Re: [Repeater-Builder] Temp Control Circuit
At 06:50 PM 01/24/08, you wrote: I've been searching for a very simple circuit that could turn on a, maybe, 10 watt resistor at 12 volts, when the temperature drops to perhaps 30F or so. Anyone have a reliable favorite? Laryn K8TVZ Use a simple heating thermostat, available at Home Depot. Have it key a 12v relay, the contacts handle the load current. The auto junkyards have gobs of 12v relays, available for pennies... grab one designed to run a heater fan ,they have 20amp contacts and 100-200ma coils). Mike WA6ILQ
Re: [Repeater-Builder] Gmrs Repeater
On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
How are you checking for desense? Are you using an isolated T between the duplexer and antenna line and doing the same when measuring desense on the dummy load? Are you measuring site noise? Do this the same way you would measure desense with the isolated T in the line. But first see what the receiver sensitivity is with the dummy load connected in place of the antenna. Then replace the dummy load with the antenna, do not key the transmitter, and measure the difference in receiver with the antenna connected verses the dummy load. With TV stations present you may be surprised at the amount of site noise present. Then key the transmitter and again measure receiver sensitivity thru the isolated T. If you haven't done this you may find that a lot of the problem is site noise rather than desense problems. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Stu Benner Sent: Friday, January 25, 2008 12:52 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Desense Problem on 222 MHz Repeater Our group has substantial technical knowledge and experience, but we've been just about beaten down by a problem with our repeater. A brief overview of our situation follows. We have a 222 MHz repeater comprised of a converted Micor mobile, Telewave TPRD-2254 BpBr duplexer, AM-6155 PA modified for class C operation at 250W, and a DB-264JJ antenna at 80 ft. fed by 1/2' Heliax on a commercial FM broadcast tower . With the duplexer terminated into a load, we have about 1 dB degradation in sensitivity when transmitting. However, with the antenna connected to the duplexer, we experience in excess 15 dB of desensitization. We have eliminated other narrowband transmitters and analog TV transmitters as contributing factors. We are left with a channel 12 digital TV transmitter at an adjacent site as a key contributor to the problem. Our hypothesis is that we have broadband IMD products from the mix of our transmitter and the DTV transmitter that are appearing in and near our receiver passband. Is it a rusty bolt problem or is there some other non-linear component somewhere on the site or in our system that is the mixing point - we don't know. I'd be interested in beginning a dialog with anyone who might be able to give us some further insight into this problem. Regards, Stu Benner W3STU Boonsboro, MD
Re: [Repeater-Builder] RC110 Group
As they say... stuff happens. (or words to that effect) :-) Joe M. WD7F - John in Tucson wrote: Yeah, I misread the post and my brain looked at 110 and recorded 210. The 110 is an old controller. So, it was Duh!, I'm an idiot! It has something to do with being 67, I'm sure. de WD7F John in Tucson - Original Message - From: MCH [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 3:48 PM Subject: Re: [Repeater-Builder] RC110 Group That was my first thought, too. But, when someone talks about the dead RC110 group, and you post that you are receiving mail fine from the RC210 group, I guess I'm just too much of an idiot to connect the dots of relevance. Maybe you could do that for me? What does the RC210 group have to do with the RC110 group in terms of activity? Or was your 'Duh!' meant for yourself because you misread the post? Joe M. WD7F - John in Tucson wrote: Duh ! - Original Message - From: MCH [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 3:13 PM Subject: Re: [Repeater-Builder] RC110 Group The 210 group is different than the 110 group. Joe M. WD7F - John in Tucson wrote: Really? I get mail from [RC210] rc210 at yahoogroups.com every day. Wonder what that's about. - Original Message - From: DCFluX To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 11:27 AM Subject: Re: [Repeater-Builder] RC110 Group Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. Never miss a thing. Make Yahoo your homepage. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links
[Repeater-Builder] Re: Stupid Question about Db antennas.
Just so we're singing from the same page, a few comments first. Pointing the dipoles all in one direction, for instance, increases the gain of a DB224 from 6dbd to 9dbd in the favored direction. And off the *back*, there is still a gain of 3dbd. It has a front-to-back ratio of 6db. Useful, but not really a beam. The -3db beamwidth of the front lobe of this beam is somewhere near 180 degrees. So the point is that aiming any one, or several, dipoles toward openings between buildings is probably not going to help huge amounts. Taking your idea a step further, it would be interesting how 3 real beams, fed with a power splitter, would work in this case. Back to the DB224 antennas, the RF lobe maximums aren't always in the direction that the dipoles are facing. As described by an engineer at DB Products, if you point 2 dipoles north, and the other 2 dipoles south, you will end up with a pattern favoring east and west with .75db more gain in those directions than the omni configuration. Must be because east and west both see all four dipoles... Fun, huh? Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, dallasreact112 [EMAIL PROTECTED] wrote: I have a question about the DB base antennas such as the DB-224, DB- 420, etc. As most of you know they consist of folded dipole trombones mounted on the mast at 90 degree angles with a phasing harness to create a omnidirectional pattern. I have heard of pointing the trombones all in one direction to create a beam. My question is has anyone pointed them in other directions? What I'd like to do is point mine in roughly 120 degree slots, to go around downtown bulidings which block the RF path due north, SW and E as we are located on a 40 story builing in the middle of downtown which has taller buildings blocking the aforementioned directions. Essentially what I want to do is beam the signal in to the open slots. 73 and Thanks, Bernie Parker K5BP
Re: [Repeater-Builder] Re: Stupid Question about Db antennas.
Taking your idea a step further, it would be interesting how 3 real beams, fed with a power splitter, would work in this case. There was an article on this many, many years ago about mounting an array of vertically polarized mounted beams (5-6 element I think in pairs) each pair fired tangentially to a face off a very large tower. You had to construct a 6 way custom power splitter (low output impedance) out of copper tubing. I was thinking about maybe building one of these for the tower I have been on for years, a 25-35 ft. wide tower at the heights I have antennas at. But the overall complexity of the system was too much for the eventual system gain achieved I thought. You did get a somewhat omni pattern, although it had a number of ripples around the tower, but the average gain achieved was not the gain of the pair of beams or even of one beam , but less. I would imagine the coax loss contributed some to this, as the length between the pair of beams across this tower was substantial. Plus, there was all that hardware up there to maintain. We have existed for years using dB 224's for 2 meter and 220 just mounting the dipoles for an Omni pattern. The tower is so large that I would imagine that no matter what we did to the antenna pattern, the gain ripple would be large around the tower. Roger W5RD - Original Message - From: Laryn Lohman To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:24 PM Subject: [Repeater-Builder] Re: Stupid Question about Db antennas. Just so we're singing from the same page, a few comments first. Pointing the dipoles all in one direction, for instance, increases the gain of a DB224 from 6dbd to 9dbd in the favored direction. And off the *back*, there is still a gain of 3dbd. It has a front-to-back ratio of 6db. Useful, but not really a beam. The -3db beamwidth of the front lobe of this beam is somewhere near 180 degrees. So the point is that aiming any one, or several, dipoles toward openings between buildings is probably not going to help huge amounts. Taking your idea a step further, it would be interesting how 3 real beams, fed with a power splitter, would work in this case. Back to the DB224 antennas, the RF lobe maximums aren't always in the direction that the dipoles are facing. As described by an engineer at DB Products, if you point 2 dipoles north, and the other 2 dipoles south, you will end up with a pattern favoring east and west with .75db more gain in those directions than the omni configuration. Must be because east and west both see all four dipoles... Fun, huh? Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, dallasreact112 [EMAIL PROTECTED] wrote: I have a question about the DB base antennas such as the DB-224, DB- 420, etc. As most of you know they consist of folded dipole trombones mounted on the mast at 90 degree angles with a phasing harness to create a omnidirectional pattern. I have heard of pointing the trombones all in one direction to create a beam. My question is has anyone pointed them in other directions? What I'd like to do is point mine in roughly 120 degree slots, to go around downtown bulidings which block the RF path due north, SW and E as we are located on a 40 story builing in the middle of downtown which has taller buildings blocking the aforementioned directions. Essentially what I want to do is beam the signal in to the open slots. 73 and Thanks, Bernie Parker K5BP -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.9/1239 - Release Date: 1/23/2008 10:24 AM
[Repeater-Builder] Re: Desense Problem on 222 MHz Repeater
This question has initiated an interesting exchange of ideas. Many good suggestions have been provided. The fact that the desensitization exists when operating duplex on either of two antennas, or when using split antennas, combined with the results of the other tests [minimal desensitization on a dummy load, measured duplexer isolation, etc.] suggests that the initial concern may be true - that the issue is related to an external mix between the repeater transmitter and the DTV signal. Issues related to IM between narrow band and wide band systems will be a growing concern as more services convert to digital formats. There is not a great deal of published guidance regarding the identification and resolution of such issues. The use of a spectrum analyzer at the receiver port of the duplexer is a good place to continue the investigation. The problem with this test is that the mix between the repeater transmitter and the DTV will produce a wide band product. Wide band digital transmissions are noise like in character and must be observed using techniques that one uses to analyze noise. [see Agilent AN150, AN150-4, AN150-7, and AN1303] You did not indicate the instrument used to make the tests or the instrument settings and configuration. The issue is that a spectrum analyzer may not be able to see the problem. The noise figure of the spectrum analyzer could be on the order of 30 dB or more. On the other hand, the repeater receiver's noise figure will be less than 10 dB. The noise figure of your analyzer can be easily determined. Modern analyzers have a noise marker function. If you activate this function with the analyzer's input terminated with a 50 ohm load, you will get a result based on the analyzer's internal noise. The readout will be in the form of dBm per Hz. This metric is used because it is independent of bandwidth. Regardless of the currently selected analyzer RBW, the analyzer's processor will compute the noise marker to yield the same result. The difference between this number and the thermal noise floor [kTB] of -174 dBm/Hz is the analyzer's noise figure. Based on the receiver's sensitivity [and hence its noise figure], it will have an inferred noise floor. Noise which enters the receiver through the antenna port will add to this noise floor resulting in degradation of your effective receiver sensitivity. This external noise will be comprised of site noise, sideband noise from your own transmitter and any IM between your transmitter and the DTV signal. This new noise level can be determined based on the amount of desensitization you have measured. Based on your measurements, the new noise level will still be perhaps 10 dB below the ability of the spectrum analyzer to observe due to its much higher noise figure. The ability of the spectrum analyzer to see noise can be enhanced through the use of a high gain low noise amplifier such as the Agilent 11909A. The LNA and the spectrum analyzer combine to comprise a receiving system with a much lower noise figure than the analyzer alone - lower even than your repeater receiver. This will allow you to see the noise that is causing the issue. [Unfortunately - you still have to figure out where the noise originates] Some analyzers have a built in preamp. Generally these are optimized for display flatness and have a lower gain than an external amplifier. The use of an internal amplifier will improve the analyzer's noise figure but not to the extent that an external high gain amp can. This improvement may be sufficient or not depending on the specific instrument and the noise level you are attempting to measure. The use of the LNA has tradeoffs in the form of reduced dynamic range and reduced IM performance of the analyzer. Additional selectivity may be required ahead of the LNA.
RE: [Repeater-Builder] Re: Desense Problem on 222 MHz Repeater
I think you may have overlooked the fact that desense was observed even when a dummy load was connected directly to the output of the duplexer. That pretty much eliminates anything external to the repeater itself, doesn't it? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of nj902 Sent: Friday, January 25, 2008 8:48 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Desense Problem on 222 MHz Repeater This question has initiated an interesting exchange of ideas. Many good suggestions have been provided. The fact that the desensitization exists when operating duplex on either of two antennas, or when using split antennas, combined with the results of the other tests [minimal desensitization on a dummy load, measured duplexer isolation, etc.] suggests that the initial concern may be true - that the issue is related to an external mix between the repeater transmitter and the DTV signal. Issues related to IM between narrow band and wide band systems will be a growing concern as more services convert to digital formats. There is not a great deal of published guidance regarding the identification and resolution of such issues. The use of a spectrum analyzer at the receiver port of the duplexer is a good place to continue the investigation. The problem with this test is that the mix between the repeater transmitter and the DTV will produce a wide band product. Wide band digital transmissions are noise like in character and must be observed using techniques that one uses to analyze noise. [see Agilent AN150, AN150-4, AN150-7, and AN1303] You did not indicate the instrument used to make the tests or the instrument settings and configuration. The issue is that a spectrum analyzer may not be able to see the problem. The noise figure of the spectrum analyzer could be on the order of 30 dB or more. On the other hand, the repeater receiver's noise figure will be less than 10 dB. The noise figure of your analyzer can be easily determined. Modern analyzers have a noise marker function. If you activate this function with the analyzer's input terminated with a 50 ohm load, you will get a result based on the analyzer's internal noise. The readout will be in the form of dBm per Hz. This metric is used because it is independent of bandwidth. Regardless of the currently selected analyzer RBW, the analyzer's processor will compute the noise marker to yield the same result. The difference between this number and the thermal noise floor [kTB] of -174 dBm/Hz is the analyzer's noise figure. Based on the receiver's sensitivity [and hence its noise figure], it will have an inferred noise floor. Noise which enters the receiver through the antenna port will add to this noise floor resulting in degradation of your effective receiver sensitivity. This external noise will be comprised of site noise, sideband noise from your own transmitter and any IM between your transmitter and the DTV signal. This new noise level can be determined based on the amount of desensitization you have measured. Based on your measurements, the new noise level will still be perhaps 10 dB below the ability of the spectrum analyzer to observe due to its much higher noise figure. The ability of the spectrum analyzer to see noise can be enhanced through the use of a high gain low noise amplifier such as the Agilent 11909A. The LNA and the spectrum analyzer combine to comprise a receiving system with a much lower noise figure than the analyzer alone - lower even than your repeater receiver. This will allow you to see the noise that is causing the issue. [Unfortunately - you still have to figure out where the noise originates] Some analyzers have a built in preamp. Generally these are optimized for display flatness and have a lower gain than an external amplifier. The use of an internal amplifier will improve the analyzer's noise figure but not to the extent that an external high gain amp can. This improvement may be sufficient or not depending on the specific instrument and the noise level you are attempting to measure. The use of the LNA has tradeoffs in the form of reduced dynamic range and reduced IM performance of the analyzer. Additional selectivity may be required ahead of the LNA.
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Just make sure to pull the unused loop out of the cavity. Steve / K6SCA Gary Schafer [EMAIL PROTECTED] wrote: If you have an extra band pass cavity then you also have a notch cavity. Just connect a T to one port of the band pass cavity and ignore the other port on the cavity. This will work as a notch cavity for your testing. 73 Gary K4FMX - From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Stu Benner Sent: Friday, January 25, 2008 4:54 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater Thanks to everyone for the replies so far. Please see comments embedded below. I think that they address most of the comments, questions, and recommendations posed by all to this point. If you suspect IMD between the channel 12 DTV transmitter and your Tx carrier, work on attenuating the DTV signal. Using cavity notch filters to reject the entire 6 MHz of DTV isn't too practical, so instead, try adding pass cavities on your Tx before the duplexer input. That will help determine if the IM is originating in your PA. An isolator *may* help, but with channel 12 being the better part of 20 MHz away (about 10%), it may not afford full protection -- isolators don't have infinite bandwidth. Likewise, finding a 250 watt 220 MHz isolator may not be easy. I think I have some 220 isolators that came off a combiner (Sinclair), but doubt they're good for 250 watts judging by their size. [Stu] Agree, notches don't work well for that plus we don't have handy any cavities that will tune there. Have used up to two BP cavities in the TX path along with a 2-stage isolator. No difference in desense is observed. If you suspect a rusty bolt mix, use an alternate antenna for testing. If nothing else, try a quarter-wave whip (suitable for operation at your 250 watts TPO), even if it's just temporarily mounted on the tower (be sure it's at a sufficient height to prevent desense due to close proximity to the repeater itself). [Stu] We're presently on split antennas. One is at about 80 ft., the other is at about 15 ft. This improves the desense on the order of 6 dB. Another good possibility is IM in your receiver front end (or preamp, if you're using one). Again, pass cavities are your friend here. Attenuate the channel 12 signal as much as possible and see if it makes a difference. Have you looked at what sigs are reaching your receiver input on a spectrum analyzer? With 15 dB of desense, you should be able to see the culprit(s); it's not like they're going to be buried in the noise if it's causing 15 dB of desense. [Stu] The desense is significant with or without a preamp. Worse with but I can't find my notes to quote numbers. Used up to 2 BP cavities on RX with no perceptable difference in desense. Have also installed a DCI 4-pole filter on RX and TX with no effect. Have looked at the receiver input with a spectrum analyzer. The most significant signal is the one FM broadcast transmitter at the site. Running power down on it or turning it off has no effect on the desense. Our TX signal at our RX input is consistent with our measured duplexer isolation (about -88 dBc or -34 dBm). Within several hundred kHz of the RX frequency there are no detectable narrowband signals. Even that 1 dB of desense would give me some agita. I'd verify that the duplexers are properly tuned and the transmitter is clean before even starting down any other paths related to the channel 12 issue. IIRC, the Telewave cavities have adjustable coupling. If necessary, sacrifice a little extra loss for additional rejection if necessary. [Stu] I tuned the duplexer myself with a network analyzer and the transmitter looks clean. I have coupling set where I get about 1 dB through loss and the notches are at about 88 dB on TX and about 90 dB on RX. I also assume you're using all known-good interconnect cables (no foil+braid or other cables not suitable for duplex operation). [Stu] All cables are either Heliax or double braided. Are you using a Polyphaser or other type of surge arrestor? If so, try bypassing it. I've seen gas discharge tube type surge arrestors become noisemakers after absorbing a strike. [Stu] Yes but there is no difference in desense when it is removed. Has the VSWR changed at all on your antenna? If so, it could indicate water in a connector or the harness which will cause all kinds of grief, including wideband noise. [Stu] The problem has existed since the repeater was installed. It exists whether we duplex on a DB264 at 80 feet or a G7-220 at 15 feet, both fed with Heliax Finally, does the desense change appreciably if you vary transmitter power output (it probably will). Do you any have desense when running on just exciter power? [Stu] The desense is roughly proportional to transmit power. Barely perceptable at 20W (exciter only) with
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
If you have an extra band pass cavity then you also have a notch cavity. Just connect a T to one port of the band pass cavity and ignore the other port on the cavity. This will work as a notch cavity for your testing. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Stu Benner Sent: Friday, January 25, 2008 4:54 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater Thanks to everyone for the replies so far. Please see comments embedded below. I think that they address most of the comments, questions, and recommendations posed by all to this point. If you suspect IMD between the channel 12 DTV transmitter and your Tx carrier, work on attenuating the DTV signal. Using cavity notch filters to reject the entire 6 MHz of DTV isn't too practical, so instead, try adding pass cavities on your Tx before the duplexer input. That will help determine if the IM is originating in your PA. An isolator *may* help, but with channel 12 being the better part of 20 MHz away (about 10%), it may not afford full protection -- isolators don't have infinite bandwidth. Likewise, finding a 250 watt 220 MHz isolator may not be easy. I think I have some 220 isolators that came off a combiner (Sinclair), but doubt they're good for 250 watts judging by their size. [Stu] Agree, notches don't work well for that plus we don't have handy any cavities that will tune there. Have used up to two BP cavities in the TX path along with a 2-stage isolator. No difference in desense is observed. If you suspect a rusty bolt mix, use an alternate antenna for testing. If nothing else, try a quarter-wave whip (suitable for operation at your 250 watts TPO), even if it's just temporarily mounted on the tower (be sure it's at a sufficient height to prevent desense due to close proximity to the repeater itself). [Stu] We're presently on split antennas. One is at about 80 ft., the other is at about 15 ft. This improves the desense on the order of 6 dB. Another good possibility is IM in your receiver front end (or preamp, if you're using one). Again, pass cavities are your friend here. Attenuate the channel 12 signal as much as possible and see if it makes a difference. Have you looked at what sigs are reaching your receiver input on a spectrum analyzer? With 15 dB of desense, you should be able to see the culprit(s); it's not like they're going to be buried in the noise if it's causing 15 dB of desense. [Stu] The desense is significant with or without a preamp. Worse with but I can't find my notes to quote numbers. Used up to 2 BP cavities on RX with no perceptable difference in desense. Have also installed a DCI 4-pole filter on RX and TX with no effect. Have looked at the receiver input with a spectrum analyzer. The most significant signal is the one FM broadcast transmitter at the site. Running power down on it or turning it off has no effect on the desense. Our TX signal at our RX input is consistent with our measured duplexer isolation (about -88 dBc or -34 dBm). Within several hundred kHz of the RX frequency there are no detectable narrowband signals. Even that 1 dB of desense would give me some agita. I'd verify that the duplexers are properly tuned and the transmitter is clean before even starting down any other paths related to the channel 12 issue. IIRC, the Telewave cavities have adjustable coupling. If necessary, sacrifice a little extra loss for additional rejection if necessary. [Stu] I tuned the duplexer myself with a network analyzer and the transmitter looks clean. I have coupling set where I get about 1 dB through loss and the notches are at about 88 dB on TX and about 90 dB on RX. I also assume you're using all known-good interconnect cables (no foil+braid or other cables not suitable for duplex operation). [Stu] All cables are either Heliax or double braided. Are you using a Polyphaser or other type of surge arrestor? If so, try bypassing it. I've seen gas discharge tube type surge arrestors become noisemakers after absorbing a strike. [Stu] Yes but there is no difference in desense when it is removed. Has the VSWR changed at all on your antenna? If so, it could indicate water in a connector or the harness which will cause all kinds of grief, including wideband noise. [Stu] The problem has existed since the repeater was installed. It exists whether we duplex on a DB264 at 80 feet or a G7-220 at 15 feet, both fed with Heliax Finally, does the desense change appreciably if you vary transmitter power output (it probably will). Do you any have desense when running on just exciter power? [Stu] The desense is roughly proportional to transmit power. Barely perceptable at 20W (exciter only) with split antennas. A little worse at 20W (exciter only) using one antenna. Have tried both tube-type and solid state amplifiers at various power levels. --- Jeff WN3A
Re: [Repeater-Builder] RC110 Group
Yeah, I misread the post and my brain looked at 110 and recorded 210. The 110 is an old controller. So, it was Duh!, I'm an idiot! It has something to do with being 67, I'm sure. de WD7F John in Tucson - Original Message - From: MCH [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 3:48 PM Subject: Re: [Repeater-Builder] RC110 Group That was my first thought, too. But, when someone talks about the dead RC110 group, and you post that you are receiving mail fine from the RC210 group, I guess I'm just too much of an idiot to connect the dots of relevance. Maybe you could do that for me? What does the RC210 group have to do with the RC110 group in terms of activity? Or was your 'Duh!' meant for yourself because you misread the post? Joe M. WD7F - John in Tucson wrote: Duh ! - Original Message - From: MCH [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 3:13 PM Subject: Re: [Repeater-Builder] RC110 Group The 210 group is different than the 110 group. Joe M. WD7F - John in Tucson wrote: Really? I get mail from [RC210] rc210 at yahoogroups.com every day. Wonder what that's about. - Original Message - From: DCFluX To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 11:27 AM Subject: Re: [Repeater-Builder] RC110 Group Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. Never miss a thing. Make Yahoo your homepage. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Desense Problem on 222 MHz Repeater
One issue may very well be the insufficient isolation considering the TX power level. If you really want to run that much power I'd highly recommend having bandpass filter(s) between the PA and the duplexer - this will help reduce broadband noise from the PA. Bandpass filter(s) between the receiver and the duplexer can't hurt either - especially if you're using a pre-amp on the receiver. Oh, another thing - if the receiver natively has a sensitivity of .2uV or better the pre-amp may not help anything but raise the noise floor. If this repeater site is relatively close to (within several miles) of a TV channel 12 or 13 (analog or digital) I'd STRONGLY recommend installing a window filter on the antenna side of the duplexer. The window filter will greatly reduce the out of band signal levels for both the transmitter receiver which will reduce and/or eliminate any IMD issues from those sources. DCI is one manufacturer of window filters for HAM bands (www.dci.ca). Some folks get all weird about inserting so many filters because they don't want all that loss. What they don't realize is even with an additional 3dB of IL if it lowers the noise floor for the repeater system by 20dB you've made a HUGE improvement in the overall performance. Also, by having 250W transmit power you can easily take a hit and still have a respectable ERP. Good luck and remember.your mileage may vary. 73 Richard
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Stu, It looks to me as if you have covered almost all of the bases, and have eliminated every one of the typical causes of desense. However, there is one possibility that has not been mentioned: Leakage inside the Micor radio. Even with a careful duplex conversion, there are several sneak paths for extraneous signals to enter the Micor receiver. One ingress point is the tiny slots around the RCA plug at the input to the helical resonator block. A wrap of metal tape around that plug will seal the plug. Additional bypass capacitors and ferrite beads on DC supply leads may help. Try using a separate DC power supply for the receiver. Moreover, I suspect that the receiver needs more shielding. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Stu Benner Sent: Friday, January 25, 2008 1:54 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater Thanks to everyone for the replies so far. Please see comments embedded below. I think that they address most of the comments, questions, and recommendations posed by all to this point. If you suspect IMD between the channel 12 DTV transmitter and your Tx carrier, work on attenuating the DTV signal. Using cavity notch filters to reject the entire 6 MHz of DTV isn't too practical, so instead, try adding pass cavities on your Tx before the duplexer input. That will help determine if the IM is originating in your PA. An isolator *may* help, but with channel 12 being the better part of 20 MHz away (about 10%), it may not afford full protection -- isolators don't have infinite bandwidth. Likewise, finding a 250 watt 220 MHz isolator may not be easy. I think I have some 220 isolators that came off a combiner (Sinclair), but doubt they're good for 250 watts judging by their size. [Stu] Agree, notches don't work well for that plus we don't have handy any cavities that will tune there. Have used up to two BP cavities in the TX path along with a 2-stage isolator. No difference in desense is observed. If you suspect a rusty bolt mix, use an alternate antenna for testing. If nothing else, try a quarter-wave whip (suitable for operation at your 250 watts TPO), even if it's just temporarily mounted on the tower (be sure it's at a sufficient height to prevent desense due to close proximity to the repeater itself). [Stu] We're presently on split antennas. One is at about 80 ft., the other is at about 15 ft. This improves the desense on the order of 6 dB. Another good possibility is IM in your receiver front end (or preamp, if you're using one). Again, pass cavities are your friend here. Attenuate the channel 12 signal as much as possible and see if it makes a difference. Have you looked at what sigs are reaching your receiver input on a spectrum analyzer? With 15 dB of desense, you should be able to see the culprit(s); it's not like they're going to be buried in the noise if it's causing 15 dB of desense. [Stu] The desense is significant with or without a preamp. Worse with but I can't find my notes to quote numbers. Used up to 2 BP cavities on RX with no perceptible difference in desense. Have also installed a DCI 4-pole filter on RX and TX with no effect. Have looked at the receiver input with a spectrum analyzer. The most significant signal is the one FM broadcast transmitter at the site. Running power down on it or turning it off has no effect on the desense. Our TX signal at our RX input is consistent with our measured duplexer isolation (about -88 dBc or -34 dBm). Within several hundred kHz of the RX frequency there are no detectable narrowband signals. Even that 1 dB of desense would give me some agita. I'd verify that the duplexers are properly tuned and the transmitter is clean before even starting down any other paths related to the channel 12 issue. IIRC, the Telewave cavities have adjustable coupling. If necessary, sacrifice a little extra loss for additional rejection if necessary. [Stu] I tuned the duplexer myself with a network analyzer and the transmitter looks clean. I have coupling set where I get about 1 dB through loss and the notches are at about 88 dB on TX and about 90 dB on RX. I also assume you're using all known-good interconnect cables (no foil+braid or other cables not suitable for duplex operation). [Stu] All cables are either Heliax or double braided. Are you using a Polyphaser or other type of surge arrestor? If so, try bypassing it. I've seen gas discharge tube type surge arrestors become noisemakers after absorbing a strike. [Stu] Yes
Re: [Repeater-Builder] RC110 Group
That was my first thought, too. But, when someone talks about the dead RC110 group, and you post that you are receiving mail fine from the RC210 group, I guess I'm just too much of an idiot to connect the dots of relevance. Maybe you could do that for me? What does the RC210 group have to do with the RC110 group in terms of activity? Or was your 'Duh!' meant for yourself because you misread the post? Joe M. WD7F - John in Tucson wrote: Duh ! - Original Message - From: MCH [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 3:13 PM Subject: Re: [Repeater-Builder] RC110 Group The 210 group is different than the 110 group. Joe M. WD7F - John in Tucson wrote: Really? I get mail from [RC210] rc210 at yahoogroups.com every day. Wonder what that's about. - Original Message - From: DCFluX To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 11:27 AM Subject: Re: [Repeater-Builder] RC110 Group Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. Never miss a thing. Make Yahoo your homepage. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links
Re: [Repeater-Builder] Stupid Question about Db antennas.
It should not matter what direction(s) they are pointed in. As you said, they can be changed from omni (all 4 directions) to all in one direction without changing anything else. It's all the same antenna. You can point two in one direction and the other two 90 degrees off those and leave a null in the one direction. Joe M. dallasreact112 wrote: I have a question about the DB base antennas such as the DB-224, DB- 420, etc. As most of you know they consist of folded dipole trombones mounted on the mast at 90 degree angles with a phasing harness to create a omnidirectional pattern. I have heard of pointing the trombones all in one direction to create a beam. My question is has anyone pointed them in other directions? What I'd like to do is point mine in roughly 120 degree slots, to go around downtown bulidings which block the RF path due north, SW and E as we are located on a 40 story builing in the middle of downtown which has taller buildings blocking the aforementioned directions. Essentially what I want to do is beam the signal in to the open slots. 73 and Thanks, Bernie Parker K5BP Yahoo! Groups Links
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
--- Eric Lemmon [EMAIL PROTECTED] wrote: Stu, I think 250 watts is far too much power for that duplexer to properly isolate. Try running just your exciter, or try no more than 30 watts or so. My 220 repeater runs just 18 watts, and it is almost perfectly balanced. I am using the same Telewave duplexer, and I have zero desense. According to my CommShop program, you need more than 90 dB of isolation for 250 watts TX and 0.25 uV RX- and that's assuming a tube amplifier. The Telewave TPRD-2254 duplexer is spec'd at 85 dB, so it is borderline, even when perfectly tuned. You might try a sharply-tuned bandpass cavity to clean up the transmitter output, to see if sideband noise is causing the desense. Also, try a bandpass cavity on the RX input. As has been explained many times on this list, a BpBr duplexer has practically no bandpass effect, and what little effect there is, is very broad. 73, Eric Lemmon WB6FLY That was my thoughts also. Seems too much power for the ammount of isolation. Especially if a preamp is used on the receiver. I would like to know the modifications to the amplifier to get it to run that much power in repeater operation. I have one that will run around 500 watts but use it for ssb. As this was origionaly a 50 watt AM amp, I might see it running 100 to maybe 150 watts out in FM repeater service. Inside the amp are several pieces of coax. Is this double shielded or has it been changed to double shielding ? Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Stu, I think 250 watts is far too much power for that duplexer to properly isolate. Try running just your exciter, or try no more than 30 watts or so. My 220 repeater runs just 18 watts, and it is almost perfectly balanced. I am using the same Telewave duplexer, and I have zero desense. According to my CommShop program, you need more than 90 dB of isolation for 250 watts TX and 0.25 uV RX- and that's assuming a tube amplifier. The Telewave TPRD-2254 duplexer is spec'd at 85 dB, so it is borderline, even when perfectly tuned. You might try a sharply-tuned bandpass cavity to clean up the transmitter output, to see if sideband noise is causing the desense. Also, try a bandpass cavity on the RX input. As has been explained many times on this list, a BpBr duplexer has practically no bandpass effect, and what little effect there is, is very broad. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Stu Benner Sent: Friday, January 25, 2008 9:52 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Desense Problem on 222 MHz Repeater Our group has substantial technical knowledge and experience, but we've been just about beaten down by a problem with our repeater. A brief overview of our situation follows. We have a 222 MHz repeater comprised of a converted Micor mobile, Telewave TPRD-2254 BpBr duplexer, AM-6155 PA modified for class C operation at 250W, and a DB-264JJ antenna at 80 ft. fed by 1/2' Heliax on a commercial FM broadcast tower . With the duplexer terminated into a load, we have about 1 dB degradation in sensitivity when transmitting. However, with the antenna connected to the duplexer, we experience in excess 15 dB of desensitization. We have eliminated other narrowband transmitters and analog TV transmitters as contributing factors. We are left with a channel 12 digital TV transmitter at an adjacent site as a key contributor to the problem. Our hypothesis is that we have broadband IMD products from the mix of our transmitter and the DTV transmitter that are appearing in and near our receiver passband. Is it a rusty bolt problem or is there some other non-linear component somewhere on the site or in our system that is the mixing point - we don't know. I'd be interested in beginning a dialog with anyone who might be able to give us some further insight into this problem. Regards, Stu Benner W3STU Boonsboro, MD
Re: [Repeater-Builder] RC110 Group
Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - *From:* Jim Brown [EMAIL PROTECTED] *To:* Repeater-Builder@yahoogroups.com *Sent:* Friday, January 25, 2008 8:36 AM *Subject:* Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT *DCFluX [EMAIL PROTECTED]* wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. -- Never miss a thing. Make Yahoo your homepage.http://us.rd.yahoo.com/evt=51438/*http://www.yahoo.com/r/hs -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM
Re: [Repeater-Builder] RC110 Group
Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. Never miss a thing. Make Yahoo your homepage. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM
Re: [Repeater-Builder] Gmrs Repeater
That's kind of a harsh statement! I know more GMRS users that are hams than are not. Many of us use GMRS so we can get others such as family members on the air and maybe they'll get interested and get a ticket. Others may know enough but simply have no desire to become hams. Many users are Fire and emergency notification nets. I can communicate with my non ham family using my same gear that I use on Ham. Craig PS, my friend who is a non ham, but a GMRS user has a PHD in Physics and a is a digital electronics design engineer! Probably knows enough. -- Original message -- From: Jack Hayes [EMAIL PROTECTED] There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question. The Desktrac is 40 (pardon my typo) 73 Jack Kris Kirby [EMAIL PROTECTED] wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly - Looking for last minute shopping deals? Find them fast with Yahoo! Search. ---BeginMessage--- There are certainly exceptions but most people I know who do GMRSdidn't know enuf to pass a ham test -- which is the reason for my question.The Desktrac is 40 (pardon my typo)73Jack Kris Kirby [EMAIL PROTECTED]us wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED]net wrote: "I can't imagine why you'd want to go to the trouble of building a GMRS repeater."It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. "Why do you keep hitting your head on your desk?" "Because it feels so good when I stop." ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED]us But remember, with no superpowers comes no responsibility.--rly Looking for last minute shopping deals? Find them fast with Yahoo! Search. ---End Message---
Re: [Repeater-Builder] Re: Motorola Micor UHF repeater manual
Thanks, Paul, and all others for the replies. Still looking for that common sense. Let you know when I find it. Matt - Original Message From: Paul Finch [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, January 24, 2008 8:20:13 PM Subject: RE: [Repeater-Builder] Re: Motorola Micor UHF repeater manual Matt and Group, I will be taking a bunch of Motorola manuals to Dayton, if you are there look me up. Besides the manuals I will have several Micor base stations, the 100 watt variety as well as test bench equipment like Motorola test panels, cables and things like that. I do not know my slot numbers but will let everyone know when I find out. Will also have a few GE Mastr II desktop base stations that are great for low power backyard repeater service. Contact me directly if interested and I will keep you informed. Moderators, if this is a No no let me know. Thanks, Paul WB5IDM -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Randy Sent: Thursday, January 24, 2008 5:43 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Motorola Micor UHF repeater manual If you guys had some common sense and try searching for the products you need, you would'nt have to wait for someone elses answer. Further the more, you can do exactly what your asking someone else to do. .. .. http://www.wiscomm.com/manuals.htm http://idenphones.motorola.com/iden/support/support_product_manuals_ma in.jsp .. .. .. In Repeater-Builder@yahoogroups.com, avelectron1 [EMAIL PROTECTED] wrote: I'm looking for any manuals pertaining to the Micor UHF repeaters. My specific model # is B84RCB-3106AT. Motorola parts says all manuals are NLA...not sure I believe them but thought I'd see if anyone has any available also. Thanks, Matt/KY5O Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1240 - Release Date: 1/23/2008 5:47 PM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1240 - Release Date: 1/23/2008 5:47 PM Yahoo! Groups Links Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs
Re: [Repeater-Builder] Gmrs Repeater
There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question. The Desktrac is 40 (pardon my typo) 73 Jack Kris Kirby [EMAIL PROTECTED] wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly - Looking for last minute shopping deals? Find them fast with Yahoo! Search.
[Repeater-Builder] Re: Motorola Vibrasponder needed
TRY: http://home.comcast.net/~msr2000/ or Panik Electronics In Repeater-Builder@yahoogroups.com, hapgriffin01 [EMAIL PROTECTED] wrote: I'm looking for a 100.0 Hz Vibrasponder for a MSR-2000 PL Module TRN5075A. Can anyone help? Hap Griffin WZ4O
Re: [Repeater-Builder] RC110 Group
The 210 group is different than the 110 group. Joe M. WD7F - John in Tucson wrote: Really? I get mail from [RC210] rc210 at yahoogroups.com every day. Wonder what that's about. - Original Message - From: DCFluX To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 11:27 AM Subject: Re: [Repeater-Builder] RC110 Group Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. Never miss a thing. Make Yahoo your homepage. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM
[Repeater-Builder] Stupid Question about Db antennas.
I have a question about the DB base antennas such as the DB-224, DB- 420, etc. As most of you know they consist of folded dipole trombones mounted on the mast at 90 degree angles with a phasing harness to create a omnidirectional pattern. I have heard of pointing the trombones all in one direction to create a beam. My question is has anyone pointed them in other directions? What I'd like to do is point mine in roughly 120 degree slots, to go around downtown bulidings which block the RF path due north, SW and E as we are located on a 40 story builing in the middle of downtown which has taller buildings blocking the aforementioned directions. Essentially what I want to do is beam the signal in to the open slots. 73 and Thanks, Bernie Parker K5BP
Re: [Repeater-Builder] RC110 Group
Really? I get mail from [RC210] rc210 at yahoogroups.com every day. Wonder what that's about. - Original Message - From: DCFluX To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 11:27 AM Subject: Re: [Repeater-Builder] RC110 Group Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. -- Never miss a thing. Make Yahoo your homepage. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM
Re: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Couple of thoughts from one who is not to technically oriented. 1. Have you tried putting any notch filters between the duplexer and rcvr. to notch the TX freq. ? 2. Have you checked all of your cables and heliax connecters for proper installation ? I only ask this because I was having erratic performance and desense on a 440 rptr. and found some bad duplexer cable connector installations when I started wiggling and moving them around. Another time while checking Fwd/Ref. power and SWR on o 160' peice of 1/2 heliax that I thought was good (and getting satisfactory readings on my Bird mtr.), I pulled the connectors of each end to inspect them. I found one connector had been improperly installed, the heliax shield had been twisted inside the connector to the point where it was almost touching the center conductor. Even though there was no direct contact between shield and the center conductor the RF on xmit. was desensing the rcvr. when the xmtr. keyed up. Reinstalling the bad cables and connectors solve the desense problem for me. -- Doug N3DAB/WPRX486/WPJL709 Stu Benner [EMAIL PROTECTED] wrote: = Our group has substantial technical knowledge and experience, but we've been just about beaten down by a problem with our repeater. A brief overview of our situation follows. We have a 222 MHz repeater comprised of a converted Micor mobile, Telewave TPRD-2254 BpBr duplexer, AM-6155 PA modified for class C operation at 250W, and a DB-264JJ antenna at 80 ft. fed by 1/2' Heliax on a commercial FM broadcast tower . With the duplexer terminated into a load, we have about 1 dB degradation in sensitivity when transmitting. However, with the antenna connected to the duplexer, we experience in excess 15 dB of desensitization. We have eliminated other narrowband transmitters and analog TV transmitters as contributing factors. We are left with a channel 12 digital TV transmitter at an adjacent site as a key contributor to the problem. Our hypothesis is that we have broadband IMD products from the mix of our transmitter and the DTV transmitter that are appearing in and near our receiver passband. Is it a rusty bolt problem or is there some other non-linear component somewhere on the site or in our system that is the mixing point - we don't know. I'd be interested in beginning a dialog with anyone who might be able to give us some further insight into this problem. Regards, Stu Benner W3STU Boonsboro, MD
Re: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Hey Jeff: I think there are some out there that might question agita. Haven't heard that term in a while (and don't want to have it). Ciao, Tony Jeff DePolo wrote: We have a 222 MHz repeater comprised of a converted Micor mobile, Telewave TPRD-2254 BpBr duplexer, AM-6155 PA modified for class C operation at 250W, and a DB-264JJ antenna at 80 ft. fed by 1/2' Heliax on a commercial FM broadcast tower . With the duplexer terminated into a load, we have about 1 dB degradation in sensitivity when transmitting. However, with the antenna connected to the duplexer, we experience in excess 15 dB of desensitization. We have eliminated other narrowband transmitters and analog TV transmitters as contributing factors. We are left with a channel 12 digital TV transmitter at an adjacent site as a key contributor to the problem. Our hypothesis is that we have broadband IMD products from the mix of our transmitter and the DTV transmitter that are appearing in and near our receiver passband. Is it a rusty bolt problem or is there some other non-linear component somewhere on the site or in our system that is the mixing point - we don't know. If you suspect IMD between the channel 12 DTV transmitter and your Tx carrier, work on attenuating the DTV signal. Using cavity notch filters to reject the entire 6 MHz of DTV isn't too practical, so instead, try adding pass cavities on your Tx before the duplexer input. That will help determine if the IM is originating in your PA. An isolator *may* help, but with channel 12 being the better part of 20 MHz away (about 10%), it may not afford full protection -- isolators don't have infinite bandwidth. Likewise, finding a 250 watt 220 MHz isolator may not be easy. I think I have some 220 isolators that came off a combiner (Sinclair), but doubt they're good for 250 watts judging by their size. If you suspect a rusty bolt mix, use an alternate antenna for testing. If nothing else, try a quarter-wave whip (suitable for operation at your 250 watts TPO), even if it's just temporarily mounted on the tower (be sure it's at a sufficient height to prevent desense due to close proximity to the repeater itself). Another good possibility is IM in your receiver front end (or preamp, if you're using one). Again, pass cavities are your friend here. Attenuate the channel 12 signal as much as possible and see if it makes a difference. Have you looked at what sigs are reaching your receiver input on a spectrum analyzer? With 15 dB of desense, you should be able to see the culprit(s); it's not like they're going to be buried in the noise if it's causing 15 dB of desense. Even that 1 dB of desense would give me some agita. I'd verify that the duplexers are properly tuned and the transmitter is clean before even starting down any other paths related to the channel 12 issue. IIRC, the Telewave cavities have adjustable coupling. If necessary, sacrifice a little extra loss for additional rejection if necessary. I also assume you're using all known-good interconnect cables (no foil+braid or other cables not suitable for duplex operation). Are you using a Polyphaser or other type of surge arrestor? If so, try bypassing it. I've seen gas discharge tube type surge arrestors become noisemakers after absorbing a strike. Has the VSWR changed at all on your antenna? If so, it could indicate water in a connector or the harness which will cause all kinds of grief, including wideband noise. Finally, does the desense change appreciably if you vary transmitter power output (it probably will). Do you any have desense when running on just exciter power? --- Jeff WN3A Yahoo! Groups Links
[Repeater-Builder] EF Johnson CR1010 Crystal Replacement
I have a CR1010 repeater that needs to have new crystals installed to change the frequency from 451.200 to 451.250 on the TX and 456.200 to 456.250 on the Rx. I tried to get crystals from EF Johnson and they said they no longer support this repeater. I then tried to get crystals from International Crystal and they said there were two types of holders new and old. They said that if I had the new type I would be unable to get crystals for them or they would never work. It just so happens this repeater has the new crystals so does anybody know where I can get a set of old crystal holders so I can change the freq. on this repeater? Also does anybody have any other good ideas on how I can proceed with this unit. Thanks
Re: [Repeater-Builder] Gmrs Repeater
I think the desktrac is 49w The Ritron is 7 or 8 which is more than enough for here. wd8chl [EMAIL PROTECTED] wrote: Jack Hayes wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. Two years ago I purchased a Motorola Desktrac UHF, tuned it up and set it up. Works fine -- no hassles. It is a little more power than I need so I'm about to replace it with a Ritron Patriot box. I can't remember to the penny but I don't think I paid more than $325 for the repeater, duplexer and programming. I like the easy way. Jack w3fun Do either of them make 50 watts? Also neither of those has a receiver that can handle high-level RF sites, especially the Riton. It's fine for in a small plant, or at your house, but I wouldn't put one up at a busy high-profile site... The Desktrac? well, maybe... - Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.
Re: [Repeater-Builder] Gmrs Repeater
According to my second sentence it is more the rule than the exception. I have said enough, I wish you the best! 73's. -- Original message -- From: Jack Hayes [EMAIL PROTECTED] THERE ARE CERTAINLY EXCEPTIONS [EMAIL PROTECTED] wrote: That's kind of a harsh statement! I know more GMRS users that are hams than are not. Many of us use GMRS so we can get others such as family members on the air and maybe they'll get interested and get a ticket. Others may know enough but simply have no desire to become hams. Many users are Fire and emergency notification nets. I can communicate with my non ham family using my same gear that I use on Ham. Craig PS, my friend who is a non ham, but a GMRS user has a PHD in Physics and a is a digital electronics design engineer! Probably knows enough. -- Original message -- From: Jack Hayes [EMAIL PROTECTED] There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question. The Desktrac is 40 (pardon my typo) 73 Jack Kris Kirby [EMAIL PROTECTED] wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly - Looking for last minute shopping deals? Find them fast with Yahoo! Search. From:Jack Hayes [EMAIL PROTECTED] To:Repeater-Builder@yahoogroups.com Subject:Re: [Repeater-Builder] Gmrs Repeater Date:Fri, 25 Jan 2008 16:52:12 + There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question. The Desktrac is 40 (pardon my typo) 73 Jack Kris Kirby [EMAIL PROTECTED] wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly - Looking for last minute shopping deals? Find them fast with Yahoo! Search. - Never miss a thing. Make Yahoo your homepage. ---BeginMessage--- THERE ARE CERTAINLY EXCEPTIONScraigclarknh@comcast.net wrote: That's kind of a harsh statement! I know more GMRS users that are hams than are not. Many of us use GMRS so we can get others such as family members on the air and maybe they'll get interested and get a ticket. Others may "know enough" but simply have no desire to become hams. Many users are Fire and emergency notification nets. I can communicate with my non ham family using my same gear that I use on Ham. Craig PS, my friend who is a non ham, but a GMRS user has a PHD in Physics and a is a digital electronics design engineer! Probably knows enough. -- Original message -- From: Jack Hayes [EMAIL PROTECTED]com There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question.The Desktrac is 40 (pardon my typo)73JackKris Kirby [EMAIL PROTECTED]us wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED]net wrote:"I can't imagine why you'd want to go to the trouble of building a GMRS repeater."It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. "Why do you keep hitting your head on your desk?" "Because it feels so good when I stop." ... And I'm working on repeater #2 now ... -- Kris
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
We have a 222 MHz repeater comprised of a converted Micor mobile, Telewave TPRD-2254 BpBr duplexer, AM-6155 PA modified for class C operation at 250W, and a DB-264JJ antenna at 80 ft. fed by 1/2' Heliax on a commercial FM broadcast tower . With the duplexer terminated into a load, we have about 1 dB degradation in sensitivity when transmitting. However, with the antenna connected to the duplexer, we experience in excess 15 dB of desensitization. We have eliminated other narrowband transmitters and analog TV transmitters as contributing factors. We are left with a channel 12 digital TV transmitter at an adjacent site as a key contributor to the problem. Our hypothesis is that we have broadband IMD products from the mix of our transmitter and the DTV transmitter that are appearing in and near our receiver passband. Is it a rusty bolt problem or is there some other non-linear component somewhere on the site or in our system that is the mixing point - we don't know. If you suspect IMD between the channel 12 DTV transmitter and your Tx carrier, work on attenuating the DTV signal. Using cavity notch filters to reject the entire 6 MHz of DTV isn't too practical, so instead, try adding pass cavities on your Tx before the duplexer input. That will help determine if the IM is originating in your PA. An isolator *may* help, but with channel 12 being the better part of 20 MHz away (about 10%), it may not afford full protection -- isolators don't have infinite bandwidth. Likewise, finding a 250 watt 220 MHz isolator may not be easy. I think I have some 220 isolators that came off a combiner (Sinclair), but doubt they're good for 250 watts judging by their size. If you suspect a rusty bolt mix, use an alternate antenna for testing. If nothing else, try a quarter-wave whip (suitable for operation at your 250 watts TPO), even if it's just temporarily mounted on the tower (be sure it's at a sufficient height to prevent desense due to close proximity to the repeater itself). Another good possibility is IM in your receiver front end (or preamp, if you're using one). Again, pass cavities are your friend here. Attenuate the channel 12 signal as much as possible and see if it makes a difference. Have you looked at what sigs are reaching your receiver input on a spectrum analyzer? With 15 dB of desense, you should be able to see the culprit(s); it's not like they're going to be buried in the noise if it's causing 15 dB of desense. Even that 1 dB of desense would give me some agita. I'd verify that the duplexers are properly tuned and the transmitter is clean before even starting down any other paths related to the channel 12 issue. IIRC, the Telewave cavities have adjustable coupling. If necessary, sacrifice a little extra loss for additional rejection if necessary. I also assume you're using all known-good interconnect cables (no foil+braid or other cables not suitable for duplex operation). Are you using a Polyphaser or other type of surge arrestor? If so, try bypassing it. I've seen gas discharge tube type surge arrestors become noisemakers after absorbing a strike. Has the VSWR changed at all on your antenna? If so, it could indicate water in a connector or the harness which will cause all kinds of grief, including wideband noise. Finally, does the desense change appreciably if you vary transmitter power output (it probably will). Do you any have desense when running on just exciter power? --- Jeff WN3A
[Repeater-Builder] Re: Motorola Vibrasponder needed
Motorola did'nt make a TRN 5075A transponder... Their numbers go from: 5073A to 5076A . . In Repeater-Builder@yahoogroups.com, hapgriffin01 [EMAIL PROTECTED] wrote: I'm looking for a 100.0 Hz Vibrasponder for a MSR-2000 PL Module TRN5075A. Can anyone help? Hap Griffin WZ4O
[Repeater-Builder] Desense Problem on 222 MHz Repeater
Our group has substantial technical knowledge and experience, but we've been just about beaten down by a problem with our repeater. A brief overview of our situation follows. We have a 222 MHz repeater comprised of a converted Micor mobile, Telewave TPRD-2254 BpBr duplexer, AM-6155 PA modified for class C operation at 250W, and a DB-264JJ antenna at 80 ft. fed by 1/2' Heliax on a commercial FM broadcast tower . With the duplexer terminated into a load, we have about 1 dB degradation in sensitivity when transmitting. However, with the antenna connected to the duplexer, we experience in excess 15 dB of desensitization. We have eliminated other narrowband transmitters and analog TV transmitters as contributing factors. We are left with a channel 12 digital TV transmitter at an adjacent site as a key contributor to the problem. Our hypothesis is that we have broadband IMD products from the mix of our transmitter and the DTV transmitter that are appearing in and near our receiver passband. Is it a rusty bolt problem or is there some other non-linear component somewhere on the site or in our system that is the mixing point - we don't know. I'd be interested in beginning a dialog with anyone who might be able to give us some further insight into this problem. Regards, Stu Benner W3STU Boonsboro, MD
Re: [Repeater-Builder] Gmrs Repeater
THERE ARE CERTAINLY EXCEPTIONS [EMAIL PROTECTED] wrote: That's kind of a harsh statement! I know more GMRS users that are hams than are not. Many of us use GMRS so we can get others such as family members on the air and maybe they'll get interested and get a ticket. Others may know enough but simply have no desire to become hams. Many users are Fire and emergency notification nets. I can communicate with my non ham family using my same gear that I use on Ham. Craig PS, my friend who is a non ham, but a GMRS user has a PHD in Physics and a is a digital electronics design engineer! Probably knows enough. -- Original message -- From: Jack Hayes [EMAIL PROTECTED] There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question. The Desktrac is 40 (pardon my typo) 73 Jack Kris Kirby [EMAIL PROTECTED] wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly - Looking for last minute shopping deals? Find them fast with Yahoo! Search. From:Jack Hayes [EMAIL PROTECTED] To:Repeater-Builder@yahoogroups.com Subject:Re: [Repeater-Builder] Gmrs Repeater Date:Fri, 25 Jan 2008 16:52:12 + There are certainly exceptions but most people I know who do GMRS didn't know enuf to pass a ham test -- which is the reason for my question. The Desktrac is 40 (pardon my typo) 73 Jack Kris Kirby [EMAIL PROTECTED] wrote: On Thu, 24 Jan 2008 [EMAIL PROTECTED] wrote: I can't imagine why you'd want to go to the trouble of building a GMRS repeater. It's for the education, experience and pride in putting something together and getting it to work. It also for ththe frustration and fun that goes along with it. Why do you keep hitting your head on your desk? Because it feels so good when I stop. ... And I'm working on repeater #2 now ... -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly - Looking for last minute shopping deals? Find them fast with Yahoo! Search. - Never miss a thing. Make Yahoo your homepage.
Re: [Repeater-Builder] EF Johnson CR1010 Crystal Replacement
Call Quadratics, (850)862-9333 ask for Bob Kernen, W4MTD. They are an EF Johnson dealer. He may be able to help you. In a message dated 1/25/2008 7:31:06 AM Central Standard Time, [EMAIL PROTECTED] writes: I have a CR1010 repeater that needs to have new crystals installed to change the frequency from 451.200 to 451.250 on the TX and 456.200 to 456.250 on the Rx. I tried to get crystals from EF Johnson and they said they no longer support this repeater. I then tried to get crystals from International Crystal and they said there were two types of holders new and old. They said that if I had the new type I would be unable to get crystals for them or they would never work. It just so happens this repeater has the new crystals so does anybody know where I can get a set of old crystal holders so I can change the freq. on this repeater? Also does anybody have any other good ideas on how I can proceed with this unit. Thanks **Biggest Grammy Award surprises of all time on AOL Music. (http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp00300025 48)
Re: [Repeater-Builder] Re: Gmrs Repeater
I was describing the many bandwidth options offered in many new PC programmable commercial two-way radios today. Maybe we're looking at two different things but I see GMRS channels as 12.5Khz apart from each other. Channel one for example is 462.5500 where channel two is 462.5625. Gary wd8chl [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Paul, the underlying and unexpected contridiction here was not between 15Khz vs. 20Khz channel spacing but instead between 20Khz and 25Khz channels more commonly found on UHF which as you know is where GMRS resides. Historically there's more than enough guard between channels to compensate for slight overdeviation or slight drift off channel but now everybody wants to tighten things up so new gear is coming stock with 4Khz max dev associated with 20Khz channels vs. 5Khz dev which we've all enjoyed for years on 25/30Khz channels. Seems a bit odd of them to expect no interference problems from +/-5Khz peak dev on a 20Khz max channel but it is better for us users to have the option I suppose. Gary Huh? GMRS channels are still spaced 25 KHz apart. If someone is making radios with 20KHz spacing, they are illegal-in the US... Yahoo! Groups Links
Re: [Repeater-Builder] Outdoor Enclosure
Thanks for all of the replies, I believe we have found one and are working to obtain it. Dan KA8YPY Yahoo! Groups Links
Re: [Repeater-Builder] RC110 Group
I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. - Never miss a thing. Make Yahoo your homepage.
RE: [Repeater-Builder] EF Johnson CR1010 Crystal Replacement
John, I suggest that you send the holders, with the old crystals, to International Crystal or to any competent crystal house. Simply instruct ICM to change the TX and RX from the existing frequencies to the desired new frequencies. It'll cost you about $100 for the pair, but you'll wind up with crystals that are guaranteed to work on the new channels. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of John D. Sent: Thursday, January 24, 2008 5:28 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] EF Johnson CR1010 Crystal Replacement I have a CR1010 repeater that needs to have new crystals installed to change the frequency from 451.200 to 451.250 on the TX and 456.200 to 456.250 on the Rx. I tried to get crystals from EF Johnson and they said they no longer support this repeater. I then tried to get crystals from International Crystal and they said there were two types of holders new and old. They said that if I had the new type I would be unable to get crystals for them or they would never work. It just so happens this repeater has the new crystals so does anybody know where I can get a set of old crystal holders so I can change the freq. on this repeater? Also does anybody have any other good ideas on how I can proceed with this unit. Thanks
Re: [Repeater-Builder] Re: Gmrs Repeater
The GMRS full power channels are 462.550, 462.575, 462.600, 462.625, 462.650, 462.675, 462.700, 462.725. Deviation is +\- 5KHz. Power output 50 watts + antenna gain, if any. The interstitle channels like 462.5625 are used by the FRS kiddie-talkies. 500mW power, +\- 2.5KHz deviation, no external antennas. Whoever thought that arrangement up had no comprehension of how a radio works. If I were going to try to use GMRS today with the prolifiration of kiddie-talkies out there I would limit my receive radio bandwidth to the 12.5K setting to cut down on the adjacent channel junk, but that means that any radio normally set for GMRS at 25KHz bandwidth will sound crappy. Thank the FCC and the radio manufacturers for killing off a good service. Milt N3LTQ - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 10:16 AM Subject: Re: [Repeater-Builder] Re: Gmrs Repeater I was describing the many bandwidth options offered in many new PC programmable commercial two-way radios today. Maybe we're looking at two different things but I see GMRS channels as 12.5Khz apart from each other. Channel one for example is 462.5500 where channel two is 462.5625. Gary wd8chl [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Paul, the underlying and unexpected contridiction here was not between 15Khz vs. 20Khz channel spacing but instead between 20Khz and 25Khz channels more commonly found on UHF which as you know is where GMRS resides. Historically there's more than enough guard between channels to compensate for slight overdeviation or slight drift off channel but now everybody wants to tighten things up so new gear is coming stock with 4Khz max dev associated with 20Khz channels vs. 5Khz dev which we've all enjoyed for years on 25/30Khz channels. Seems a bit odd of them to expect no interference problems from +/-5Khz peak dev on a 20Khz max channel but it is better for us users to have the option I suppose. Gary Huh? GMRS channels are still spaced 25 KHz apart. If someone is making radios with 20KHz spacing, they are illegal-in the US... Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Thanks to everyone for the replies so far. Please see comments embedded below. I think that they address most of the comments, questions, and recommendations posed by all to this point. If you suspect IMD between the channel 12 DTV transmitter and your Tx carrier, work on attenuating the DTV signal. Using cavity notch filters to reject the entire 6 MHz of DTV isn't too practical, so instead, try adding pass cavities on your Tx before the duplexer input. That will help determine if the IM is originating in your PA. An isolator *may* help, but with channel 12 being the better part of 20 MHz away (about 10%), it may not afford full protection -- isolators don't have infinite bandwidth. Likewise, finding a 250 watt 220 MHz isolator may not be easy. I think I have some 220 isolators that came off a combiner (Sinclair), but doubt they're good for 250 watts judging by their size. [Stu] Agree, notches don't work well for that plus we don't have handy any cavities that will tune there. Have used up to two BP cavities in the TX path along with a 2-stage isolator. No difference in desense is observed. If you suspect a rusty bolt mix, use an alternate antenna for testing. If nothing else, try a quarter-wave whip (suitable for operation at your 250 watts TPO), even if it's just temporarily mounted on the tower (be sure it's at a sufficient height to prevent desense due to close proximity to the repeater itself). [Stu] We're presently on split antennas. One is at about 80 ft., the other is at about 15 ft. This improves the desense on the order of 6 dB. Another good possibility is IM in your receiver front end (or preamp, if you're using one). Again, pass cavities are your friend here. Attenuate the channel 12 signal as much as possible and see if it makes a difference. Have you looked at what sigs are reaching your receiver input on a spectrum analyzer? With 15 dB of desense, you should be able to see the culprit(s); it's not like they're going to be buried in the noise if it's causing 15 dB of desense. [Stu] The desense is significant with or without a preamp. Worse with but I can't find my notes to quote numbers. Used up to 2 BP cavities on RX with no perceptable difference in desense. Have also installed a DCI 4-pole filter on RX and TX with no effect. Have looked at the receiver input with a spectrum analyzer. The most significant signal is the one FM broadcast transmitter at the site. Running power down on it or turning it off has no effect on the desense. Our TX signal at our RX input is consistent with our measured duplexer isolation (about -88 dBc or -34 dBm). Within several hundred kHz of the RX frequency there are no detectable narrowband signals. Even that 1 dB of desense would give me some agita. I'd verify that the duplexers are properly tuned and the transmitter is clean before even starting down any other paths related to the channel 12 issue. IIRC, the Telewave cavities have adjustable coupling. If necessary, sacrifice a little extra loss for additional rejection if necessary. [Stu] I tuned the duplexer myself with a network analyzer and the transmitter looks clean. I have coupling set where I get about 1 dB through loss and the notches are at about 88 dB on TX and about 90 dB on RX. I also assume you're using all known-good interconnect cables (no foil+braid or other cables not suitable for duplex operation). [Stu] All cables are either Heliax or double braided. Are you using a Polyphaser or other type of surge arrestor? If so, try bypassing it. I've seen gas discharge tube type surge arrestors become noisemakers after absorbing a strike. [Stu] Yes but there is no difference in desense when it is removed. Has the VSWR changed at all on your antenna? If so, it could indicate water in a connector or the harness which will cause all kinds of grief, including wideband noise. [Stu] The problem has existed since the repeater was installed. It exists whether we duplex on a DB264 at 80 feet or a G7-220 at 15 feet, both fed with Heliax Finally, does the desense change appreciably if you vary transmitter power output (it probably will). Do you any have desense when running on just exciter power? [Stu] The desense is roughly proportional to transmit power. Barely perceptable at 20W (exciter only) with split antennas. A little worse at 20W (exciter only) using one antenna. Have tried both tube-type and solid state amplifiers at various power levels. --- Jeff WN3A
Re: [Repeater-Builder] Desense Problem on 222 MHz Repeater
Any chance you can connect a spectrum analyzer to the duplexers receieve port? Make tests to look at the IF range and the receiver range with and without the transmitter active. This will tell you alot. For example on a 2m repeater we had a dirty SMPS in the vicinity of the antenna that opperated at approx. 600kHz. As soon as the transmitter came on at any level 2 sidebands were created + and - 600kHz from the transmitters carrier.
Re: [Repeater-Builder] RC110 Group
Duh ! - Original Message - From: MCH [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 3:13 PM Subject: Re: [Repeater-Builder] RC110 Group The 210 group is different than the 110 group. Joe M. WD7F - John in Tucson wrote: Really? I get mail from [RC210] rc210 at yahoogroups.com every day. Wonder what that's about. - Original Message - From: DCFluX To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 11:27 AM Subject: Re: [Repeater-Builder] RC110 Group Yeah, he says the group has been dead for sometime. Anyway I cancelled the request. On 1/25/08, WD7F - John in Tucson [EMAIL PROTECTED] wrote: Ken Arck - AH6LE de WD7F John in Tucson - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Friday, January 25, 2008 8:36 AM Subject: Re: [Repeater-Builder] RC110 Group I tried to join several times a couple of years ago, and was refused by the moderator. My RC110 has been back to Ken Arc and was returned still unreliable. It will ocationally do a reset while you are trying to enter a macro, and will ocationally fail to turn on the audio to the link when it keys up. Mine has never worked and I gave up with no support. NHRC controllers work great! 73 - Jim W5ZIT DCFluX [EMAIL PROTECTED] wrote: Anyone know who runs the RC110 yahoo group? I've been trying to sign up but it seems it requires approval. Never miss a thing. Make Yahoo your homepage. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.10/1241 - Release Date: 1/24/2008 9:58 AM -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008 11:24 AM Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
