Re: [Repeater-Builder] Mixing problem?
At 6/11/2005 10:06 AM, you wrote: Ray, I've seen the same symptoms occur when an inexpensive multi-band ham antenna is used, especially when the antenna is fairly close to the repeater and single-shielded coax feedline connects the duplexer to the antenna. Multi-band antennas single-shielded coax have nothing to do with desense. Most amateur grade multi-band antennas duplex just fine out of the box. What happens afterwards depends upon the environment in which it's installed how well it's weatherproofed. There are problems with one or two specific models (Cushcraft and/or Hustler) which have been previously discussed here. The problem with braided coax is the eventual oxidation of the copper braid, which will cause desense; silver-plated shielding does not have this problem. For antenna feeds it makes no difference if the shield is single or double, only if it's silver plated or not. As it turns out, you will probably have a hard time finding any single-shielded silver-plated braided coax, but if you did it would work as well as RG-214 for an antenna feed. The important point here is the opposite case: double-shielded copper-braided feed will NOT work for antenna feeds! Try using a good, broadband antenna that is known to perform well in duplex operation, and use Heliax or RG-214/U coax as feedline. Good points, just make sure the RG-214/U is silver plated. As others have previously pointed out here, there is some RG-214 TYPE coax out there that is double-shielded but NOT silver-plated. Using that to feed your duplex antenna will also eventually result in desense. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
I want to thank all that responded to this problem. The problem has been identified and now i need to figure out how to solve it. the problem is the CATV system is very leaky in this area and what we are hearing on the repeater input is the video carrier for channel 18. when i put an ht on the repeater antenna i have a near full scale signal on 149.750 wich is the center of the audio part of channel 18. I will be going to the cable company on tues. afternoon with a list of several locations that are leaking. i have located three different locations in approx. a 1 mile radius of the site and i will expand my search even more and turn in my finding to them. Does anyone have suggestions on how/who to aproach with this problem? 73 Ray BTW: to answer some of the question on this threed it is a Mastr2 mobile running a 6 cavity north shore duplexer with ldf4-50 feedline. the antenna is a Hustler G6. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
Mike Morris WA6ILQ wrote: At 08:41 AM 6/12/05, you wrote: Bearcat scanners are notorious transmitters. Try listening on 136.83 and 158.43 for a carrier on your repeater receiver 147.63. Try other combinations of plus or minus the scanner IF freq of 10.8 mhz. Gary K2UQ Then try plus or minus 10.7, 11.7, and 21.4 I've also seen a vintage of Bearcat scanner that had a 10.85 Mhz IF. -- Jim Barbour WD8CHL Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
I saw this happen once. Turned out to be a bearcat scanner. the right combination of IF's and it stopping on the right programmed channel would lock things up. Sometimes it sounded like a clicking noise as it was scanning. Just a thought of something to look for. Mike KA2NDW - Original Message - From: Ray Retzlaff [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, June 10, 2005 2:27 AM Subject: [Repeater-Builder] mixing problem? I just re-built a ge mastr II mobile for use as a repeater on 147.030+ and everything went great here on the bench. when we installed the machine at its new home at a residence on a hilltop we emediatly started having problems with noise on the input freq. it only apears when the repeater is in TX and it appears right on the input 147.630. I have ruled out desense because you can hear the noise on a HT (on 147.630) but only when the repeater is transmitting. I think this might be a mix of some sort but i have no clue what to look for. can anyone help point me in the right direction? 73 Ray K6PNG Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
Bearcat scanners are notorious transmitters. Try listening on 136.83 and 158.43 for a carrieronyour repeater receiver 147.63. Try other combinations of plus or minus the scanner IF freq of 10.8 mhz. Gary K2UQ Yahoo! Groups Links To visit your group on the web, go to:http://groups.yahoo.com/group/Repeater-Builder/ To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Re: [Repeater-Builder] mixing problem?
At 08:41 AM 6/12/05, you wrote: Bearcat scanners are notorious transmitters. Try listening on 136.83 and 158.43 for a carrier on your repeater receiver 147.63. Try other combinations of plus or minus the scanner IF freq of 10.8 mhz. Gary K2UQ Then try plus or minus 10.7, 11.7, and 21.4 The most interesting example of a broadcasting local oscillator was reported on a Chicago 220 repeater about 20 years ago. The repeater (carrier squelch) was located in the equipment room on the top of an office building. Every s o often the repeater would unsquelch and fade in (as if ramping up the TX power) play a local radio station quite clearly, then anywhere from 30 seconds to an hour or two later it would slowly fade out (not suddenly drop off) and the squelch would close. There was no pattern except that it was most often in the morning and evening, and would rarely happen on a week end, but when it did it might last for hours. To make a long transmitter-hunting story short (it took a couple of months), the source turned out to be a harmonic of the local oscillator of the FM receiver in the elevator car of the same office building where the repeater was. The FM receiver was on the roof of the car, and powered by the lighting circuit. Only when the car was within two floors of the roof did the problem happen, the second-to-the-top floor was only partially rented, and the top floor was storage and air conditioning. The control system of the elevator was relay based and left the car at whatever floor was it's last destination. The assumption was that the receiver filter caps were a little old and the LO was being slightly modulated by the received audio. The cure? Twist the knob to change stations on the FM receiver. I had a similar situation as I was driving down the highway one day. My UHF Micor receiver (on 445.xxx MHz) unsquelched and I started to hear a FM station. It got stronger as a new Toyota Cressida pulled along side, peaked as it passed me and then squelched as the car reached a distance of about 5-6 car lengths ahead. I was not in a hurry so I followed it off of the next ramp and then into a fast-food chain restaurant parking lot. The Toyota's driver went inside, I pulled into a nearby parking spot and as I walked inside to get a drink I walked past the Toyota and looked at the dashboard - a brand new Sony high-end aftermarket receiver. Oh well, that's what PL on the repeater output is for... Mike WA6ILQ Yahoo! Groups Links To visit your group on the web, go to:http://groups.yahoo.com/group/Repeater-Builder/ To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Re: [Repeater-Builder] Mixing problem?
Ray, I've seen the same symptoms occur when an inexpensive multi-band ham antenna is used, especially when the antenna is fairly close to the repeater and single-shielded coax feedline connects the duplexer to the antenna. Try using a good, broadband antenna that is known to perform well in duplex operation, and use Heliax or RG-214/U coax as feedline. It may help to install the antenna so that it is directly above the repeater equipment, and as high as possible, to minimize RF leakage into the radio. When a Mastr II radio is converted to duplex operation, special care must be taken to avoid leakage between the RX and TX sections, since the Lexan partitions don't have very good shielding properties. 73, Eric Lemmon WB6FLY Ray Retzlaff wrote: I just re-built a GE Mastr II mobile for use as a repeater on 147.030+ and everything went great here on the bench. When we installed the machine at its new home at a residence on a hilltop we immediately started having problems with noise on the input freq. It only appears when the repeater is in TX and it appears right on the input 147.630. I have ruled out desense because you can hear the noise on a HT (on 147.630) but only when the repeater is transmitting. I think this might be a mix of some sort but I have no clue what to look for. can anyone help point me in the right direction? Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Mixing problem?
At 12:06 PM 6/11/2005, Eric Lemmon wrote: Ray, I've seen the same symptoms occur when an inexpensive multi-band ham antenna is used, especially when the antenna is fairly close to the repeater and single-shielded coax feedline connects the duplexer to the antenna. Try using a good, broadband antenna that is known to perform well in duplex operation, and use Heliax or RG-214/U coax as feedline. It may help to install the antenna so that it is directly above the repeater equipment, and as high as possible, to minimize RF leakage into the radio. When a Mastr II radio is converted to duplex operation, special care must be taken to avoid leakage between the RX and TX sections, since the Lexan partitions don't have very good shielding properties. 73, Eric Lemmon WB6FLY Ray Retzlaff wrote: I just re-built a GE Mastr II mobile for use as a repeater on 147.030+ and everything went great here on the bench. When we installed the machine at its new home at a residence on a hilltop we immediately started having problems with noise on the input freq. It only appears when the repeater is in TX and it appears right on the input 147.630. I have ruled out desense because you can hear the noise on a HT (on 147.630) but only when the repeater is transmitting. I think this might be a mix of some sort but I have no clue what to look for. can anyone help point me in the right direction? Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] mixing problem?
Does the noise go away when transmitting into a dummy load? Second, can you unhook the receiver from the duplexer and use a clip lead for a receive antenna for a test and see if the signal is still present? GL, Steve -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ray Retzlaff Sent: Friday, June 10, 2005 1:28 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] mixing problem? I just re-built a ge mastr II mobile for use as a repeater on 147.030+ and everything went great here on the bench. when we installed the machine at its new home at a residence on a hilltop we emediatly started having problems with noise on the input freq. it only apears when the repeater is in TX and it appears right on the input 147.630. I have ruled out desense Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
- Original Message - From: Steve Bosshard (NU5D) [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, June 09, 2005 11:38 PM Subject: RE: [Repeater-Builder] mixing problem? Does the noise go away when transmitting into a dummy load? Yes Second, can you unhook the receiver from the duplexer and use a clip lead for a receive antenna for a test and see if the signal is still present? Yes it is still present when i used a short piece of wire as the antenna. GL, Steve Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] mixing problem?
At 11:38 PM 6/9/05, you wrote: Does the noise go away when transmitting into a dummy load? Second, can you unhook the receiver from the duplexer and use a clip lead for a receive antenna for a test and see if the signal is still present? GL, Steve And while you are at the site collect the TX frequencies of everything else in the building... Then sit down with one of the mix and intermod calculators listed at http://www.repeater-builder.com/rbtip/ant-sys-index.html and click on Calculators in the jump table at the top. Mike Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
And while you are at the site collect the TX frequencies of everything else in the building... there are no other transmitters at the site. infact it is a house that happens to have a good location. 73 Ray K6PNG Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] mixing problem?
Well lets see, is the interfering noise present every time you key the transmitter, or sometime yes, and some times no? Reason for this question being most LMR stuff that may be mixing is on and off, broadcast is usually steady on. Also is there any intelligible information in the offending signal, like faint voice, etc? Also, how far are you from any other radio stations, LMR, Broadcast, etc? Sorry to sound like a trial lawyer grilling a witness, but just trying to put the pieces together. Hopefully you have a new antenna installation and new or known to be good cable, etc. Tell me a little about the site, cable lengths, type of cable, antenna, tower, etc. Steve -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ray Retzlaff Sent: Friday, June 10, 2005 1:46 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] mixing problem? - Original Message - From: Steve Bosshard (NU5D) [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, June 09, 2005 11:38 PM Subject: RE: [Repeater-Builder] mixing problem? Does the noise go away when transmitting into a dummy load? Yes Second, can you unhook the receiver from the duplexer and use a clip lead for a receive antenna for a test and see if the signal is still present? Yes it is still present when i used a short piece of wire as the antenna. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] mixing problem?
Ray Retzlaff wrote: I just re-built a ge mastr II mobile for use as a repeater on 147.030+ and everything went great here on the bench. when we installed the machine at its new home at a residence on a hilltop we emediatly started having problems with noise on the input freq. it only apears when the repeater is in TX and it appears right on the input 147.630. I have ruled out desense because you can hear the noise on a HT (on 147.630) but only when the repeater is transmitting. I think this might be a mix of some sort but i have no clue what to look for. can anyone help point me in the right direction? Do you have a signal you can hear on 148.230 or thereabouts? Kevin Custer Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * 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/
