the Autopatch--Keep 911
In a few days we will be dropping dialtone service to our repeater. However, there is still a desire to somehow dial 911. An archive search of the list yielded no relevant advice on how to use an old cellphone to do this. We have no internet service in the radio room, but there *may* be free/open wifi available. We just haven't looked for it yet. Of course we could run a dedicated full-duplex link to somewhere with dialtone, but seems like a ton of work... If a cellphone (without purchased service) is a feasible solution, which one(s) are good to use and don't require microsurgery inside? What other ways are there? Laryn K8TVZ
[Repeater-Builder] Re: Rolling Pipe Sound
Do you have two FM stations in your area that are separated by 600 kc.? That will definitely do exactly what you describe. We had it on our repeater. I caught in one of your posts that your transmitter needs to be on for the problem to appear, so that's intermod causing your interference, not just a random carrier coming from a router or whatever device. The problem here was caused by an FM station on 89.9 about a mile away, and another one on 89.3 roughly six miles away, plus our transmitter on 147.06. A+B-C=D 147.06 + 89.9 - 89.3 = 147.66. The thing to watch for with FM broadcast intermod is the wide bandwidth of the intermod product. There was no interference until BOTH stations were quiet -- no modulation. Obviously, the instances of both being quiet simultaneously are quite random in length and occurrence, depending on the program material of each. I tracked the location of the mixing with the aid of a spectrum analyzer, which turned out to be safety cables threaded through the turnbuckles. Laryn K8TVZ
[Repeater-Builder] Re: Linking Repeaters Remotely
In-band RF linking on the user input frequencies is a kludge at best. It can double with users, and has other timing problems... Nate Duehr, WY0X n...@... Nate, just a comment on the above. We've used in-band on-channel (IBOC??) linking to a nearby repeater for weather nets for many moons now. It has worked absolutely great for us. Sure, it's not elegant; a dedicated link is probably the better way. And, users are going to double anyway. Can't get away from that. We've not found any timing problems you refer to... Laryn K8TVZ
[Repeater-Builder] Re: Mastr II Power Draw with P/A?
--- In Repeater-Builder@yahoogroups.com, AJ aj.grant...@... wrote: Ball park guess for current draw? I'd say 6-7 amps with the exciter. Laryn K8TVZ
[Repeater-Builder] Re: Lightning Rod (Bolt)?
I agree about the survivability of folded dipole arrays, but they don't seem to be an option at 900 MHz- at least I don't see them in commercial catalogs and have never encountered an 800 or 900 MHz. Telewave makes them... http://www.telewave.com/pdf/TWDS-7019.pdf Laryn K8TVZ
[Repeater-Builder] Re: Voice and digipeater on same antenna
Yep thanx Frank, that's the article I was thinking about... Laryn K8TVZ
[Repeater-Builder] Re: Pager Interference to 2-meter VHF Public Service Band
We had a similar problem here years ago, caused by a city fire dispatch transmitter 30 miles away. It had a spur that we could follow around in frequency too. Our repeater is on 2M and their transmitter was on 154.37, if I remember. Their transmitter was the entire cause of the problem; no mixing was involved. I'd carefully check that, in fact, the suspect transmitters were disabled for the tests you mentioned. The linking scheme to them is also suspect as suggested. Are you hearing any other audio in the spur? If not I think it's a dirty transmitter; no mixing or intermod involved. Laryn K8TVZ
[Repeater-Builder] Re: Voice and digipeater on same antenna
--- In Repeater-Builder@yahoogroups.com, wb5hqh garyhanc...@... wrote: How do you combine a 2 meter voice and 2 meter digipeater on the same antenna?? Here, we have a repeater on 147.06 and digi on 144.39. We're using an old Sinclair Q2B05D duplexer to combine the two. The voice repeater has it's own duplexer. The antenna port of that duplexer feeds the high frequency port of the Sinclair duplexer. The Sinclair pass response is wide enough to pass both .66 and .06 with no problem. The digi radio feeds the low frequency port of the Sinclair. In addition, we needed to add a pass cavity to the digi radio, and a pass cavity to the repeater receiver. It all works great, with no desense to either receiver from either transmitter. Several months ago (May or June?) on this list, someone posted *their* method and diagram for doing the same thing. Perhaps that person could re-post the info. Or, search the list archives. Laryn K8TVZ
[Repeater-Builder] Re: Spectrum UHF Repeater SCR Crowbar circuit activating during TX
When the transmitter puts a load on the power supply, some AC ripple is getting through that trips the crowbar. 73, Joe, k1ike It could easily be any one of the electrolytics on the regulator board. I'd shotgun them all with new. I've seen this problem cured with new caps. Laryn K8TVZ
[Repeater-Builder] Re: Antenna question
--- In Repeater-Builder@yahoogroups.com, W3ML w...@... wrote: Now I realize that the DB type antenna is the best, but we do not have 800 bucks to buy one. You can do FAR better than that price. Primus Electronics, Joliet, IL. 800.435.1636. I have no connection with them other than being a very satisfied customer. Laryn K8TVZ
[Repeater-Builder] Re: ARRL Approves Study Committee to Research Develop Plan for Narrowband Channel Spacing
--- In Repeater-Builder@yahoogroups.com, James Delancy ctra...@... wrote: however I have only one ham rig (other than my HF radio (FT-847)) that will do 2.5 KHz as a selectable channel step, James, you leave the impression that a rig capable of 2.5 kc. channel steps is capable of narrowband. I'm thinking you'd want to re-state that, just to avoid confusing the issue among some. Laryn K8TVZ
[Repeater-Builder] Re: coax cable
--- In Repeater-Builder@yahoogroups.com, Eric Lemmon wb6...@... wrote: To get the best performance, you should use Andrew LDF5-50 Heliax, which is 7/8 diameter, or larger. If I may argue Eric's good advice here, for a 100' or so run, I would not be bothered by using 1/2 Heliax. For less than 1db more loss at 70cm, it's much cheeper and easier to run... As always, here comes the obligatory line avoid the temptation to use copper braided or aluminum-braid-over-foil types of coax for duplex use. Laryn K8TVZ
[Repeater-Builder] Re: Antenna SWR = Desense?
I still think it may be something in the vicinity of the antenna. What kind of building is the antenna mounted on/above? You've stated that the repeater is in a metal pole building that's 100ft. away from the antenna. It's been mentioned before in this thread, but that could be a noise nightmare. You'll need to get your antenna much farther away or higher to get away from that noise if that's it. If you have a small beam that you can hand-hold, that might be interesting to point around and see of there's changes in desense. Laryn K8TVZ
[Repeater-Builder] Re: UHF Connectors for 1/2 Andrew Superflex
Chuck, if you use a reducer made for RG59 (and RG8X?) there's no need to drill. Perfect fit. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, Chuck Kelsey wb2...@... wrote: I've used 1/4 superflex with PL259 reducer. Works fine. Seems like I had to drill the reducer, but that's easy anyway. Chuck WB2EDV
[Repeater-Builder] Re: information requested re broadband internet canopy equipment interference
One of our 2M receive sites is shared with Canopy operating on 900. Our physical configuration is on top of a grain elevator. Our 2m antenna was mounted on a 30ft. tower which put our antenna about 20ft. horizontally at about the same height as the Canopy panels. We had moderately severe interference which sounded more like digital junk than something caused by the 900 mc. transmitters themselves. But couldn't tell for sure. We solved it by moving our antenna horizontally to 80 ft. away from Canopy. No interference at all now. Laryn K8TVZ
Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed
One comment if I may, I noticed the UHF version shown had the dipoles spaced around the mast instead of directly one above the other. Spacing around the mast like that at this frequency gives very bad vertical and horizontal patterns and much reduced gain. That's because the horizontal displacement between dipoles is a large fraction of a wavelength. Laryn K8TVZ
[Repeater-Builder] Re: 50-Ohm Pads
Unfortunately, transmitters and receivers are likely nowhere near 50 ohms. Best to terminate properly. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, n3dab rb_n3...@... wrote: I just use a 50 ohm dummy load on the open ports when tuning a duplexer, or leave one of the cables connected to the Xmtr. or Rcvr.
[Repeater-Builder] Re: Cable length
Well Ian, a foot or three longer or shorter with almost any cable will not make any measurable difference in power out, at least caused by cable loss. But depending on your transmitter, duplexer, antenna, and other variables, changing cable lengths could make your transmitter put out more or less power, and/or cause other effects. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, kerinvale kerin...@... wrote: Hi again guys .This has been brought up before I know but I thought I need to ask this .With the length between the transmitter and diplexer should we keep the cable as short as possible because I seem to find I have more loss with longer rg223u cables (aprox 1 meter ) .I tried a isolator inline and it produced lower output than the cable did.Should I be using shorter lengths so to lower the loss .Maybe I should try heavier cable like hard line and see how much loss I get from that Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Phone 0749922574 or 0409159932 www.kerinvalecomaudio.com.au
Re: [Repeater-Builder] Diversity FM reception
--- In Repeater-Builder@yahoogroups.com, Gary Schafer gascha...@... wrote: You can not transmit both horizontal and vertical polarization at the same time. Feeding a horizontal antenna and a vertical in phase will give 45 degree polarization. For simultaneous vertical and horizontal the antennas must be fed as circular. Years ago before CP antennas were commonly available, FM stations would feed two separate antennas on the tower. One was H, the other V. Was that then 45 degree polarization?? TV has no need to transmit anything other than horizontal polarization as most TV reception is done with a horizontal antenna. The local channel 8 analog station here had a CP antenna. To get their 316KW horizontal ERP they put 77KW up the coax from a many-yards-long Larcan transmitter. They had a whopper signal around here and it was very easy to get a great picture even with rabbit ears. I know that their excellent signal wasn't just because of CP, but it had to help. I wonder what their reasons were to go CP? Laryn K8TVZ
Fw: Re: [Repeater-Builder] Diversity FM reception
--- In Repeater-Builder@yahoogroups.com, John Sehring wb...@... wrote: Oh, I forgot...circular polarization would be excellent to use on VHF and UHF repeater. We want the extra signal strength the multipath would be way less; CP has always intrigued my for amateur repeater use, although I've not tried it yet. Yes there would be less multipath fading, but the extra signal strength woulnd't appear unless you keep the same ERP in both H and V. And that requires a larger antenna or double the transmitter power. John is it really true that CP causes MORE multipath distortion in FM broadcast?? And TV?? Laryn K8TVZ
[Repeater-Builder] Re: Diversity FM reception
By default, a voting remote receiver system does that. Two of our remote receivers for our 2M repeater happen to be about 14 miles apart. I can hear the link transmitters from those sites and will often switch between the two to compare. On a fixed-station user maybe more than 50-60 miles away, one of the sites may hear the user full quieting and the other noisy. 30 seconds later the situation could completely reverse. Mobiles are always heard with non-correlating fade patterns among the receivers (unless full-quieting of course) so the voter takes the best receiver on the fly and often sends a considerably better voted end-product to the transmitter than either receiver by itself. Laryn K8TVZ BTW, nothing sez that 2m couldn't use diversity reception on repeaters. Groundwave sigs suffer from multipath as well. On HF its tough to get enuf antenna separation to give space diversity gain (a wavelength or two) but easy above HF. --John WB0EQ
[Repeater-Builder] Re: Friday Humor
hehehe And I say if he can get that amount, more power to him. He's not the dumb one... Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, skipp025 skipp...@... wrote: re: Friday Humor There's a guy on Ebay selling a Holzberg ComLink CS540 UHF Repeater with a starting bid price of $1700.00
[Repeater-Builder] Re: Friday Humor
hehehe And I say if he can get that amount, more power to him. He's not the dumb one... Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, skipp025 skipp...@... wrote: re: Friday Humor There's a guy on Ebay selling a Holzberg ComLink CS540 UHF Repeater with a starting bid price of $1700.00
Fw: Re: [Repeater-Builder] Diversity FM reception
In reference to below, what would be the real advantage to using CP antennas in addition to the V and H you'd have already? Any signal that arrives will excite a V and/or H antenna according to it's arriving polarization, and I don't see where CP would be a help. Most FM broadcasters use CP. Those that don't are licensed for only V or H or choose to use a less-expensive single-polarization antenna. And many of them look like rototillers, and other shapes. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, John Sehring wb...@... wrote: There's more to be done with polarization as well: Circular, both RH LH. It is possibile to make omnidirectional CP antennas. FM broadcasters use a lot of them. They look like a bunch of arrows.
[Repeater-Builder] Re: DB-224 Matching
Perhaps drilling a hole through the original element for connection might be better. Uh, I wouldn't drill holes in elements. I did drill small holes in each of four elements years ago and within a year all four elements had cracked right where I drilled. Laryn K8TVZ
