RE: [Repeater-Builder] Wacom WP-639 Duplexer question
The PLL exciter is why you're having such good success running a 4-cavity duplexer. If you had a PM exciter, chances are you'd be experiencing desense. The PLL exciter produces about 22 dB less noise at 600 kHz offset, reducing the noise supression requirement of the duplexer by a like amount. See: http://www.repeater-builder.com/pdf/GE_Isolation_Curves.pdf The OP also mentioned he was using a preamp - that's not helping his situation either. Even with a good receiver he's probably on the edge of crunching it with only a 4-pack. Personally, I'd never run a preamp with nothing but a 4-cavity duplexer on 2m, but if it works for you, God bless... A Q202G gives more isolation than a WP639 from what I've seen/measured, in part because the cavities are larger diameter (I think they're 7 versus 5?). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of NORM KNAPP Sent: Wednesday, September 08, 2010 11:38 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Wacom WP-639 Duplexer question I got a set of 4 sinclair cans, like a Q202g on a GE mastr II running 100 watts with pll exciter and GE preamp with no desense. Antenna is roughly 300' away fed with LDF7-50A. Is this a miracle or typical? - Original Message - From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Wed Sep 08 20:10:44 2010 Subject: RE: [Repeater-Builder] Wacom WP-639 Duplexer question I'm not surprised- you're asking too much of a duplexer that has four 5 cans. According to my CommShop program, a duplexer with an 80 dB spec is more suitable with transmitter power in the 10-15 watt range, assuming a solid-state PA and a receiver sensitivity around 0.35 uV at 12 dB SINAD. On a 100 watt repeater, I'd expect something like a WP-642, which has six 8 cans. BTDT, got the T-shirt and mug... 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of RichardK Sent: Wednesday, September 08, 2010 3:11 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] Wacom WP-639 Duplexer question Good evening, our club has a Wacom WP-639 four can duplexer as part of our repeater system. Input Fq is 147.915 and Output Fq is 147.315. We have a 600kHz (+) offset. Very simply, our main problem is when we run the transmitter at full power 100 watts, there is a HUGE desense on the receive side of things. When we drop the transmitter power level to around 20-50 watts, the receive side opens WAY up to a large area where people can get into the repeater. As we begin to bring up the transmitter power, white noise begins to appear and the receive side starts to desense again. All the cables have been switched to double sheilded cables and all the same wavelength in length. We have the duplexer seperated sheilded from the transmitter preamp parts. We have not replaced the antenna feed coax with double sheilded coax yet. Antenna is a Hustler G7 atop a 55' mast. The duplexer was retuned just over 1 year ago. Any suggestions as to what we could look into next? Some of us believe the problem is with the tuning of the duplexer receive cans. Thank you very much.
RE: [Repeater-Builder] To DVP or not to DVP
If you have a nearby first adjacent (especially at 20 kHz), you might be better off with a standard receiver. Might be worth measuring it and comparing it against a standard receiver - I'd be curious to hear the results as I've never done that test myself. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Tuesday, September 07, 2010 5:45 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] To DVP or not to DVP Hmmm... I didn't realize the DVP has a wider IF. I gather DVP requires up to 6 Khz of audio. So now I'm thinking that this receiver is not suitable for my busy hill (Santiago Peak). What do you think? -- Tim :wq On Sep 6, 2010, at 8:17 PM, Jeff DePolo wrote: The SP docs show it being a DVP station. DVP receivers have wider (and flatter) IF filtering than standard Micor Sensitron receivers. They need a flatter IF passband to decode DVP properly. I'm wondering if that's why the 20 dBQ reading comes out higher than normal.
RE: [Repeater-Builder] Micor UHF Sensivity
Not all voltmeters behave the same with complex AC waveforms (such as noise). Some of my Flukes are inaccurate at higher AC frequencies (like above a few hundred Hz) - and they're spec'ed that way. What kind of meter are you using, and where are you measuring (speaker terminals is where you should be measuring from)? Do you know what, exactly, the SP features/modifications are on your SP Micor? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Monday, September 06, 2010 6:07 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor UHF Sensivity The Micor book says less than 0.5 uV for 20db quieting or 0.35 for 12 db SINAD. So the two are in fact equivalent. I get better than 0.35 for 12 db SINAD but I don't measure 0.5 for 20 db quieting. I must be doing something wrong. -- Tim :wq On Sep 6, 2010, at 12:52 PM, John J. Riddell wrote: 2V AC down to .2 v. AC is 20 DB quieting John VE3AMZ - Original Message - From: Tim Sawyer mailto:tisaw...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 3:48 PM Subject: Re: [Repeater-Builder] Micor UHF Sensivity I'm getting about 0.35 for 12 db SINAD. But that looks about 10 db quieting to me. What I typically do is open the squelch with no signal and set the volume to 2 Vac then crank up the signal to 0.2 vac. Isn't that 20 db, or am I missing something? -- Tim :wq On Sep 6, 2010, at 10:46 AM, Eric Lemmon wrote: spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 12 dB SINAD method
RE: [Repeater-Builder] Re: no power out of duplexer SOLVED with more questions
Or speed up the CWID one or two WPM, or change to a slightly higher tone frequency. Top 40 stations sometimes still do this trick (pitching up their CD players or automation system playback speed maybe 1%) - some PD's are convinced that it improves ratings for one reason or another... --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Monday, September 06, 2010 6:38 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: no power out of duplexer SOLVED with more questions I agree. Put it back to the original output. I always like to turn my stuff back at least 10%. Turn the beep tone up in volume, tell them you increased the power. see what they say. 73, Joe, K1ike On 9/6/2010 5:04 PM, Paul Plack wrote: John, here's a more subtle lesson on repeaters, and it has nothing to do with hardware... If you dial the power back 1 dB, your PA may be much happier. If you simultaneously change the courtesy beep to be 10% faster, users will ask you what's changed on the repeater. Tell them you've increased the transmitter output 3 dB, and they'll claim to have noticed the improved coverage. Tell him guys...am I wrong? ;^) 73, Paul, AE4KR - Original Message - From: Tim Sawyer mailto:tisaw...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 2:43 PM Subject: Re: [Repeater-Builder] Re: no power out of duplexer SOLVED with more questions
RE: [Repeater-Builder] Micor UHF Sensivity
I have tried with 3 volt meters and 2 SINAD meters: a Fluke 77, a Sinadder 3 (SINAD AC voltmeter) and a HP8924c. Pretty much same results with all. That is 20 db quieting around 0.7 uV, SINAD around 0.35. So what's the recommended meter? Should I trust the SINAD reading and chock the quieting reading up some unknown meter problems? Very odd. I'd probably want to load the speaker PA; I usually just leave the speaker connected or use a load box. Yes. The Micor came with a 3 page document detailing SP71 modifications. Would you like me to scan and email you a copy? I'd be curious to see if any of the mods would affect AF response, IF bandwidth, or anything else that could be throwing off your numbers. IIRC, older Micor manuals didn't even have a 12 dB SINAD sensitivity spec, only a 20 dBQ spec/test procedure. That's what I remember always using as a pass/fail reference. Of course, SINAD is a better test, but you should expect an in-band Micor to still meet the quieting spec. --- Jeff WN3A
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
It looks like the FCC rules give you extra power when opting for dual polarization. No, they don't give you extra power. For commercial stations, horizontal polarization is the standard. You can supplement it with vertical, either as cross-polarized linear, or as elliptial/circular, but that Vpol component's ERP can't exceed the Hpol ERP. For non-commercial stations in the reserved band (i.e. below 92 MHz) within the affected area of a channel 6 station, there are many cases where they are authorized for more Vpol than Hpol to protect channel 6 (which is presumed to always be horizontally polarized). The only extra power you get is additional transmitter power output (TPO) due to the reduced antenna gain (assuming the number of bays remains the same, and the same bay spacing) when you go from horizontal polarizaton to mixed polarity. That's a confusing point, I know. Every circularly-polarized FM station I've seen (and that's a lot of them) use an antenna design that handles the phasing and time-delay to create the circularly-polarized signal. That's pretty much correct, but there are many stations that have a vertical component added that isn't necessarily part of a circularly-polarized array. The vertical may be added as a separate radiator, but not phased with the Hpol radiators to yield circular, so you just have two non-coherent linear polarizations. Or a single linear radiator may be tilted to give slant polarization, which the FCC will accept as having both an Hpol and Vpol component, with the ratio being a function of the tilt angle. The license reference to H and V powers (regarding c-pol station) is intended to say how much ERP should some out when the signal is V and how much when it is H. It is possible to make the two components different, resulting in elliptical polarization rather than circular. They can be different, and yet not be elliptical. If they aren't phased together to yield a coherent rotation at all azimuthal angles, it's just random cross-polarization, not elliptical. 99% of the current topic was covered a year or so ago on this list - might want to revisit the archives. For those thinking about building Cpol bays, I'd suggest starting out with something simple like a ring-stub. Easy to make with a tubing bender (or Armstrong method), feed with a gamma, DC-ground at the mounting bracket at the rear of the bay, decent pattern circularity (but not great axial ratio symmetry), cheap and easy way to start. For those not familiar, a ring stub bay looks like this (I don't recommend OMB, it's just a decent picture of a very basic ring stub bay): http://www.omb.com/en/index.php?option=contenttask=viewid=78Itemid=38 Ring stubs are sometimes also called cycloids (albeit sometimes erroneously), often built with a balanced feed. You can try Googling cycloid, ring stub FM antenna, etc. for more pics and design ideas or email direct. --- Jeff WN3A
RE: [Repeater-Builder] DB212-3
I'm doing this from memory - I have the docs at home and can verify later. The DB lowband dipoles are 50 ohm feed Z due to the close spacing to the tower leg. 1 dipole - fed directly with 50 ohm coax (VB-8) 2 dipoles - fed with equal legs of 50 ohm coax (VB-8) to a tee, match 25 ohms from tee to 50 ohm feedline with quarter-wave transformer (35 ohm VB-83) 3 dipoles - fed with equal legs of 50 ohm coax (VB-8) to two mated tees (two mated tees give you four ports - three to bays, one for input) yielding 17 ohms. First transform 17 ohms to 72 ohms via a quarter-wave of 35 ohm VB-83. Then transform 72 ohms to 50 ohms with a 'twelfth-wave' transformer (1/12 wave of 50 ohm cable then 1/12 wave of 72/75 ohm cable) to result in 50 ohms to feedline. 4 dipoles - same as 2 dipole case, but add another tee, two more equal-length 50 ohm cables from the added tee to the 35 ohm matching sections on the bay pairs described above, and another final 35 ohm Q section from the new tee to the feedline These dipoles couple a lot of energy to the tower - you'll likely need even more vertical isolation than what free-space curves might otherwise predict. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Monday, August 30, 2010 2:35 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] DB212-3 Doug - Do you know how the phasing harness was constructed for the three-element version? I don't, and that's why I suggested to Norm that he go with four - the phasing harness is easy. Or, he could use two elements for transmit and one for receive. I don't know how much isolation he'll need, but he might just get away without a duplexer if there's enough tower. Chuck WB2EDV - Original Message - From: Doug Rehman d...@k4ac.com mailto:doug%40k4ac.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Monday, August 30, 2010 2:28 PM Subject: RE: [Repeater-Builder] DB212-3 In a previous life I managed the communications for a state police agency. We used 45 MHz for our main system and had forty some odd tower sites, almost all running DB212-3 antennas. Two of the sites were on 1000+ towers and used a single DB-212 element due to the large tower face and the great height. One was a repeater using a receive antenna at 1450' and a transmit antenna at 1350'. The other was a remote base station with the single loop at about 850'. As we were an investigative agency, almost all of the mobiles were using AM/FM disguise antennas. (Yeah, I know, but we were stuck with the band that the State Division of Communications had dictated...) Despite the radiating dummy load antennas, we had excellent mobile coverage in virtually all of the state. A consideration for DB212 antennas is that lining them up on one leg can make them pretty directional. For towers that were very close to the coast, I would put all three elements on a single leg, but skew them so that only one was pointed directly off of the leg. This seemed to give me a somewhat cardioid pattern, but with a little better pattern to the back than if all three elements were in line. Another consideration is that they were designed to be used on Rohn 45/55/65 sized tower. If you put them all on one leg, a larger tower face doesn't matter much except that the rearward pattern will likely have a larger null. Mounting them on all three legs of a larger face tower will result in reduced gain and a pretty messed up pattern. I don't know if I'd worry a whole lot about adding a fourth element- the three element antenna will deliver excellent results. Doug K4AC (Running for ARRL Southeastern Division Director- please check out my website at www.k4ac.com)
RE: [Repeater-Builder] Running a Mastr II Repeater QRP
I don't know the current frequency, but suspect it's in the 460/465 MHz range. Will it move down into the 440s without a lot of grief? Yes. Also, I don't need anywhere near 100 watts, and need to avoid abusing the good nature and power bill of my landlord. (Also hope to have battery backup.) Can the 100-watt UHF PA be jumpered from an intermediate stage to the filter, bypassing the final? I seem to recall these would run at something in the 10-25-watt range with such a mod. The driver is 40 watts, just bypass the final board. But if you're really trying to safe your landlord's electric bill, the ferro power supply is really what you should be eliminating. That's a real beast of a vampire. Or, is this just gross overkill for a local repeater, and the Mitrek-based idea more appropriate? I'd go with the M2, hands down. --- Jeff WN3A
RE: [Repeater-Builder] dumb question: what is purpose of lock on Mitrek?
I'm assuming this is a CW beacon? I would think that whether rockbound or synthesized, you'd probably be best off having the oscillator running all the time and keying RF at a gain or multiplier stage. You might have to do some keying waveform shaping to avoid keyclicks. I'd take a real close look at the output spectra with something capable of catching transients or any spurs that occur during the keying ramps; maybe key it on/off at a rapid rate repeatedly while doing a peak-hold with the SA for a few minutes to look for any anomalies as a first pass. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jeff KP3FT Sent: Sunday, August 29, 2010 1:16 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] dumb question: what is purpose of lock on Mitrek? Thanks guys. Looks like this radio might work; need something for a 6-meter beacon transmitter. Tried a Mocom but it wasn't functional. Tried a Maxtrac but the carrier was really squirrely even when I tried the various mods, must be due to the PLL instead of crystal-control. Have to see how the carrier sounds on the Mitrek; if it's good I'll have one of the TX channel elements re-crystalled. Been trying to get something for a 6-meter beacon that doesn't cost a fortune, on and off for the past few years between other projects, and finding it a lot more difficult than it was finding a suitable 10-meter beacon transmitter! Learning a lot in the process though, that's a good thing... 73 Jeff KP3FT --- On Sun, 8/29/10, Eric Lemmon wb6...@verizon.net wrote: From: Eric Lemmon wb6...@verizon.net Subject: RE: [Repeater-Builder] dumb question: what is purpose of lock on Mitrek? To: Repeater-Builder@yahoogroups.com Date: Sunday, August 29, 2010, 12:56 PM Jeff, The reason that most trunk-mount radios are locked is to prevent theft and tampering. The lock has no electrical function. You will need the ubiquitous #2135 key to unlock your Mitrek drawer. You definitely want to open up the radio before applying power to it, so that you can ascertain if the channel elements are in place, and what optional components are installed. Since Motorola shipped two keys with every radio sold, most radio shops will have a drawer full of #2135 keys. If you ask, you will likely get one or two free. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of KP3FT Sent: Sunday, August 29, 2010 9:09 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] dumb question: what is purpose of lock on Mitrek? Hi, I know it's a dumb question, but after scouring the internet for info, I find everything about locks and replacement keys for Motorolas and other radios, but I still don't know what locking the Mitrek actually does. Does it kill all power to the radio, or disable certain functions? I'm asking because I just acquired a low-band Mitrek that I need to power up and verify its working condition. It doesn't have a control head, so I need to use the front panel pins, but if the radio is locked, I may end up getting nowhere and still not know if it's either the radio that is bad, it is locked out, or I wired it wrong. This is the first Mitrek I've had. Thanks for any help. Jeff KP3FT
RE: [Repeater-Builder] Re: Intermod Calculation
The deviation is 15 kHz, or you're seeing 15 kHz of bandwidth on the spectrum analyzer? The latter would be normal, the former wouldn't be. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Saturday, August 21, 2010 1:33 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Intermod Calculation I haven't noticed a hum. There's more of a scream on it. It's POCSAG. Is that analog? The dev is basically 15 Khz but there is, what I going to call splatter that is like 30 Khz. -- Tim :wq On Aug 21, 2010, at 10:14 AM, MCH wrote: Many times (but not all), there will be a grungy sound with the spur. Think of a very loud 60 cycle hum. And 15 kHz is higher than normal. I think the typical shift is 5 kHz (+/- 2.5 kHz) if we are talking about digital paging. Analog might be 15 kHz, as the bandwidth limit would be 16 kHz. Joe M. Tim Sawyer wrote: I'm not sure what you mean by grungy. What are you getting at? -- Tim :wq On Aug 21, 2010, at 6:59 AM, MCH wrote: Does it have a 'grungy' sound to it when you hear it on your input?
RE: [Repeater-Builder] Intermod Calculation
Before we get into the math, an important question that needs to be answered is whether or not this mix occurs when your repeater transmitter is unkeyed. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Friday, August 20, 2010 6:36 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Intermod Calculation I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm 100% sure there is another transmitter involved in the mix because sometimes the pager is transmitting and I have no interference. I have an intermod calculator program but it wants all the known transmitters and the target receiver. But I need to solve for an unknown transmitter. Is there a way to calculate the other possible soruce(s)? -- Tim :wq
RE: [Repeater-Builder] Celwave CC460-A circulator
The simplified instructions for tuning an isolator are: 1. Tune input (tx port) for maximum return loss with antenna port terminated in 50 ohms and reject load connected to reject port 2. Tune output (antenna port) for minimum insertion loss, sweeping from tx port to antenna port, again with reject load connected to reject port 3. Tune reject port for maximum isolation (i.e. best match into load), sweeping from antenna port to transmitter port, adjusting for minimum amplitude 4. Repeat. If you're trying to use it far from its design frequency, you may not get it to meet spec, or you may find that the return loss maximum in step #1 doesn't align well with insertion loss minimum in step 2, or other similar performance problems. The Celwaves usually tune over a fairly broad range, so I think you have a good chance of having it work right, assuming you have the right test equipment to tune it. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of cruizzer77 Sent: Wednesday, August 18, 2010 3:19 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Celwave CC460-A circulator Does anyone have a datasheet or tuning instructions for this kind of circulator? It's a single stage with 3 adjustment screws and right now the sticker says it's on 420 MHz and I would like to know how I get a working range from 430 to 440 MHz. If somebody can explain without the doc this is fine as well. 73 Martin
RE: [Repeater-Builder] Coax length, etc.
But why? If all of the power (or, let's hope, at least 99.99% of it) is on-channel, *should* a properly-designed and properly-functioning transmitter misbehave due to the poor match a duplexer presents at frequencies far removed from the channel center? Well yes, properly designed transmitter. But how much do you want to pay for it? Me personally? I'll pay for a transmitter that works, and works right. The way I see it, repeaters are like cars. You have to get your car inspected for safety. Your car doesn't pass safety inspection? You can't drive it on the public roads, lest you'd be putting other people at risk. Same with a repeater transmitter. If it's unstable and has the potential for causing interference other systems (ham repeaters, public safety, aviation, etc.), it shouldn't be on the air. Either fix it, or if you can't afford to fix it, take it down. I don't want some scmuck driving a beat-up 1972 pickup down the interstate in front of me and having his rear bumper fall off any more than I want somebody putting some clunker up on a mountantop and having it go spurious and interfering with EMS or ATC. That's just the way I see it, sorry if that rubs some people the wrong way. A built in isolator will solve all of those problems as an example. Maybe. An isolator will help flatten the load on, and around, the carrier frequency, but isolators, too, have a finite VSWR bandwidth, they won't provide a perfect load across the entire spectrum. And if you can afford an isolator, you can probably afford a better PA. It is almost impossible for a high Q cavity to not present some reactance away from the tuned frequency. It's not almost impossible, it's definately impossible. If it didn't then it would not have any selectivity. Right. The random length cable of course transforms that reactance to something that the transmitter may or may not be comfortable with as discussed above. Just to clarify, the complex Z is being transformed (both R and jX), not just the reactive component. The thing with random-length cables is just that - they're random. How do we know what cable length is going to make the transmitter happy? Does the transmitter like more XL or more XC, or bigger R's or smaller R's, and at what frequency, because as I'm sure you know, the complex Z is going vary wildly at different frequencies, due to the duplexer's Z, its behavior as a transformer with respect to the load Z at the antenna port, the antenna feedline acting as a transformer with respect to the antenna feedpoint Z, and the cable between the PA and the duplexer also acting as a transformer, so you end up with this complex system of cascaded transformers. Chances are if the PA is that picky, its behavior may also change with temperature, voltage, who knows what else. Antenna feedpoint Z's change with environmental conditions (precipitation, icing, etc.). Feedline electrical lengths (phase) change with temperature, so the resulting Z at the duplexer antenna port is also going to change. There are *so many variables* that will constantly be changing over time that what may seem to work when you walk off the site may fail miserably months, days, maybe even hours later after you think you've found that magic cable length. At least with an isolator we've taken the bulk of those external variables out of the equation - I can agree with that. But, call me a fundamentalist, I still believe that a PA should work, and work right, when it sees 50 ohms on-channel no matter what's happening off-channel. --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
Actually I think that even though Service Monitors have finally become *relatively* commonplace in the Ham Shack, the VNA is not something most hams have seen or know how to use. For $100, Rick's (Amtronix) return loss bridge is a must-have for anyone that has a SM with a SA/TG. With it, there's no longer any excuse for not being able to tune cavities properly for maximum return loss. Like Service Monitors used to be before the flood of HPs on eBay in the last few years, I hear rumors of great deals on VNAs, and yet never see them in any way plentiful, easy to acquire, or affordable, but then again I'm also not exactly looking that hard, and perhaps I'm missing one of those everyone knows about Bob's VNA Warehouse! kinds of sources for such things. Hey, I didn't say they were cheap, nor that everybody can or should own one. There's nothing more enjoyable than tuning up a $100 duplexer from Dayton on a $50,000 network analyzer, especially when it's a 3-porter and you don't even have to swap cables around :-) --- Jeff WN3A
RE: Properly designed PAs (was: Re: [Repeater-Builder] Coax length, etc.)
Jeff, out of all the PAs you've seen out there, both commonly used and not-so-common... which ones (in your opinion) are properly designed (when working right)? I think a lot of them, generally speaking, are properly designed. That's not to say that some of them don't have some downsides or specific, recurring points of failure (to wit: the beloved Mastr II output strap connection failure). I'd name manufacturers that are on my $^!+ list, but I'd rather not do that here, but I will say that most of them are the made-for-amateur brands. I've had great luck with just about anything Micor (and, I have to say, significantly better long-term results with Micor over M2, sorry GE fans). Crescend and *newer* TPL amps have been good to me. EFJ CR1010 PA's have also been workhorses. I have this feeling that most, if not all, have various problems... but you've seen a heck of a lot more of them in-service than I have. Well, I dunno, there are probably others on this list in the two-way business that have seen more than me. I do broadcast for a living; I'm generally an RF guy, my interest in repeaters is just a subset of that. I have a bunch of ham repeaters (20-some I think), and maintain a bunch for other individuals/clubs, and have built or maintained many for others over the years, but I'm sure there are others that do two-way on a daily basis that can give more points of reference as far as recurring problems with other brands/models that I'm not as familiar with. I ask, because this is always the kind of mature, well-developed tech I'm looking for. Price is still a factor, but when you find something that just works... it's truly grand in the tech world, for all sorts of reasons that tend to degrade what something was intended to be, vs. what it really ended up being. To me, the cost of the radio hardware is the least of my worries. I'm not saying that to sound like an alpha-hotel. I look at it this way. I've got all of these repeaters to deal with. I have no free time the way it is. When one breaks, that means I have to take a day off work (or away from family, or away from something else) to go deal with it. It probably means a few hundred miles of driving. And, more than likely, if it's a major failure, I'm probably going to have to make a return trip, doubling the time/cost. So do I really want to take a chance on low-grade hardware up front? No way. Whoever said time is money was an idiot. Time is worth inifinitely times more than money. You can make more money. You can even borrow money. Hell, if you were desparate you could even steal money. You can't do any of those things with time. Time is the one resource you can't make more of. And, for me, I've never had enough time to get everything done that I want to get done. Life's too short to waste time on high-maintenance equipment. I'm also curious to see if your recommendations are new gear, or 20+ year old gear. Both. While I still believe the glory days of two-way turned out the best damned equipment ever made, there is still some decent stuff being made today. I really like MASTR II Stations, but I will admit to some consternation over how the PAs *sometimes* act. We've had 'em run for a decade, and we've had 'em pop like light bulbs every few months. With the exception of the PA's, they generally just run. 100 watt UHF M2 PA's have been rather disappointing for me, both with and without matching networks, with or without isolators. 75 watters seem to run forever. Highband and lowband, much fewer problems. I have a bunch of the 200 watt solid state M2 stations, and have pulled them all out (except for one, which is coming out in a week or two), they're just a nightmare to keep all three PA's working all the time. Is the answer to this question the Crescend amps perhaps? I've been happy with them. I have 7 or 8 of the previous-vintage UHF Crescend/Milcoms (the gold-alodined ones that you're probably familiar with) on the air, and they've been fine, running in the 150-175 watt range. I ordered a couple 100 watt highband amps for a local club about a year ago, they seem OK. I have a bunch of their 900 MHz linear amps in use on STL's and they've been solid. I wouldn't hesitate to buy them. How did their acquisition of Vocom affect their quality? They did change their design, and talking to their engineers a few months ago, they're doing some re-designs due to some of the devices they had been using going on EOL, so more changes will be forthcoming. Some of the older pre-Crescend Vocom amps weren't very good. I haven't looked lately, did they mix up the model line and keep the Vocom stuff? They still have the Vocom line which they market as a lower-cost alternative. I like the TPL RXR series because they are extremely simple. They also have one device per board, so in the event that you have a device fail or burn up a collector trace or something, you only have
RE: [Repeater-Builder] Coax length, etc.
I know I'm going to regret stepping into this one, but since when has that stopped me before... Thanks, Gary, for admitting the 43 doesn't measure power directly. What do you mean by measure power directly? If you're talking about comparing a thruline measurement against absorptive/calorimetric techniques, then that's apples and oranges, one is measuring power in a transmission line (either with or without reflections present), the other is measuring power absorbed into a load, big difference. Please clarify what you mean by measuring power directly so at least we're all on the same page. Of course, it is a directional coupler, no argument. That makes it a reflectometer No, it's not a reflectometer, it can't do forward and reverse measurements concurrently. If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point Not without knowing the phase between the two it couldn't. BTW, my POS Daiwa can show me a 100% reflected condition, just like the Bird. And just like the Bird, it doesn't indicate if that's an open or a short. A Bird isn't a VSWR bridge, it's a directional wattmeter. Yes, it can be used in a roundabout way to measure/calculate VSWR, but it's not a VSWR meter. Sidebar. I grit my teeth when I hear someone on the radio say my SWR meter shows I'm putting out 100 watts. Since when does a SWR meter measure power!???! Do you use your bathroom scale to check your blood pressure? Egads. I'm not taking a stance here (at least not yet) on the relative merits of the Bird 43 or other thruline-type wattmeter line sections or elements, I'm just trying to get a handle on the matter that is the subject of debate... --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
Because the impedance is not matched between the transmitter and duplexer, the 'apparent' loss of the duplexer is greater than the manufacturers stated loss of the duplexer. Changing the cable length is not changing the loss of the duplexer, it's changing the power that is accepted at the transmitter port of the duplexer by matching the output impedance of the transmitter to the input impedance of the transmitter port of the duplexer. But if the duplexer is tuned to 50 ohms, and the cable is 50 ohms, varying the cable length isn't going to change the Z seen by the transmitter. Or are you suggesting the duplexer is purposely de-tuned from 50 ohms? And also that by varying the cable length between the transmitter and the duplexer that you can vary the reflected power on that same line? Yes. With all due respect, that's not possible, regardless of what the Z is of the duplexer. The only time it could have an effect on the reflected power would be if the transmitter/PA were spurious, and the amplitude/frequency of the spurs changed with varying load Z, and I think we can both agree that if that's the case, we have bigger fish to fry. Not to belabor the point, but whatever the VSWR is on a length of transmission line, that's the VSWR that's on the line *regardless of length*. You can't change the VSWR by changing the length of the line. As you vary the length, you go round n' round the Smith Chart in a constant VSWR circle, with the Z repeating cyclicly every half-wavelength, but you've still got a complex Z that nets a 1:5:1 VSWR relative to 50 ohms at the end of whatever length of line you choose (cable loss effects notwithstanding). There are an infinite number of complex Z's that yield a 1.5:1 VSWR - cut the line to any random length and you'll hit one of them. In a situation where the duplexer and transmitter have differing impedances, and a cable optimized in length matches these impedances, the mismatch at the duplexer is minimized, therefore the power reflected by the duplexer is minimized. I think what you're really saying is that the mismatch at the *input to the matching section* (i.e. the cable between the PA and the duplexer), NOT the mismatch at the duplexer, is minimized. The duplexer's input Z isn't changing; you can't change that unless you re-tune the cavities or change the load at the antenna port. Whether or that the transmitter likes/dislikes the different Z it sees as you change cable lengths is, I guess, what's up for debate... I have found that when you get a transmitter that is 'picky' about the length of interconnecting cable, power being read at the output port of the duplexer is low and you cannot alter the tuning of the cavity closest to the transmitter to make things right. In other words, the place where lowest VSWR and maximum power transfer occurs is at two completely different places, and power transfer is not up where it should be (transmitter makes 100 watts into a dummy load but only shows 50 watts on the output port of the duplexer that has a stated 1.5 dB loss (29 %)). That would imply that either duplexer is presenting a load Z substantially far removed from 50+j0, OR the transmitter doesn't like a 50 ohm load, or something inbetween, would it not? As you get close to the 'optimum' cable length, the lowest VSWR and maximum power transfer occur near the same place when tuning the cavity closest to the transmitter. But again, *you're NOT changing the VSWR*! You can't change the VSWR by varying the length of the line! I just want to make sure we're on the same page - the VSWR on a transmission line doesn't vary with length (loss notwithstanding). I usually pay more attention to what is coming out the antenna port of the duplexer - first. Then, when things are right, comparing forward power going to the duplexer and power going to a good dummy load will be very close the same, since matching the impedance of the transmitter to the impedance of the duplexer was accomplished by some means. Can you give me some real-world examples of what combinations of duplexers and transmitters you've run across that just didn't want to play nice without having to resort to changing cable lengths? Like a highband Micor 110 watt H split paired with a Q2220E or whatever. I'm just curious if I've done any of the same combinations. I think you know me well enough by now Kevin that I'm not looking to pick a fight, I'm just a hard-ass when it comes to basing technique on solid engineering foundation. I can't say I've ever had to play with cable lengths to either get a transmitter/PA to make rated power, or to get the apparent loss of a duplexer to meet spec. Have I just been lucky? Maybe. But if I'm *that* lucky, I'm in the wrong business, I shouldn't be sitting a hotel room in Harrisburg on a Saturday waiting for a tower crew to show up, I should be living the good life in Vegas
RE: [Repeater-Builder] Coax length, etc.
Jeff, you aren't stepping on my toes at all. Glad to see your comments. OK, good. Since you've never met me, I can assure you, you definately DO NOT want me stepping on your toes, it would be painful. I do have to agree with Kevin that most duplexer manufacturers recommend different cable length trials between the transmitter and the duplexer when full power can not be reached into the duplexer. Ah, but the crux of the matter is that we're not changing the performance of the duplexer, we're just getting the transmitter to transfer more power into the line. Over the years I have been a manufacturers rep for TX-RX, Sinclair and Telewave. All of them recommend the same thing. Again, it's a CYA measure as Kevin pointed out. PA won't make power? Don't blame us, try mucking with the cable length, see if that helps. I am not a transmitter expert but it is my understanding that the problem is not one of the duplexer not presenting 50 ohms at the wanted frequency but the impedance that it presents off frequency to the transmitter finals. Some solid state devices do not like to see high reactance, even off frequency. But why? If all of the power (or, let's hope, at least 99.99% of it) is on-channel, *should* a properly-designed and properly-functioning transmitter misbehave due to the poor match a duplexer presents at frequencies far removed from the channel center? For one thing the reactance causes them to draw more current than normal. Again, why? This may be why you find that tuning for minimum pa current and maximum power out don't exactly agree with one another. I can promise you they almost never do, but that's not any great mystery. You are probably finding a balance between the off frequency reactance and the on frequency wanted load that the finals see. No, that's not it. The off-frequency Z issue is a totally separate topic from the efficiency vs maximum output subject. Let's keep those two topics separate for the sake of this discussion. If you have the duplexer properly tuned to provide 50 ohms at its input port, the transmitter may still not be happy because of the off frequency reactance presented by the duplexer. I disagree. I would accept the notion that the transmitter may not be happy (and I put that in quotes not to mock you, but becuase I can't come up with a better word either) because it is not *properly matched* when looking into a 50+j0 load. This indicates a deficiency in the amplifier; if it were designed and working right, it *should* make rated power when terminated in a 50 ohm load on-channel. Changing the cable length in this case really does nothing for the on frequency load between the duplexer and transmitter, when the duplexer is presenting 50 ohms, but it can change the off frequency impedance transformation that the transmitter sees. Yes, but again, I argue that this all points back to a PA problem. Or the input Z of the duplexer really isn't 50 ohms and the line is acting as a transformer. Detuning the duplexer and or changing cable length to get the transmitter power up is the wrong way to go here. First the transmitter should be optimized into a 50 ohm load. Then optimize the duplexer input for 50 ohms input. Yes, yes, yes, amen! Someone asked about a rule of thumb for transmitter to duplexer cable length. There is none! Yes there is. You take out a tape measure and the distance from the transmitter to the duplexer. You make the cable at least that length. The cable length between multiple cavities is predictable. As an example between two notch cavities; the first notch presents a very low impedance. With a quarter wave line to the next cavity that low impedance is transformed to a high impedance at the input to the next cavity. That high impedance is then presented with a very low impedance of the second cavity. This critical length cable increases the ultimate notch depth because the high impedance that the cable presents and the low impedance of the cavity form a voltage divider. The greater the ratio the better the rejection. 'zactly. When done right, you can pick up close to 6 dB additional net notch depth when cascading notch (or pass/notch) cavities when the intra-cavity cables are cut this way. Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
So will someone post a simple rule of thumb. If you have the option of optimizing cable length from PA to first cavity, IE you haven't made them yet what's the best simple rule of thumb to follow to build them to avoid reactance. 1/2wl if allowed minus coupling loop depth? Or is that past a simple thumb. Also, This will obviously not work well for 220 or 440 or a most vhf repeater setups. So what would the next ideal cable wl be? And so forth. The reason I ask, if your building new cables why not? Answers on here seem to range a lot. There is no simple rule of thumb, and if anybody tells you that there is, ask them how do you account for the unknown-length of coax that's *inside* your transmitter/amplifier before it gets to the antenna jack. --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
OK, I think, for the most part, we're on the same page. I'm cuttin' and trimmin' a lot here... And this is where I believe the duplexer manufacturers are covering their butt. They don't want the problem with complex reactance presented by the duplexer to be their problem. Not that I don't agree, because it's usually the transmitter that is really at fault. I think that last sentence speaks volumes on the matter. Joe Ham buys a new duplexer and hooks it up to his 110 Watt MASTR II repeater and gets 50 watts out the antenna port. He does his homework and realizes that he should only be loosing 29% with the 1.5 dB of insertion loss stated in the paperwork - but he's loosing over 50%. Ah, but is he really *losing* 50 percent in the duplexer, or is transmitter not making the full 110 watts output to start with? Maybe his transmitter is really only delivering 70 watts to the duplexer. Is it an issue of the duplexer's loss being high, or is the problem the transmitter's not making power? Seems to me it's really the latter. The duplexer manufacturer supposedly engineered and tuned it for a 50 Ohm system. Well, kinda. Many duplexers are spec'ed for 1.5:1 (14 dB RL) input VSWR max. Fortunately, I rarely see any that are that bad. I'll gladly trade off a tenth of a dB of insertion loss for several (if not 10 or more) dB of return loss improvement when I'm tuning on the VNA, but some hams are greedy and don't think along those lines when they're tuning... He knows that the cable he connected to the transmitter is good, because when he disconnects the end going to the transmitter port of the duplexer and connects it to his Bird 43 terminated with a good load - it reads 110 watts. Yes, but did he have a second Bird between the Tx and the duplexer when he was measuring power output? That would have told the real story. Now, is the transmitter becoming spurious Now all bets are off. and the cable length being changed in length satisfies the match between the duplexer and transmitter - I don't know... All I can tell you is I have followed the suggestions written in the WACOM manual and it has worked. I had one instance of a ham radio club loosing PA's left and right on their 2M machine. They told me of the situation and I offered to do a little testing. The 110 watt PA would put out 110 watts into a Bird and dummy, but only 45 watts was coming out the antenna port of the duplexer. At the time I didn't own a spectrum analyzer. The repeater wouldn't duplex without desense. I changed the length of the line between the PA and duplexer until I got the power to read about 75 Watts as I remember. That was 13 years and they still have the same PA - no desense either. Out of morbid curiosity, what kind of PA was it? You are changing the VSWR when tuning the cavity closest to the transmitter. Yes, but once you've adjusted that cavity, from that point on, changing the cable length doesn't vary the VSWR. That was my point - changing the cable length doesn't change VSWR. I realize that impedance transformation cannot occur when you have a 50 Ohm cable (of any length) and a perfect 50 Ohm load - but I think you will agree that a duplexer doesn't, in any way shape or form, present a nice 50 Ohm load. Well, it can get pretty damn close. I can send you some VNA plots of duplexers with input Z's well in excess of 30 dB return loss, some approaching the limits of my test equipment. Of course, when hooked up to an antenna instead of being terminated in a precision load, all bets are off, but hey, that's not the fault of the duplexer... Some transmitters just cannot deal with it without some form of matching after the fact - like a Z-Matcher, Isolator, Circulator, or even a critical cable length. I don't like those transmitters :-) GE MASTR II 110 watt 150.8 to 174 MHz PA and WACOM WP-641. Thinking...thinking...no, haven't done that one. Motorola MICOR 150.8 to 162 MHz PA and WACOM WP-641. Yes, have done that combo, several times that I can think of. Actually, one of the repeaters was low-split from the factory (out of Canada) now that I think about it, so that doesn't count, the others were all H split with no PA mods. Didn't do anything special with cable lengths. Hamtronics 45 Watt 2M PA and Sinclair Q-202. Haven't done any Hamtronics. Well, I cannot believe that I'm the only person on this list that has had success with optimizing the length of cable between the duplexer and transmitter/PA. I don't doubt that others have seen positive (or negative) effects from varying cable lengths - I just said I've never had to resort to doing it, using the equipment that I've used, with the equipment tuned the way I've tuned it. I'll get us some tickets for Vegas - Jeff. I think ZZU has the right idea. He's down in MX-land right now, probably sitting on a beach laughing at us working
RE: [Repeater-Builder] Re: Coax length, etc.
I'm going to take a stab at this, at the risk of possibly stepping on Gary's toes. 1. RF amplifiers in general (not only solid state) don't *have* a 50 ohm source impedance, they're (nominally) designed to work *into* a 50 ohm load. The difference is subtle, but significant. Transmitters aren't classic generators. 2. GE offered the matching network on station PA's for a number of reasons, among them: a) Amplifier circuit designs (solid-state or otherwise) have a finite bandwidth; a tuning network allows for some output matching adjustment b) Ideally the transmitter will be looking into a nice 50+j0 load (assuming that's what it was designed for), but the world isn't perfect, hence the adjustable output matching network to correct for *minor* load mis-match (strong emphasis on minor) c) Although not explictly described in GE's tuning procedures, significant improvement in efficiency can be obtained with proper tuning of the Z-matcher. Tuning for 50+j0 at the input to the Z-matcher is NOT necessarily the RIGHT match! d) To charge more. I'm half-joking on this; I can't say I've statistically seen more or less failures on M2 PA's with or without the Z-matcher, so I'll give this answer half a smiley: .-, 3. As far as Gary's comment about off-channel Z and its effect on transmitters, some sub-par (or damaged) PA's will go spurious when looking into a load that presents a bad match off-channel, even if it presents a nice flat load on-channel. Some manufacturers suggest playing with cable lengths to tame misbehaving PA's. Again, this is a shortcoming in the PA, and I, for one, am not into band-aid fixes for design flaws or defective equipment; I fix (or replace) the PA. When I walk off the site, I want to KNOW the PA is going to be stable in the future as the load changes, because it WILL change... As far as optimium power transfer, anyone that has passed their tech test probably already knows the textbook answer to that question (the maximum power theorem). But that's not really the issue here, is it OM? Again, we have to accept the fact that amplifiers aren't classic generators; we can't just look at the problem from the perspective of power transfer into a 50 ohm load. We have to look at the devices being used in the PA, the networks doing the impedance transformations, the behavior of the amplifier as a whole (including all cascaded gain stages), its behavior as voltages and temperature are varied, and, one of the most important parameters, efficiency. Just to back up a step, let's revisit the textbook answer of optimum power transfer, which again, is based on a classis generator. In such a case, the optimum power transfer is the *maximum* power that is received by the load. Well, in our little RF corner of the power transfer world, it's not that simple. We're not out eek the last watt out of our amplifier - that's not the goal (or at least it shouldn't be). We all know we can sometimes squeeze a fraction of a dB more out of an amplifier by purposefully mis-loading it, but is that a good thing? Does that make it an optimum match? Hell no. Among other things, we need to look at *efficiency*, and plotting that against power output if we want to find the sweet spot. Efficiency is a primary performance metric for RFPA matching, especially when it comes to continuous-duty solid-state RFPA's where heat is your worst enemy. As far as SS VHF/UHF amplifiers go, good RFPA design should dictate that you have adequate hardware headroom such that you're not stressing the devices or any support components to make rated output, so maximum power transfer should be the least of the worries for the tech tuning the equipment. Stability and spectral purity should be a given in a properly-designed RFPA. So the only parameter that should need to be monitored during fine-adjustment at the output is really efficiency/current draw if everything else was done right from the get-go. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of allan crites Sent: Friday, August 13, 2010 5:41 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Coax length, etc. Gary, Perhaps you can give us some examples to illustrate your thoughts. Perhaps you can also explain why GE chose to include a pi network on the output of the HB M-2 base xmtr to match the xmtr output to 50 Ohms, the shunt capacitor values and the series inductor value used. I'm interested to hear your explaination on how you would determine the length of cable needed. AC From: Gary Schafer gascha...@comcast.net To: Repeater-Builder@yahoogroups.com Sent: Fri, August 13, 2010 2:36:23 PM Subject: RE: [Repeater-Builder] Re: Coax length, etc. Hi Allan, Do we really care what the output impedance of the transmitter is? Most
RE: [Repeater-Builder] Re: Mirage B-320-G as a Repeater Amp
The amp does fine without the duplexer inline. Full power and it follows the Mirage chart. But I had a thought (that's SCARY) I pulled out my seldom used MFJ 259 and dialed in my output. I plugged it into the duplexer TX side and noted that it reads 39 ohms. I disconnected the remaining two cans and attached a dummy load to the output of the can and still read 39 ohms. I'm not sure what conclusion to take from this. I mean, low tech! What does the dummy load alone read? How about my other question - do you have grunge with the repeater transmitter NOT keyed (i.e. just listening on the local repeater receiver with the repeater transmitter disabled)? Thank you for your best wishes re: my daughter. She has had a tremendously bad week. The high dose chemo has burned her body and worse that I won't share. But she's a sick little 8 year old. http://princessrachael.com Tried to go to the URL but it took me to some other web site and asked me to log in? Again, best wishes. I have a 1 year old and a 3 year old, they're my best buddies, I can't imagine what you're going through. --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
I must have missed some posts - my inbox ran out of space (I'm on the road and not checking email as often as I usually do), so my apologies if I'm asking questions that have already been answered... Allan Crites and I are currently in discussion which will be used as the basis of a RB web article that will explain exactly what is happening, why it happens, and why an 'optimized' cable length can be used to transfer power ending up with the stated loss of the duplexer and have little reflected power toward the transmitter - so long as the duplexer is tuned properly and exhibits good return loss on the frequency it's designed to pass. Maybe I'm not understanding right. Are you saying that by varying the cable length between the transmitter and the duplexer that you can affect the insertion loss of the duplexer? And also that by varying the cable length between the transmitter and the duplexer that you can vary the reflected power on that same line? Please tell me I'm reading this wrong...I've been on the road a long time and working a lot of long hours, so it's quite possible... --- Jeff WN3A
RE: [Repeater-Builder] Re: Mirage B-320-G as a Repeater Amp
The grungy audio isn't related to the amp. Yes, I know, you said that. My question was whether the grunge was there whether or not the repeater transmitter was keyed. The TKR may be turned down to 20-30 watts and not trip the amp. By not trip, do you mean not key or not cause the amp to fault? I'm guessing the latter. What power output do you measure at 20-30 watts drive? The amp may easily be made continuous duty by driving it at a lower level and adding fans and blowing on it from an inch or so away, or by sucking on it. For the heck of it, I looked at Mirage's specs on their web site. They have a handy-dandy chart showing power in to power out. They're showing that with 25 watts of drive it puts out 165 watts. Doubling the drive to 50 watts, it puts out 200 watts. In other words, a 3 dB increase in drive is yielding only a 0.8 dB increase in output. That tells me you're way into saturation at 200 watts output. Now, saturation in class C is generally a good thing, but that's kind of pushing it. Looking at the power saturation profile, it seems to me that somewhere in the 150-175 watt range is really where that amp would seem to want to be run. And that's based on the intermittant mobile/HT kind of use it was designed for. I think you're only asking for trouble trying to run that amp continuous duty at 20-30 watts of drive no matter how much forced air cooling you push through the fins. We know that the repeater, amp and antenna play nicely and show a 1.1:1 SWR. It's just the duplexer and it appears that the tuning was not done based on the reference I was given earlier. But you said that the VSWR from the amp to the duplexer shows 1.1:1 and the cans are tuned right on the money, so why do you think the duplexer is the problem? Yes, it's a G6-144 and I typed in a state of near exhaustion. I'm living in a children's hospital with a seriously ill daughter. My best wishes for your harmonic. Again, without being there with a spectrum analyzer, it sure sounds like your Mirage is off wandering in the weeds. There's more to building a repeater-grade amplifier than just being able to make gobs of power... --- Jeff WN3A
RE: [Repeater-Builder] Mirage B-320-G as a Repeater Amp
Before adding a Mirage 320 our TKR 750 was putting out 50 watts into a 6 cavity Wacom WP-642 at the cost of 2-3dB loss on TX (as the spec sheet said.) The cans are tuned right on the money and the Hustler G5-144 fed with LMR-400 is 1.1:1. I'm guessing that's a G6...? This has worked for over a year just fine (except for grungy weak signal audio.) Is that grungy weak signal audio with the repeater transmitter keyed, unkeyed, or both? Now add the Mirage B-320-G 200 watt amplifier. Egads. If you have problems without a high-power amplifier, seems only prudent that you should deal with those issues first... Unless I'm mistaken, the B-320G isn't a continuous-duty amp, is it? But as soon as we tune it all up and connect it to the duplexer the Mirage SWR/Drive trips and the amp goes to sleep. A SWR meter between the repeater and the amp shows 1.1:1. The amp to the duplexer shows 1.1:1. How do you know the VSWR is 1.1:1 between the PA and the duplexer if the amp shuts down before you can measure it? In other words, how do you know the amp isn't shutting down because it's going spurious, resulting in high reflected power coming back from the duplexer, tripping the VSWR overload? At the risk of disparaging a particular manufacturer in a public forum, my experience with Mirage repeater amps has been horrific. I wouldn't expect the results of one of their non-repeater amps pressed into repeater service to be any better... Before we go spelunking into the dark underworld of making your Mirage play nice, let's work on fixing your original noise problem. Start by answering the above questions and we can go from there... And for the love of John, get rid of the LMR400 before this turns into a Holy War. --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
The cable length issue is a brother to if you don't like your VSWR, change the point along the transmission line where you're measuring it. I don't know what that's supposed to mean. The VSWR on the line is the same no matter where along the line you measure it. If you're using a meter that reads a different VSWR depending where on the line you put it, you need a new meter... --- Jeff WN3A
RE: [Repeater-Builder] Measuring duplexer insertion loss
Can somebody please explain how the insertion loss of a duplexer is properly measured using a HP 8920A (with specan). 1. Connect duplexer Tx port to duplex port on 8920. 2. Connect antenna port on duplexer to antenna port on 8920. 3. Go to spectrum analyzer screen. 4. Set center frequency = repeater tx frequency 5. Set generate mode to TRACKing 6. Set input to ANTENNA 7. Set generate port to DUPLEX 8. Set generate level to 0 dBm 9. Set the sweep span to something reasonable, like 500 kHz. 10. By default, the marker should be at the center graticule, which should be the Tx frequency you entered in #4 above (if not, go into the marker menu, and set the marker to 5.00, which is the center of the display). The difference between the marker level and the generated level is the loss, minus your cable losses. For example, if you're generating 0 dBm, and the amplitude at the marker is -2.10 dBm, and you have 0.5 dB of patch cable loss, the insertion loss through that leg of the duplexer is 1.6 dB. Repeat the same test for the Rx leg of the duplexer by moving the cable from the Tx port to the Rx port, and changing the center frequency to the Rx frequency. P.S.: Is it correct that a duplexer that has 40 dB isolation in each leg does have 80 dB overall isolation? No. --- Jeff WN3A
RE: [Repeater-Builder] Measuring duplexer insertion loss
Oh, I guess I should have thrown in a couple of generally-applicable guidelines that should go without saying when using ANY sweep gear like this: - terminate the unused port on the duplexer with a high-quality 50 ohm load - it's a good idea to use 6 dB or greater pads on inputs and outputs of the test equipment - use high-quality test cables (double-shielded when you're measuring isolation) - avoid using adapters etc. etc. etc. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jeff DePolo Sent: Friday, August 06, 2010 4:21 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Measuring duplexer insertion loss Can somebody please explain how the insertion loss of a duplexer is properly measured using a HP 8920A (with specan). 1. Connect duplexer Tx port to duplex port on 8920. 2. Connect antenna port on duplexer to antenna port on 8920. 3. Go to spectrum analyzer screen. 4. Set center frequency = repeater tx frequency 5. Set generate mode to TRACKing 6. Set input to ANTENNA 7. Set generate port to DUPLEX 8. Set generate level to 0 dBm 9. Set the sweep span to something reasonable, like 500 kHz. 10. By default, the marker should be at the center graticule, which should be the Tx frequency you entered in #4 above (if not, go into the marker menu, and set the marker to 5.00, which is the center of the display). The difference between the marker level and the generated level is the loss, minus your cable losses. For example, if you're generating 0 dBm, and the amplitude at the marker is -2.10 dBm, and you have 0.5 dB of patch cable loss, the insertion loss through that leg of the duplexer is 1.6 dB. Repeat the same test for the Rx leg of the duplexer by moving the cable from the Tx port to the Rx port, and changing the center frequency to the Rx frequency. P.S.: Is it correct that a duplexer that has 40 dB isolation in each leg does have 80 dB overall isolation? No. --- Jeff WN3A
RE: [Repeater-Builder] Narrowbanding
Florida Repeater Coordinator proposes narrowbanding: http://www.florida-repeaters.org/FRC%202meter%20narrowband%20p olicy%20released%207-18-10.pdf Apparently Carson's Rule works different in Florida than it does everywhere else. --- Jeff WN3A
RE: [Repeater-Builder] Repeater transmit levels at the receiver?
With 250mW (+24dBm) into the transmit port... antenna port is a quality 50 ohm load, I see -72dBM at the receiver port. (pretty much what I expect.. 1.8dB loss through the xmit side, 100dB notch through the RX side. Those numbers are fine. With it all hooked up receiving an input signal of about 0.7uV, application of the 250mw to the transmitter side will cause noise in the receiver, although not much. That's bad. With the amount of isolation you have (assuming you have the same amount of noise supression - did you confirm that?), you shouldn't need any more isolation. Whatever problem you have that's manifesting as desense is NOT due to insufficient carrier supression or noise supression (assuming they're symmetrical - again, you should measure the latter). How are you injecting the signal into the receiver while transmitting, by the way? Lossy tee or some other method? So, it appears that if I add an additional 30dB notch (another 'can'), the problem at high power may go away. Probably not. If I compare what 50 watts with an additional can would be (-130dB) to what I get with 250mW current notch (100dB), then it looks like I just need to add an additional can. Probably not. With the current notch @ 50 watts, I see a receive signal of -53dBm. Some have said that the Micor can handle that, while others (off-line) have said no way. The others are wrong, and if they they want to defend their position, I invite them to do it here on the list. -53 dBm 1 MHz away is not a problematic signal by any stretch of the imagination. Here's a simple sanity check for those that feel otherwise. I like using real-world examples as sanity checks. How many thousands of 2m repeaters are out there running 100 watts at 600 kHz offset without desense? Let's be generous and say they have 100 dB of isolation in the duplexer. +50 dBm TPO - 100 dB = -50 dBm transmit carrier hitting the receiver. No big deal. And that's on 2m. The offset on 2m is only 0.4% (0.6 MHz / 146 MHz), whereas on 6m, it's 1.9% (1 / 53 MHz), making isolation requirements that much more stringent on 2m. Now let's look at a 6m example. You have a 6m repeater on a 1 MHz split? Let's say it's on 53.99-, highest channel in the band, putting your receiver on 52.99. Some other ham is working simplex on 52.525, using 100 watts into a unity-gain antenna, and he's 40 miles away. His signal into your receiver, assuming unity gain on your end too, and line-of-sight, is -53 dBm (that's what the free-space path loss works out to: 103 dB for 40 miles on 6m, check my math). Would you expect this guy 40 miles away talking on 525 to desense your repeater? If so, then you should expect *every* ham who transmits on 525 (or potentially any other frequency within 1 MHz of your receiver) within a 40 mile radius of your repeater to cause you desense; those that are closer than 40 miles are just going to desense it even worse. Silly. Just plain silly. This setup appears to support the opinion that -53 is still way too much. No, it doesn't. You're drawing a conclusion from incomplete data. The only thing you know at this point is that what you have DOESN'T work, but what you DON'T KNOW is WHY it doesn't work. And I'm telling you, with the utmost certainty, that based on the numbers you've given, lack of carrier supression and/or noise supression in your duplexer at your operating frequencies is NOT the problem, you should be looking elsewhere. There are many potential causes of desense beyond just carrier supression and transmitter noise supression afforded by the duplexer at the Tx and Rx frequencies proper. To say that all of your problems will be solved by increasing either/both is not a valid conclusion to draw. Just a few of many possible issues that could be causing your desense problem: - lack of mid-band isolation - noisy components/connections in your duplexer, cabling, etc. - spurious transmitter - spurious LO - component breaking down/arcing when excited by RF - insufficient shielding (cabling, radio chassis/subassemblies, etc.) - bad test load or antenna - bad channel element or crystal - corroded/oxidized connector, contact, pin, etc. - cracked/broken/microscopically-intermittent connection, trace, conductor, etc. - bad/cold solder joint - other problem in exciter or receiver - loose, mis-installed, or otherwise faulty RF connector - bad RF cables (LMR, bare copper braid, etc.) - bad luck, bad karma, bad mojo, phase of the moon, alignment of the planets, etc. When you're duplexing, everything has to be damn near perfect otherwise you end up with desense. On 6m, you have a few things going for you, including a wide frequency split (percentage-wise), a high ambient noise floor (hides some sins/duplex noise), but otherwise, all of the same issues/caveats apply as they do on any other band when duplexing, noise is noise, dynamic range is dynamic range, whether you're on 50 MHz or 50 GHz.
RE: [Repeater-Builder] Repeater transmit levels at the receiver?
You did an excellent job of explaining the complex interrelationships among 2m repeaters. However, not all 6m repeaters have a 1 MHz split; my 6m repeater on Tranquillon Peak follows the California band plan and has a 500 kHz split. The duplexer has four cans about 12 in diameter and five feet tall. 73, Eric Lemmon WB6FLY Even at 500 kHz split, 100+ dB is more than enough isolation on channel center on 6m. Using simple frequency scaling (not to say that's truly the way to compare, but it gives a rough approximation), that would be like 1.4 MHz split on 2m with the same (100 dB) isolation. 500 kHz on 6m is about 0.9%, still more than twice as much as 0.4% on 2m with 600 kHz split. --- Jeff WN3A
RE: [Repeater-Builder] Repeater transmit levels at the receiver?
At this point, I'm leaning towards the bad mojo/karma phase of the moon! Let's start out with the basics: 1. How much desense do you have? 2. How are you injecting the Rx signal, and what are you using for the signal source? 3. What are you using for a dummy load when doing the desense test? 4. Have you look at both the Tx and the Rx LO to confirm neither are spurious? 5. For the heck of it, have you tried using a totally different Tx and Rx (even just using ham mobile rigs, you have 100 dB of isolation which should make even ham rigs play without desense on the bench, though I'd never use them in production). 6. If do #5, and you still have desense, try flipping Tx and Rx frequencies and see if you still have desense, it might help point to a problem on one side of the duplexer versus the other (e.g. something on the Tx leg generating noise which ceases to be a problem when you're not passing high-level RF through that leg when you have the frequencies flipped). --- Jeff WN3A
RE: [Repeater-Builder] Repeater transmit levels at the receiver?
I wonder how many of the -53 naysayers have or have used a Cushman CE-3? LOL! The folks that have looked at the output of one of these on a spectrum analyzer will get it. K Where I come from, we call that a comb generator, not a signal generator... Ya gotta know the limitations of your test equipment. I recently went several rounds via telephone with a friend of mine who was trying to troubleshoot an apparent desense problem on the bench involving a Mastr II and a 6-cavity DB Products duplexer that I had tuned up for him on the VNA. Long story short, it turned out that when he was doing the desense test using his service monitor (R2600?) as the dummy load and signal source simultaneously that the sig gen would go spurious and result in apparent desense. When he finally did a lossy tee test using an external dummy load, no desense, and likewise when hooked up to the antenna at the site, no desense. --- Jeff WN3A
RE: [Repeater-Builder] Re: Base station coax connector weatherproofing recommendations?
I think you (Skipp) may be confusing 130C with one of the other 3M products. 130C is the self-vulcanizing (self-amalgamating?) tape. It has no adhesive; it's not sticky or gooey; itt doesn't leave any residue. In fact, it doesn't even leave a black stain on connectors like regular vinyl electrical tape; it leaves nothing behind. 3M et al make mastic pads/tapes which, for lack of a better descrption, are like vinyl electrical tape with taffy already attached to one side, with a liner that you remove before applying (i.e. to keep the taffy from sticking to the next layer of tape in the roll. Maybe that's what you're thinking of, Skipp? Even without a courtesy wrap, 130C comes off nice a clean when you slit it with a knife, no muss, no fuss. I've been a big fan/proponent of splicing tape for many years, having been introduced to it by a power plant engineer who showed me how they used it for underground direct-bury high voltage splices. Alternate the 130C with 88, each with an up-down-up wrap, and I've never had a leak. Tape n' taffy is quite effective, and arguably, requires less skill to apply (i.e. I don't force tower crews to use 130C/88 if they're comfortable/trained to do it with taffy), but it's messy if you have to open up the connection, but that can be partially alleviated by using a courtesy wrap. But when I'm doing it myself, I use splicing tape and 88. For the splicing tape I use either 3M 130C or the Plymouth equivalent (can't think of the number off the top of my head). I have a few rolls of the self-fusing silicone tapes that Times, Nashua, Andrew, et al are pushing. It's OK, but I don't see it as being any better than 130C+88. It's a lot more expensive too. Too early to tell how well it holds up to UV, but I would imagine it would do OK. Being silicone, other adhesives (such as vinyl electric tape) don't stick to it well. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of ve7fet Sent: Thursday, July 29, 2010 12:22 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Base station coax connector weatherproofing recommendations? Pulling it back apart isn't an issue with the 130C if you apply it sticky side out. Once you slit down through the vinyl and 130c with a knife, you can peel it apart to open up the splice. Yeah, its a little work to get it to release from the jacket of the cable... but its doing its job keeping the water out. It usually releases from the metal connector parts fairly readily. Lee --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , skipp025 skipp...@... wrote: I lay down a base wrap of decent quality tape before applying the Scotch 130c because I do work for (other) people who very often change their mind. Pulling 130c direct from a connector is a real $#$%* Having a base layer of tape below the 130c can and will make your change order life much happier. s.
RE: [Repeater-Builder] Re: Repeater receiver testing
Kevin, I'm sorry to have to tell you this but I think your calculator batteries need to be changed. 0 dBM = 0.2236 volts in a 50 Ohm circuit. +20 dBM is indeed 100 mW and P=EI and inserting 100 mW into the Eq. for Volts in a 50 Ohm system, E= the sq. rt. of the quantity (.100 x 50) = sq. rt. of 5 = .707 V. or 707 mV. not the 2.24 V. you indicated. I think you blew that one OM. Too much tequila down in XE land perhaps? The square root of 5 is 2.2236 volts, not sure where you got 0.707, that would be square root of 0.5. Kevin was right. Or, to make it even simpler without having to do any real math, +20 dBm is 20 db greater than 0 dBm. 20 dB more than 0.2236 volts is, obviously, 2.236 volts. --- Jeff WN3A
RE: [Repeater-Builder] 420Mhz Radio for Voter?
What is a good radio for building a one way 420 link? The link will be for a remote receiver and will not need to be duplex... RX at the voter and TX at the remote receiver. The link RX has to live on a noisy hill. Thanks for your advice. My preferences, in no particular order, would be Micor/SpectraTAC (low split), Mastr II (77 split), and Delta-S (low-split). MVP/Exec II (again, 77 split) would be fine too. All have excellent front ends. They can be found if you look a bit, especially check Canadian sources; they're not as easy to find stateside as 450-470 radios, but they're not unobtainium either. --- Jeff WN3A
RE: [Repeater-Builder] Re: 420Mhz Radio for Voter?
When you say low split, are you talking about the Motorola TRE1201/TRE8031 406-420 Mhz receivers? I don't have a manual in front of me, but yes, 406-420 receivers, they'll work fine well into the mid 430's without mods. What Canadian sources might have these? Well, Spantek comes to mind as a dealer. CW Wolfe used to get a lot of stuff out of Canada, but I haven't talked to Bud in quite a few years, not sure if he's still in business. This list is probably the best resource. eBay as an alternative. If you get desperate I still have a few dozen low-split Micors in the warehouse, but really don't have the time (or patience) to deal with packing and shipping radios for what few dollars I'd get out of them (i.e. value of my time $value of radio). But if you just wanted a receiver, you can consider me a last resort if you strike out everywhere else... --- Jeff WN3A --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Jeff DePolo j...@... wrote: What is a good radio for building a one way 420 link? The link will be for a remote receiver and will not need to be duplex... RX at the voter and TX at the remote receiver. The link RX has to live on a noisy hill. Thanks for your advice. My preferences, in no particular order, would be Micor/SpectraTAC (low split), Mastr II (77 split), and Delta-S (low-split). MVP/Exec II (again, 77 split) would be fine too. All have excellent front ends. They can be found if you look a bit, especially check Canadian sources; they're not as easy to find stateside as 450-470 radios, but they're not unobtainium either. --- Jeff WN3A
RE: [Repeater-Builder] Re: Repeater receiver testing
Good thoughts Milt, and I'll add a few While not an easy thing to find I would suggest that you most likely need some sort of a bandpass cavity on the receiver to protect from the noise that gets past the heliax notches. Remember that a notch duplexer only removes the notched portion of the TX signal on the RX side and the RX signal on the TX side, all other noise is passed directly to the load. Thus you only have two small notches, one at the RX frequency and one at the TX frequency. Everything else is passed. A duplexer specification that often goes overlooked is mid-band isolation; that is, how much isolation there is between Tx and Rx ports mid-way between the Tx and Rx frequencies. For notch-only duplexers, this value is often very low, often less than 10 dB. The effect of low mid-band isolation is that wideband noise or spurs from the transmitter can result in receiver desense, even if there is enough isolation at the operating frequencies. In other words, the wideband noise passes right across the duplexer at frequencies far enough removed from the notches to cause problems. For pass/reject or bandpass duplexers, the mid-band isolation will be substantially higher, may be somewhere in the range of 30 to 60 dB depending on band, offset, number of cavities, etc. Mid-band isolation is often quoted in manufacturer's specs as a simple scalar value, if it's given at all. Quite often they just give you isolation, and that's just at the Tx and Rx frequencies proper; it doesn't tell you anything about what's happening at other frequencies. A swept transmission response across a broad range from Tx to Rx port with the antenna port terminated will show the true isolation you're getting. As far as adding a pass cavity to attenuate desense caused by noise or spurs coming from the transmitter, it would most likely be more effective if you put it on the transmitter leg of the duplexer rather than the receiver leg. You probably should also look at the TX signal to check for spurs. Micors are generally pretty clean machines, but keep in mind that lowband repeaters were fairly rare back in the day; I don't know if duplex isolation curves were ever published for lowband Micors (ZZU, you QRV?). For the Mastr II you only needed about 50 dB of carrier supression and a little over 60 dB of noise supression for 100 watts at 1 MHz split. I also have had duplexers that look good with a tracking generator but fail under TX power. And we've all had antenna systems that did the same. And I've had dummy loads that did the same as well; point being, don't rule out a problem in your test equipment... --- Jeff WN3A
RE: [Repeater-Builder] Repeater receiver testing
The holy grail for FM performance testing, which includes adjacent channel rejection measurements, is EIA/TIA-603. I believe revision C is the latest. Unfortunately, you'll have to pay to get a copy of that document unless you can scrounge one up. To summarize how the test is done (and I'm doing this from memory, so someone please verify/correct me). 1. You need a way to sum the output of the two sig gens together such that they are properly isolated from each other, and done in such a way that the amplitudes can be calculated accurately at the output of the summing device. 2. You start out by measuring the 12 dB SINAD of the receiver with only the on-channel signal generator active (standard SINAD test, 3 kHz deviation, 1 kHz tone, typically measured at the speaker terminals after deemphasis/filtering/etc.). Simple enough. 3. Increase the RF level of the on-channel generator 3 dB higher than the 12 dB SINAD sensitivity value you found in step 2. This will push the measured SINAD up higher than 12 dB obviously, that's what's supposed to happen. 4. While still generating the on-channel signal, now also generate a signal on the adjacent channel, modulated by a 400 Hz tone at 3 kHz deviation. 5. Increase the level of the adjacent-channel signal until you degrade the SINAD reading of the on-channel signal back down to 12 dB (remember, it was something greater than 12 dB, because you had increased the RF level by +3 dB before you started introducing adjacent-channel dinterference). 6. The difference (in dB) between the offending signal and the 12 dB SINAD sensitivity measured in step 2 is the adjacent channel rejection ratio. So, for example, if the 12 dB SINAD sensitivity was measured at -117 dBm in step 2 without any interference, and you were back down to 12 dB SINAD in step 5 when you had the interfering signal cranked up to -30 dBm, the adjacent channel selectivity would be 87 dB. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Saturday, July 24, 2010 10:27 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Repeater receiver testing I have this lowband Micor receiver that I want to test for adjacent channel rejection. I have two calibrated signal generators and a calibrated spectrum analyzer if I need it. How can i measure the rejection of the off channel signal? Thanks, Tim
RE: [Repeater-Builder] Re: Repeater receiver testing
Hi you beat me to it, I would suggest a duplexer problem as -55dB isn't a lot you should have ideally better than 80dB. It also could be the fact that you are running too much tx pwr, have you tried dropping it down. 73 Steve, M1SWB(UK) He said he measured the Tx carrier at the Rx port of the duplexer at -55 dBm; he didn't say he had 55 dB of isolation...
RE: [Repeater-Builder] Re: Repeater receiver testing
Hi Jeff yes I know -55db is I think around 399 microvolts No, you're still missing it. He said -55 dBm (m = milliwatts), not -55 dB. which will flatten any receiver -55 dBm at 1 MHz offset isn't going to bother any half-decent receiver. A decent receiver would have 100 dB of adjacent-channel selectivity (that would be 20 kHz away on lowband), so if we assume the sensitivity is -117 dBm (0.3 uV), it should tolerate a signal int the vicity of -17 dBm at only 20 kHz away with only slight degradation. At 1 MHz away, a good lowband receiver with a real front end will tolerate much, much more, probably on the order of 0 dBm (over 2/10ths of a volt). 80 watts TPO = +49 dBm. He's measuring -55 dBm at the receive port, so he has 104 dB of carrier supression, way way way more than is necessary for a Micor at 1 MHz split. --- Jeff WN3A
RE: [Repeater-Builder] Repeater transmit levels at the receiver?
Ok, now I hook the spectrum analyzer up to the receiver port, and I see about -55dBm. 50 watts = +47dBm, minus the 100dB notch = -53dBm that is pretty close to what I'm seeing at the rx antenna port. Question is: Should this good enough for a low band micor receiver? Thanks, Tim W5FN Yes, should be good enough for even 500 kHz split. However, at close tx-rx offsets, transmitter noise is often more of an issue than carrier supression, so test your duplexer backwards to make sure you have the same isolation in the other direction. And don't forget the noise foor on 6m is usually pretty high, so even if you have a trace of desense on the bench using a dummy load and lossy tee, you may not even notice it in the field. --- Jeff WN3A
[Repeater-Builder] (Ware)house cleaning - connectors, radios, etc.
Continuing to consolidate three warehouse/storage locations and getting rid of some excess in the process. I posted some of these on another list but still have a lot left, posting them here with ham discounts. Qty 60+ RFS/Cablewave 738801 1/2 N female, NOS, military packaging (fits Andrew LDF4, RFS FLC12 and LCF12 and most other 1/2 non-Superflex cables) - $7 ea Qty 6 Andrew H7PNF - N female, silver-plated, for HJ7-50 1-5/8, NOS - $75 ea Qty 100+ Andrew F2PNM N male connector, silver-plated (fits Andrew FSJ2, RFS SFC38 and other 3/8 Superflex), NIB - $8 ea Qty 20+ Andrew L5NF N female for LDF5-50 7/8 (fits RFS FLC78, LCF78, and others too), NIB - $15 ea Qty OTW - Used 1/2, 7/8, 1-1/4, 1-5/8 connectors, foam, air, Superflex, type N, DIN, EIA flanges, etc. - let me know what you need Qty 40+ Andrew SGL12-10B2 ground kits, clip-on type, NIB - $9 ea Qty 10+ Mastr II 44 cabinets - $50 each PICKUP ONLY Qty 20+ Mastr II stations, mostly UHF, some with IDA controller, various power levels up to 200 watt solid state, with or without cabinets, starting at $200 PICKUP ONLY Qty 100+ Micor, Mastr II, Exec II, etc. mobiles, various bands/power levels, boxes of parts/boards/etc. PICKUP ONLY, you pick through the stacks, prices vary. 20+ Motorola SpectraTAC coded squelch (PL) modules - $25 each 500+ GE/Moto/EFJ/etc. channel elements/ICOM's/crystal modules, all flavors, all bands - let me know what you need, prefer to sell in substantial quantities. 150? Motorola Vibrasponder paging reeds, $50 for all Abbreviations: NIB - new in box/bag NOS - new, old stock (may have signs of having been in storage a while, dirty/dusty package, etc.) OTW - out the wazoo All items shipped either USPS or UPS at-cost plus $5 packing charge regardless of quantity. Pickup only items located in Philadelphia area. Will consider trades - only thing I can think of I need right now are long runs of new 1/2 line (Andrew or RFS, no Superflex), 1/2 ground kits, and/or 1/2 hoisting grips. Please reply direct. Thanks. --- Jeff WN3A
RE: [Repeater-Builder] VHF REPEATER USING DELTA or RANGR
They're great radios. I'd strongly recommend a Delta-S (narrowband front end) over a wideband SX or Rangr due to the front end being much tighter. I have many UHF Delta-S's (probably about 60 or 70) on the air, mostly for aux links, and have set up VHF and UHF Deltas as repeater radios, packet nodes, etc. as well. I'd recommend sticking with a low-power radio, and driving an outboard amp if you need significant power. What I usually do is take low-power PA's and transplant them onto the larger heatsink of a high-power radio, run them at low power (like 15 watts or less), and drive an outboard PA. With the big heatsink, no fans required. The highband and UHF radios are extremely stable PA-wise, you can turn them down without a problem. Lowband is another story...they get squirrelly at low power, especially when used out-of-band on 6m. I have probably 50 pages' worth of notes covering all kinds of mods, measurements, etc. that I've done on Deltas over the years, and know them inside-out, so email if you have any specific questions. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tomnevue Sent: Thursday, July 08, 2010 10:54 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] VHF REPEATER USING DELTA or RANGR Has anyone made a VHF repeater using 2 Delta or Rangr radios? Were the results OK? Any unexpected problems? Tom
RE: [Repeater-Builder] Proto boards
Vector Electronics (Google vectorbord and circbord, not typos), GC Electronics, and Radio Shack (if you can find a store still stocking them). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Ralph S. Turk Sent: Tuesday, July 06, 2010 3:17 PM To: Repeater-Builder Subject: [Repeater-Builder] Proto boards Hi All Looking for small etched, maybe drilled, small boards with layout for several transistors, resistors etc all isolated pads Also looking for ones that have layouts for 8pin, 14 pin or 16 pin dip with isolated pads for hook up I have some misc of the above and they are great for inverters, buffers, little op amps for increasing the level of the disc or tx audio. Any ideas? Ralph
RE: [Repeater-Builder] MASTR II LOW BAND TUNING
I took a quick look at them, and what stands out like a sore thumb is 1.6 db insertion loss with a 150 watt power rating. That means they'll be dissipating close to 50 watts in such a small package. Doesn't give me a warm and fuzzy feeling... --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Eric Lemmon Sent: Monday, July 05, 2010 8:02 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] MASTR II LOW BAND TUNING I see what the sales flyer says, but the response plots show no real bandpass action. Indeed, the plots depict exactly how a notch-only duplexer responds. In fact, the plots look faked, IMHO. I have tuned many duplexers over the years, and none of the plots look so perfect. If Fiplex duplexers are so great, why aren't they used by large state patrol systems? Is there a list of satisfied customers? Maybe I'm just too cynical, but I think the specs for those duplexers are just too good to be true. I'm going to keep my money in my pocket until I see some credible evidence that these duplexers perform as advertised. 73, Eric Lemmon WB6FLY -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 Joe Sent: Monday, July 05, 2010 4:18 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] MASTR II LOW BAND TUNING The spec sheet shows them to be bandpass/band reject. From the document: These duplexers utilize six high Q (helical) resonant cavities, interconnected in a band pass-band reject configuration which allows close spaced transmit-to-receive frequency operation. Joe On 7/5/2010 6:33 PM, Chris Curtis wrote: They are notch only devices and I've used similar devices using that helical design for years.
RE: [Repeater-Builder] Re: [Repeaters] Looking for HD 440 Yagi
Yeah, forgot to mention Scala. I use a lot of their antennas in non-amateur endeavors. --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Fred Seamans Sent: Friday, July 02, 2010 7:53 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: [Repeaters] Looking for HD 440 Yagi Jeff: Kathrein-Scala Antennas makes good heavy duty yagi and a log periodic antennas with radom and without. I have used them before. They will survive most mountain tops with ice and salt water sprays. They are expensive. Fred W5VAY From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jeff DePolo Sent: Thursday, July 01, 2010 11:29 PM To: Repeater-Builder@yahoogroups.com; repeat...@yahoogroups.com Subject: RE: [Repeater-Builder] Re: [Repeaters] Looking for HD 440 Yagi I'll echo most of Dave's comments, and add a few... The MYA's tend to have finicky tuning, and I've never seen one sweep correctly out of the box. Close enough probably, but not optimized either. The BMOY's are broad band, with one model covering 406-440 MHz and another from 440-480 MHz. Maxrad stopped making the MYA antenna that I used a lot - MYA43012 - 12 elements, 430-450 MHz. Now you can only get the 12 element model in 450-470 range :-( I never had much problem tuning up the MYA yagis, but as Dave said, they usually weren't tuned well out of the box. Sealing up the connector is a PITA; I always removed the rear (reflector) element, removed/loosened the hardware to allow the feed to be slid to the rear of the boom, and then proceeded to put my jumper on it and seal it up right before sliding it back into position and tuning it. I'm now buying Sinclair SY307 series and Comprod 430-70 yagis (7 element, 10 dBd each, very close to being clones of each other) at about $140 each. Have about a dozen in service and more in stock for upcoming projects. My only complaint thus far is that they seem to not be consistant on what kind of connector is on the end of the pigtail - some came with N males, some with N females - picky picky. The Antennex gamma-fed UHF yagis are real dogs. The tuning is extremely touchy. Minor changes in placement of the jumper/feedline throw the tuning all over the place, and slight changes in distance from the mast and/or changing polarization will require retuning. The Sinclairs and Comprods are mostly immune to detuning in that regard, and always sweep well across the entire spec'ed range. I bought four of the 12-element models (two silver, two gold) when I found out I couldn't get the Maxrads any more, and they're still sitting in the warehouse, I wasn't happy with them after I tested them. I, too, had/have a lot of the old Larsen's in operation (5 and 8 element), but they don't make the ham splits any more. Although they aren't built as rugged as some of the others mentioned, they've held up pretty well. I just took down two of the 8-element models that had been up on a mountain for about 15 years and, aside from a couple of bent elements from falling ice, had held up pretty well. I replaced them becuase a) they were getting old and beat up, and b) I wanted to replace the feedline runs anyway so I figured I may as well swap out antennas at the same time, one less 200+ mile trip and tower climb to make in the future. I still have four of them at a site that have been up for just about 20 years now and they're still working. --- Jeff WN3A
RE: [Repeater-Builder] Re: [Repeaters] Looking for HD 440 Yagi
I'll echo most of Dave's comments, and add a few... The MYA's tend to have finicky tuning, and I've never seen one sweep correctly out of the box. Close enough probably, but not optimized either. The BMOY's are broad band, with one model covering 406-440 MHz and another from 440-480 MHz. Maxrad stopped making the MYA antenna that I used a lot - MYA43012 - 12 elements, 430-450 MHz. Now you can only get the 12 element model in 450-470 range :-( I never had much problem tuning up the MYA yagis, but as Dave said, they usually weren't tuned well out of the box. Sealing up the connector is a PITA; I always removed the rear (reflector) element, removed/loosened the hardware to allow the feed to be slid to the rear of the boom, and then proceeded to put my jumper on it and seal it up right before sliding it back into position and tuning it. I'm now buying Sinclair SY307 series and Comprod 430-70 yagis (7 element, 10 dBd each, very close to being clones of each other) at about $140 each. Have about a dozen in service and more in stock for upcoming projects. My only complaint thus far is that they seem to not be consistant on what kind of connector is on the end of the pigtail - some came with N males, some with N females - picky picky. The Antennex gamma-fed UHF yagis are real dogs. The tuning is extremely touchy. Minor changes in placement of the jumper/feedline throw the tuning all over the place, and slight changes in distance from the mast and/or changing polarization will require retuning. The Sinclairs and Comprods are mostly immune to detuning in that regard, and always sweep well across the entire spec'ed range. I bought four of the 12-element models (two silver, two gold) when I found out I couldn't get the Maxrads any more, and they're still sitting in the warehouse, I wasn't happy with them after I tested them. I, too, had/have a lot of the old Larsen's in operation (5 and 8 element), but they don't make the ham splits any more. Although they aren't built as rugged as some of the others mentioned, they've held up pretty well. I just took down two of the 8-element models that had been up on a mountain for about 15 years and, aside from a couple of bent elements from falling ice, had held up pretty well. I replaced them becuase a) they were getting old and beat up, and b) I wanted to replace the feedline runs anyway so I figured I may as well swap out antennas at the same time, one less 200+ mile trip and tower climb to make in the future. I still have four of them at a site that have been up for just about 20 years now and they're still working. --- Jeff WN3A
RE: [Repeater-Builder] Quantar Simulcast Issue
To get the RF phase accuracy you're implying that is required would mean that everything in the RF path would have to guarantee that phase relationship. That means the same length RF interconnect cables inside the cabinet, same RF feedline length (or full-wavelength multiples thereof), same antenna type, etc. Even if you could guarantee that kind of accuracy at the time of installation, thermal effects would quickly throw it way off (cables expanding/contracting with temperature for example). Not to mention the propagation delay will vary a whole lot with temperature, humidity, etc. Just not gotta happen --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of DCFluX Sent: Thursday, June 24, 2010 12:51 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Quantar Simulcast Issue Well if the transmitters are running at the same frequency but at a different phase it is reasonable to expect that there would be some point where the 2 transmitters are at close to the same power level, but 180 degrees out of phase which should cancel out the receiver or at least make interesting noises. Well, yeah, I know what propagation delay is, but I don't see where the phase of the reference has an effect on anything. Are you thinking that the transmitter's RF carrier needs to be launched with phase coherence at each site? --- Jeff WN3A Yahoo! Groups Links
[Repeater-Builder] I've been lookin' for line in all the wrong places...
Anyone have, or know of, a surplus of 1/2 line? I've been scouring the surplus places, eBay, etc., but haven't found any decent deals. I can use pieces or reels anywhere from a few hundred to a few thousand feet. RFS, Andrew, et. al., anything but Commscope. Thanks in advance. --- Jeff WN3A
RE: [Repeater-Builder] Simulcast Information on-line
Yes, but you'll probably find them most often in Micor PURC (paging) stations. Components of interest include the high-stability and ultra-high-stability oscillators, simulcast control card, audio delay unit (usually made by Allen Avionics), etc. By no means a state-of-the-art system, but they worked...more or less...at least for paging. --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of TGundo 2003 Sent: Thursday, June 24, 2010 6:13 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Simulcast Information on-line Were there specific UHF MICOR components that suited themselves to Simulcasting? Tom W9SRV --- On Thu, 6/24/10, Kevin Custer kug...@kuggie.com wrote: From: Kevin Custer kug...@kuggie.com Subject: Re: [Repeater-Builder] Simulcast Information on-line To: Repeater-Builder@yahoogroups.com Date: Thursday, June 24, 2010, 3:50 PM skipp025 wrote: For those of you who'd like to see a few different examples of various Simulcast Systems explained. http://www.simulcastsolutions.com/case-studies.htm http://www.simulcastsolutions.com/case-studies.htm Another explanation is available here: http://www.repeater-builder.com/k7pp/index.html http://www.repeater-builder.com/k7pp/index.html Kevin Custer Yahoo! Groups Links (Yahoo! ID required)
[Repeater-Builder] Tessco - free shipping promotion
My Tessco account rep emailed me that they're running a promotion this week - free shipping. So if you're thinking about buying a big repeater antenna or a reel of Heliax, save big money on truck freight if you order this week. --- Jeff WN3A
RE: [Repeater-Builder] Quantar Simulcast Issue
Are the cables coming from the GPS reference are the same length at both sites? Maybe I'm missing something here, but how the heck would the length of the cable from the reference oscillator to the transmitter/exciter matter? It's just the frequency reference (10 MHz or whatever) for the synthesizer; it has no effect on delay, phase, amplitude response, or anything else related to the modulated audio. Also if these are VHF it could be that the reference frequency (channel spacing) is 5 kHz, if that is the case a harmonic of a paging tone might get past the audio pass band filtering 300 - 3000 Hz typically and is fooling the PLL divider. This seems like a longshot. I think Bill's original guess is most likely on the right track - a DC offset problem. I'm assuming the transmitters are being modulated through a non-DC-coupled input to the modulator? Maybe look for a coupling cap with high leakage. Another thought is asymmetrical clipping of the audio. --- Jeff WN3A
RE: [Repeater-Builder] Quantar Simulcast Issue
Propagation delay in the coax. Propagation delay doesn't affect anything on the reference output side of the GPSDO. The phase of the reference oscillator can vary -- the synthesizer doesn't care about the phase of the reference oscillator, only the frequency. Likewise, the VCO output isn't synchronized in any way to the reference oscillator as far as phase goes. Get a dual trace oscilloscope and feed it with a 10 MHz GPS, off of a Tee and into 2 different lengths of coax. Well, yeah, I know what propagation delay is, but I don't see where the phase of the reference has an effect on anything. Are you thinking that the transmitter's RF carrier needs to be launched with phase coherence at each site? --- Jeff WN3A
RE: [Repeater-Builder] Astron RS50 Power Supply
Everyone is entitled to make an ass out of himself now and then, but you're abusing the privilege... -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kevin valentino Sent: Sunday, June 20, 2010 9:21 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Astron RS50 Power Supply Hey you still owe me 3 # bucks for sending you a Uniden key! Hope the whole world knows know! you just blew me off?!!! it was over a year ago at least! sent you several emails. guess if you can't afford a couple bucks then you should not to try to make yourself out to mister want to be!Which for a couple bucks is nothing!!!Guess you can't be trusted! Mr. Mike Morris! Wa6ilg, so impressed, no code! wannabie!!! yes you are!!! --- On Sun, 6/20/10, Mike Morris wa6...@gmail.com wrote: From: Mike Morris wa6...@gmail.com Subject: Re: [Repeater-Builder] Astron RS50 Power Supply To: Repeater-Builder@yahoogroups.com Date: Sunday, June 20, 2010, 6:23 PM At 11:22 AM 06/20/10, you wrote: Hi Guys, I am trying to download a schematic on this site for the RS50M Power Supply and keep getting a 404 Error on each attempt on all the supplies. Any ideas? Did you use the email link on the 404 page to tell the guys at repeater-builder? I just checked the RS50 links and they all seem to work... Let me know which link doesn't work and I'll fix it. You might want to read the repair and modification notes on the Introductory Information page. At the least you should add the missing compensation cap and the missing lock washers. Make sure the negative side of the supply is NOT connected to the case. Eric WB6FLY posted a informative note about that a while back. It's reproduced on the Introductory Information page. According to the schematic the main diodes in the RS-50 is the 1N1184A. International Rectifier calls it a 40 amp diode. What brand is in your unit? I rebuilt an RS50 a couple of years ago and used a pair of the 1N2129A (60 amp diode). If I were to do it over again I'd use a 100a diode like the 1N3288 that I use in the RS-70. Mike WA6ILQ
RE: [Repeater-Builder] Astron RS50 Power Supply
Also our above mentioned power supply which operates our 2 Meter and 440 Repeaters and a low power link started humming yesterday. A trip to the tower showed that the two large wires coming from the Pass Transistors to the post on top of the regulator board and into the 1000 Uf Electrolytic got so hot it melted the insulation an inch back on the wires, burned an area the size of a quarter on the fiter side of the regulator board, turned the terminal black on the Cap. and cracked the plastic on the cap. It never blew the fuse and a check of the voltage showed it regulating under load and hardly a trace of AC on the 13 volt output. The MOV or eight amp AC fuse never blew. All the equipment hooked to the supply took off and worked well on another supply. Anyone have a guess as to what caused this obvious surge ontop of the cap? I am going to replace the Cap. and one resistor on the regular board which is discolored and hope for the best. Any advise appreciated. Thanks in advance JIM KA2AJH Wellsville, N.Y. I've seen this happen a number of times to RM-50's and RS-50's, most recently to an RS-50M that's one of my bench supplies. That connection (where the high-current wires connect to the top of the filter cap with the PC board sandwiched inbetween) leaves something to be desired. Eventually it becomes a point of high resistance, either due to the screws/lockwasher no longer being tight due to vibration or through thermal cycling, or the copper foil oxidizes a bit, or similar causes. Once the resistance goes up even a little, the heat caused by I2R at that point only worsens the problem, and ultimately it becomes a thermal runaway kind of a situation, yielding the results that you saw. Bottom line - there probably wasn't any surge that set this off, it was a function of design and age. --- Jeff WN3A
RE: [Repeater-Builder] Micor COS issues.... continuing
I always use an NPN transistor (2N4401 or whatever floats your boat) as an inverter on the Micor COR, with a voltage divider on the base. Micor COR to base through 10K, 4.7K from base to emitter, ground emitter, collector becomes active-high COR. Pull up collector with 12V through 1K (or whatever) if your controller doesn't have a pull-up internally. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Josh Sent: Monday, June 21, 2010 11:58 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor COS issues continuing I've been fighting this issue for a while now. I've tried some bandaids to deal with it, tried multiple repeater controllers (including one I designed myself with an ATMEGA328 Microcontroller (I'll probably be releasing this design as open source coming up)... and I'm fighting the same problem everywhere... My micor COS signal is weird. When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). What is the deal here? I've tried adding resistors in series to fudge things and cause voltage drop, but thats not really even working that well. I've tried the 2n circuit, but that doesnt really have a lot to do with this (although a variation of that might come into play I suspect) How do I best solve this so I can get my repeater on the air?? This is very close to the last issue I have remaining to solve. Help / advice is greatly appreciated. Josh
RE: [Repeater-Builder] Micor COS issues.... continuing
Here's how we've designed our controllers' COR, CTCSS, and logic inputs for many years: Feed the COR signal to the top of a voltage divider. The upper resistor is 10K and the lower is 4.7K. Feed the junction of the divider to the base of an NPN such as a 2N3904, 2N, etc. You'll have a 3:1 voltage divider that in essence multiplies the transistor's base-emitter drop by three, so the input threshold will be ~2V instead of ~0.7V. And, you'll have 10K and an NPN to buffer the outside world from whatever logic IC you're using for your input port. Seems that sick minds think alike, Bob :-)
RE: [Repeater-Builder] Re: Alinco DR-03T
Have a 110 watt Mastr II station on 33 MHz that would be a nice 10 repeater (or remote base for that matter), with power supply and cabinet, $200, pick up only (Philly). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of K4SLB Steve Butler Sent: Monday, June 14, 2010 1:55 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Alinco DR-03T I would love one. contact me off forum K4SLB at R2I.NET From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of terry_wx3m Sent: Monday, June 14, 2010 08:51 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Alinco DR-03T I have some Micor mobiles on 31 MHZ 100 Watt would make dandy 10 meter radios. Yours free for the shipping, --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Doug Hutchison specialq@... wrote: Hi Andrew, Initially thank you for announcing the new box - cannot find it here yet. Have a DR-M03 obsolete (no T). It is OK as a link TXR, duty cycle might be a problem for repeater but a big enough cooler may solve that. Mine is 10w o/p, performs OK. Doug On 13/06/2010 20:30:33, vk4jv (vk...@...) wrote: Hi Guys Has anyone used the new alinco DR-03T 10M rigs in a repeater ? I wish to get a 10M repeater going but have to use split sites and use UHF links between them... also.. any other ideas on radios to use ? cheers Andrew Yahoo! Groups Links
RE: [Repeater-Builder] MOVs for power supply primary
OK, you're looking for something in the middle then. For parallel protectors, LEA CFS or SP series, or Transtector Apex II, may be more in the price range you're looking for (under $1000). Since I don't use protectors of that kind regularly, I don't have any other recommendations other than to stick with repetuable manufacturers and read the data sheets. The cheaper ones will probably be MOV-only. Others may use a combination of MOV's, SAD's, and/or gas discharge tubes. There are pros and cons to each... I don't know of any series protectors that fall into the price range of what I would think you're looking for. Someone else (Eric?) mentioned Square D. The only Square D ones I've used are the ones that are built into the panel (Surgelogic or something like that?), not the add-on ones. We had to replace one in a 3-phase 480/277 panel not too long ago, that's the only reason I'm familiar with them (they have an audible alarm that goes off when the arrestor detects a fault, a nice feature). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Wednesday, June 09, 2010 8:51 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary OK, I'm familiar with those single-point grounding panel protection devices. How about a service panel protector for home use? And a service panel protector for a small (200A) 3-phase panel? I ask, rather than simply Google for it, because Google could come up with some units that are not good. Chuck WB2EDV
RE: [Repeater-Builder] MOVs for power supply primary
Hmmm. That's a tougher one. Mostly I use the Polyphasers (PLDO-120US-15A or -20A) at sites that don't have facility-wide protection. The TrippLite Isobar Ultra series is another (ISOBAR8ULTRA et al). The Isobars also have a $50,000 equipment warranty (can't say I've ever had to use it, don't know how much red tape there is to go through). I like the Polyphasers because it's designed to mount to a ground panel/bus bar, so I mount it to the bus bar that has all of my other arrestors (coax, telco, etc.) on it to provide a common-point ground. The Isobar doesn't have provisions for direct grounding - it relies only on the equipment grounding conductor in the AC cord, but the TrippLite has arguably better EMI/RFI filtering than the Polyphaser. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Tuesday, June 08, 2010 4:48 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary OK, I should have been more specific. What would be a reasonable unit for a repeater site that may have only a couple thousand dollars worth of equipment inside? Chuck WB2EDV - Original Message - From: Jeff DePolo j...@broadsci.com mailto:jd0%40broadsci.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Tuesday, June 08, 2010 4:22 PM Subject: RE: [Repeater-Builder] MOVs for power supply primary Probably the ones I've had the most luck with are the Islatrol series from Control Concepts. I think they have been bought out by Emerson or Liebert or one of the other companies that have power divisions. Anyway, they call these active tracking filters. They not only are TVSS's but also filter noise, low-amplitude spikes, etc. Right now I'm typing from a mountaintop site (broadcast) that we re-built a few years ago. We put in an Islator I-2100 (120/240V single-phase). The old equipment shelter which had been here since 1990 had the same model unit. In the 15+ years we've been managing and maintaining the site, we've had zero surge-related failures, and this site sticks out like a sore thumb as far as lightning goes. In the last few years I've used the same series of arrestors for new site builds at a dozen sites or so and have had no power-related problems. Others that make comparable-quality products include Joslyn, Transtector, and Innovative Technologies. There is one big difference (to me anyway) between TVSS's, that being whether they are the series or parallel type. Series type takes the utility service (or transfer switch output if there's a generator too) as its input, and provides a protected output to feed the panel(s). Parallel type is typically connected to a breaker in the panel, which puts it in parallel with all of the loads. I much prefer series. Parallel type can be less effective because a) there will always be some inductance and resistance in the wiring between the panel and the protector, b) if the TVSS conducts, there's a good chance it will trip the breaker in the panel, resulting in no protection until the breaker is reset, and c) they are much less effective as a noise filter. The upside to parallel type is they can easily be added at any time just by popping breakers in the panel and feeding the arrestor. Series, on the other hand, are in-line with the service conductors, so if you want to add one (or repair one), you have to take the service down. Series tends to also be more expensive, especially for three-phase and unlike parallel type, the price goes up as the current rating goes up for obvious reasons. A good 200A single-phase arrestor of the ilk I'm talking about starts at about $1000 and goes up quite a ways from there. I think these single-phase I-2100's were in the $2000 range. I recently spec'ed a 120/208 3-phase Transtector (parallel type) for another site where I'm much less concerned about power-wise, and that was about $1800. No cheap, but where you're protecting equipment in the 6 and 7 figure range, it's a no-brainer. If you're repeater is a Micor mobile and an Astron, it might be hard to justify... :-) --- Jeff
RE: [Repeater-Builder] MOVs for power supply primary
Probably the ones I've had the most luck with are the Islatrol series from Control Concepts. I think they have been bought out by Emerson or Liebert or one of the other companies that have power divisions. Anyway, they call these active tracking filters. They not only are TVSS's but also filter noise, low-amplitude spikes, etc. Right now I'm typing from a mountaintop site (broadcast) that we re-built a few years ago. We put in an Islator I-2100 (120/240V single-phase). The old equipment shelter which had been here since 1990 had the same model unit. In the 15+ years we've been managing and maintaining the site, we've had zero surge-related failures, and this site sticks out like a sore thumb as far as lightning goes. In the last few years I've used the same series of arrestors for new site builds at a dozen sites or so and have had no power-related problems. Others that make comparable-quality products include Joslyn, Transtector, and Innovative Technologies. There is one big difference (to me anyway) between TVSS's, that being whether they are the series or parallel type. Series type takes the utility service (or transfer switch output if there's a generator too) as its input, and provides a protected output to feed the panel(s). Parallel type is typically connected to a breaker in the panel, which puts it in parallel with all of the loads. I much prefer series. Parallel type can be less effective because a) there will always be some inductance and resistance in the wiring between the panel and the protector, b) if the TVSS conducts, there's a good chance it will trip the breaker in the panel, resulting in no protection until the breaker is reset, and c) they are much less effective as a noise filter. The upside to parallel type is they can easily be added at any time just by popping breakers in the panel and feeding the arrestor. Series, on the other hand, are in-line with the service conductors, so if you want to add one (or repair one), you have to take the service down. Series tends to also be more expensive, especially for three-phase and unlike parallel type, the price goes up as the current rating goes up for obvious reasons. A good 200A single-phase arrestor of the ilk I'm talking about starts at about $1000 and goes up quite a ways from there. I think these single-phase I-2100's were in the $2000 range. I recently spec'ed a 120/208 3-phase Transtector (parallel type) for another site where I'm much less concerned about power-wise, and that was about $1800. No cheap, but where you're protecting equipment in the 6 and 7 figure range, it's a no-brainer. If you're repeater is a Micor mobile and an Astron, it might be hard to justify... :-) --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Tuesday, June 08, 2010 11:34 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary Jeff - Could you suggest some makes and models and maybe explain why they are superior to others? Chuck WB2EDV - Original Message - Good surge arrestors/TVSS's are expensive, and like most things in life, you get what you pay for. If your site has a good surge arrestor at the service entrance, you really shouldn't need anything extra. --- Jeff WN3A
RE: [Repeater-Builder] Re: Milcom International UHF PA
If I want the caps changed, is there anyone in particular at Crescend I need to talk to? I wasn't aware that they would support the Milcom line. No, just fill out the RMA form from their web site. You might want to ask for an estimate or quote before you send the unit in, but they'll want the RMA form first. --- Jeff WN3A
RE: [Repeater-Builder] Micor Repeater Question
I have a friend running a 75W Micor UHF repeater and he needs to operate it for a single user who uses regular PL tone. My friend has a PL module installed on the Tone Squelch board in I presume you mean audio-squelch board. Does he need a single PL tone encoder card for the card cage? 146.2 Hz. is the tone he needs. The PL encoder plugs into the exciter, not the card cage. One jumper cut on the exciter board is required. After he installs such a card, would the repeater transmit the 146.2 PL tone, even if activated by the Tone Remote? Yes. Third question - Are there any other cards or PL modules out there besides the Card Cage type, or are they all strictly the ones that fit in the Unified Chassis? See above. Don't confuse a PL encoder board with an F1-PL card in the cage, totally different animal... --- Jeff WN3A
RE: [Repeater-Builder] MOVs for power supply primary
Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. I'm not that big of a fan of MOV's, but if you really feel the need to add them across the transformer primary, as long the input to the power supply is properly fused, whatever floats your boat. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... I'm not sure that there's anything that Radio Shack sells any more that's any good, is there? Seriously, I'd buy Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. My experience that small MOV's fail in one of two ways. Either they fail shorted, quite often with no outward visible signs, or they fail open catastrophically as a zillion pieces of shrapnel that can cause damage to nearby components, wiring, people, livestock, etc.. Another downside to MOV's is that after they've successfully quenched an over-voltage event of any significant energy, their clamping voltage changes. So, you may end up with less and less protection over time. Good surge arrestors/TVSS's are expensive, and like most things in life, you get what you pay for. If your site has a good surge arrestor at the service entrance, you really shouldn't need anything extra. --- Jeff WN3A
RE: [Repeater-Builder] Re: Milcom International UHF PA
28-29 amps is on the high side. Are you using the amp at more than maybe 5 MHz or so from the original frequency? Some of the Milcom/Crescend amps are tunable, but many used fixed-value metal-clad mica capacitors in the base and collector matching. The values of the caps and/or their placement along the microstrips is varied depending on frequency. While you could experimentally determine the right values/placements using common sense techniques, it's probably easier just to send it to Crescend to have them move it to your frequency. I have a 350 watt Vocom UHF amp that had the same issue - fixed caps. After counting how many caps I'd have to futz with, I concluded it was cheaper to send it to them and letthem do it for $200. They turned it around in about a week. If you need 250 mW in and 100 watts out, a Mastr II PA would do you nicely (and cheaply!). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Adam Feuer Sent: Saturday, June 05, 2010 11:35 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Milcom International UHF PA Hi Alex, Thanks for the reply! Your description of the pots was great but I don't see ANY tuning caps on any boards in this amp. There's a 10watt board that feeds a 65w board. Then, this 65w board gets split to feed two more 65w boards which get combined as the final output. I can easily set R10 to 100 watts but I would like more info on the tuning caps if it's applicable to this amp. At 100 watts the amp is drawing about 28 to 29 amps. I may be incorrect but I thought some of my other 250mw in 100w out PA's only draw 22 amps. Thanks again! Adam N2ACF On 6/5/2010 6:04 PM, opelgtalex wrote: Adam- R10 controls the bias voltage to the first stage driver- this sets the power out of the amp. Turn this pot down (lower the PA output) peak out all tuning caps starting at the 1st stage, then the 2nd and on to the 4 driver boards. Once all tuning caps are adjusted for peak output, then adjust R10 for the amplifiers rated power out (100W in your case). R9 controls the foldback power in case of a high temp condition the power output is cut by 3dB- the thermal switch is located just below the control board. As per manual R9 is adjusted by removing power from the cooling fan, key the RF source, wait for the unit to reach 135deg F and adjust R9 for 3dB below rated amp output- this is per manual. Hope this helps, Alex --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Adam Feuerfeu...@... wrote: Hello All, I have a Milcom International UHF PA on the bench. Model number is P12-O5HA1-C1 rated at 250mw in with 100w out. I'm trying to identify what two pots (R9 R10) do on a board that seems like a control board. Both pots appear to vary the output power and current draw, although one does it more dramatically than the other. Anyone have a manual or information for this PA? Any help would be greatly appreciated. Thanks!! Adam N2ACF Yahoo! Groups Links
RE: [Repeater-Builder] Re: Which Micor RX for Two Meters
Start with the basics: 1. Clean all of the contact pins and female contacts with a good contact cleaner like Deox-It. When re-installing each of the boards/cards, check check to make sure that all of the male pins are straight and that none of the female contacts have spread - tighten up by squeezing gently with needle-nose pliers where necessary. 2. Clean (or replace) the IDC pot if you haven't already. If speaker audio is normal and doesn't vary in level, and/or if PL injection doesn't change when the audio level changes, chances are it's somewhere in the repeat audio path. But if speaker audio level changes too, then clean/replace the audio level pot on the audio/squelch board as well. Those are my first-pass suggestions. If you want to provide more detail on the problem, including what cards you are using and how you have Tx and Rx wired from the controller to the station, I can probably offer some other suggestions. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Lee Pennington Sent: Sunday, June 06, 2010 10:42 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Which Micor RX for Two Meters No, I did every thing from the RB station to repeater conversion instructions. My problems with the Xmitter involve fluctuating audio deviation levels. It is frequency stable and I have a solid 75-78 watts out of the cans. Thanks for your concern and keep up the good work. de Lee K4LJP 73 On Sun, Jun 6, 2010 at 9:57 AM, Scott Zimmerman n3...@repeater-builder.com mailto:n3...@repeater-builder.com wrote: Did I do the transmitter as well? (I don't remember. I do so many projects.) Scott Scott Zimmerman Amateur Radio Call N3XCC 474 Barnett Road Boswell, PA 15531 Lee Pennington wrote: Exactly right, Scott did the coils and castings on mine five years ago.Hasn't been touched since.now the xmitter, well that's another story. On Sun, Jun 6, 2010 at 8:36 AM, terry_wx3m wx3m.te...@gmail.com mailto:wx3m.terry%40gmail.com mailto:wx3m.te...@gmail.com mailto:wx3m.terry%40gmail.com wrote: Do yourself a favor and send the receiver and $100 to Scott n3...@repeater-builder.com mailto:n3xcc%40repeater-builder.com mailto:n3xcc%40repeater-builder.com mailto:n3xcc%2540repeater-builder.com . Then you will have a receiver that is in the 131-150 range. It is worth EVERY penny. It will exceed book specs. --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%2540yahoogroups.com , Tim - WD6AWP tisaw...@... wrote: I have the following Micor receivers. TLD4071B, TLD5781AV, and TLD8271B3. Unfortunately none are in range 2. Which, if any of these would be the best for a receiver on 144.5 Tim WD6AWP -- Always drink upstream from the herd. -- Always drink upstream from the herd.
RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer
Mine don't have labels on them. Usually they were sold as part of an SP package that included the window filters, multicoupler, etc. I haven't tuned or swept this particular set, but from experience, the cavity resonance will tune over a wide swath, probably the full 406-512 MHz, but the loop lengths may not be optimal over such a wide span (depending on how the cavities are being used), and likewise, the cable lengths will vary. You have something in particular in mind you want me to test? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Eric Lemmon Sent: Sunday, May 30, 2010 12:29 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer Jeff, Can you positively identify the window filters by part number? Also, what is the useful frequency range of the units you purchased? 73, Eric Lemmon WB6FLY -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 Jeff DePolo Sent: Sunday, May 30, 2010 8:39 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer snip I bought two sets of those window filters from the same guy, but I knew what they were, caveat emptor is the golden rule at Dayton or any other hamfest. Actually I think I gave him $75 for the pair, and I took the two cleanest/newest ones he had (the newer dark-tan ones). --- Jeff WN3A snip
RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer
Yes, they did sell window filter as a separate catalog item, but if they were sold as such they would have had a factory sticker on it. The ones I have don't have a sticker, which is why I said they were probably part of a package that would likely have had an SP part number rather than a DB. These cavities are very tightly coupled, typically about 0.3 dB or so insertion loss per cavity. Strung together, the total insertion loss is about 1.5 dB. Because of the coupling, each cavity individually doesn't have a very high Q, so if you were to take one of these units and split it to try to make a duplexer out of it, you'd probably only get about 40 dB or so of isolation at 5 MHz offset. Even if you did want to try it, you'd have to change cable lengths to get the pass response of each cavity to add on-frequency rather than creating a wide window filter passband as they were originally cabled. They do tune fine down to 440 as-is (i.e. as a window filter). --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Eric Lemmon Sent: Monday, May 31, 2010 12:52 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer Not really. I had not seen this in any of my older catalogs, and I wondered if in fact the unit was made by Decibel Products. Like many RF products, ferrite isolators in particular, the frequency range stated in a manufacturer's catalog refers to the capability to construct- which is not the same as the field-tunable range of a specific product. I was curious if the window filter (AKA preselector) could be useful in the 70 cm Amateur band without modifying the coupling loops or jumper cables. 73, Eric Lemmon WB6FLY -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 Jeff DePolo Sent: Monday, May 31, 2010 6:09 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer Mine don't have labels on them. Usually they were sold as part of an SP package that included the window filters, multicoupler, etc. I haven't tuned or swept this particular set, but from experience, the cavity resonance will tune over a wide swath, probably the full 406-512 MHz, but the loop lengths may not be optimal over such a wide span (depending on how the cavities are being used), and likewise, the cable lengths will vary. You have something in particular in mind you want me to test? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Eric Lemmon Sent: Sunday, May 30, 2010 12:29 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer Jeff, Can you positively identify the window filters by part number? Also, what is the useful frequency range of the units you purchased? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Jeff DePolo Sent: Sunday, May 30, 2010 8:39 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer snip I bought two sets of those window filters from the same guy, but I knew what they were, caveat emptor is the golden rule at Dayton or any other hamfest. Actually I think I gave him $75 for the pair, and I took the two cleanest/newest ones he had (the newer dark-tan ones). --- Jeff WN3A snip
RE: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer
Sorry to hear you got the proverbial shaft. But all's not lost. If you need a duplexer, I'll trade you a Motorola T1504 (pass/reject) duplexer in good shape that I had on my table at Dayton that didn't sell. I was asking $125 for it. I'll trade you straight across if you pick up shipping in both directions, and I'll even tune it on the VNA and send you the plots. I bought two sets of those window filters from the same guy, but I knew what they were, caveat emptor is the golden rule at Dayton or any other hamfest. Actually I think I gave him $75 for the pair, and I took the two cleanest/newest ones he had (the newer dark-tan ones). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Josh Sent: Saturday, May 29, 2010 9:27 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Help Needed (Guidance and advice) tuning a DB Products Duplexer Certainly not what I was expecting... Yeah, I bought one from 'that guy'. It's more than an untrained eye - he straight lied to me... said 'under these caps are where you'll tune the capacitors' - I should have popped one off and looked down the hole. Maybe he was clued in, maybe he wasnt - either way, that's what I bought. Dangit :P So if all I have are pass cavities what 'are' they good for ? Guess I've got to find another dupelxer. j --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Jeff DePolo j...@... wrote: Ok so here's what I've got (I think) http://www.n2ckh.com/FORSALE/REPEATERS/DUPLEXERS/DB4076/DSC02678.JPG Hamvention special, 4 cavities, appears to be a DB Products 4076 family unit. My bench tools: HP 8924c w/ Spec Analyzer and Tracking Generator. There was a guy at the Hamvention that had several sets of Decibel four-cavity window filters, selling for $50 each, which, to the untrained eye, would look like an older DB4076. As you said, there would be nothing in the hole where the capacitor would be in a regular DB4076. In essecence, what you have are just plain-jane pass cavities. As a second means of confirming that you do, in fact, have a window filter, is there an antenna tee, or are the four cavities cabled together in cascade? If the latter, then you probably have a window filter. And as a third means of confirming, is there is a label on the front? If not, was there any signs of a label having once been there? If not, then that's yet one more indication that it isn't a DB4076. Decibel made two varieties of pass cavities used in window filters in that era. One had adjustable loops (less common), the other had fixed loops. If your loop connectors have a rectangular chrome plate around them with insertion loss calibration marks, you have the less-common adjustable ones. If you just see four philips-head screws and no chromed plate around the connectors, then yours is not adjustable. If you have the adjustable type, you could probably use them as a pass-only duplexer, but with mediocre isolation, even with the insertion loss cranked up higher than you'd like. If you have the non-adjustable ones, they have very tight coupling, so you're not going to get the isolation you'd need for a repeater. Did I buy a piece of junkola? Teach me obie-wan. Not junk, but maybe not what you were expecting... --- Jeff WN3A
RE: [Repeater-Builder] Help Needed (Guidance and advice) tuning a DB Products Duplexer
Ok so here's what I've got (I think) http://www.n2ckh.com/FORSALE/REPEATERS/DUPLEXERS/DB4076/DSC02678.JPG Hamvention special, 4 cavities, appears to be a DB Products 4076 family unit. My bench tools: HP 8924c w/ Spec Analyzer and Tracking Generator. There was a guy at the Hamvention that had several sets of Decibel four-cavity window filters, selling for $50 each, which, to the untrained eye, would look like an older DB4076. As you said, there would be nothing in the hole where the capacitor would be in a regular DB4076. In essecence, what you have are just plain-jane pass cavities. As a second means of confirming that you do, in fact, have a window filter, is there an antenna tee, or are the four cavities cabled together in cascade? If the latter, then you probably have a window filter. And as a third means of confirming, is there is a label on the front? If not, was there any signs of a label having once been there? If not, then that's yet one more indication that it isn't a DB4076. Decibel made two varieties of pass cavities used in window filters in that era. One had adjustable loops (less common), the other had fixed loops. If your loop connectors have a rectangular chrome plate around them with insertion loss calibration marks, you have the less-common adjustable ones. If you just see four philips-head screws and no chromed plate around the connectors, then yours is not adjustable. If you have the adjustable type, you could probably use them as a pass-only duplexer, but with mediocre isolation, even with the insertion loss cranked up higher than you'd like. If you have the non-adjustable ones, they have very tight coupling, so you're not going to get the isolation you'd need for a repeater. Did I buy a piece of junkola? Teach me obie-wan. Not junk, but maybe not what you were expecting... --- Jeff WN3A
RE: [Repeater-Builder] Lost 10 volts in a Master II UHF Repeater
I would look for a shorted tantalum capacitor hanging somewhere on the 10V rail. I agree. If you hook 10V from an outside source to the 10V buss, you'll probably find it's drawing all kinds of current. The 10V regulator circuit will go into fold back before burning up. This is by design. I usually hook a source of 10V at about 1.5A and look for smoke. It's usually one of the tantalum capacitors that starts to smoke. Once it's done smoking, problem solved!! Put a DMM on the 10V line, then start disconnecting things until you narrow it down, divide and conquer. Pull all of the cards out of the cage (except the 10V reg card obviously), disconnect the exciter, remove the receiver, etc. With a good ohmmeter that measures fractions of an ohm, you should be able to narrow it down further once you've found the suspect module/board. I have lost track of how many shorted tantalums I have had over the years. When they occur in the B+ of the high current PA supply, they simply burn up and th problem fixes itself. They make a cool purple smoke with lots of sparks when they flame out! --- Jeff WN3A
[Repeater-Builder] Dayton to Evansville, IN
Leaving for Dayton tomorrow morning (weather forecast has improved a bit, looks like both Saturday and Sunday will be decent). After Dayton I'm headed to Evansville, IN. Any repeater-builders out there with machines between Dayton and Evansville (via Cincinnati and Louisville - I-75, I-71, I-64)? Got a new truck in March and still haven't had time to put the stack in, so will just have 2m and 440 this trip. --- Jeff WN3A
RE: [Repeater-Builder] Dayton
Our usual clan which includes a number of repeater-builder denizens will be in 2370 et al, at the end of a row. Come by for free 807's and bring lots of money to buy stuff, nothing I bring to sell is coming back home with me this year... Long-range forecast for Dayton doesn't look all that great, Sunday looks like the nicest day. The best deals are to be had in the rain! --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Andrew Seybold Sent: Thursday, May 06, 2010 10:42 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Dayton Our Flea market spots are 737-739, come by and say hello, second row, near the Bar. Andy W6AMS cid:image001.jpg@01CA5969.2F1EB460 aseyb...@andrewseybold.com mailto:aseyb...@andrewseybold.com 315 Meigs Road, Suite A-267 Santa Barbara, CA 93109 805-898-2460 office 805-898-2466 fax www.andrewseybold.com http://www.andrewseybold.com No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2842 - Release Date: 05/06/10 14:26:00
RE: [Repeater-Builder] Re: CTCSS Encoder/Decoder
Building a PL decoder out of NE567's is old-school, and I've never seen a design that didn't have drift problems. The MX-COM (now CML Micro) tone chips were a better way to go, but many have been discontinued. If you can find them on the surplus market, that would be the easiest way to go. The part numbers were MX-3x5, where x was one of several numbers. Some were designed to be used with a DIP switch for frequency selection, others were designed to tie to a uP and took serial data to select the tone. Dig around for the datasheets, I'm sure they're out there... --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tracomm Sent: Friday, May 07, 2010 10:14 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: CTCSS Encoder/Decoder I have to agree, unless you need to Reminisce about the good old days when men actually built the things they used, there are so many inexpensive options for ctcss that actually work, very well. There are a few Selectone units on ebay at about $2.00 and I am certain members here could supply more than a few boards very cheaply that actually work reliably. CJD --- In Repeater-Builder@yahoogroups.com, kevin valentino kevinvalent...@... wrote: Grab an old Standard HX300 or C734 etc. off ebay for practically nothing(if you find one) the enc/dec board is a plug in w/wire leads, very small, dip select, and rock solid. I have one kickin around with the schematic if your interested. I have adapted these to many old crap radios and they always work perfectly. Just a suggestion :-) --- On Thu, 5/6/10, James ka2...@... wrote: From: James ka2...@... Subject: [Repeater-Builder] CTCSS Encoder/Decoder To: Repeater-Builder@yahoogroups.com Date: Thursday, May 6, 2010, 10:35 AM Hi Guys, We have been experimenting with building CTCSS Units using the 567 Tone Chip and good components, i.e. Caps, multi turn pots etc. The stability is not good in my opinion. We will set it to 107.2 and the next time you check it is off enough to where it won't decode until it is re-tuned slightly. I am wondering what your experiences may have been with this CTCSS Chip. Many articles say they work well with the addition of a stable voltage regulator, so we added a five volt regulator, no difference in stability. Any comments and experiences with this and other chips would be appreciated. The availability of CTCSS Chips seems limited. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2842 - Release Date: 05/07/10 02:26:00
RE: [Repeater-Builder] Skip At Dayton
Hi Skip, What Booth are you going to be in at Dayton?,Will you be going? Wesley AB8KD P.S. I want to see how Ugly you are There are plenty of people at Dayton much more ugly than Skipp - anyone who has attended Dayton before knows what I mean :-) When he's not mowing down pedestrians with a Hamvention security golf cart, Skipp goes slumming at our spaces periodically, stealing beverages and expensive items off the table. Beware of him. Keep one hand on your wallet at all times, and make sure your YL/XYL stays far, far away.
RE: [Repeater-Builder] Re: LDF1-50 with PL259 UG-176 ?
Depending on the PL-259 in question (i.e. who manufacturered it), sometimes you can get them onto FSJ2 without any problem, other times you need to take a bit off the threads to get it to thread onto the shield. But to complicate matters, some PL-259's are manufacturered such that the ID in the area where the solder holes are located is too small for FSJ2, in which case, you can't use those, unless you just thread them on up to where the ID tapers down, and then sweat-solder the shield to the PL-259 from the rear (i.e. you won't be able to solder through the solder holes). The center conductor fits into the PL-259 pin no problem regardless of manufacturer. Bottom line - try a few PL-259's and stick to manufacturer that works. If I could remember which ones do or don't fit I would tell you, but to be honest, I don't use PL-259's very often, so when I do need to put one on FSJ2, I usually just try a few until I find one that fits... --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Howard Z Sent: Tuesday, May 04, 2010 10:18 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: LDF1-50 with PL259 UG-176 ? DCFluX, So, you have placed a standard PL259 on Andrew FSJ2-50 3/8 cable? Any problems or advise? Howard --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , DCFluX dcf...@... wrote: Yes, I've done it. On Mon, May 3, 2010 at 7:25 PM, Howard Z howar...@... wrote: I found some more specs: fsj1-50a diameter over dielectric 0.190 inner conductor OD 0.0750 Outer Conductor OD 0.250 fsj2-50 diameter over dielectric 0.280 inner conductor OD 0.1100 Outer Conductor OD 0.380 fsj4-50b diameter over dielectric 0.350 inner conductor OD 0.1400 Outer Conductor OD 0.480 ldf1-50 diameter over dielectric 0.270 inner conductor OD 0.1000 Outer conductor OD 0.310 ldf2-50 diameter over dielectric 0.340 inner conductor OD 0.1200 Outer Conductor OD 0.380 So, it looks like both FSJ2-50 and also LDG2-50 have an outer conductor OD of 0.380 inch. Do you think these cables might be able to use regular PL-259 connectors without any reducer? Howard Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2842 - Release Date: 05/04/10 02:27:00
RE: [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 Pin 701 on the board (base of Q704) is PL Inhibit - pull to ground to kill the encoder. --- Jeff WN3A
RE: [Repeater-Builder] Micor PL encoder modification (TLN5731A)
You can try a bipolar, but you might have some residual leakage which will show up as a low-amplitude distorted (clipped) waveform. I'm trying to remember what option card(s) used that P701 to kill the PL encode so I could look at the schematic to see what they're keying it with, but I can't remember. Maybe Eric knows off the top of his head? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of N1BUG Sent: Monday, May 03, 2010 1:41 PM To: Repeater-Builder@yahoogroups.com Subject: 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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2842 - Release Date: 05/03/10 02:27:00
RE: [Repeater-Builder] LDF1-50 with PL259 UG-176 ?
Hi, I have read that one can put plain low cost PL259 connectors on FSJ1-50A Andrew 1/4 inch suplerflex using a UG-176 reducer. Yep. Can the same be done with the Andrew LDF1-50 1/4 hardline? Nope. The OD of the shield is too big to fit into a UG-176 reducer. FSJ1 is exactly a quarter inch OD without the jacket. LDF1 is 0.31. A UG-176 reducer is designed to fit over RG8X, RG59, et al which are typically 0.242 OD. You can usually coerce the reducer onto FSJ1, but you'd have to drill it out bigger to fit LDF1 into it. --- Jeff WN3A
RE: [Repeater-Builder] Wind noise wire rope guide for ladder
Trylon, through Tessco, Hutton, et al. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gran Clark Sent: Monday, May 03, 2010 2:56 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Wind noise wire rope guide for ladder Joe Thanks a bunch! Yes I believe I saw one of these some time in the past. The metal is covered with some insulating material. The big question! Where can I get one? Gran K6RIF At 09:24 AM 5/3/2010, you wrote: I think this is what you are looking for. Joe On 5/2/2010 11:03 PM, Gran Clark wrote: Is there a source of wire guides that do not have this problem and still pass safety requirements.? Gran K6RIF No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2842 - Release Date: 05/03/10 02:27:00
RE: [Repeater-Builder] IDEA? Re: Micor PL encoder modification (TLN5731A)
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 -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of N1BUG Sent: Monday, May 03, 2010 3:18 PM To: Repeater-Builder@yahoogroups.com Subject: [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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2842 - Release Date: 05/03/10 02:27:00
RE: [Repeater-Builder] LDF1-50 with PL259 UG-176 ?
A UG-176 *is* a reducer for RG-8X. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of DCFluX Sent: Monday, May 03, 2010 4:39 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] LDF1-50 with PL259 UG-176 ? Try the reducer meant for RG-8X. On Mon, May 3, 2010 at 11:21 AM, Jeff DePolo j...@broadsci.com mailto:jd0%40broadsci.com wrote: Hi, I have read that one can put plain low cost PL259 connectors on FSJ1-50A Andrew 1/4 inch suplerflex using a UG-176 reducer. Yep. Can the same be done with the Andrew LDF1-50 1/4 hardline? Nope. The OD of the shield is too big to fit into a UG-176 reducer. FSJ1 is exactly a quarter inch OD without the jacket. LDF1 is 0.31. A UG-176 reducer is designed to fit over RG8X, RG59, et al which are typically 0.242 OD. You can usually coerce the reducer onto FSJ1, but you'd have to drill it out bigger to fit LDF1 into it. --- Jeff WN3A Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2842 - Release Date: 05/03/10 02:27:00
RE: [Repeater-Builder] LDF1-50 with PL259 UG-176 ?
How about doing it without a reducer at all then? According to this the dielectric size of RG-8 is 0.285 and LDF-1 is 0.29 Cant find the dimensions of the shield of RG-8 but it brings the size of LDF-1 to 0.30 which should fit nicely inside a PL-259. Just calipered (is that a word?) a PL-259. 0.37 ID to the tips of the threads, so there will still be some play if you used it on LDF1 without a reducer. I guess you could fudge it with a lot of solder, or use something else to shim it up. --- Jeff WN3A
RE: [Repeater-Builder] Mitreks as UHF Repeaters?
Because of the internal desense issue, I'd build them the same, but operate the two radios separately. That is, use one as a transmitter and the other as the receiver by default. No duplex mods required. If the Tx dies on one, swap the system cables around to make the formerly-transmitter radio the receiver, and vice-versa. You could even automate the changeover via a couple of coaxial relays and some simple homebrew transistor and/or relay logic tied into your controller. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Paul Plack Sent: Monday, April 26, 2010 1:49 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Mitreks as UHF Repeaters? ? Tim, My plan at this point is to convert them to full duplex, so I can use the second Mitrek to prepare a complete, plug-in, standby set of RF decks. The mods look very straightforward, but I was wondering if there were any gremlins people discovered. Your heatsink approach, however, is exactly what I was talking about. I have several very large heatsinks originally designed for use with big SCR switching circuits which look to be more than generous for a 30w PA at 100% duty cycle. My first repeater was built from a 2w Repco exciter board repurposed from RFID service. It was supposedly rated for continuous duty, but had to run very hot to dump the heat it produced through the little aluminum tab mounted to its own PC board within the case. I fashioned a new tab with a 90º twist which allows sinking the little PA to the case itself, and it never got above warm to the touch, even after hours key-down. Guys, I appreciate all the input. 73, Paul, AE4KR - Original Message - From: w7...@comcast.net mailto:w7...@comcast.net To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com Sent: Monday, April 26, 2010 10:16 AM Subject: Re: [Repeater-Builder] Mitreks as UHF Repeaters? Isn't the rpt. going to be built using (2) Mitrex, thus shielding should not be a problem. I have, in the past (with the help of a Bridgeport mill), fashioned Larger Heatsinks, that bolt onto the orig. Mitrex heat sinkseems to dissipate heat well... No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.801 / Virus Database: 271.1.1/2792 - Release Date: 04/26/10 02:31:00
RE: [Repeater-Builder] Mitreks as UHF Repeaters?
I appreciate the thoughts. Anytime I've looked at a scheme which allows simply swapping the TX and RX to get back on the air, I arrive at the same conclusions... (1) If I took a lightning hit at the site, I'd want my spares to have been stored somewhere else. (2) Once I swap the TX and RX, I still can't bring either home for repair without taking the machine off the air. Understood. As far as the automated switchover, the 7K has three receiver and two transmitter ports, so I wouldn't even need coax relays to provide remote swap capabilities. I could just crystal each radio for simplex, wire both receivers and both transmitters into the controller, issue a remote DTMF command to swap them, and instantly implement a second repeater on the upside-down split. Yikes, upside-down? Your co-channel neighbors will just love that! I think my answer is going to end up being building a stash of spares, and using two radios. Yeah, I'd definately go with split radios however you end up doing it. If you're going to assume you're going to make the trip to the site in the event of a failure, then there's probably no need to order two sets of crystals, just move the elements when you swap radios and net them on frequency. These days, the cost of crystals is usually more than the cost of the radio they're going into...which is why I've mostly gone synthesized. --- Jeff WN3A
RE: [Repeater-Builder] Sinclair C-Series cable lengths
Yep, I did get one. I did some preliminary testing and it compares favorably to the Eagle in most regards. Rick is contemplating making some additional refinements, some of which are based on my testing, so I'm waiting to hear back from him. If he decides to make changes, I'll wait until he sends me the final version for complete testing. --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Don Kupferschmidt Sent: Wednesday, April 21, 2010 12:26 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Sinclair C-Series cable lengths Jeff, Speaking of the RLB, did you ever get one of the newer RLB's from Amtronix? I still interested in someone measuring the parameters of that unit against one of the more expensive RLB's, such as the Eagle brand. If the measurements are fairly close to each other, then the Amtronix RLB would be a good unit to have, especially for the price that he's asking. Also, your post below was really good information to have. Thanks! 73, Don, KD9PT - Original Message - From: Jeff DePolo mailto:j...@broadsci.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com Sent: Tuesday, April 20, 2010 5:46 PM Subject: RE: [Repeater-Builder] Sinclair C-Series cable lengths I adjusted the loop positions, trying to maintain symmetry of the curve, aiming for 1 db on the analyzer. I didn't adjust the loops while looking at the RL. How would I translate RL into IL? You can't directly translate from RL to IL or vice-versa. Here's how to tune a pass cavity: 1. Ballpark the insertion loss using the stickers on the loops and/or by measuring the insertion loss at whatever frequency the cavity is presently tuned to. 2. Rough-tune the cavity to something near your desired frequency. Don't bother being too critical here - the resonant frequency is going to wander a bit as you adjust the loops in the following steps. 3. Terminate one cavity port with a high-quality 50 ohm load (high quality: = 30 dB return loss). Connect your RLB to your SA/TG, with the DUT port connected to the other port on the cavity. You *must* use a cable between the DUT port and the cavity that is known to have excellent return loss! The cables between the SA/TG and RLB should be good quality, but are nowhere near as critical as the cable between the RLB and the device under test. 4. While measuring the return loss, make minor adjustments to one of the loops to maximize the return loss. Again, ignore the frequency of the return loss dip, it's going to vary slightly as you adjust the loop, just go for maximum return loss at whatever frequency the dip happens to fall at. Keep the screws snugged down well on the loop assembly; if it's not sitting tight and flush in the top of the cavity the tuning will change when you go to tighten the screws later. There's a little chicken-and-egg here; you have to loosen the screws to adjust the loop, but when you tighten them it's going to change it a bit, so you have to emperically find the sweet spot. With most cavities, you should have no problem getting well in excess of 20 dB return loss - shoot for 30 dB if you can, even though at that point uncertainty due to the test equipment's limitations will be dominating the measurement accuracy. 5. Reverse the connections you set up in #2 above. Check to make sure the return loss is still high looking into the other port (it should be). 6. NOW, adjust the resonant frequency using the rod to put the return loss maxima it where you want it (i.e. at your pass frequency). Assuming the cavity was rough-tuned in step #2 above, the return loss should not change as you fine-tune the resonant frequency. 7. THEN, check the insertion loss through the cavity using the SA/TG. It should be fairly close to what you set it to in #1 above; if it's more/less than what you'd like, adjust ONE loop for more/less insertion loss, and then repeat again from step #3. DO NOT adjust the resonant frequency via the tuning rod during this step!!! Unless the cavity was poorly designed, tuned, or handled, the return loss maximum should align very closely with the insertion loss minimum. Once you've properly tuned the cavities individually, then cable them together and re-check return loss and insertion loss. Report back how
RE: [Repeater-Builder] Sinclair C-Series cable lengths
I have 2 C-Series bandpass cavities, with individual I.L. set at 1.0 db each. When I couple them together and measure, I get a total I.L. of 2.9 db. I should see something like 2.1 or 2.2. I have measured the coupling cable and see .1 db, so the cable is good. Anyone have an idea why the loss is so high when coupled? Most likely they aren't tuned correctly for maximum return loss, and when you cascade them, the resonant frequency is no longer where you thought it was (i.e. a detuning effect). Have you measured the return loss of the cavities individually? --- Jeff WN3A
RE: [Repeater-Builder] Sinclair C-Series cable lengths
The cavities were initially tuned individually and the loop positions set for 1 db IL. They were then coupled together using a 18.5 cable and the rods touched up to re-establish resonance. If the cavities had good return loss individually, there shouldn't be a need to touch up the tuning when they are cascaded. That's what I was saying originally with my detuning comment. The loop positions were not changed after coupling. But were the loops adjusted to maximize return loss at the desired inseretion loss setting? That's the key point. Or did you just dial in 1 dB of insertion loss and call it good? When using the RL bridge I do not see one clear notch, but rather a notch that has a bump; kinda looks like 2 notches. Again, this may be indicitive of them not being tuned correctly. This is what I always see even when cavities are factory tuned ??? There's no acceptable generalization when it comes to how cavity filters behave when cascaded. Two cavities used as a window filter with an extended passband will look different for both transmission and reflection than would two cavities tuned (and cabled) to pass a single frequency. I'm confident that the tuning is OK. I wouldn't be so sure, as it seems likely that's the problem. --- Jeff
RE: [Repeater-Builder] Sinclair C-Series cable lengths
What process did you go through when setting the insertion loss to the 1 dB you were targetting? Did you optimize the coupling angle of the loops for maximum return loss at (or near) the desired 1 dB of insertion loss? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Larry Horlick Sent: Tuesday, April 20, 2010 5:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Sinclair C-Series cable lengths But were the loops adjusted to maximize return loss at the desired inseretion loss setting? That's the key point. Or did you just dial in 1 dB of insertion loss and call it good? Not sure what u mean?? No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.801 / Virus Database: 271.1.1/2792 - Release Date: 04/20/10 02:31:00
RE: [Repeater-Builder] Sinclair C-Series cable lengths
I adjusted the loop positions, trying to maintain symmetry of the curve, aiming for 1 db on the analyzer. I didn't adjust the loops while looking at the RL. How would I translate RL into IL? You can't directly translate from RL to IL or vice-versa. Here's how to tune a pass cavity: 1. Ballpark the insertion loss using the stickers on the loops and/or by measuring the insertion loss at whatever frequency the cavity is presently tuned to. 2. Rough-tune the cavity to something near your desired frequency. Don't bother being too critical here - the resonant frequency is going to wander a bit as you adjust the loops in the following steps. 3. Terminate one cavity port with a high-quality 50 ohm load (high quality: = 30 dB return loss). Connect your RLB to your SA/TG, with the DUT port connected to the other port on the cavity. You *must* use a cable between the DUT port and the cavity that is known to have excellent return loss! The cables between the SA/TG and RLB should be good quality, but are nowhere near as critical as the cable between the RLB and the device under test. 4. While measuring the return loss, make minor adjustments to one of the loops to maximize the return loss. Again, ignore the frequency of the return loss dip, it's going to vary slightly as you adjust the loop, just go for maximum return loss at whatever frequency the dip happens to fall at. Keep the screws snugged down well on the loop assembly; if it's not sitting tight and flush in the top of the cavity the tuning will change when you go to tighten the screws later. There's a little chicken-and-egg here; you have to loosen the screws to adjust the loop, but when you tighten them it's going to change it a bit, so you have to emperically find the sweet spot. With most cavities, you should have no problem getting well in excess of 20 dB return loss - shoot for 30 dB if you can, even though at that point uncertainty due to the test equipment's limitations will be dominating the measurement accuracy. 5. Reverse the connections you set up in #2 above. Check to make sure the return loss is still high looking into the other port (it should be). 6. NOW, adjust the resonant frequency using the rod to put the return loss maxima it where you want it (i.e. at your pass frequency). Assuming the cavity was rough-tuned in step #2 above, the return loss should not change as you fine-tune the resonant frequency. 7. THEN, check the insertion loss through the cavity using the SA/TG. It should be fairly close to what you set it to in #1 above; if it's more/less than what you'd like, adjust ONE loop for more/less insertion loss, and then repeat again from step #3. DO NOT adjust the resonant frequency via the tuning rod during this step!!! Unless the cavity was poorly designed, tuned, or handled, the return loss maximum should align very closely with the insertion loss minimum. Once you've properly tuned the cavities individually, then cable them together and re-check return loss and insertion loss. Report back how it goes and what numbers you come up with. --- Jeff WN3A
RE: [Repeater-Builder] Sinclair C-Series cable lengths
Thanks for the detailed instructions. I understand everything, but I'm confused about one detail. Using this method will produce the largest RL and consequently the lowest IL. Well, sort of. You want the most return loss AT THE DESIRED INSERTION LOSS. Maximizing return doesn't mean you have the minimum insertion loss. A 20 dB pad might have great return loss, but obviously it also has 20 dB of insertion loss! But I don't want the lowest IL; I want a specific value, i.e. 1 db per cavity. Right, and that's what you set in #1 in my instructions/notes. You rough in the insertion loss setting initially, but the actual tuning of the cavity is done based on return loss. In step 7 you measure the final insertion loss after you're done tuning. If it's too high or too low, you increase/decrease the coupling respectively and re-tune from scratch. If my instuction on changing the coupling again in step #7 and then re-tuning from scratch confused you, I apologize, I probably should have been more clear. If you change the coupling of one loop to increase/decrease the insertion loss, then you should be adjusting the OTHER loop in the next round of tuning. Obviously if you adjust one loop and then go back through the same procedure with the test equipment connected to that same loop you just adjusted, you're just going to end back up where you started. So, just so we're clear, if you're going to connect the RLB to port A, you would want to increase/decrease the insertion loss by adjusting the port B loop in step 7 before re-tuning starting at step 3. How do I use RLB to set a specific IL? You don't. An RLB measures return loss (obviously). The SA/TG alone is used to measure the insertion loss. --- Jeff WN3A 1. Ballpark the insertion loss using the stickers on the loops and/or by measuring the insertion loss at whatever frequency the cavity is presently tuned to. 2. Rough-tune the cavity to something near your desired frequency. Don't bother being too critical here - the resonant frequency is going to wander a bit as you adjust the loops in the following steps. 3. Terminate one cavity port with a high-quality 50 ohm load (high quality: = 30 dB return loss). Connect your RLB to your SA/TG, with the DUT port connected to the other port on the cavity. You *must* use a cable between the DUT port and the cavity that is known to have excellent return loss! The cables between the SA/TG and RLB should be good quality, but are nowhere near as critical as the cable between the RLB and the device under test. 4. While measuring the return loss, make minor adjustments to one of the loops to maximize the return loss. Again, ignore the frequency of the return loss dip, it's going to vary slightly as you adjust the loop, just go for maximum return loss at whatever frequency the dip happens to fall at. Keep the screws snugged down well on the loop assembly; if it's not sitting tight and flush in the top of the cavity the tuning will change when you go to tighten the screws later. There's a little chicken-and-egg here; you have to loosen the screws to adjust the loop, but when you tighten them it's going to change it a bit, so you have to emperically find the sweet spot. With most cavities, you should have no problem getting well in excess of 20 dB return loss - shoot for 30 dB if you can, even though at that point uncertainty due to the test equipment's limitations will be dominating the measurement accuracy. 5. Reverse the connections you set up in #2 above. Check to make sure the return loss is still high looking into the other port (it should be). 6. NOW, adjust the resonant frequency using the rod to put the return loss maxima it where you want it (i.e. at your pass frequency). Assuming the cavity was rough-tuned in step #2 above, the return loss should not change as you fine-tune the resonant frequency. 7. THEN, check the insertion loss through the cavity using the SA/TG. It should be fairly close to what you set it to in #1 above; if it's more/less than what you'd like, adjust ONE loop for more/less insertion loss, and then repeat again from step #3. DO NOT adjust the resonant frequency via the tuning rod during this step!!! Unless the cavity was poorly designed, tuned, or handled, the return loss maximum should align very closely with the insertion loss minimum. Once you've properly tuned the cavities individually, then cable them together and re-check return loss and insertion loss. Report back how it goes and what numbers you come up with.
RE: [Repeater-Builder] Sinclair C-Series cable lengths
Jeff, But for the purpose of this exercise, setting the loops, the position of max RL has to be the position of min. IL? No? That's what I said in #7. After you've tuned the cavity to resonance based on RL, you check the IL. The frequency of the RL maxima (dip) should coincide with the insertion loss minima (peak) if everything is done right. I've never used an RLB to set the loops; I've always used an SA/TG. Like I said, you have to use the SA/TG to view the transmission response in order to quantify how much insertion loss you have, and that's why I suggested you rough in the insertion loss initially, and, if necessary, do a second round of tuning if you find, after all's said and done, that the final measured insertion loss is too far off your original target. To say it another way, you coarse-tune the loops targeting your desired insertion loss, then you fine-tune looking at return loss. Note that everything I'm telling you is how to tune up a single cavity. Once you have the two tuned up independently, go ahead and connect them together and report back the results. I also have several different tutorials on cavity tuning, but none even touch on the IL adjustment. I think a lot of manufacturers assume that the field tech has no way of measuring return loss (either with a SNA, VNA, or SA/TG+RLB). So, they put those little stickers near the loops with index marks that indicate (sometimes vaguely) where the loops need to be set to achieve the desired insertion loss, and they assume that the return loss will come out close enough for field work. --- Jeff WN3A
RE: [Repeater-Builder] crimping assistance please
I know this has been thrown around a bit before but I could use a little assistance. Go through the repeater-builder message archive on Yahoo groups. On 7/22/09 I posted a long message on the subject. Basically I am not sure what size hex to use for the above stated RG-58A/U and BNC and TNC connectors. The manufacturer's docs for the connectors will specify which die size to use. *Usually* the ferrule crimp for RG58 is 0.213. The center pin varies a bit between manufacturers. The biggest difference with the center pins is whether or not there is an area for the crimp close to the coax that is smaller diameter than the rest of the cylindrical part of the pin. Personally, I always solder the center pin, especially on cable with a solid center conductor. Also, I have a question regarding stripping the cable. I am not going to be doing high volumes of cables, but probably will be doing them on different size of coax. Would you recommend a stripper or will a razor knife suffice. A good utility knife will suffice with a little practice. Lastly, and relating to the coax strippers: Don't different connectors, even on the same type/size of coax, need different stripping lengths? Sometimes yes. This would probably translate into quite a few different strippers for different cables and connectors, no? Yes, it could. That's why it's worthwhile to standardize on what connectors and tools you use. --- Jeff WN3A
RE: [Repeater-Builder] crimping assistance please
Not from what I've seen/read. Tin/lead and even the newer RoHS-compliant solders don't have ferrous components which is one of the biggest PIM concerns. Besides, just about every device in the RF path has some solder somewhere (cavity loops, integral connectors on equipment, heck even the antenna for most collinears). Suggested reading: http://www.amphenolrf.com/simple/PIM%20Paper.pdf http://www.sinctech.com/pdfs/Intermod.pdf http://www.imscs.com/passive-intermodulation.html I've been considering buying a PIM tester (Boonton PIM 20). If/when I do I guess I could give you my personal conclusion on the matter, but for now, all I have to go by is what I read... Later gator. You going to Dayton? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of allan crites Sent: Monday, April 12, 2010 11:27 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] crimping assistance please Jeff Doesn't soldering of the center contact to the center conductor affect the connector PIM adversely vs not soldering? AC No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.801 / Virus Database: 271.1.1/2792 - Release Date: 04/12/10 02:32:00
RE: [Repeater-Builder] Motorola Micor Part TCN1383A
TLF is 800/900. TLE is UHF, TLD is highband, TLC is midband, TLB is lowband... -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of La Rue Communications Sent: Thursday, April 08, 2010 12:08 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Motorola Micor Part TCN1383A Good suggestion, I might try that. I was under the impression that the part number starting with TLF was indicative of an 800MHz part. Now Im gonna need to try to confirm whether its 800 or UHF. :) John Hymes La Rue Communications 10 S. Aurora Street Stockton, CA 95202 - Original Message - From: DCFluX dcf...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Thursday, April 08, 2010 9:02 AM Subject: Re: [Repeater-Builder] Motorola Micor Part TCN1383A They appear to be tripler / 2W amplifier sections from the Micor station. Possibly UHF. If its like the 2W UHF version you can disconnect and sweep the filter that is attached to the lid with a spectrum analyzer and that will tell you what frequency it is for. On Thu, Apr 8, 2010 at 8:23 AM, La Rue Communications laruec...@gmail.com wrote: Not sure if the pics will show up on the Group List, but here goes. John Hymes La Rue Communications 10 S. Aurora Street Stockton, CA 95202 - Original Message - From: wd8chl wd8...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Wednesday, April 07, 2010 1:42 PM Subject: Re: [Repeater-Builder] Motorola Micor Part TCN1383A On 4/7/2010 4:31 PM, DCFluX wrote: Lets get some pictures Well, TLF would indicate 800 MHz... On Wed, Apr 7, 2010 at 1:12 PM, La Rue Communications laruec...@gmail.comwrote: Eric, No results as the Parts Department says they're obsolete. Duh - tell me something I dont know. I was not able to get any info on the remote chassis, and two triplers that I have. TLF1053A and TLF1332A. Sorry I could not report better news. I will just keep scavaging unless someone else on the RB list has a similar model and can share what they know... Anyone? Bueller? Bueller? John Hymes La Rue Communications 10 S. Aurora Street Stockton, CA 95202 - Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.800 / Virus Database: 271.1.1/2792 - Release Date: 04/07/10 14:32:00
RE: [Repeater-Builder] Re: D-Star (Protocol and Repeaters)
Anyone who is currently building analog AllStar Link repeaters using a DMK URI already has the parts for a D-Star repeater .. assuming your TX and RX will handle GMSK data of your repeater.. This includes many Mastr II stations which seem to be a large portion of the amateur repeater world.. What are people doing about narrowbanding the RF hardware? There's no geo-spectral advantage to be gained by using D-Star/GMSK with a theoretical OBW of 6 kHz when the RF equipment is still wideband (mainly Rx IF, but also Tx must also be limited and LPF'ed). --- Jeff WN3A
RE: [Repeater-Builder] Helix / Connectors
RFS also has aluminum-shield versions of their standard LCF line too - the part numbers all end in L for Lite (such as LCF78-50JL). Aluminum-shielded cable isn't anything new. It's pretty much the standard in CATV, and was quite common in two-way back in the day as well. Andrew, Prodelin, Phelps-Dodge, et al made different flavors of it, both corrugated and smooth-wall, jacketed and unjacketed. I've had way too many problems with aluminum shielded cables to ever consider buying it again. I'll spend the few extra pennies on the good stuff (copper). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bill Smith Sent: Tuesday, March 30, 2010 3:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Helix / Connectors It's what Andrew calls Heliax 2.0 AVA, Andrew Virtual Air and AVAL Andrew Virtual Air Aluminum. They are using a new lower density foam and thinner copper to get slightly improved attenuation. Stay away from the aluminum stuff, the corrugated shield is too thin and brittle. It's hard to install connectors on and it doesn't bend very well. Been there too many times already, got the hat but not the T-Shirt. ;-) Bill KB1MGH DCFluX wrote: The connectors should be fine, I wouldn't trust the aluminum feedline. You may want to try using an anti-oxidation compound, such as No-Ox or Aluminum Ox-Gard during assembly. Aluminum Heliax? Never heard of it. I didn't get the beginning of this thread...
RE: [Repeater-Builder] Helix / Connectors
When you're pricing out 440 feet of coax, the pennies add up to quite a few dollars. Depends on how you look at it. The difference becomes insignificant when you look at the big picture. The price of 440 feet of line is a small fraction of the total project cost once you add in connectors, hoisting grips, ground kits, hangers, weatherproofing, jumpers, plus the cost of the actual antenna, mount, pipe, etc.. Then add in installation labor. By the time all is said and done, the difference in the total project cost for copper versus aluminum ends up being negligible. While the cost of the cable alone may be 15% mroe for copper versus aluminum, the total project cost variation is likely going to be only a few percent. Typical installation, throwing out rough numbers: 440' of 7/8 AL5-50 @ $3/ft = $1320 2 connectors = $60 4 ground kits = $80 2 hoisting grips = $40 100 snap-ins = $150 Antenna = $1000 Mount = $250 Jumpers = $100 Lightning arrestor = $100 Labor = $1500 (lowballed - 3 men @ $500/day) PROJECT TOTAL: $4,600 Vary the cost of the feedline by +15% (the difference in cost between aluminum and copper line), project total becomes $4,798, a bottom-line difference of 4.3%. To me, it's not worth the gamble. One trip up the tower to investigate a problem and you've already blown that tiny differential in cost savings. If we assume that properly-installed Heliax should last 20 years, the aluminum needs to last at least 19 years in order to break even (ignoring inflation). Sure, I'd like to pocket the $200 difference, but I'd much rather sleep well at night knowing that I haven't cut corners. And antennas and feedlines are NOT where you cut corners... Also note that the Al cables have slightly more loss than their Cu counterparts, so there's a slight performance tradeoff as well. By the way, Andrew's prices are going up across-the-board on April 8th (I think that's the right date), so if you're planning on ordering anything, do it sooner rather than later. --- Jeff WN3A
RE: [Repeater-Builder] Service Monitor (HP) calibration
Does anyone know of a place relatively close to CT (or NYC metro area) that does service monitor calibrations? Amtronix (www.amtronix.com) in NY state. Extremely reasonable, top notch service. If shipping it is your concern, call him (Rick) and ask if he can send you a shipping box or transit case specific to your service monitor. --- Jeff WN3A
