Re: [Repeater-Builder] What's the point of the PL input on the RLC4?
Mike, You have programmed active low for both COR and PL but it sounds as though you have not used command 005 to set the receiver access mode to require both COR and PL. By default it requires only COR for the repeater to go active. In that state the PL input will simply be ignored. With command 005 you can set receiver and DTMF decoder access conditions. If you want to require both COR and PL for both repeater access and to send DTMF commands to the RLC-4, the proper command would be 005 1 3 3. Paul N1BUG Mike Lyon wrote: Howdy, This may sound like a dumb question but I am stumped. On my RLC 4, I put in code 013 1 0 0 for port 1, PL low, COR low. So when my COR goes low, it keys up the transmitter, just like it should do. But how does the PL input help make this decision? If my PL input is low or high, the COR is able to key up the transmitter, regardless of the state of the PL input. What I want it to do is not key up the transmitter UNLESS it sees a LOW on BOTH PL and COR. Is this possible? Thanks, Mike
Re: [Repeater-Builder] information requested re broadband internet canopy equipment interference
Hi Bruce, I am currently experiencing similar problems with a Canopy system that went on a nearby tower. However in my case it turns out to be their 900 MHz not the 5.8 GHz backhaul. It appears to be intermod since it only happens when my 147 MHz transmitter is up. There have been other instances of similar problems at nearby sites that were cured by replacing a switching power supply on the Canopy stuff. I'm assuming mine won't be that easy since it appears to be intermod not just switching PS crud. Paul N1BUG ve1ii wrote: Hi, I would like to hear of any details regarding interference caused to VHF repeaters sharing the same site with broadband internet Canopy equipment. I have a repeater which is experiencing a frying like noise on received signals being transmitted by the VHF repeater. As the VHF received signal becomes weaker, the noise appears to increase. Prior to the internet canopy being turned on there was no such noise. Any info, especially methods used to eliminate the noise would be very much appreciated. Any references to material on this problem would be especially useful also. Thanks, Bruce, ve1ii Yahoo! Groups Links -- Paul Kelley, N1BUG http://www.n1bug.com
[Repeater-Builder] Isolator vs intermod panel?
I guess I was lucky in my first few years as a repeater owner. Lately I have nothing but grief in many forms. (Yeah I know, welcome to the real world!) Can someone tell me in basic terms what is the difference between an isolator and an intermod suppression panel which contains an isolator? If one has a high power tube PA on a repeater, I assume he would need to use a high power isolator or intermod panel after the PA? Or would it be sufficient to use a lower power one between the solid state exciter and tube PA? Thanks... Paul N1BUG
Re: [Repeater-Builder] SRL235-2 Bi-Directional Antenna, which direction has gain?
If the Comprod is really the equivalent of the Sinclair SRL235-2, I must respectfully disagree with this. The instruction sheet for the SRL235-2 says the opposite, that maximum radiation would be perpendicular to a line drawn as described. I can scan a page from the Sinclair instruction sheet to back up this statement. Paul N1BUG Jeff DePolo wrote: If all of the elements are parallel as in your photo, then it's bi-directional. If you drew a line through one element, through the mast, and through the other element, maximum radiation would be along that axis. If the elements are staggered such that each bay pair is rotated 90 degrees from the bay above/below it, then it's basically omnidirectional. --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jesse Lloyd Sent: Tuesday, June 23, 2009 8:28 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] SRL235-2 Bi-Directional Antenna, which direction has gain? Hi all, I acquired a Comprod equivalent to the SRL235-2. Basically the same, just heavier duty and the cabling harness is in the boom. Anyway, which way is it directional? In the case of this picture of one http://www.repeater.n1bug.com/sinclairant.jpg http://www.repeater.n1bug.com/sinclairant.jpg is it diectional through the dipoles, or 90 degrees from them, ie in the diection of the tower (and opposite to) in that case. Thanks, Jesse
Re: [Repeater-Builder] SRL235-2 Bi-Directional Antenna, which direction has gain?
Yup. I completely agree with the theory of operation as you stated it for free space in-phase dipoles and dipoles 1/4 wave from a mast but not fed in pairs on opposite sides of a mast. It would certainly be interesting if someone were to model this thing. My take on it is that having two side by side dipoles fed in phase (which they are) changes the situation. The fed in phase dipoles largely overcome the tendency for the mast to act as a reflector. There may be some pattern disruption from the presence of the mast. That may be why there don't seem to be any deep nulls in the SRL235-2 pattern, where with a free space array I would expect to see fairly deep nulls in-line with the dipole pairs. But who knows... it has to be a rather complex situation. 73, Paul N1BUG Jeff DePolo wrote: Now you have me second-guessing myself. Over-simplying greatly: If the dipoles are spaced roughly 1/2 wave apart or less, it's going to be broadside to the axis of the elements (assuming the elements are fed in phase, which I presume they are). That's in free-space; but here we have a mast right in the middle of the two elements. If the elements are spaced somewhere in the vicinity of 1/2 wave apart, that means the mast is roughly 1/4 wave from each bay. A mast 1/4 wave behind a dipole would normally yield a cardiod pattern, with maximum gain away from the mast. So, two such cardiods back-to-back would yield an end-fire figure 8 pattern. That contradicts the first analysis (broadside). Maybe time to model it... I checked a Sinclair catalog (circa 1990) and, although it showed the elliptical pattern, it didn't say how the antenna was oriented for the plot. I don't have Comprod docs other than what's on their web site. --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Paul Kelley N1BUG Sent: Wednesday, June 24, 2009 5:36 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] SRL235-2 Bi-Directional Antenna, which direction has gain? If the Comprod is really the equivalent of the Sinclair SRL235-2, I must respectfully disagree with this. The instruction sheet for the SRL235-2 says the opposite, that maximum radiation would be perpendicular to a line drawn as described. I can scan a page from the Sinclair instruction sheet to back up this statement. Paul N1BUG Jeff DePolo wrote: If all of the elements are parallel as in your photo, then it's bi-directional. If you drew a line through one element, through the mast, and through the other element, maximum radiation would be along that axis. If the elements are staggered such that each bay pair is rotated 90 degrees from the bay above/below it, then it's basically omnidirectional. --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Jesse Lloyd Sent: Tuesday, June 23, 2009 8:28 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] SRL235-2 Bi-Directional Antenna, which direction has gain? Hi all, I acquired a Comprod equivalent to the SRL235-2. Basically the same, just heavier duty and the cabling harness is in the boom. Anyway, which way is it directional? In the case of this picture of one http://www.repeater.n1bug.com/sinclairant.jpg http://www.repeater.n1bug.com/sinclairant.jpg http://www.repeater.n1bug.com/sinclairant.jpg http://www.repeater.n1bug.com/sinclairant.jpg is it diectional through the dipoles, or 90 degrees from them, ie in the diection of the tower (and opposite to) in that case. Thanks, Jesse
Re: [Repeater-Builder] Connector plating vs PIM etc.
Jeff DePolo wrote: Now, having said all of that, my real-world experience with single-frequency-pair repeaters (not combiners or other multicarrier systems) is that I've never had a PIM problem that I could attribute to connector plating. Any connector that I install is silver-plated (or H+S Succoplate), but I don't go to the trouble/expense of replacing non-silver-plated connectors on equipment like duplexers, radios, etc.. Jeff, Thanks for all the info and the links for further reading! I appreciate the wealth of information. I had a very busy weekend and am still digesting some of the info, but I will come away with a much better understanding of the subject. The bottom line for me is probably this is something I don't need to worry about. It is a low RF site and I have just one transmitter. Paul N1BUG
Re: [Repeater-Builder] Connector plating vs PIM etc.
John J. Riddell wrote: Paul, there is a product made here in Canada by DW Electro chemicals called Stabilant 22 that works wonders on connectors. It is a liquid and is about 35 dollars for a very small bottle. You just put a very small amount of it on each mating surface of the connectors and it becomes highly conductive between the two metal surfaces. I used it on all of my repeater antenna connections and had excellent results in lowering noise problems. Interesting! I've heard of that stuff and probably need to get some and try it on the pins of the audio processor board on my Mastr II PLL exciter. Every once in a while the audio goes away, but pulling that module and re-inserting it fixes it every time. I'm staring to believe the noise problems I've been fighting for years were just band antennas... an old fiberglass collinear that had gone bad, and a new Sinclair dipole array that apparently had issues from day one. Everything is running *perfect* with the single dipole I threw up on the tower. Paul N1BUG
[Repeater-Builder] Testing the Sinclair dipoles
I did a brief test (a few minutes each) on the remaining 7 dipoles from the noisy SD2352 array. The only way I know to see if they are noisy in duplex service is to stick them on the repeater and see what happens. I used a weak signal radiated into the dipole under test for audible indication of noise, switching the transmitter on and off to compare. The one dipole on the tower continues to run perfectly noise free even with higher than normal power, so I'll call that one good. Of the remaining 7, all were absolutely noise free at a typical power level of 50 watts into the antenna. At 200 watts (which I use only for testing to see if I have any extra margin), 5 of them were noise free and 2 showed just a bit, maybe 1 to 2 dB. I did not have time to reassemble the entire thing and test it again. That will have to be a project for another day. I must decide whether to take a chance on using some of these dipoles and building my own harness to make a 4-bay in-line array or scrap the whole thing and buy another antenna. The first option is much cheaper but if it doesn't work it would end up being money thrown away. Paul N1BUG
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Nate Duehr wrote: I would also cautiously throw in here (knock on wood) that we've had EXCELLENT luck with the 2-bay vertical Sinclair folded-dipole antennas (snip) (Heck, if I knew the 2-bays worked THAT good from this type of site, I'd have put these things up sooner! S much easier to lift a 2-bay VHF than a 4 or 8 bay... no need for trucks or winches or big brute muscles... just a dude or two on the ground and a pulley... GRIN!) Thanks for sharing your experience Nate. In the last week I have been consistently surprised by how well the single dipole I put up on the tower is working. Signals are down a bit from the 8 element array in what were its favored directions, but not by as much as I was expecting. Perhaps I should consider making a 2-bay out of parts from the beast and evaluate that for a while before deciding about going to a 4-bay. Assuming I don't run into noise problems again when I start combining these dipoles into arrays, I'll end up going to 4 eventually. I'm trying to cover an impossible area from the only site available. It's a good site but our terrain around here is NOT VHF friendly. Yep... that darn 8-bay was HEAVY. Ya don't even wanna know how that was installed! Er... or I'm afraid to tell anyone for fear they'd wanna have someone who shall remain nameless committed! ;-) Paul N1BUG
[Repeater-Builder] Connector plating vs PIM etc.
OK, I guess it's about time I asked this. Is there someplace I can find a reference on various connector types (plated or not, type of plating) vs PIM/IMD/noise in duplex systems and/or in high RF environments? I am looking at replacing my run of LDF5-50A and wonder what type of connectors I *should* use. I always *thought* silver plated connectors were the way to go. But it is obvious none of the connectors on my DB4062B duplexer are silver plated. They are silver in color but they do not tarnish at all after many years... clearly not silver. I've also noticed on this Sinclair dipole array that I had problems with, the 3 x N(f) tees are silver plated but the mating N(m) connectors on the harness are not. Brass, silver, gold, tri-metal (?)... help! What are the accepted rules for connector choice for duplex systems and/or in high RF environments, and why? What about mating connectors with different plating? If a repeater is in a very low RF environment, does it even matter? Thanks! Paul N1BUG
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
Skipp, Do you have any idea WHY the models with two dipoles side-by-side are problematic and the in-line models are not? Are there differences in the construction of the individual dipoles that cause problems? Differences in the phasing harness? I'm thinking about using these dipoles to build an in-line 4 bay array with my own harness, but if the dipoles themselves are prone to problems that would seem a waste of more time and money. I was considering doing that even before the array became a noise nightmare, since it would produce a pattern somewhat more to my liking and maybe (depending on how it was done) reduce weight and wind load. When (if?) I recover from blood loss to black flies at the repeater site today, I will report on my findings testing individual dipoles from the problematic array Paul N1BUG skipp025 wrote: Note the problematic Sinclair VHF dipole arrays are/were the models with two Dipoles per mast position, which means each location on the mast has a horizontal bar with a folded dipoles at each end of the mast (two parallel dipoles per horizontal mast). The traditional in-line folded dipole arrays work muy bueno... (very well). Just the dual side-by-side FD arrays are the train wreck (in what appear to be the 4 and 8 bay assemblies).
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Chuck, They are hot dip galvanized and there is no sign of rust (yet). When I took this apart I checked every bit of hardware for looseness and rust, found nothing suspect. One thing I did notice when I got the antenna was the factory Y splices and heat shrink over the 1/4 wave 35 ohm matching section were anything but water tight. I added waterproofing (butyl rubber and tape) in which I had total confidence but now paranoia is making me doubt myself. :-) I will rip into it today. Paul N1BUG Chuck Kelsey wrote: Paul - Were the U-bolts that attach each element arm to the mast stainless or hot dip galvanized? I do know of one (UHF) Sinclair array that used plated U-bolts and they rusted. Chuck WB2EDV Several weeks ago I posted about my ongoing battle with duplex noise on a 2 meter repeater. I have now found a big piece of the problem (maybe all of it) but I'm a little surprised. I am wondering if others have had similar experiences. Two years ago I put up a new (well... NOS, actually) Sinclair SD2352 antenna (8 dipoles, bidirectional pattern). I had no noise for several months after that, but then it started coming back. By this Spring the repeater had become all but unusable.
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Thanks Burt! Great info there. If all the dipoles seem to be OK (not noisy) I am thinking of making my own harness to use 4 of them. I've constructed several multiple-antenna EME arrays so I understand the concepts and the importance of equal lengths, etc. My only concern with making my own harness is that the length of coax attached to each dipole is not long enough to reach a tee connector on the mast and allow sufficient vertical spacing between dipoles. (The original configuration had four bays of two side by side dipoles, so the shorter length was appropriate there.) It will be easy enough to add on some coax but since the impedance at my 147 MHz frequency is not exactly 50 ohms and somewhat reactive it will vary somewhat with the coax length. I don't think it will be enough to cause major issues. I see that I will need to use some odd multiple of a quarter wavelength for the 50 ohm coax sections from the array center tee to each of the outer tees feeding pairs of dipoles. I need to see if I can figure out what failed and why in the original configuration before I go investing time and money into a rebuild though. Its useful service life before becoming too noisy was less than a year! Paul N1BUG Burt Lang wrote: The matching section inside the loop is a 1/4 wavelength of RG-63B 125 ohm coax. The overall outside diameter is the same as RG-214 but the dielectric is semi-air (like a large version of RG-62 93 ohm coax) and the center conductor is quite small, like RG-59. I have a few hundred feet of RG-63B if you want to experiment. The actual length of the matching section in the commercial loop is not however a 1/4 wavelength at the center freq of the dipole but rather on the high side. A Sinclair loop I dismantled had a matching section that was 1/4 wave at 182 MHz. I believe that this is the secret to the extra wide bandwidth of the dipole. Using a matching section that is 1/4 wave at the center freq of the dipole (156 MHz) gives a much better return loss at 156 MHz but is at least 20% narrower bandwidth. I have made a number of clones with both the dipole and the matching section tuned to 146MHz. The return loss was very good at 2m (SWR very close to 1:1 vs the commercial antenna that was 1.2:1 at its lowest point over the 138-174 MHz bandwidth.) I also used the same design in several 4 bay 220MHz versions that have been in service for up to 15 years. Check the following URL for a diagram of my clone design: http://www.gorum.ca/fdipolev.gif One point of warning: It is very hard to insert the coax into the loop. You have to make as short a splice as possible since it must slide past the 180 deg bend in the loop. Avoid messing with this coax unless absolutely necessary. As for the harness, the key point is that the electrical length of the RG-213 from each dipole must be identical. The actual electrical length is unimportant, it just has to be the same for all dipoles. The actual configuration of the harness depends on the number of dipoles. One and 4 dipoles can be made entirely with RG-213 whereas 2 and 8 dipoles require a 1/4 wave section of RG-83 35 ohm coax. The one mystery I have is how Sinclair inserts the harness into the mast for the fully enclosed model. The matching section parts of the harness are completely inside the mast and is beyond the means of us amateurs. However an external harness is very practical. Burt Lang VE2BMQ
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
That is interesting Gran. The noise did not change with weather conditions, be it wet or dry, dead calm or gale force winds. I didn't try spraying with water while testing, but did tap on all the dipoles and wiggle as much coax as I could reach. It didn't seem to react to any of that. It was very noisy during all this testing, but not much more or less so than at any other time. Paul N1BUG Gran Clark wrote: Paul I have recently had to deal with the same problem. Note if the noise goes away when the antenna is wet for frozen. If this is the case try selectively spraying elements with water while whacking the antenna with a rubber hammer. I will leave the mechanics of doing this up to youHI.Feed line noise due to flexing could be eliminated as a cause with this test also. Tightening hardware helped in my case but the final answer was going to all welded construction. Gran K6RIF
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Hi Burt, Let's hope you don't need to get inside the dipole itself. BTW what is the diameter of the aluminum tubing used on the SD2352? The SD214 uses 3/4in OD. I *am* hoping! They use 3/4 in. OD on these also. The width of the folded dipole is 4.25 inches and the tip to tip (outer radius of bend to outer radius of bend) length is 34.5 inches. You could try using 3/4 wavelength matching pieces to get the extra length. That should be equivalent to 1/4 wave but will be more sensitive to frequency changes. I only need to extend them by about a foot to get ideal spacing between dipoles, so 1/4 wavelength with .66 VF would be enough. Never having seen one of those antennas (the SD2352) up close, I am not sure of the harness configuration and how it would compare to the SD214 that I am familiar with. Total of 8 dipoles. Impedance at end of coax coming from each dipole approximately 50 ohms. Two dipoles connect to a type N tee, so at the tee center should be about 25 ohms. From there, 1/4 wavelength RG-213 to a a factory harness 'Y' splice, coax should transform the impedance to about 100 ohms, divided by 2 at the Y so we're back to 50 ohms coming out of there. From there, approximately 66 inches RG-213 to the center Y splice of the overall harness. This coax should maintain 50 ohms, divided by two at the center Y splice = 25 ohms. There is a 1/4 wavelength of some coax coming out of there, spliced to a length of RG213 running down to the bottom of the mast. I'm assuming the 1/4 wavelength matching section is 35 ohm coax, but cannot confirm that. This description may be clear as mud... I can make a diagram of it later if you want. Figuring out the failure mode is the most important first step. Then you can go from there to possible solutions whether it is harness replacement, repair or dig into the dipoles. I have decided no matter what I'm not putting it back up as an 8 dipole bidirectional array so I will take apart the original harness for inspection. I will also test each of the dipoles on the repeater individually to check for noise. If I do not find any problems in either of these processes, then I will have no clue what caused the problem! Paul N1BUG
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Update... the entire harness looks pristine. No sign of any problem. That goo they put inside the plastic clam shells around the factory Y splices is rather interesting stuff! I hope I find one or more noisy dipoles when I test 'em... otherwise I'll be left with a mystery and have no idea what was wrong. Meanwhile the repeater continues to be 100% perfectly free of noise on the single dipole from this array. It was never this good with the whole SD2352 up there... not even on day one. Paul N1BUG Chuck Kelsey wrote: Or the white, powder residue. That's just as bad as the green stuff. From: Burt Lang Consider the possibility that water has got into the RG-213 and corroded the shield. This would likely give noise when RF is applied but not be particularly sensitive to vibration. Look for green copper shields, it is not environmentally friendly :-)
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
You didn't say, but are you running on some other antenna right now. (I'm looking here for how you know it was the Sinclair making the noise, and not some nearby rusty joint problem in a high RF field environment. (Are you in a high RF field environment? Any new transmitters right on top of your new Sinclair antenna?) Nate, I would call it a low RF environment. There are two cell towers, both about 500 feet away, neither has any VHF or UHF repeater tenants. The nearest broadcast station of any type is at least 15 miles away. There are one or two other VHF transmitters nearby but they are very rarely up and I had noise all the time. Right now I am running on one single dipole removed from the Sinclair array and it is working perfectly. Zero noise. Just thinking through it and wanting to make sure you didn't do anything drastic to the antenna before you KNOW it was the antenna and not something else nearby... I appreciate it! This problem has really had be baffled. In fact I DON'T KNOW it is the Sinclair. Here's the story: Two years ago my very old top-mounted PD220 failed (repeater signal dropped, lots of crackling noise). No surprise there, I had been wondering when that thing would die. I replaced it with the Sinclair but unfortunately I extended the tower at the same time so I introduced many new variables. I noticed right away there was some noise every time my transmitter came up but couldn't find any obvious cause and most of the time it wasn't enough to really be an issue. A year later the noise started increasing rapidly, sometimes some crackling but more often a highly variable white noise, basically just an unstable increase in receiver noise floor. It got worse and worse until at the end I had at least 10 dB noise increase every time my transmitter came up, varying to sometimes more than 30 dB. Ouch! Much testing and fooling around was done over a period of several months... dummy load at duplexer (no noise), at top of tower (no noise), swapped out the transmitter (no change), swapped out receiver (no change), tried using two antennas (that helped especially when the Sinclair was NOT the transmit antenna, but did not get rid of the noise entirely). Shook, wiggled, prodded and aggravated every metal and quasi-metal object within several hundred feet... nothing seemed to react. A week ago I pulled the Sinclair off the tower and stuck an old IsoPole up in the same spot. Zero noise! Huh? I increased transmitter power by several dB, still no noise whatsoever. I now have one dipole removed from the Sinclair on the tower, and there is no noise at all with that arrangement. My gut tells me this is a rusty bolt / bad connection kind of thing, but it goes away when the Sinclair isn't on the tower. I know that doesn't prove anything, but I have no idea where else to look other than the Sinclair antenna. I'm open to suggestions. Paul N1BUG
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
There's nothing crazy about that idea Nate! I get creative thoughts when sleep deprived too. :) I had been thinking the transmitter might be doing something funny. I don't have easy access to a spectrum analyzer, but I think I've ruled out spurs as the primary cause? Correct me if my logic is flawed. I did some tests before I pulled the Sinclair off the tower. With the Sinclair and another antenna on the tower, here is what I found: RX TX on Sinclair SEVERE noise, 10 to 40+ dB RX on other ant, TX on Sinclair moderate noise, peaks to 10+ dB RX on Sinclair, TX on other ant... mild noise, nil to maybe 5 dB RX and TX on other ant... maybe traces of noise??, barely detectable RX and TX on other ant, Sinclair removed from tower... no noise detected... dead quiet I think this suggests something in the Sinclair is generating noise, and that even when transmitting into another antenna it picks up enough RF to make some noise? You wouldn't believe how many pages of notes I have on various tests and experiments over the last year or so... I don't even know what's in there any more! I was hoping to get up to the site today to do a brief test duplexed into each of the other dipoles pulled from the Sinclair, but no go. Maybe tomorrow. Paul N1BUG Nate Duehr wrote: A TOTALLY crazy idea Paul... Just going off of your comment that it gets better when you split antennas but is always there when the Sinclair is on the tower... Could the Sinclair be doing something funny to your transmitter and causing it to throw spurs? Things would be really bad when duplexed on it, and get better as you move the receive antenna away from it. Just a thought... would need to look at your output on a spectrum analyzer to see that one... preferably first on one of the antennas that works and then on the Sinclair. Nate WY0X (Sleep deprivation will lead to some creative thoughts, I'm finding today. It was a lng night last night.)
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Ed, That is true. I stupidly neglected to do that after removing it from the tower and have been kicking myself ever since! I will probably end up re-assembling it to try that... but of course now everything has been disturbed so it may or may not act as it did before. I did do a brief test on it before it went up the tower two years ago and noted a couple dB of noise. I dismissed it as probably somehow related to the antenna being too close to the repeater equipment etc. but had about the same observed noise after mounting it on the tower. It held that way for months and then started getting worse. Paul N1BUG Ed Yoho wrote: Paul, One test I have not noticed listed is if you've tried the Sinclair while it was not attached to the tower (and a reasonable distance away from anything that could affect it). Ed Yoho W6YJ
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Chuck Kelsey wrote: You could test the harness with dummy loads connected in place of each element, if you can round up enough dummy loads. I like that idea. I would have to buy a bunch of loads though, not much chance of borrowing that many around here. And you could install the entire array at a different location and test it there. I wish I had at least checked it at ground level after pulling it off the tower... I goofed there! If the single element is mounted in the same location as where the array was, I'd not be terribly suspicious of a near-field noise maker - rusty bolt, guy wire, etc. It is at the same location, but is not mounted with the same hardware. Paul N1BUG
Re: [Repeater-Builder] Re: Sinclair dipole array premature failure (noisy)
That's interesting Skipp. I'm searching. I did find a couple references to PIM/IMD problems and one about poor signal with this type antenna. The latter caught my eye as I've been sitting here half thinking coverage with this single dipole I tossed up there *seems* to be as good as with the whole array. I can't be sure since I haven't been out there to really see for myself what it is doing. At this point it's just a funny feeling I keep getting. Might be nothing to it... I'd have to go drive around for half a day to be sure. I will keep digging for old posts on the subject... Paul N1BUG skipp025 wrote: There are known problems with this series of antennas... see my previous posts bad-mouthing Sinclair regarding this same situation. I was only told that Sinclair has reworked the model and the update reportedly fixed the problem. I never received a return phone call or Email regarding my same type of problem with a lot of similar type/model Sinclair antennas I purchased. So I bad mouth that antenna model/series all I can and give Sinclair grief about their customer service and engineering at the IWCE Convention. So far they haven't cared to resolve my, nor 3 known similar customer/owner problems. When you start to stack more than one of that series/type folded dipoles into an array... they start to glitch themselves up pretty bad with IMD/PIM Issues. You will find the same type/series of antenna under a few different labels/model numbers. But it/they are still a very bad design. Search back through the group archives for more details regarding my previous posts. It's not a happy story... cheers, skipp
[Repeater-Builder] Sinclair dipole array premature failure (noisy)
Several weeks ago I posted about my ongoing battle with duplex noise on a 2 meter repeater. I have now found a big piece of the problem (maybe all of it) but I'm a little surprised. I am wondering if others have had similar experiences. Two years ago I put up a new (well... NOS, actually) Sinclair SD2352 antenna (8 dipoles, bidirectional pattern). I had no noise for several months after that, but then it started coming back. By this Spring the repeater had become all but unusable. Recently I took down the Sinclair and installed a temporary antenna. Noise gone! Huh? I subsequently disassembled the Sinclair to check for problems. Every piece of hardware was tight. I found no evidence of water in any of the N connectors on the harness, which I had wrapped with Scotch 23 rubber tape followed by Super 88 vinyl tape. The impedance of the complete array and of each individual dipole was still nominal, as it had been prior to being installed. I have now put one dipole from the array on the tower and it is running absolutely noise free. Moving it around on the tower doesn't have any affect... it is noise free wherever I put it. Lacking any other explanation it would seem something in the array became noisy after a short time. I don't know if it is a problem with one or more of the dipoles or perhaps something in the factory assembled portion of the harness. I have not yet attempted to do a post mortem on the factory harness assemblies. I am wondering if this is a unique experience or if this is a common failure mode in exposed dipole arrays? I don't recall hearing much about such arrays becoming noisy, at least in such a short time. Since these dipoles are 50 ohms, I think it would be easy enough to build two 4-dipole cardioid arrays from it, *if* the problem lies in the harness and not in one or more of the dipoles. I wonder if anyone knows what (if any) gimmick Sinclair used to get such broad SWR bandwidth on these dipoles? The exposed portion of the coax on each dipole is RG-213, 50 ohms... but I'm wondering if they may use some quarter wavelength (or ???) of some other impedance on the part hidden inside the dipole, especially since these things exhibit a clear double dip SWR curve (one dip near the low end of the design range, 138 MHz, and another dip near the upper end, 174 MHz, with a somewhat reactive bump in between). 73, Paul N1BUG
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Mike, Thanks. That is interesting. I don't recall hearing about this with dipole arrays before. What is the failure mechanism? Deterioration of the coax due to repeated slight flexing? The antenna was supported bottom and middle. Paul N1BUG Mike Mullarkey wrote: Paul, I have a question as to how you are mounting the antenna. If you are not top supporting the antenna and mounting it on top of the tower that would explain why as to you getting noise in your transmit signal. Same goes for DB antennas especially the DB224 being so long and not top supported you will eventually get noise in the signal as well.
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
That's what I thought Chuck. Thanks! I haven't yet decided whether I want to rip the heat shrink tubing off an element and disassemble it to see what coax is inside, which is why I asked. I was sort of contemplating whether it might be possible to replace all that coax with RG-214 in an attempt to build a noise free harness. But if there's a matching section, I'm sure the return loss without it would be really ugly. Paul N1BUG Chuck Kelsey wrote: There is a 1/4 wave impedance matching section of coax (125?) inside the element. The matching section is stagger tuned from the element itself. That's why it is more boadbanded and why you see two return loss dips. Chuck WB2EDV - Original Message - I wonder if anyone knows what (if any) gimmick Sinclair used to get such broad SWR bandwidth on these dipoles? The exposed portion of the coax on each dipole is RG-213, 50 ohms... but I'm wondering if they may use some quarter wavelength (or ???) of some other impedance on the part hidden inside the dipole, especially since these things exhibit a clear double dip SWR curve (one dip near the low end of the design range, 138 MHz, and another dip near the upper end, 174 MHz, with a somewhat reactive bump in between). 73, Paul N1BUG
Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)
Well the 125 ohm quarter wave info sounds reasonable. That would imply the actual impedance of the folded dipole is in the vicinity of 300 ohms. I think my strategy at this point is to test each element by itself. I'll have to actually put each one on the repeater and check for noise as that's the only way I know to see if they are noisy in duplex operation or not. If all the elements test good, I will rip apart the factory interconnection harness to see if I can find anything wrong with the Y splices. Meanwhile if anyone else has any insight on exposed dipole arrays going noisy within a short time after installation, please chime in. I would really like to understand the issues with this. Paul N1BUG Chuck Kelsey wrote: Sounds like something in the harness went intermittent. To get at the inner element connection, you'd need to cut the shrink tubing on the outside of the element. That should gave you access to the connection point of the 125-ohm matching section that is spliced to the RG-213. You could then pull that out. However, if each element plays alone with no noise, I'd leave the element wiring alone and check the harness that connects the elements together. All that said, I've never worked on a Sinclair. I'm going by info that I believe to be correct as to what is inside the element. Chuck WB2EDV - Original Message - From: Paul Kelley N1BUG paul.kelley.n1...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, May 18, 2009 6:58 PM Subject: Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy) That's what I thought Chuck. Thanks! I haven't yet decided whether I want to rip the heat shrink tubing off an element and disassemble it to see what coax is inside, which is why I asked. I was sort of contemplating whether it might be possible to replace all that coax with RG-214 in an attempt to build a noise free harness. But if there's a matching section, I'm sure the return loss without it would be really ugly. Paul N1BUG Chuck Kelsey wrote: There is a 1/4 wave impedance matching section of coax (125?) inside the element. The matching section is stagger tuned from the element itself. That's why it is more boadbanded and why you see two return loss dips. Chuck WB2EDV - Original Message - I wonder if anyone knows what (if any) gimmick Sinclair used to get such broad SWR bandwidth on these dipoles? The exposed portion of the coax on each dipole is RG-213, 50 ohms... but I'm wondering if they may use some quarter wavelength (or ???) of some other impedance on the part hidden inside the dipole, especially since these things exhibit a clear double dip SWR curve (one dip near the low end of the design range, 138 MHz, and another dip near the upper end, 174 MHz, with a somewhat reactive bump in between). 73, Paul N1BUG Yahoo! Groups Links Yahoo! Groups Links -- Paul Kelley, N1BUG http://www.n1bug.com
Re: [Repeater-Builder] Adding Extra Cavities to Duplexer
Dave, I'm not familiar with that particular duplexer, but I will take a stab at this. I have had some experience adding to duplexers, re-cabling, etc. I am assuming the additional cans are identical to the ones used in your duplexer and that if there is a difference between high pass and low pass cans that you have one additional of each. You should be able to get at least 100 dB with the additional cans. If the original is really giving 80 dB at your frequency separation, theoretically you may see 120 dB. The cabling will have to be exactly right to see that much, and you'd better have very well shielded cables everywhere or leakage may spoil the 120 dB notches. Insertion loss should increase about 50%. If it is 2 dB now, it should be about 3 dB with the added cans. I would duplicate the cable type and length that is used between the existing cans. Use the same connector types also. And if there are T connectors on the cans, use the same type. Good luck and let us know your results when you're finished! 73, Paul N1BUG David Struebel wrote: I have a Phelps Dodge 506-1 four cavity duplexer. Just recently picked up two additional cavities from someone who was parting out his duplexer... all cavities are BP/BR... Would like to add these to the duplexer to get additional isolation. The original duplexer is spec'd at 80 dB isolation... What do you think I can get with the two additional cans? I realize the insertion loss will be higher.. Any idea how much? The cabling between the cans is still 1/4 wavelength in coax, right?? since I will have to add some cabling...I have seen some discussion in the duplexer info on the site about maybe using a diffrent length cable when adding more cavities... Can anyone comment on all this? Dave WB2FTX No virus found in this outgoing message. Checked by AVG - www.avg.com Version: 8.5.325 / Virus Database: 270.12.26/2110 - Release Date: 05/12/09 06:22:00 -- Paul Kelley, N1BUG http://www.n1bug.com
Re: [Repeater-Builder] Ham installation quality/non-quality
Got one here too! Honestly you should see some of the professionally installed repeaters with mobile radios screwed to plywood, wires dangling everywhere, exposed electrical connections, repeater buildings with rusty metal sheets for siding flapping in the wind, bent leaning towers (installed that way), RG-58 jumpers, etc. etc. And then they complain about having intermod and can't figure out why!? It really annoys me to think they get paid to put up such crap. Paul N1BUG mwbese...@cox.net wrote: Got one like that here too. It ain't just the hams that are amateurs! Mike WM4B On Mon, May 4, 2009 at 3:22 PM , Chuck Kelsey wrote: I know a radio shop that does installs like that. It's been in business for over 30 years. Chuck WB2EDV
Re: [Repeater-Builder] Re: W1GAN and square duplexers aka homebrew duplexer
Mike Morris WA6ILQ wrote: As I recall, an early ARRL VHF manual had a brief chapter on repeaters, and I believe there were two articles that were of interest. One was the duplexer and another was a four bay folded dipole antenna for repeater use. I'd like to get a scan of that ARRL antenna article for the antennas page (repeater-builder has permission from the ARRL to post PDFs of any articles in QST or their books). I think this may be the one he was referring to: http://www.repeater-builder.com/projects/exposeddipole.html 73, Paul N1BUG
Re: [Repeater-Builder] Remote receiver suicide control
Mike Morris WA6ILQ wrote: The lock-shut-through-its-own-contacts latching relay uses power as long as it is activated. As another gentleman pointed out, the magnetic latching relay only uses power when the coil is activated (i.e. a pulse to change the state of the relay). I would want to use the magnetic latching type, since I see no sense in wasting solar power if the package is shut down. The 12v circuit breaker with the shunt trip coil sounds like the most feasible, and besides it's designed exactly for the job. I'm researching that, as I wasn't aware of these devices. Sounds interesting. So far I haven't found a source of suitably rated units, but I haven't had much time to devote to it. dropping a dead short (even momentary) across the battery is not going to do it any good. Good point. You could use an old IMTS horn honker decoder to trigger the trip coil. Do you recall how much power they consume? I'm leaning toward the Selectone ST-809B for its negligible power consumption. My working theory is that (within reason) it's cheaper to spend money on low power consumption electronics than to buy more solar panels. :) Paul N1BUG
[Repeater-Builder] Remote receiver suicide control
I am also working toward a multiple receiver voted system and have a question. I was reading http://www.repeater-builder.com/tech-info/votingcomparators.html and wondering about how to implement a site suicide command where power is disconnected from the entire remote package requiring a trip to the site to bring it back to life. I definitely want some way to kill an entire package at a remote site. Assume a remote receiver at a location that is extremely difficult to access in winter, and solar power so current drain needs to be kept as low as possible. Any suggestions on how to implement a suicide command for such a remote package? I can think of a couple ways to do it but usually someone here has better ideas than mine! 73, Paul N1BUG
Re: [Repeater-Builder] Remote receiver suicide control
RAMSEY KITS has a unit that is supposed to work from commands via your telephone touch pad. It’s about $39. You call the unit up, touch the phone keys, and the dtmf commands can turn on and off devices plugged into it. I wonder could this be converted to work on the input of a recvr, accessed by PL tone, etc to turn ON and OFF a power supply, controller, etc? If you find out…LET ME KNOW. ’73, Mike I'm not familiar with that specific kit, but I suspect it could be interfaced to receiver audio output instead of a phone line. It could probably be used for what you want. There are other DTMF decoder units around also. For my application I'm wondering about how to interface the DTMF decoder output to permanently kill power to a site. I'm thinking I want to have it do something like deliberately blow a fuse... but maybe there are better ways to handle it. Paul N1BUG Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: mailto:repeater-builder-dig...@yahoogroups.com mailto:repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Remote receiver suicide control
Randy, I will be using a small repeater controller. What I want is some way to kill power to everything in the box... receiver, link transmitter, controller, the whole works. This would be a last resort in the event something fails in such a way that it is critical to shut it down, at a time when I can't physically get to the site. Some sites here are not easily reached in winter. Since I really want to be able to kill power to everything, including the controller, it will pretty much end up requiring a later trip to revive the site. Hopefully I will never need to use the last resort kill command, but I consider it a must have feature. My main concern is that the kill switch be as reliable as possible. Of course nothing is 100% reliable! If a receiver or DTMF decoder dies, I will lose the ability to kill the site anyway. Paul wb8art wrote: Paul, I have a question on this suicide control. Are you killing everything thus no ability to revive the site without visiting it? Not withstanding I would use a simple small repeater controler. Chose your poison there, but in any case, there are some that give you a small amount of logic outputs to drive whatever kill switch you decide on. Added plus you have control of remote on/off, ID PL on/off etc. Just a thought. Randy
Re: [Repeater-Builder] Remote receiver suicide control
Mike, Paul, Mike, Martin, and others... Thanks for the ideas. I will try out a couple of them and then make a decision on exactly what method to go with. I had not thought of using a latching relay. The idea of a husky relay or maybe a beefy SCR to short the supply on the inboard side of a fuse or circuit breaker did occur to my feeble mind, but I wanted see what others could come up with for ideas. Paul N1BUG
