Re: [Repeater-Builder] Moisture/condensation (was: Duplexers)
Condensation and moisture can be a strange thing... I have 2 meter and 440 repeaters in my own unheated building on a local hill. Several years ago in the middle of a cold Maine winter, both repeaters started having assorted audio problems and controller glitches. Upon arriving at the site I was horrified to find a thick layer of white frost completely covering every surface inside the building. Floor, walls, ceiling, every bit of equipment, cables, everything pure white and hairy with frost. I scraped away some frost and removed the cover from the repeater controller cabinet... and was even more horrified to find the controller PCB completely covered in frost! Couldn't even recognize the larger individual components on the board... What to do? I VERY slowly brought up the building temperature with a temporary heater over a period of a few days. The frost slowly vanished, not so much by melting and forming water but by dissipating into the air. Everything returned to functioning normally. The funny thing is, it never happened before or since. Just that one time. I never did figure out exactly what conditions caused it. Paul N1BUG
Re: [Repeater-Builder] Moisture/condensation
Yeah... it was strange. The building sits up off the ground and there were no holes for water entry. Snow outside, but ground under the building was bone dry. There had been a rainy spell a week or two earlier. The only thing I can think of is very moist air was trapped in the building when the temperature dropped. It must have been a rather uncommon set of circumstances since it just happened that one time. It's hard to believe there could have been enough moisture in the air to form so much frost! Paul N1BUG Paul Plack wrote: Wow...sounds like somehow, moisture was released inside the building. If it's 20ºF outside the building, and 22ºF inside the building, it's hard to imagine how frost could form on the equipment, since the relative humidity indors would have to be lower, unless...there was water forced up through a crack in the floor, etc. 73, Paul, AE4KR
Re: [Repeater-Builder] Silver Plating - Cheap Easy
There was an article in Ham Radio magazine describing a variation of this method of silver plating. It was in the mid 1980's. The method involves attaching the negative lead of the DC current source to the piece to be plated. The positive side is connected to a carbon rod with a sponge wrapped around it. The rod/sponge is dipped into the used fixer, then slowly wiped along the piece to be plated, where it deposits silver. It takes patience and a bit of practice but I silver plated the tank circuit in a 1 kW 2 meter amplifier and got a small (but worthwhile for what I was doing) improvement in efficiency and power output. Paul N1BUG George Henry wrote: It's actually used photographic FIXER that contains a lot of free silver... the fixer removes any unexposed silver in the film emulsion. For many years I recovered the silver from my fixer by adding powdered zinc, which will dissolve more easily in the solution than silver will, causing the silver to precipitate out. Collected over 28 ounces over the years. His method of silver plating probably involved connecting the negative lead of a low-voltage source to the can, filling it with used fixer, and then suspending a zinc electrode in the solution, connected to the positive lead. The zinc goes into solution, and the silver, instead of precipitating out, plates out onto the can. If the fixer is sufficiently loaded with silver (exhausted, in photo-speak), it will plate out on copper without any current source, but adding the batteries will speed things up result in a thicker layer of silver. George, KA3HSW From: cecil ferguson ke4...@bellsouth.net mailto:ke4nna%40bellsouth.net To: Repeater Builder Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Mon, July 12, 2010 7:08:36 AM Subject: [Repeater-Builder] Silver Plating - Cheap Easy A couple of years back, in an exchange with an engineer from Texas Instrument Germany, who is working in Freising, Barvaria, I was told of a cheap and easy silver plating procedure he uses on his duplexers. He uses Photographic Developer (which has a really high level of 'free silver') and a simple one or two cell power source = 1.5 to 3.0 volts. (While not discussed, I would suggest that 'used fluid' may be better than new and may be obtained very cheaply). This should be an ideal solution for the DIYers in our group. If interested, why not contact Hans-Juergan Schott directly at h-scho...@ti. com ? This should be an interesting topic for our Tecnical Info page as well. Hans-Juergan, if you are monitoring, pls forward this procedure to us as I think many of us would be interested. Tnx. 73 to all, Cecil E (Gene) Ferguson. W4FWG 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: repeater-builder-dig...@yahoogroups.com 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] Silver Plating - Cheap Easy
JG wrote: Good fishing !!, or is your memory that good:) I poked Ham Radio magazine into Google and found a few articles on silver plating in this list: http://webhome.idirect.com/~griffith/hr/hrind05.htm Safe, Sensible Silverplating ... that rings a bell! That is the one I was thinking of. Feb 1985. Hmm. My guess of mid 1980s wasn't too far off the mark. Now if only I knew what I did yesterday. :-) Now, here's the Million Dollar question.. where are these articles archived ?? Nowhere that I know of. I wish I had saved that article, and would like to read the earlier ones on silverplating too. Actually I did save that issue for years but eventually lost track of it. May still be in a forgotten/buried box from my last move... 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: repeater-builder-dig...@yahoogroups.com 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] Sinclair dipole phasing harness
Nate Duehr wrote: I am not an expert, but most of the Sinclair stuff I've used had the elements welded in place. These are the HD models (heavy-duty) They also make them welded in the Low PIM models... no moving parts to make noise... Interesting. I was wondering what was different about the low PIM models. I should have guessed they would be welded construction. I wonder if they also use different types of coax in the harness? I have often wondered if single copper braid cables weren't a potential source of noise, especially as they get older? I think you're right in the lower-end Sinclair line, there are elements that are just bolted to a mast Correct. I am not an expert either, but have seen quite a few of these in various configurations and spent some time perusing the product line, wishing I could buy a new one. Some have the dipoles just a few inches from the mast, and are field adjustable for offset or omni pattern. For offset, all dipoles go on one side of the mast. For omni they go on opposite sides or spiral around the mast. These models generally seem to have a bandwidth of about 10 MHz, eg. they come in 142-152, 152-162 MHz models, etc. Some have the dipoles roughly a quarter wavelength from the mast, all on one side, and are intended to provide an offset pattern only. These usually cover 138-174 MHz. Some have the dipoles roughly a half wavelength from the mast, all on one side, and are intended to provide and elliptical pattern. These usually cover 138-174 MHz. There are also a few that have pairs of dipoles side by side, with spacing somewhat less than a quarter wavelength. These are field adjustable for elliptical or omni, and the ones I've seen (and owned) were 138-174 MHz. There very likely may be others that I am not familiar with, these are just some observations I have made. I'll take the expensive antenna, any day... over farting around with a lower quality one! I would if I could! Maintaining a repeater is becoming a full time job. Much of the time that goes into it is directly related to farting around trying to keep something on the air and working reasonably well with a zero budget. But one does what one can. If it was just another repeater serving an area that already had several repeaters sitting idle, I'd have walked away from it in frustration long ago! 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: repeater-builder-dig...@yahoogroups.com 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] Sinclair dipole phasing harness
Hi Burt, Did I hear my name mentioned??? Maybe just ESP:-) Yes you did, Great Sinclair dipole guru! :-) I got the dipole drawing from your new web site. Thanks! That part I'm clear on, but still a bit confused on the phasing harness. I would suggest that you don't even consider putting the harnass inside the mast (unless Harold can tell us how Sinclair does it). Put the harness on the outside of the mast like the SRL210A4. Uh, yeah, I hear that. I like the idea of the internal harness, but I just spent 3 hours getting the old harness *out* of the mast. I can't imagine how it was put *in* there. To combine the impedances on a 4 bay Sinclair array is simple. Divide the dipoles into pairs and parallel them. This gives 25 ohms. Then add an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 100 ohms. Combine the matching coax from each pair in parallel to give 50 ohms. Then you can connect your feedline at any length from this latter 50 ohm connection. Here is a crude drawing of what I think you are saying: http://www.n1bug.com/dipoleharness1.jpg Points X and Y are the 100 ohm points created by adding an electrical quarter wave of RG-213 coming out of the 25 ohm point where two dipoles are connected in parallel. But points X and Y are physically several feet apart. That being said, I think the coax that joins those points at the final parallel junction (to connect to the feedline) would have to be a multiple of an electrical half wavelength in order to repeat the 100 ohms at the other end (thus ending up with 50 ohms when you parallel them)? If so, I'm still confused on how they did this for both cardioid and bidirectional versions of this antenna with the harness inside the mast. Required physical lengths would be different due to the different dipole spacing from the mast. One can only work with physical lengths that fit inside the mast (I guess?) but this seems to clash with the electrical length required for impedance matching. It's a non-issue since I have no way of getting a new harness inside the mast. With an external harness I can just coil up or loop any extra length required for matching reasons. But I'd still like to understand how they did it. :-) In any case, the phasing harness on my 210C4 was done differently. It uses a combination of RG-213/U and RG-63B/U in the harness itself. Here is a sketch of it: http://www.n1bug.com/210C4harness.jpg Here, if we assume points X and Y are 100 ohms, point Z (where the feedline attaches) would fall somewhere between 50 ohms and 78 ohms, depending on the electrical length of the RG-63B/U coax connecting them. I'm trying to look up the velocity factor of RG-63B/U (part PE, part air dielectric), but having no luck so far. All of which seems completely different from the picture at http://forum.radioamateur.ca/index.php?topic=2245.0 where there appears to be just a quarter wave section of coax off each side of point Z to the T for each pair of dipoles. I don't know how that was physically possible given the dipole spacing. I think we can safely assume I'm missing something here. :-) 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: repeater-builder-dig...@yahoogroups.com 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] Sinclair dipole phasing harness
Thanks. That makes sense and should work out quite well for a harness external to the mast. Of course the quarter wave of 125 ohm coax will still be required inside each dipole, but the use of all 50 ohm coax beyond that point simplifies construction. Apparently Sinclair had different ways of doing it, perhaps depending on the exact model. Or maybe they changed the harness design at some point. Paul N1BUG Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh
Re: [Repeater-Builder] Sinclair dipole phasing harness
That's correct. The folded dipole impedance is 300 ohms. The 1/4 wavelength of 125 ohm coax transforms that down close to 50 ohms. This 1/4 wavelength matching section is completely inside the dipole itself. The transition to 50 ohm cable occurs somewhere near the top of the folded dipole, so we see the 50 ohm cable exiting the dipole. In my dipoles the 125 ohm cable is RG-63B/U which, owing to its partly air dielectric, no doubt has a higher velocity factor than solid dielectric coax. So the section is somewhat longer than 13.5 inches. I'm still trying to find a reference to the exact velocity factor of RG-63B/U. It sounds like you have some very interesting (and rare) Sinclair documentation there! Paul N1BUG Larry Horlick wrote: On the drawing it does not show any 125 ohm cable, but I think what you are saying is that from the feedpoint of the folded dipole, inside the tubing there is a 1/4 wavelength piece of 125 ohm cable (about 13.5 inches at 2m) that is joined to 50 ohm cable. What we see exiting the tube (opposite the feedpoint) is the 50 ohm stuff. If this is correct it fully explains a drawing on the previous page showing a cross section of a single element folder dipole. \ lh On 5/18/10, *N1BUG* p...@n1bug.com mailto:p...@n1bug.com wrote: Thanks. That makes sense and should work out quite well for a harness external to the mast. Of course the quarter wave of 125 ohm coax will still be required inside each dipole, but the use of all 50 ohm coax beyond that point simplifies construction. Apparently Sinclair had different ways of doing it, perhaps depending on the exact model. Or maybe they changed the harness design at some point. Paul N1BUG Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh 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: repeater-builder-dig...@yahoogroups.com 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/
[Repeater-Builder] Re: Sinclair dipole phasing harness
Not much info out there on these Sinclair products. However I did find a barely readable label... the antenna I have is an SRL210C4. I found this: http://forum.radioamateur.ca/index.php?topic=2245.0 which is helpful. (Google Chrome translated it fairly well, except for the last post by VE2TBU. Given the limitations on translation, I'm not quite sure what he said. :-) I'm working on disassembling the old beast now. Naturally there are a few stuck set screws. I will share whatever I learn during this project. Unfortunately my digital camera died so I won't be able to take pictures. Paul N1BUG wrote: Me again. I just got handed a potential project. I am looking for information on the phasing harness for Sinclair VHF 4-bay dipole arrays with the coax inside the mast. I want to know types of coax and lengths so I can understand the matching. I could use info on both the bidirectional and cardioid versions, but especially cardioid. The harness lengths must be different in order to cram it inside that mast. Burt? Or anyone can shed some light on this? (I was thinking Burt had some info on a web site somewhere, but I can't seem to find it) I am aware of the 125 ohm quarter wave section inside Sinclair dipoles, but want to know about the rest of the harness. I am wanting to attempt the difficult or, maybe, impossible... I am trying to figure out if it would be possible to use dipoles from an SRL235-2 to rebuild what is believed to be and SRL214, and at the same time convert the antenna from bidirectional to cardioid pattern. I would be constructing my own harness. I think this might be possible, if I can find out how the phasing harness for the SRL214/cardioid version was made. Any info out there? Paul N1BUG
Re: [Repeater-Builder] Re: CTCSS Encoder/Decoder
And then there are those who need to 'have' a repeater but have next to no money and lots of time. As a member of that group I also appreciate discussions like this! I do the best I can with what I can get, and often end up spending untold hundreds of hours re-inventing the wheel. 73, Paul N1BUG ae6zm wrote: I think this thread has clearly demonstrated that there are a couple different groups involved in building/maintaining repeaters. Those who are involved in commercial systems are likely best served by purchasing commercial grade parts/packages/systems, as their focus is on 'having' a repeater. Then there are those of us who are interested primarily in the experience of 'inventing /designing/ building/ debugging a repeater, and then starting over with a new idea. In behalf of all of us in this category, I say thank you all for your ideas, experiences and words of wisdom. As one who spent many years in the first group, I find it immeasurably enjoyable to now be one of the second group. No pressure to 'GET IT BACK ON THE AIR'. Just have some fun, learn something, and try to pass it on.
[Repeater-Builder] Micor PL encoder modification (TLN5731A)
I'm guessing I am not the first to want to do this... I want to use a UHF Micor for a link. I want to be able to stop the PL encode immediately when a user unkeys, but I want the controller to be able to hold the transmitter up (without PL tone) for sending IDs. There appears to be no PL on/off gate on the TLN5731A encoder. The only tone gate is Q703 which only gates the out of phase tone used for reverse burst. Other than using a mechanical relay to interrupt the encoder tone output, any suggestions? Thanks, Paul N1BUG
Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
Jeff DePolo wrote: Pin 701 on the board (base of Q704) is PL Inhibit - pull to ground to kill the encoder. Thanks Jeff, I did notice P701 on the schematic. Any experience on whether a transistor will pull it low enough or do I need something better? Guess I'll try a transistor and see what happens unless I hear that won't work! Paul
Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
wd8chl wrote: The usual method we've used is to pull it to ground when you don't want tone with a transistor or a FET. You can remember though that, depending on your link rx, letting the Micor encode reverse burst will close the squelch quicker than just letting it coast. My experience is that the reverse burst on the stock Micor encode board works on the vast majority of radios, both Motorola and not. It worked on every Kenwood I had except for the old TK-801. Ham or commercial. The only other radio I have had in recnt years that it did not work on is the Yaesu VX-1R. Not even chicken burst works with that radio. I can't say for sure, but I think that if you key it with the PTT input, after the reverse burst delay, the tone will shut off...I could be wrong though...I'm sure there's a simple way to do it though. A one-transistor switch in the right place shoule do it. Thanks. It looks to me like the stock encoder supplies PL tone to the transmitter continuously, whether PTT is active or not. The only exception I can see is that for ~150 milliseconds after PTT input to the encoder goes inactive, it switches to reverse burst - then back to regular PL tone. It seems like a mod to keep reverse burst but kill the regular PL tone while still allowing the controller to keep the transmitter up (without tone) for IDs would be more complex. Unless I'm overlooking something, which I've been known to do! Squelch tails are *probably* not going to be much of an issue since I plan to use AND squelch with PL and the infamous Micor carrier squelch at the receive end of the link. That Micor squelch chip really clamps off the audio quickly if it's a full quieting signal. If there is enough of a squelch click to annoy me I can just add an audio delay in the appropriate spot. Paul
Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
N1BUG wrote: Squelch tails are *probably* not going to be much of an issue since I plan to use AND squelch with PL and the infamous Micor carrier squelch at the receive end of the link. DUH! Not my best day... Looks like I will end up killing squelch crashes with an audio delay in any case, since there will be occasions the transmitter stays up after the tone drops (during IDs). Unless, of course, I figure out a way to keep the reverse burst capability while still allowing the controller to keep the transmitter up with *no* tone after the reverse burst. Paul
Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
Leroy A. M. Baptiste wrote: I have a question for the group. What is reverse burst? And when is it used? Motorola radios. Leroy, I'm sure others can explain it better, but... Reverse burst was / is used by Motorola and others to eliminate squelch crashes at the receiving end of a comm circuit. It works like this: after a transmission, the transmitter stays keyed momentarily, during which time an out-of-phase version of the PL tone is transmitted. This out-of-phase tone causes the tone decoder at the receive end to shut off audio before the transmitter carrier disappears. Someone will correct my errors here :) This might help: http://www.repeater-builder.com/rbtip/reverseburst.html Paul
Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
Tony KT9AC wrote: Would this still allow the reverse-burst to pass through, or just abruptly cut off? Pin 701 on the board (base of Q704) is PL Inhibit - pull to ground to kill the encoder. Grounding pin 701 would kill the tone entirely, including reverse burst. Which is what I asked for... although now I feel on the verge of getting a clue about how to keep reverse burst and still do what I want...maybe! Paul
Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
That's right Leroy, reverse burst was invented to overcome the problem of tone decoders being relatively slow to realize the tone went away and thus producing a somewhat long burst of noise before muting the speaker. Paul Leroy A. M. Baptiste wrote: Hi Paul, thanks, I think that answers my question adequately. In other words if I am using an open repeater without PL tones, I do not need reverse burst? 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: repeater-builder-dig...@yahoogroups.com 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/
[Repeater-Builder] IDEA? Re: Micor PL encoder modification (TLN5731A)
My original plan was to let the transmitter PTT control the Micor encoder board as usual, but supply a valid user signal present logic input to abruptly stop the tone when there is no user signal present... thus allowing the controller to keep the transmitter keyed for IDs without PL tone. This would also kill the reverse burst capability. But wait! (this is a little complicated to explain) What if I divorced J401-2 from keyed filtered A+ on the exciter and instead used my valid user signal present logic to supply keyed filtered A+ to that pin? The controller PTT would control transmitter PTT as normal. Valid user signal logic would control the tone encoder. Suppose I then put a diode between the collector of Q707 and J401-4 (delayed keyed filtered A+) and used logic from the collector of Q707 (inverted) to pull Pin 701 low when Q707 shuts off. I think this would: 1) allow the controller to keep the transmitter keyed for *both* valid user signals and IDs by way of normal transmitter PTT 2) allow valid user signal logic to control the tone encoder in such a way that there would be no tone output unless there was a valid user signal... and allow the decoder to do reverse burst after loss of valid user signal, then abruptly kill the tone instead of reverting to normal tone. If anyone followed my poor description... are there flaws in my thinking? Perhaps I am over-engineering here? Paul
Re: [Repeater-Builder] IDEA? Re: Micor PL encoder modification (TLN5731A)
Thanks Jeff! Having someone to kick this around with is helping. Very good point about the ratty user signal. I hadn't thought of that. You are exactly right. I need to make sure the controller is set up to always keep the transmitter up for a short time after loss of user signal on the repeater, and just kill the tone. Paul Jeff DePolo wrote: I don't have a schematic in front of me, but if your plan is to key voltage to the board on/off, this won't work ideally because the vibrasender reed takes a little time to come up to speed. Since the repeater transmitter is still keyed long after a user unkeys, just muting the encoder seems like it would work fine all by itself. Whether the radio does or does not understand reverse-burst shouldn't matter. RB would mute the receiver quicker on radios that do understand RB, but unless your courtesy tone, ID's, etc. start to be played out very quickly (like within a few hundred ms) of a user unkeying, even radios looking for RB should mute before those ID's and CT's air. Also consider what happens if a user is noisy/ratty/fluttery into the repeater. As the COR briefly goes inactive during a fade, you're going be switching PL phases. This will tend to make the user sound even more choppy on listener's radios that are using PL decode. You'd be better off not having the phase change, and just having the PL drop out briefly without RB, and then recovering in-phase when COR goes active again - less chance of having the user radio mute intermittantly. --- Jeff WN3A 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: repeater-builder-dig...@yahoogroups.com 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] IDEA? Re: Micor PL encoder modification (TLN5731A)
Thanks Don. Yep, I was over-thinking the problem! Links are new to me. Somehow I was forgetting I have control over keeping the link transmitter up after I drop the PL tone, so I can eliminate squelch crashes at the receive end of the link that way. All I need to do is ground that trusty pin (P701) on the Micor encoder, and possibly tweak some timer settings in the repeater/link controller. I was also forgetting I can force messages (ID) to start some specified time after I drop the PL tone and before the transmitter drops. I may be able to control P701 directly from an output on the RLC-4 controller. Needs some research. I'm not sure I understand exactly how some of the event triggers (029-044) work (or rather exactly what triggers them) but I will ask and/or figure it out. Paul N1BUG Don Kupferschmidt wrote: There was an earlier post concerning grounding a pin on the backplane which instantly disables the PL tone on the transmitter. I've got a VHF unified chassis MICOR which is controlled by an SCOM 7K controller. I used one of the digital outputs of the controller and tied it directly to the PL disable connection on the backplane. Then, I programmed a macro which was tied to a command function to have the line go low 1 or 2 seconds just before the transmitter shuts down. I works flawlessly. I don't have the manual or the code in front of me, but if anyone is interested in this I can provide details. Obviously you would need either a controller or some type of interface to accomplish this. 73, Don, KD9PT 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: repeater-builder-dig...@yahoogroups.com 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] 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
Re: [Repeater-Builder] Decibel dipole array sweeps
n...@no6b.com wrote: At 3/22/2009 11:32, you wrote: The document can be found here: http://www.broadsci.com/Antenna Sweeps r1.pdf I get a The file is damaged could not be repaired error. And I get a 404 Page not found error. Paul
Re: [Repeater-Builder] Re: LMR-400 and Belden 9914 DuoBond
Thanks Mark and Mike! The great news is there is a tremendous amount of good information at the repeater-builder site. The less-great news is I'm an idiot and can't always find what I'm looking for. ;-) I appreciate the help finding this stuff. Paul N1BUG Mike Morris WA6ILQ wrote: The word wrap broke his link. Try this: http://www.repeater-builder.com/antenna/recommended-coax-and-connectors-for-iden.pdf http://www.repeater-builder.com/antenna/andrew-braid-over-foil-imd.pdf http://www.repeater-builder.com/rbtip/double-shielded-coax.html The arrows (upper case comma and period) on either side of a link prevents the broken links if the program that you are using to read your mail follows the rules contained in RFC1738 (the spec that defines what is and is not a URL). Mike WA6ILQ At 08:49 PM 03/20/09, you wrote: Paul, The one you are looking for is: http://www.repeater-builder.com/antenna/recommended-coax-and-connectors-for- iden.pdf Others for reference are: http://www.repeater-builder.com/antenna/andrew-braid-over-foil-imd.pdf http://www.repeater-builder.com/rbtip/double-shielded-coax.html 73, Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Paul N1BUG Joe wrote: There is a Motorola letter that warns about the problems of braid-over-foil coax. You can find it on the repeater Builders site. I just tried looking and searching for it on the Repeater Builder site and came up empty. If it's there could someone point me to it please? I would VERY much like to see it before Monday, for reasons I won't go into right now... I did find something on the subject by Andrew but since they make Heliax that likely won't help my case. Paul N1BUG Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] Re: LMR-400 and Belden 9914 DuoBond
Joe wrote: There is a Motorola letter that warns about the problems of braid-over-foil coax. You can find it on the repeater Builders site. I just tried looking and searching for it on the Repeater Builder site and came up empty. If it's there could someone point me to it please? I would VERY much like to see it before Monday, for reasons I won't go into right now... I did find something on the subject by Andrew but since they make Heliax that likely won't help my case. 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: Quieting duplex noise from a tower
Aircraft handhelds are AM in the 120MHz region. Some handheld scanners do aircraft AM just fine. Ah! Somehow that hadn't occurred to me. The president of our club is a pilot and has one. I guess there are no weak, constant signals in the aircraft band (?) but maybe it's not necessary. I will try climbing the tower with it and see if it does anything when I move or vibrate guy wires and other hardware with the repeater transmitter on of course. It's possible the aircraft handheld will just be desensed by 2 meter RF and unable to hear the noise (?) but it will be interesting to see what happens. Paul N1BUG
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Yeah, I was going to suggest a simplified version of what you're talking about - climb the tower with a little AM transistor radio tuned to a weak station, key the transmitter on and off, and see if you can find a noise hot spot or anything that when moved or vibrated causes the noise level to increase. However, I haven't tried this using VHF excitation, but I've used the same technique to find all kinds of other broadband noise sources. The local power company uses an AM receiver operating in the VHF range (I think I was told it was around 110 MHz) to locate bad/arcing insulators, fuses, etc. on primary lines. Thanks Jeff. I will try that, and also inducing vibration in the tower structure(s) by wrapping it with something as soon as I can. Maybe I will get lucky and find something. If I don't find any specific problem areas, I'm leaning strongly toward trying Phillystran guys when I can come up with the $$$ to do it. I appreciate the input from everyone on this problem. Paul N1BUG
[Repeater-Builder] Quieting duplex noise from a tower
OK guys... I thought I could figure this out on my own, but I was wrong. I could use some wisdom from the group! I have been chasing a stubborn case of duplex noise for a long time without success. The 2 meter repeater will run clean all day at 100 watts (or any lower power level) into a quality RF load placed on the antenna port of the duplexer. It will run clean all day with the same load placed at the antenna end of the feedline. With the antenna connected it will SOMETIMES run clean. At other times we get the crackling and popping of duplex noise. And at times we get increased noise floor (I can see it on the receiver limiter current but it has no specific sound, it's just like the normal receiver noise floor came up 20 to 30 dB!) None of this happens when it is run into the RF load. It is only when running into the antenna, and then only sometimes. The steady high noise floor, when present, happens only when my transmitter is up. It happens even if no other transmitters on the hill are up. It will occasionally go for days or even weeks without a glitch, then be essentially unusable for hours or days. The crackling does seem to be worse in windy weather. The steady noise does not seem to be better or worse in any kind of weather, but occurs completely at random as far as I can tell. Three different antennas (all DB or Sinclair, two of them NEW) have been tried with no significant change. The feedline (Andrew LDF5-50A) has been swapped out once with no change. I think that leaves the tower or other nearby metal structures as the prime suspects. The tower is 100 feet of Rohn 25G guyed with 3/16 EHS. I have tried more than once to bond the sections of tower with straps across the leg joints, and similarly where guys attach to the tower and/or turnbuckles etc. at ground level. These efforts did not help and seemed to actually make matters worse. By the way, the guy ends use Big Grips, not clamps. Was that a mistake for a repeater tower? I am looking for advice. If anyone has solved noise problems in a similar tower, I would very much like to know specifically what materials you used and how you installed them that worked for you! I do have another newly erected 100 foot tower close by. It could be part of the problem. However, I was having this problem long before that tower went up so I'm still pointing fingers at my own stuff. A 440 repeater on the same tower does not have any problems. Neither repeater seems to be affected by the other's transmitter. It is only the 2 meter repeater killing itself. Both my tower structure and the new adjacent tower structure are hot with RF from my 2 meter transmitter, as evidenced by horrible noise when something like a screwdriver shaft is lightly rubbed against the towers or guys. I do not find any other metal structures in the vicinity that react that way. There is NO loose hardware in my system. I've been over it time and time again. There is NO visible rust anywhere. Any suggestions before I pull the rest of my rapidly thinning hair out? Here's one for ya... this problem first reared it ugly head right after I put up the tower. For years prior to that I had run the antenna on a rusty metal mast with loose fitting joints without ever a hint of trouble!!! Paul N1BUG 147.105 and 444.950
Re: [Repeater-Builder] Quieting duplex noise from a tower
Thanks Chuck. What would you consider nearby? There is one fiberglass antenna on a tower 60 feet away. It was new when it went up 2 years ago, but my problem existed before that tower/antenna went up. Aside from that the nearest other fiberglass antenna (or antenna of any kind) is 250 feet away. Paul Chuck Kelsey wrote: Suspect any other nearby fiberglass antenna in your search. Chuck WB2EDV
Re: [Repeater-Builder] Quieting duplex noise from a tower
Great questions, Jeff. Thanks! Answers below... Have you looked at the transmitter output with a spectrum analyzer during the occasions when you have desense to see if it's getting sloppy? No. I wanted to but I'm very isolated up here and do not have access to one. Have you tried other transmitters and/or amplifiers? Several PAs have been tried. Solid state and tube, GE and Motorola. No change with any of them. There is very little change in desense when I vary the power level unless I drop the power very low, like less than a watt. Then it goes away like somebody threw a switch. The exciter has not been swapped out for a different type. However I have tried 4 of the same type exciter (PLL variety Mastr II), no change. Another thing I tried was essentially a homebrew Z match between the PA and duplexer, no change. Do you have Polyphasers or anything other than coax between the duplexer and the antenna? I know I should have them, but I don't. Have you tested with the transmitter off? Yes, many, many times. It never happens with the transmitter off. I'm very confident about that. Are you using a preamp? If so, what do you have ahead of it for filtering, and/or have you tested without the preamp? Yes I use a preamp. DB4062 duplexer and two DB4002B 11 pass cavities, pass cavity loops set for 1 dB insertion loss each cavity. I tried tightening it up to 3 dB per cavity, no help there. The problem is still there without the preamp. Have you tried an antenna installed at a different height on the tower than the current antenna to see if anything changes? Yes, and it does change but does not go away. If I take the antenna off the tower and put it 20 to 30 feet away from the tower, the problem is drastically reduced but not completely gone. I can't quantify changes with absolute numbers... only generalizations... since the problem is intermittent and varies greatly even when I'm not changing anything. Do you have ground kits on the feedline going up the tower, and if so, are they properly attached/bonded, particularly avoiding any dissimilar metal contact? Another thing I should have but don't. Big Grips (usucally called preforms) are generally OK, many a tower much bigger than a 25G uses them. They need to be properly protected to avoid coming un-twisted due to ice sliding down the guy wire. Pull-out strength, if installed properly, is as good as conventional mechanical clamps. Preforms, right. I was wondering about the integrity of RF contact between the preform and the EHS wire since the preforms are coated with whatever that stuff is on the inside. To help determine if you have a mechanical problem that is being manifested as noise when excited by the high RF field of the transmitter, try rapping on the tower at the base and at the guy anchors with something (like a crescent wrench). The goal isn't to shake the tower, but instead to induce a significant mechanical vibration. See if the noise increases (either audibily or visibly on the spectrum analyzer) with the vibration, and dampens out as the vibration decays. I missed that test! I have tried shaking the tower, which seems to have no consistent affect. I will try inducing vibration by rapping it with a wrench. What else is nearby? Buildings, utility lines, etc.? A couple small wood buildings, including my own. Mine was the only one there when this problem started. I have been over my internal wiring and every piece of metal under my control, no suspected items found. There is a 13.2 kV rural distribution power line and phone line running past the site about 70 feet from my tower, plus power drops to my building and another nearby. My antenna was closer to the utility lines when it was on the mast and was not having problems. If the antenna was top-mounted on the rusty mast, but is now side-mounted on the new tower, that could explain a lot of the difference. The top-mounted antenna will couple much less energy to the supporting structure than would a side-mounted antenna. Good point. I have tried top and side mounting on the tower. Top mounting helps, but not nearly enough. Paul
Re: [Repeater-Builder] Quieting duplex noise from a tower
Have you tried putting one or more pass cavities on the transmitter? It's more of a longshot, but if there's something strong coming back down your feedline it could be getting to your PA resulting in intermod. The problem would come and go with the strong signal obviously, and only when your Tx was keyed. I have tried putting one of the 11 pass cavities on the transmitter. No change. There is a fairly low traffic APRS digipeater (144.39) on a tower 250 feet away but my noise problem does not come in packet-length bursts. It was also down for a while and I still had the problem. The only other VHF transmitter is 158.x on the tower that is only 60 feet away. However I have never yet found that transmitter to be up when my problem was occurring. It sees VERY little use. The only other sources of RF are cell towers several hundred feet away. Yeah, they're coated with that semi-clear plasticy stuff usually. I wouldn't consider that to be a high risk factor, but hard to say. How close is the nearest guy wire attachment point on the tower to your antenna? Close, just a couple feet below the antenna at the present time. In general, moving the antenna closer to a set of guys does seem to make the problem worse. If I could somehow get to a point where I believe it's the guys, I would seriously consider replacing them with Phillystran, leaving a few feet of EHS at the anchor end. Is your antenna currently side-mounted or top-mounted? If side-mounted, at what height? Half and half at the moment, actually... the 20 foot stick is mounted on side arms at the 90 foot level of a 100 foot tower. Moving it to top mount does seem to decrease the desense by some 5 to 10 dB (hard to quantify due to variability) but I still have 20 to 30+ dB desense at times. When side mounted, spacing from the tower also makes some difference (wider spacing = less desense) but again not enough to be truly helpful. What kind of mounting brackets/clamps for the antenna? Sinclair heavy galvanized mounting clamps on the antenna, side support arms are heavy galvanized angle stock. Galvanized U bolts to tower legs. Other mounting arrangements have been tried, including the use of insulating material for side arms. Some change (less desense with the insulated mount) but still not enough to be really helpful. What else is on the tower? The only things on the tower are my 147.105 and 444.950 antennas. I tried completely removing the 440 antenna and feedline from the tower, but nothing changed. How are the feedlines attached to the tower? They are both LDF5-50A up the inside of the tower (that was fun), attached by many heavy duty nylon cable ties. Does the noise get any better or worse when it's raining out? There *seems* to be some tendency toward the noise being worse during the first hour or so of a rain or snow event. But it is not always so. The noise is sometimes there when it is raining, but not always. It sometimes there when it is dry, but not always. How are the guy wires attached to the tower (looped around a leg, with or without thimbles, torque triangle/arms, etc.)? The preforms are looped around a leg and through the Z braces of the tower. No thimbles at that end, there are some where the guys attach to the turnbuckles. I'm guessing not, but is the tower lit? It is not. When you changed out antennas and heliax, I presume you replaced any topside jumpers as well? Topside jumper and the jumper between duplexer and feedline were replaced. Where is your equipment with respect to the tower (i.e. how close to the base)? About 30 feet away. And how well-shielded is the equipment (enclosed metal cabinet hopefully), and are you taking the usual precautions as far as cabling into, and within, the cabinet to keep RF out? Hmm. The cabinet (rack) is not completely enclosed. Each piece of equipment is in a shielded enclosure. There are feedthrough capacitors and chokes/beads on every non-RF lead entry point to a piece of equipment. However, the 13.6V interconnecting cables and 117VAC power cords are not shielded. They do have the filtering wherever they enter equipment. Paul
Re: [Repeater-Builder] Re: Quieting duplex noise from a tower
Hi Randy, I remember working you on 2 meters. That is very interesting. I tried bonding all the joints. If anything it actually seemed to make things worse!? I have been seriously thinking about Phillystran. It's a big expense not knowing for sure where the problem lies, but the only way to find out may be to try it and see! Paul wb8art wrote: Hello Paul, Worked you a few times many moons ago. I would agree with Jeff with tapping and slightly causing movement with the repeater up with a weak signal. I have before experiened both an antenna (stationmaster) with internal broken joint which caused severe noise and desense but also dependent on movement in the structure. Also have seen with a 100ft. guyed 3/36 town like yours having the same issue. I tried grounding bonding all joints on guys to tower and between tower sections to no avail. Also tried isolating the preforms from tower and bottom supports with no change. I decided that the 3/16 stranded was the generation source. We changed the guys to Phillystran and never had another issue.
Re: [Repeater-Builder] Quieting duplex noise from a tower
Also, I'll ask the dreaded question... You are not using any foil/braid coax (LMR-400, 9913, etc.) for any jumpers are you? Nope, won't allow the stuff near my repeaters! grin LDF5-50A runs up the tower, RG-214 mil spec double silver shield for all jumpers. Paul
Re: [Repeater-Builder] Quieting duplex noise from a tower
What type of power supply is in your system? Do you have a back up battery? If so what type of charger is on it? Any other repeater systems in close proximity? There is a backup battery which is float charged from the 13.8V DC power supply. Presently the supply on duty is a homebrew beast of a linear supply (no switchers). I have tried Astron supplies in place of that, no changes noted. There is one public safety repeater, transmit 158.x on a tower 60 feet away. It was not there when my problem started, nor have I ever found their repeater to be in use when my problem is occurring. Actually I'm hard pressed to find that repeater in use, period. Paul
Re: [Repeater-Builder] OT DTV
Yup. Woefully inaccurate (too optimistic) for my location too, but after zooming all the way in I am impressed with their terrain data. :-) Chuck Kelsey wrote: I just checked this against my location and the results were woefully inaccurate. Chuck WB2EDV http://www.fcc.gov/mb/engineering/maps/
Re: [Repeater-Builder] 900 MHz WISP on repeater tower?
Kevin Custer wrote: Ethernet cabling should be of the shielded type and bonded at one end to earth. If they are putting up a 900 MHz access point, will it be sectorized? If yes, how many sectors (how many transmitters)? What frequencies and bandwidths on 900 (20 MHz) (10 MHz) (5 MHz) ? How is the input bandwidth being delivered? Fiber, DSL, wireless link on another band (2.4 GHz) (5.3 GHz) (5.8 GHz)? What kind of antenna system... 3 - 120 degree sectors, 1 - omni? What kind of equipment (Alveron) (Motorola) (home-made) (don't laugh, I build my own) Answering the above will give me an idea of what you can expect. Thanks Kevin, that gives me some questions to ask them! I do know the input bandwidth would be via 5.8 GHz wireless link and they would be using Motorola Canopy equipment. I will ask about the rest... I failed to mention I have reason to expect they will be putting equipment in the immediate vicinity of my repeaters one way or another... either on my tower or on an adjacent tower. Paul
[Repeater-Builder] Re: 900 MHz WISP on repeater tower?
Thanks to everyone for the input on this. It's appreciated. Now I have a better idea what I should be asking them. As I noted in a response to Kevin, they're probably going to end up either on my tower (where I might have some control) or on a tower 50 feet away (where I have zero control). Paul N1BUG
[Repeater-Builder] 900 MHz WISP on repeater tower?
I could use a little help here. I have a repeater tower with 2 meter and 440 repeater on it. I have been contacted by a wireless internet service provider about putting some 900 MHz stuff on my tower. The deal they are offering is attractive but I'm wondering if there would be interference issues between their stuff and my repeaters. I'm going to be setting up a meeting to discuss technical aspects of the proposed system, but I have no experience or knowledge in this area and am not sure what questions I should be asking them. Any suggestions or advice? Thanks! Paul N1BUG
Re: [Repeater-Builder] DTV ch 2 vs 6m
Thanks everyone for the comments on this topic. I will report back later and let you all know how DTV 02 and 6m get along. Paul N1BUG
Re: [Repeater-Builder] OT: digital TV channels
Buddy Case wrote: It is my understanding there will not be any channels between 2 thru 6 anymore. The govt proposes to auction these frequencies. Checking the list on www.nab.org http://www.nab.org shows no stations below ch 7. Buddy KS4QA I only wish it were so. If you are referring to: http://www.nab.org/AM/ASPCode/DTVStations/DTVStations.asp you need to look more closely. It shows at least one station currently broadcasting DTV on each of the VHF low 2 thru 6 channels. After transition, some stations currently broadcasting digital on temporary UHF or VHF high assignments will move to the VHF low channels. That is what is happening in my area. WLBZ, now broadcasting analog on ch 2 and digital on ch 25, will switch its digital transmission to ch 2 after transition. It is my understanding the original plan was to completely free up ch 2-6, but the FCC changed its mind and will allow some stations to remain on those channels. Paul
Re: [Repeater-Builder] DTV ch 2 vs 6m
That's what I'm afraid of. It's already nearly impossible to do anything on 6m around here without problems with ch 2 analog. Once they go digital on ch 2 I'm expecting even more issues. But I guess time will tell... Paul MCH wrote: If it's like any other digital transmitters, more. Joe M. Paul N1BUG wrote: I think this is on topic for the list since it could affect some 6 meter repeater owners. After transition I will have a local channel broadcasting DTV on their low VHF channel 2 assignment. I'm curious... does anyone know whether DTV will be more (or less) susceptible to interference from ham radio transmissions than analog TV? Thanks 73, Paul N1BUG Yahoo! Groups Links Yahoo! Groups Links
[Repeater-Builder] DTV ch 2 vs 6m
I think this is on topic for the list since it could affect some 6 meter repeater owners. After transition I will have a local channel broadcasting DTV on their low VHF channel 2 assignment. I'm curious... does anyone know whether DTV will be more (or less) susceptible to interference from ham radio transmissions than analog TV? Thanks 73, Paul N1BUG
Re: [Repeater-Builder] OT- Digital TV converter box issues
I TRY not to respond to OT posts, but boy am I fed up with DTV! I could get all the high power analog stations in my market snow-free with a small rooftop antenna. No go with DTV so I've been incrementally upgrading. I now have a very large antenna residing at 70 feet on one of my towers. Now I can get SOME of the digital signals. I'm going to try a mast mounted amplifier as soon as I'm able to climb again (currently recovering from surgery). I've already tried several TVs with ATSC tuners and converter boxes. There is some variation, but none of them can get all the digital signals that theoretically should be available to me. According to the FCC and other resources, I should be getting all of the high power DTV stations. I have talked to engineers at two of the stations I'm having trouble getting. They both said more than likely I'm getting a too high bit error rate due to signal multipath with all the hills around here. They said it is proving to be an issue for some viewers, and suggested I try VERY large directional antennas and experiment with antenna bearings, but admitted I'd probably need several antennas, one for each DTV station I'm not yet getting. Aarrgh! But of course many DTV's and converter boxes can only add channels by auto search; there's no provision for adding channels manually. That pretty much rules out switching between multiple antennas, unless I got the timing just right while the TV was performing its channel search. I could combine several antennas, but then I'd probably have the high BER due to signal reflections again. Grrr! Oh, and some of the stations that were/are broadcasting analog on VHF now have temporary UHF DTV assignments (higher power than their analog VHF). Next month they will be switching digital broadcasts to their old VHF channel assignments. This will probably change what I'm able to get and not get yet again... this time in the middle of a Maine winter. Grrr! Thanks FCC, or whoever is to blame for this bit of idiocy. I will admit when it works, picture and sound quality is fantastic with DTV. Being able to get free OTA HDTV is nice too. Paul
Re: [Repeater-Builder] Desense has me pulling my hair out! (Was DB4060 Duplexer Cables
Mike, OK, that makes sense re the 004/005 markings. And OK on the knobs. That really messed with me at first. I thought they were glued or something. It was only when I tried heating one to see if the glue would soften that I found out it was solder! I didn't have any trouble with the top of the inner tube catching on the finger stock when I put them back in, but it was a real close fit getting them in without that happening. On each cavity there were, as I recall, two or three fingers that were sprung inward a little more than the others, possibly having to do with the ends of the two coil springs putting extra pressure on them. Those were the ones I had to watch closely. As long as it hasn't compromised the solder bond of the finger stock in some way, I'm not sure the worn copper plating will do much harm. Of course if the copper plate between the finger stock solder and the inside of the fixed inner tube has deteriorated in any way (which you can't possibly determine by looking), then that would be a serious issue. My guess is it's probably OK. I would just clean them up as best I could and try it. If you can't find someone who knows where the 004 and 005 loops go, I would try an experiment. I would put both 004 on one side of the duplexer, both 005 on the other side. I would then tune it up for high pass on the 004 side (low on the 005) and make a note of the performance measurements (notch depth, insertion loss, VSWR or return loss - measure all parameters on both low and high pass sides of course). Then I would retune it so the 004 side was low pass (and 005 side high pass) and measure the performance again. If there was any difference, I'd go with the configuration that produced the better numbers. If you try this, I would be interested in what you find out. Having said all that, it's also possible the loops were intended to go the way you found them... one 004 and one 005 on each side. That wouldn't be my first guess, but it's possible. It might have something to do with making the impedances look a little nicer or some such... Paul N1BUG Mike Besemer (WM4B) wrote: Paul, I just noticed that what I wrote here was backwards... the 004s had the strap all the way around and the 005s had the wire extension. If I figure out what goes where, I'll let you know. Did you have trouble with the top of the inner loop catching on the fingerstock and tweaking it a bit? I bent a couple of mine, but it tweaked back into place okay. Mike WM4B
Re: [Repeater-Builder] Desense has me pulling my hair out! (Was DB4060 Duplexer Cables
Mike, Thanks for this information. I will make a note of this. The DB4060 and 4062 duplexers I've seen had identical loops (all strap) throughout. Apparently some were different for whatever reason. Here's another interesting bit... mine all had 004 penciled on them but they were built like your 005's... strap all the way around the loop. Were your knobs also soldered on? Fun, aren't they... Good luck with the cleaning. Hopefully it will help! 73, Paul N1BUG Mike Besemer (WM4B) wrote: Paul, I got the knobs off two of them and got them totally pulled apart. Both of them have a lot of lubricant on the inner tubes… looks like somebody may have lubed the threads with 3-in-1 oil or something and it ran inside. The inside of the outer tube on one of them has some white ‘stuff’ growing in there… have not examined it yet. The most interesting thing I noticed is that the notch filters are different. Two of them have the number 004 penciled on the bottom of the enclosure and the other two are marked 005. The ones marked 005 are copper strip all the way around the loop. On the ones marked 004, the strip stops an inch or so from the notch capacitor and has a wire connecting the cap to the strap. The way they were arranged in my setup was mixed… a 004 and a 005 on the TX and the same on the RX. I assume that was part of the problem. The question is… which goes where? I guess trial and error might solve the problem. 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:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Desense has me pulling my hair out! (Was DB4060 Duplexer Cables
Mike Besemer (WM4B) wrote: I have a strange feeling that it’s arching around the fingerstock. The inner tuning tubes showed definite signs of wear, but I THOUGHT the fingerstock was making good contact. Is there any ‘approved’ conductive lubricant for that area? Your problem sounds a lot like the trouble I was having with my DB4062 (the 6 cavity version of the 4060). I would get it tuned and think all was well, only to have major desense the next day. It nearly drove me nuts! What happens desense-wise if you tap lightly on the big tuning knobs while the transmitter is running? Do the cans make a nice scraping sound when you turn the knobs during tune up? Mine had the moving part of the center conductor and the finger stock coated with some kind of lubricant, which had partially dried up and was interfering with contact. Check the coil springs around the finger stock to make sure they are applying adequate pressure and are not stretched out. I also recommend you check and clean EVERY metal to metal mating surface, including where the box containing the coupling loop bolts to the cavity top. I wrote up something (incomplete) on my restoration project, which can be found here: http://www.repeater.n1bug.com/duplexerrefurb.html I think Mike Morris was going to put this on the repeater-builder site, but I don't see it there yet or I'd have given that link instead. (Mike Morris: I can supply a version of this minus the DHTML menu etc. if you want it) Almost one year since the restoration now and all's well... 73, 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:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Desense has me pulling my hair out! (Was DB4060 Duplexer Cables
Mike, I can hear the fingerstock scraping against the inner tube... not a BAD scraping... just what sounds like good metal-to-metal contact. That is normal. The reason I asked is mine had stopped making that noise. It was almost completely silent when I rotated the knobs. That was one of the major things that led me to conclude something was really wrong inside. I knew silence when being tuned wasn't normal for those cans. After being refurbished it is back to making a healthy scraping sound. I was also thinking about cleaning the mating surfaces on the top... just need to get the gumption to do it. I'm getting tired of having my butt kicked! I know that feeling! I cleaned *every* mating surface while I had them apart, corrected some manufacturing sloppiness, and made a minor modification (which, I'm sure, was totally unnecessary, but I wasn't leaving any stone unturned). Good luck! 73, Paul N1BUG
Re: [Repeater-Builder] RE: DB4060 Duplexer Cables
Mike Besemer (WM4B) wrote: And as a follow up to my first question, as I understand it… there should be no problem with swapping the TX and RX cans (and retuning them), correct? That's correct for the DB4060 since the cans, coupling loops and notch capacitors are all the same. But it's not true for all cavities/duplexers. Some are designed to have the notch on one side of the pass only, where a specific can is either high pass or low pass but not the other. Actually even then it's more a matter of the coupling loops and/or notch tuning parts being different, not the actual cans themselves. I can't help with the cable length question. When I had my DB4062 (6 can version) apart I marked the cables. BUT, looking at them I thought they were all the same length. I didn't attempt to measure them since I was afraid straightening them to do that would put undue strain on them. 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:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] PLL UHF EXCITER
kb4ptj wrote: HI I WENT TO LBI 30200 AND LBI31209 THIS IS FOR THE EXCITER THAT I HAVE THE TUNE UP FOR I NEED THE PLL UHF 406-470 IF YOU CAN HELP ME WITH THIS I NEED THE TUNEING STEPS FOR PLL GE EXCITER There may be confusion as to what you really want. There is a UHF *FM* MASTR II exciter, but it is *NOT* PLL (it's the VHF FM that is PLL). The part number for your exciter would help clear things up... but try this one, for the UHF FM (non-PLL) exciter and see if it is what you want... http://repeater-builder.com/ge/lbi-library/lbi-31543.pdf If that is the exciter you have, the following LBI is also relevant... http://repeater-builder.com/ge/lbi-library/lbi-31209g.pdf Paul N1BUG
Re: [Repeater-Builder] db 4060 high band
Since you are not seeing a doubling of the notch depth with the two cavities in line, I suspect the cable length is incorrect as Eric pointed out. You also mention the tuning caps seems a little flaky. They shouldn't. It may be that they have been lightning damaged, since that is a known issue with these cavities. Or it may be something else. Some of my notch caps were very flaky (on a DB4062, which is the 6 cavity version of the 4060). Disassembly and thorough cleaning cured the problem. There was gunk interfering with contact between the finger stock and the tuning plunger. I also disassembled all the coupling loop assemblies and cleaned all mating surfaces. The duplexer is working perfectly now, with the caps being very smooth and stable. I am also getting deeper notches than I had before. Paul N1BUG Joel Hall wrote: Hope some of you guys that have some experince with db 4060 duplexer,the pass is fine but the notch is the problem I can see the notch at around 35db on my ifr 1600s per each can but when i combine them together about 50db is the best i can get I have new cables made 1/4 wave long , the tuning caps seem a little flakey may have had been hit with a lightning surge. I have not taken them apart yet so any thoughts? Thanks kj4si
Re: [Repeater-Builder] Build your own
Dave Gomberg wrote: I have long considered building my own 2m repeater out of 2 Icom 2100 or 2200 back to back thru a repeater controller, using a good duplexer and a Comet or Hustler antenna. My comments are not meant to discourage you but I once started out thinking along similar lines and it didn't take long for me to find out why it's not a great idea. Good luck. The receiver is broader than a barn door and I have no doubt the transmitter has higher noise surrounding the carrier than a good GE or Motorola crystal controlled radio. With the ham grade radios you will be far more likely to have desense problems and will likely need a larger, more expensive duplexer to have any hope of cleaning it up. 1. Nobody seems to like the Comet or Hustler antennas. Why? I have no ice here, lots of wind tho. I once wasted a month trying to make a brand new Hustler G6-144B run noise free in duplex service. Every time the wind blew I had loud crackling noise on my repeater. This may have been a problem specific to that individual antenna, since I know some people do use them successfully on repeaters. But it was so aggravating I never again tried using a ham grade antenna in repeater service. 2. Why is a 50w 2m transceiver, derated to 25w and driving a power amp a bad choice? Or is it OK? It might be OK if you put a fan on the heat sink. Most radios of this type will get far too hot even running at half power. Remember the duty cycle of a repeater transmitter is much higher than a user radio. Heat may not be the only issue. Some of the internal components may just be too marginal to handle high duty cycle service. 3. Any suggestions on how to keep the duplexer cavities affordable? Nope. 4. Which repeater controller? Or is that a religious question? Decide what features you want, then look to see which controllers offer what you want. Once you narrow it down to ones that meet your needs, you can decide based on price and user satisfaction (ask owners of those models how they like them). Anything else I should be wary of? As has already been mentioned, no foil/braid coax cables, and forget the single braided shield types too. You really want solid copper shield heliax, or at least mil spec RG-214 (double silver shield) if you don't want noise problems on your repeater. 73, Paul N1BUG
Re: [Repeater-Builder] db products 4060
I have a DB-4062, which is the 6 cavity version of the 4060. It was old when placed in service in 1997 but worked OK. Over the years it just slowly deteriorated until it became essentially unusable. Finally I took the thing apart to investigate, and was able to restore it to excellent function. Rather than typing up a lot of details, let me refer you to something I wrote about this a while back. http://repeater.n1bug.com/duplexerrefurb.html 73, Paul N1BUG Aaron Sloan wrote: Hello gang, I am wondering what the opinion is of the decibel products db4060 duplexers for 2m service. We have a set that are nearing 30yrs old and looking for a replacement. The current model never really preformed as well as the specs. Is this an experience shared by anyone else? Thanks, Aaron ka0zoz
Re: [Repeater-Builder] db products 4060
Dave Gomberg wrote: http://repeater.n1bug.com/duplexerrefurb.html Great write up, Paul, can you say something about how many hours you put in on it??? Uh, sure too many! Heh. Seriously, I didn't really keep track but must have been around 15 to 20 hours. Getting some of the parts clean enough to suit me was agonizingly slow. 73, Paul
Re: [Repeater-Builder] Power Supply from a PC. Slightly OT
The May 2002 QST article is available as a members only PDF. Just go to arrl.org and search for St Louis Switcher. Paul N1BUG kf0m wrote: May 2002 QST had the computer power supply conversion article QST switching power supply product reviews are July 2006, January 2000, and Sept 2000 John Lock kf0m at arrl.net
Re: [Repeater-Builder] DB4055 Duplexer
Nate, Thanks for bringing that to my attention! That is weird. The info I have in the document came from a Decibel Products catalog. We now have three freq ranges for the DB4076, all from manufacturer documents. Hm. Since official info conflicts, I guess all I can (or should?) do is add a note about the situation and list the various frequency ranges we have. I will add what specs that document provides on the 4075 while I'm at it. I'll add a note about the Z and W suffix which I wasn't aware of either. Sounds like you had a fun project there! 73, Paul Paul, Confused here... your document at that specs page shows the DB-4076 as being a high UHF duplexer (485-505 MHz) while right here on RB, the duplexer's manual says it's much wider (404-512) on the top of the manual, and then that same manual says it's a completely different range (450-512) in the description text in the document. Weird. http://www.repeater-builder.com/db/db-4076-tuning.pdf I'd just say it's a typo in the title of the manual... but... A friend and I just tuned a 4075 with an added can -- making it into a 4076 (the square/brown painted variety that were often found in GE MASTR II cabinets with a GE part number on them) -- to the 446 range tonight. Nate Duehr, WY0X [EMAIL PROTECTED]
Re: [Repeater-Builder] Freak Propigation
Jim Brown wrote: Is the big mountain behind it reflecting the signal over the pass to the south west? It's certainly possible. Big mountains make great VHF reflectors. I can often work stations to the north or east of my location on 2m FM simplex or SSB with stronger signals if we both point antennas at Mt Katahdin (which is generally north of all stations involved) than if we have beams pointed at each other... especially if the station is in a valley. This is true even when the reflected path off the mountain may be much longer than the direct path between stations. Also don't forget about knife edge diffraction of VHF signals over a mountain. I don't have a lot of personal experience here, but in theory I believe this works best if the mountain or ridge has a sharp rocky peak. 73, Paul N1BUG
Re: [Repeater-Builder] DB4055 Duplexer
Thanks Ron, I will include these specs in the next revision of the Guide to Duplexer Specifications on the RB site. http://www.repeater-builder.com/rbtip/duplexerspecs.html I'm always keeping an eye out for data that isn't in there yet. I've added several since the current posted version so it's probably about time to send in an update. 73, Paul N1BUG Ron Wright wrote: Eric, The DB4055 is 5 cavity band reject duplexer from Decibel Products. Its notch is 75 to 80 db at 5 MHz. Min freq separation is 5 MHz making it useless for 2 meters Ham repeater. TX noise suppression at RX freq 70 db RX isolation at TX freq 70 db. Max power is 150 W continuous and insertion loss is 0.7 db. The versions ar A=150-162 and B 160-174. Would be good for something like MARS or other commercial repeater. 73, ron, n9ee/r
Re: [Repeater-Builder] Re: Antenna Tower
You added www which wasn't in the original link. Try this (it's your first try with www removed) http://good-times.webshots.com/album/562985533mLTuoH 73, Paul Dexter McIntyre W4DEX wrote: I've tried several ways to put the link together with no success. These don't work for me: http://www.good-times.webshots.com/album/562985533mLTuoH http://www.goodtimes.webshots.com/album/562985533mLTuoH Is the picture still available? I've seen some 40+ year old towers that are still in very good condition. But I agree most that age aren't worth much if anything. Dex Rich [EMAIL PROTECTED] wrote: Antenna Tower steal 95 Ft tapered. Built in 1960, Central Pennsylvania. Must remove from the site owner wants a donation for it. Photo's available at http://good- times.webshots.com/album/562985533mLTuoH Contact Rich [EMAIL PROTECTED]
Re: [Repeater-Builder] Off Topic (but with on topic questions): NTIA propaganda
While it was told that ALL VHF television would move to UHF, I don't believe that is going to be reality. I could be wrong, however My local channel 12 is moving to channel 9 with the digital transition... 73, Paul N1BUG
Re: [Repeater-Builder] Re: Duplexers (budget test equipment)
Oops. I forgot to mention double shielded cable for ALL interconnects is an absolute MUST, at least with my duplexer - it has notches in excess of 120 dB deep after refurbishing. It doesn't take much leakage cause problems when you're dealing with notches like that. Paul N1BUG Paul N1BUG wrote: Jim Brown wrote: I have found that the main problem in using a talkie as the receiver for tuning the notch in a duplexer is the possible leakage of RF between the signal source directly into the talkie. Most talkies are not shielded at all, and any leakage will cause you to tune a combination of the signal through the duplexer and the direct signal leaking into the talkie. Yes, I had that problem as well. When I built my last 2 meter repeater (a semi-homebrew using custom re-packaged GE modules, mostly) I crystalled the receiver for both the repeater receive and transmit frequencies with a service switch to select the second frequency. I also built a simple op amp DC amplifier sampling second limiter voltage at a metering point in the receiver and use it to drive a signal strength meter on the repeater front panel. Of course my custom chassis is very well shielded. The receiver is peaked for the repeater input frequency, so it isn't as sensitive on the other frequency; but it is good enough to see the depth of my duplexer notches. I use an old (cheap!) Boonton 202E generator as a signal source, and put 3 dB pads on the duplexer ports (and a 50 ohm termination on whatever port is not used at any specific point in the tune up process). The Boonton is surprisingly stable once it has warmed up for a couple of hours. I've had good luck with this simple setup. But adding the signal strength meter to many commercial repeaters (or worse yet mobiles converted to repeater) could be more of a challenge. Paul N1BUG
Re: [Repeater-Builder] Re: Micor conversion question
15 pf and 12 pf in series would give you 6.7 pf, but if you have the space you could put them in parallel and have 27 pf. I'm sure that's what you meant to say. No guarantees on the specific item you're working with but usually putting a couple of caps in parallel to arrive at a needed value works just fine. I'd try that if it were me. Paul fxbuilder wrote: Thanks for the info. I found 39pf, and the 12pf, but the 27pf is illusive. I do have 33pf and 15pf. I'll assume I can try one as the replacement for the 27pf or can I put a 15 and a 12 in series?. Appreciate the help. Craig
Re: [Repeater-Builder] DB4062 woes...
Hi John, If you can get in touch with him I would interested to know more about what he did, especially if he cleaned the silver plated part (the plunger). Mine isn't all that dirty but I would like to clean them if I can do it safely. Also if he replaced the compound that the plunger is coated with, I would like to know what he used. I'm not sure what the stuff is, or why it is there - scratch prevention/lubrication, as and aid to electrical conductivity, anti-oxidation? In some of my cavities the stuff has started to dry out, so it ought to be cleaned off and replaced. Cavities I've worked on in the past didn't use any paste on the moving parts. 73, Paul N1BUG kf0m wrote: Hey Paul, another ham in my area had our DB4062 apart earlier this year for a similar problem lots of rx noise when I wiggled on two of the tuning knobs in the rx chain. He reported it to be discolored inside on the threads and rod but no pits and he cleaned them up. I will try to reach him and see if he remembers anything about the construction inside. John Lock kf0m at arrl.net -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Paul N1BUG Sent: Wednesday, October 24, 2007 11:20 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB4062 woes... Well I finally got the courage to tear apart my duplexer. The spring and finger stock appear to be in excellent condition with good contact pressure. However... If you look at this picture: http://www.n1bug.com/cavity.jpg You can see the end of the tuning plunger. The tuning rod is soldered to this end plate. Silver solder I'd guess. What you can't see in this picture is that at the top of the plunger there is a similar metal plate... the rod runs through a hole in that plate, but is NOT soldered to it, and there is considerable play. This is where the audible vibration comes from when I lightly tap the tuning knob. My first thought was since this is up inside the center part of the cavity there wouldn't be any RF voltage/current at that spot. BUT... this cavity is extremely sensitive to vibration, producing severe desense with the slightest tap on or near it. I can find NO other sign of anything that might cause it. Could this loose metal to metal contact where the tuning rod enters the top of the plunger cause this problem? If so, why would it not have this problem when new, but develop it after many years? Seems there must have always been a bit of play there... no? I used this successfully for several years, then it became progressively more sensitive to vibration and started having intermittent periods of severe noise desense... but a tap or two here and there on the duplexer will either greatly aggravate it or temporarily cure it. If that could be the problem, the challenge is getting at it to fix it. The plastic knobs apparently have a metal insert and are securely SOLDERED onto the rod, so getting them off without burning them up is not trivial (at least not for me). If I unsolder the rod from the plate at the bottom of the plunger I would be able to pull the plunger part out the bottom, leaving the rod in place... but then there's no way to solder or otherwise secure the rod to the top end of the plunger to fix the problem. The only solution I can think of is to cut the rod just below the knob, and screw the whole thing out the bottom... solder the rod to the plunger top end plate, screw it back into the cavity and put a new knob on it. Any thoughts, please Paul N1BUG Yahoo! Groups Links Yahoo! Groups Links
[Repeater-Builder] Thanks re DB4062 project
Thanks to all who responded to my request for help/info on this duplexer restoration project. I returned it to service yesterday. I'm now seeing better measured performance than ever before, and I am unable to make it go noisy by lightly tapping it as I could previously. I have a good feeling about this, but because its problems were somewhat intermittent before I hesitate to say it is fully cured at this point. I see no evidence to suggest it isn't... I just want to see it stay this way for a while before I proclaim success. If there is interest I can post a lengthy report on what was done and the results, or maybe even write up an article about it. 73, Paul N1BUG
[Repeater-Builder] DB4062 woes...
Well I finally got the courage to tear apart my duplexer. The spring and finger stock appear to be in excellent condition with good contact pressure. However... If you look at this picture: http://www.n1bug.com/cavity.jpg You can see the end of the tuning plunger. The tuning rod is soldered to this end plate. Silver solder I'd guess. What you can't see in this picture is that at the top of the plunger there is a similar metal plate... the rod runs through a hole in that plate, but is NOT soldered to it, and there is considerable play. This is where the audible vibration comes from when I lightly tap the tuning knob. My first thought was since this is up inside the center part of the cavity there wouldn't be any RF voltage/current at that spot. BUT... this cavity is extremely sensitive to vibration, producing severe desense with the slightest tap on or near it. I can find NO other sign of anything that might cause it. Could this loose metal to metal contact where the tuning rod enters the top of the plunger cause this problem? If so, why would it not have this problem when new, but develop it after many years? Seems there must have always been a bit of play there... no? I used this successfully for several years, then it became progressively more sensitive to vibration and started having intermittent periods of severe noise desense... but a tap or two here and there on the duplexer will either greatly aggravate it or temporarily cure it. If that could be the problem, the challenge is getting at it to fix it. The plastic knobs apparently have a metal insert and are securely SOLDERED onto the rod, so getting them off without burning them up is not trivial (at least not for me). If I unsolder the rod from the plate at the bottom of the plunger I would be able to pull the plunger part out the bottom, leaving the rod in place... but then there's no way to solder or otherwise secure the rod to the top end of the plunger to fix the problem. The only solution I can think of is to cut the rod just below the knob, and screw the whole thing out the bottom... solder the rod to the plunger top end plate, screw it back into the cavity and put a new knob on it. Any thoughts, please Paul N1BUG
Re: [Repeater-Builder] DB4062 woes...
Thanks Scott, I really appreciate the reply! I find it extremely strange the knobs are soldered on also. You're probably right, although these knobs sure look identical to the ones in all the old Decibel Products catalogs, etc. But these knobs have NO holes for set screws or anything of the sort. At the repeater site I thought they were glued on. It was only after getting it home and in better light I realized they have a hefty brass insert and it's soldered to the rod. Strange, indeed. Thanks for the info about the grommet. Are there some with very thin walls? The hole the rod passes through appears to be only a few thousandths of an inch larger than the rod. I'd guesstimate maybe .020 clearance. I will see if I can unsolder a knob without incinerating it. I would like to keep the rods full length if I can, but there is enough length to tune my frequency even if I hacksaw through the rod below the knob/solder... drastic, but it has become pretty much unusable the way it is. 73, Paul Scott Zimmerman wrote: Paul, I have seen similar construction in cans. All of the ones I have seen have a small plastic grommet insert in the hole in the top of the plunger. It's a plastic insert like would be in a hole where wire passes through it. They are available at Lowe's and other hardware stores. I also find it EXTREMELY strange that the tuning knob is SOLDERED to the tuning rod. I guarantee this is NOT factory. There should be 2 set screws on the knob. Once they are loosened, the knob should spin right off. If I were to make a guess, someone has been playing around with this can(s). As I see it, you have 2 options: Fix it right - Unsolder the knob, take the plunger out, clean up the threads, re-insert the grommet and reassemble using a new knob if necessary. The other option is to unsolder the plunger using a torch, replace the grommet in the top, clean the solder from the hole in the plunger and the rod, and solder the plunger back on the rod. Alignment is not critical since you can simply change the tuning to compensate for any misalignment. I had done a similar procedure to a set of Wacom cans that the silver plating on the plunger had gotten wore off. (how I don't know) I unsoldered the plunger, cut about 1/4 off the rod and soldered it back fast. While I had the cans apart, I used some silver plating compound used for plating circuit boards on the plunger to re-plate them. I used LOTS of no-ox on them when I reassembled to try to keep them from being damaged again. After I was done, the cans tuned great and are working fine. The only thing noticeable is that the tuning rods are a bit further into the can when compared side-by-side with an un-modified set. Good luck, Scott Scott Zimmerman Amateur Radio Call N3XCC 612 Barnett Rd Boswell, PA 15531
Re: [Repeater-Builder] DB4062 woes...
Progress! Scott, or anyone... I got one of the knobs off. Removing them is not such a big deal as I thought. It turns out the brass insert in the knobs is threaded. They are screwed onto the rods AND soldered. Sheesh! The hole in the top metal end plate of the plunger is indeed just a little bigger than the rod... not much more than .010. Photo: http://www.n1bug.com/cavity2.jpg If there originally was an insulated insert I suspect it was a special item for this application (or at least not hardware store variety). But if there wasn't one then I'm left with the original mystery of why it didn't have this noise problem until fairly recently. So what now? I think I could solder the rod to the top of the plunger without dislodging the whole end plate. Is that a bad idea? Better ideas? Alternatively, I think I could just squeeze some .005 PTFE sheet in that gap, but there isn't enough clearance to allow overlapping the ends at all. Also it might not stay put or hold up well with time and vibration. I still can see no other possible source of the noise/desense in this cavity. Paul N1BUG
Re: [Repeater-Builder] DB4062 woes...
Thanks Ian. I've realized my idea of soldering these two pieces together is horrible. The length of invar rod from the top of the cavity to its bottom attachment point may be critical for temperature compensation of the cavity! I can't believe I was proposing to do such a thing! Looks like I need to insulate it somehow. I've been trying for hours to slip a piece of .005 PTFE sheet in that gap but it just won't go. 73, Paul N1BUG IM Ashford wrote: Paul, Excellent photos! The only reason these two pieces of metal have began touching each other is that the invar plunger or the silver tuning sleeve have become bent. This could be due to some rough handling of the unitsprobably when you were absent? Personally, I would drill a series of small holes around this top plate to produce a larger hole,cleaning up with a small round file, giving about 1/8 clearance between the plunger and the sleeve. I agree that any kind of heating would ruin the plating.. If the plunger is now free of the tuning knob then perhaps you could slip some heatshrink tubing into the gap and fix it with a heatgun.. Ian G8PWE - Original Message - *From:* Paul N1BUG mailto:[EMAIL PROTECTED] *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Wednesday, October 24, 2007 7:36 PM *Subject:* Re: [Repeater-Builder] DB4062 woes... Progress! Scott, or anyone... I got one of the knobs off. Removing them is not such a big deal as I thought. It turns out the brass insert in the knobs is threaded. They are screwed onto the rods AND soldered. Sheesh! The hole in the top metal end plate of the plunger is indeed just a little bigger than the rod... not much more than .010. Photo: http://www.n1bug.com/cavity2.jpg http://www.n1bug.com/cavity2.jpg If there originally was an insulated insert I suspect it was a special item for this application (or at least not hardware store variety). But if there wasn't one then I'm left with the original mystery of why it didn't have this noise problem until fairly recently. So what now? I think I could solder the rod to the top of the plunger without dislodging the whole end plate. Is that a bad idea? Better ideas? Alternatively, I think I could just squeeze some .005 PTFE sheet in that gap, but there isn't enough clearance to allow overlapping the ends at all. Also it might not stay put or hold up well with time and vibration. I still can see no other possible source of the noise/desense in this cavity. Paul N1BUG
Re: [Repeater-Builder] DB4062 woes...
Nate, I appreciate the sanity check. I've been known to overlook things like that and make some fine blunders! The gouges you refer to appear to be tool marks of some sort. What you can't tell from the photo is it looks like they were made BEFORE it was silver plated, so I'm assuming some tooling they used during manufacture. They are not as deep as they appear in the photo. Yup, I've checked the harness and connectors, etc. Yup, it does misbehave off site when hooked to other radio(s). Here's a possible clue I forgot to mention. The passband loss, SWR, and even the notches appear to be quite stable when I tap on it (using test equipment of course). However if tapped with transmit RF present, noise on the receiver is very bad. Two of the six cavities misbehave. The other four seem OK... for now... I hate to chop on these at all! But... Paul N1BUG Nate Duehr wrote: Paul N1BUG wrote: I still can see no other possible source of the noise/desense in this cavity. Just a sanity checking question... You were able to get the cavity to misbehave OFF the site and hooked to completely different interconnect cables and a different radio, right??? You've also carefully checked the input connectors and loops for being loose (center pin falling out, etc...)? Just asking if you've made sure you're chasing the right problem. Anything that could have physically moved when you were even lightly tapping the cans is suspect until the can was proven for sure to exhibit the problem and the connectors were carefully checked, right? Just checking... before you chop on those any further... In the first photo, what were the big gouges in the plate from? Those didn't look real good... but didn't seem to be sticking out off the edges at all. Any thoughts as to how those got there? Nate WY0X
Re: [Repeater-Builder] Re: DB4062 duplexer disassembly
Ralph Mowery wrote: It may not be glue but a form of locktite. If you heat the parts the locktite will usually let loose. OK, thanks. I tried heat but next time I will try a bit more. I've been preoccupied with another repeater issue this week. About 30 years ago we had a Phelps Dodge 6 cavity set that would give the same simptoms . Sent it back and it came back the same way. We opened up one of the cavities and found about a teaspoon of solder dropings in the cavity. A couple years ago I bought a DB4002 pass cavity and noticed it rattled when I picked it up to move it around. It worked fine, but being curious I opened it up. I found what I would guess to be a tablespoon of solder droppings in the bottom. It was interesting. Apparently loose metal laying at the bottom of a cavity doesn't adversely affect its operation, so long as it is operated in an upright position. 73, Paul N1BUG
