Re: [Repeater-Builder] Receiver overload
David, try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley [EMAIL PROTECTED] wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. http://overview.mail.yahoo.com/
Re: [Repeater-Builder] Receiver overload
David, As suggested in another post a bandpass cavity might be in order. You idea of a stub, open ended 1/4 wavelength coax, will probably help. Just have to make sure it don't affect your 900 MHz signal, but would be cheap thing to try. I have 2 m repeater antenna about 100 ft vertically from 2 100 kW ERP, 40 kW RF, FM stations. I have no problem and bet if I sampled on my antenna I would have enormous level from them. If over load from the FM carrier it should be simple to solve. 73, ron, n9ee/r From: David Epley [EMAIL PROTECTED] Date: 2007/11/21 Wed PM 10:03:29 CST To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Receiver overload I have a repeaterreceiver overload problem I am trying to cure. The repeater is a 900mhz927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz.The repeater works fine at another site. My transmitter is a Motorola Purc 5000running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexersare Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3different antennas on the tower. When I use a 900mhz dish antenna pointed awayfrom broadcast tower I only have 3 db degradation. I have tried 3 different maxtracreceivers, added 2 more BpBr cavities in the receiver side and used 3 polefilters in the receivers with no improvement. Today I looked at the signallevel getting to the receiver at 104.9. To my surprise I was getting -8 dbm atthe receiver. I believe this level is overloading the front end of my repeater.I was wondering if a stub cut for the broadcast frequency would work. Anythoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: RE: [Repeater-Builder] Receiver overload
David, I assume the antenna system at the now location was different than the other that worked. What kind of feedline and antenna??? 73, ron, n9ee/r From: David Epley [EMAIL PROTECTED] Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jim Brown Sent: Thursday, November 22, 20076:13 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder]Receiver overload David,try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley [EMAIL PROTECTED]wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana __ Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. http://overview.mail.yahoo.com/ Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: RE: [Repeater-Builder] Receiver overload
Analyzer was connected to the receiver port of the duplexers. The noise floor looked good. The amount of degradation does not seem to change. There are 900mhz pager transmitters on site but none are on full time and I do not see any change as each one transmits. I can also have my transmitter turned off and the degradation is still here. _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Thursday, November 22, 2007 9:19 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: [Repeater-Builder] Receiver overload David, Your problem might be harmonic related. Might do some calculator work. I can see no muliple of 104.9 related to your 2 frequencies or IF related. There are other 900 MHz stuff around. Would be good to get a spectrum analyzer on your receiver port, but know spectrum analyzers are not easy to come by. Might be noise floor emissions from the FM station which could be on your receiver input. Now this one would be a real problem. 73, ron, n9ee/r From: David Epley [EMAIL PROTECTED] mailto:depley%40starband.net net Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of Jim Brown Sent: Thursday, November 22, 20076:13 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: Re: [Repeater-Builder]Receiver overload David,try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley [EMAIL PROTECTED] mailto:depley%40starband.net netwrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana __ Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. http://overview. http://overview.mail.yahoo.com/ mail.yahoo.com/ Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: RE: [Repeater-Builder] Receiver overload
Same antenna and feedline at both sites Decible 896-960mhz with 15/8 feedline. _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Thursday, November 22, 2007 9:22 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: [Repeater-Builder] Receiver overload David, I assume the antenna system at the now location was different than the other that worked. What kind of feedline and antenna??? 73, ron, n9ee/r From: David Epley [EMAIL PROTECTED] mailto:depley%40starband.net net Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of Jim Brown Sent: Thursday, November 22, 20076:13 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: Re: [Repeater-Builder]Receiver overload David,try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley [EMAIL PROTECTED] mailto:depley%40starband.net netwrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana __ Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. http://overview. http://overview.mail.yahoo.com/ mail.yahoo.com/ Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Receiver overload
I also share a site with an FM broadcaster. I use an all band notch filter from Microwave Filter Company on my receivers ahead of the preamp. Mine were custom made for 50 ohm input and output and are good for about -40 dB. http://www.microwavefilter.com/ David Epley wrote: To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated.
RE: RE: [Repeater-Builder] Receiver overload
An easy way to check for overload would be to install a HPF before the RX, this would greatly cut down the 104.9 signal. If you have a 2M/440 diplexer, like people use to split or combine antennas, that would probably work, at least for a test to prove or disprove this thought. Just connect antenna to the common port, and RX to HPF port, terminating LPF (2M) port. These things will usually have low insertion loss at 900, but 50+ dB of rejection at 100MHz. Someone around there is likely to have one you can borrow for a test. Joe --- David Epley [EMAIL PROTECTED] wrote: Analyzer was connected to the receiver port of the duplexers. The noise floor looked good. The amount of degradation does not seem to change. There are 900mhz pager transmitters on site but none are on full time and I do not see any change as each one transmits. I can also have my transmitter turned off and the degradation is still here. _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Thursday, November 22, 2007 9:19 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: [Repeater-Builder] Receiver overload David, Your problem might be harmonic related. Might do some calculator work. I can see no muliple of 104.9 related to your 2 frequencies or IF related. There are other 900 MHz stuff around. Would be good to get a spectrum analyzer on your receiver port, but know spectrum analyzers are not easy to come by. Might be noise floor emissions from the FM station which could be on your receiver input. Now this one would be a real problem. 73, ron, n9ee/r From: David Epley [EMAIL PROTECTED] mailto:depley%40starband.net net Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of Jim Brown Sent: Thursday, November 22, 20076:13 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: Re: [Repeater-Builder]Receiver overload David,try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley [EMAIL PROTECTED] mailto:depley%40starband.net netwrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana __ Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. http://overview. http://overview.mail.yahoo.com/ mail.yahoo.com/ Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now. http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ
Re: [Repeater-Builder] Receiver overload
Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
RE: [Repeater-Builder] Receiver overload
The only transmitter that is on all the time is the FM broadcast My tx plays no part in the noise _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:55 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
Re: [Repeater-Builder] Receiver overload
I agree with Eric about the shielded enclosure especially. And be sure to use a connector on the coax where it passes through the box. Just running the coax through a hole in the box defeats all, most or some the shielding of the box. Chuck WB2EDV - Original Message - From: Eric Lemmon [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, November 22, 2007 11:10 AM Subject: RE: [Repeater-Builder] Receiver overload David, My first move would be to add a bandpass cavity in front of the receiver. All cabling between the receiver and the RX output of the duplexer should be double-shielded, with proper connectors on each end- no adapters, and no nickel-plated connectors. The mini-UHF connector going to the MaxTrac should be the only exception, but it's okay if very tight. If that doesn't cure the problem, then enclose the receiver in a shielded box, and bring the signal and power leads out through feedthrough capacitors. The MaxTrac radio has a lot of plastic in its case, and is susceptible to signal intrusion. The best shielded box to use is a die-cast aluminum enclosure from Hammond. I have assumed that the FM transmitter carrier is pure, without harmonics or spurious artifacts. If the FM transmitter is radiating on a frequency close to your desired input frequency, the above fixes may not have any effect. 73, Eric Lemmon WB6FLY
Re: RE: [Repeater-Builder] Receiver overload
David, Have we ask if you can verify the problem is the FM transmitter??? 73, ron, n9ee/r From: Eric Lemmon [EMAIL PROTECTED] Date: 2007/11/22 Thu AM 10:10:19 CST To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload David, My first move would be to add a bandpass cavity in front of the receiver. All cabling between the receiver and the RX output of the duplexer should be double-shielded, with proper connectors on each end- no adapters, and no nickel-plated connectors. The mini-UHF connector going to the MaxTrac should be the only exception, but it's okay if very tight. If that doesn't cure the problem, then enclose the receiver in a shielded box, and bring the signal and power leads out through feedthrough capacitors. The MaxTrac radio has a lot of plastic in its case, and is susceptible to signal intrusion. The best shielded box to use is a die-cast aluminum enclosure from Hammond. I have assumed that the FM transmitter carrier is pure, without harmonics or spurious artifacts. If the FM transmitter is radiating on a frequency close to your desired input frequency, the above fixes may not have any effect. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of David Epley Sent: Thursday, November 22, 2007 7:02 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload The only transmitter that is on all the time is the FM broadcast My tx plays no part in the noise From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:55 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: [Repeater-Builder] Receiver overload
David, My first move would be to add a bandpass cavity in front of the receiver. All cabling between the receiver and the RX output of the duplexer should be double-shielded, with proper connectors on each end- no adapters, and no nickel-plated connectors. The mini-UHF connector going to the MaxTrac should be the only exception, but it's okay if very tight. If that doesn't cure the problem, then enclose the receiver in a shielded box, and bring the signal and power leads out through feedthrough capacitors. The MaxTrac radio has a lot of plastic in its case, and is susceptible to signal intrusion. The best shielded box to use is a die-cast aluminum enclosure from Hammond. I have assumed that the FM transmitter carrier is pure, without harmonics or spurious artifacts. If the FM transmitter is radiating on a frequency close to your desired input frequency, the above fixes may not have any effect. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of David Epley Sent: Thursday, November 22, 2007 7:02 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload The only transmitter that is on all the time is the FM broadcast My tx plays no part in the noise From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:55 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
RE: [Repeater-Builder] Receiver overload
I have tried all the above. I even change out the mini UHF connector to an N female when I use the maxtrac for repeater use. All cables are ¼ hardline. When I use a 900mhz dish mounted at the same level as my primary antenna but pointed away from the FM Broadcast tower I have considerably less degradation. _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Thursday, November 22, 2007 11:10 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload David, My first move would be to add a bandpass cavity in front of the receiver. All cabling between the receiver and the RX output of the duplexer should be double-shielded, with proper connectors on each end- no adapters, and no nickel-plated connectors. The mini-UHF connector going to the MaxTrac should be the only exception, but it's okay if very tight. If that doesn't cure the problem, then enclose the receiver in a shielded box, and bring the signal and power leads out through feedthrough capacitors. The MaxTrac radio has a lot of plastic in its case, and is susceptible to signal intrusion. The best shielded box to use is a die-cast aluminum enclosure from Hammond. I have assumed that the FM transmitter carrier is pure, without harmonics or spurious artifacts. If the FM transmitter is radiating on a frequency close to your desired input frequency, the above fixes may not have any effect. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of David Epley Sent: Thursday, November 22, 2007 7:02 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload The only transmitter that is on all the time is the FM broadcast My tx plays no part in the noise From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:55 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
RE: RE: [Repeater-Builder] Receiver overload
Yes when broadcast goes off problem goes away _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Thursday, November 22, 2007 11:14 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: [Repeater-Builder] Receiver overload David, Have we ask if you can verify the problem is the FM transmitter??? 73, ron, n9ee/r From: Eric Lemmon [EMAIL PROTECTED] mailto:wb6fly%40verizon.net net Date: 2007/11/22 Thu AM 10:10:19 CST To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload David, My first move would be to add a bandpass cavity in front of the receiver. All cabling between the receiver and the RX output of the duplexer should be double-shielded, with proper connectors on each end- no adapters, and no nickel-plated connectors. The mini-UHF connector going to the MaxTrac should be the only exception, but it's okay if very tight. If that doesn't cure the problem, then enclose the receiver in a shielded box, and bring the signal and power leads out through feedthrough capacitors. The MaxTrac radio has a lot of plastic in its case, and is susceptible to signal intrusion. The best shielded box to use is a die-cast aluminum enclosure from Hammond. I have assumed that the FM transmitter carrier is pure, without harmonics or spurious artifacts. If the FM transmitter is radiating on a frequency close to your desired input frequency, the above fixes may not have any effect. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of David Epley Sent: Thursday, November 22, 2007 7:02 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload The only transmitter that is on all the time is the FM broadcast My tx plays no part in the noise From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:55 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: RE: [Repeater-Builder] Receiver overload
Is the FM broadcast studio located at the transmitter site, or is it linked? If the studio is remote to the transmitter, it could be a harmonic of the studio uplink freq. But now I:m shooting in the dark. Mark - N9WYS _ From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley Analyzer was connected to the receiver port of the duplexers. The noise floor looked good. The amount of degradation does not seem to change. There are 900mhz pager transmitters on site but none are on full time and I do not see any change as each one transmits. I can also have my transmitter turned off and the degradation is still here. _ From: Repeater-Builder@yahoogroups.com On Behalf Of Ron Wright David, Your problem might be harmonic related. Might do some calculator work. I can see no muliple of 104.9 related to your 2 frequencies or IF related. There are other 900 MHz stuff around. Would be good to get a spectrum analyzer on your receiver port, but know spectrum analyzers are not easy to come by. Might be noise floor emissions from the FM station which could be on your receiver input. Now this one would be a real problem. 73, ron, n9ee/r From: David Epley Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of Jim Brown David,try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
RE: [Repeater-Builder] Receiver overload
If you want to try constructing a stub filter to notch out the FM carrier, look here: www.repeater-builder.com/ge/datafile-bulletin/df-10002-01.pdf 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of David Epley Sent: Thursday, November 22, 2007 8:42 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I have tried all the above. I even change out the mini UHF connector to an N female when I use the maxtrac for repeater use. All cables are ¼ hardline. When I use a 900mhz dish mounted at the same level as my primary antenna but pointed away from the FM Broadcast tower I have considerably less degradation. From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Thursday, November 22, 2007 11:10 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload David, My first move would be to add a bandpass cavity in front of the receiver. All cabling between the receiver and the RX output of the duplexer should be double-shielded, with proper connectors on each end- no adapters, and no nickel-plated connectors. The mini-UHF connector going to the MaxTrac should be the only exception, but it's okay if very tight. If that doesn't cure the problem, then enclose the receiver in a shielded box, and bring the signal and power leads out through feedthrough capacitors. The MaxTrac radio has a lot of plastic in its case, and is susceptible to signal intrusion. The best shielded box to use is a die-cast aluminum enclosure from Hammond. I have assumed that the FM transmitter carrier is pure, without harmonics or spurious artifacts. If the FM transmitter is radiating on a frequency close to your desired input frequency, the above fixes may not have any effect. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of David Epley Sent: Thursday, November 22, 2007 7:02 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload The only transmitter that is on all the time is the FM broadcast My tx plays no part in the noise From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:55 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Can you give us a list of all the transmitters that are at/near the site? Ones that are on the air all the time such as the FM station. Does your transmitter have to be keyed to get the desense? 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
RE: RE: [Repeater-Builder] Receiver overload
David, This is definitely an interesting thread! I cannot think of a more suitable topic to discuss in this forum. You mentioned in your original post that you are using a converted 800 MHz MaxTrac mobile radio as your 900 MHz receiver. Could you please elaborate a bit on what you did in this conversion? Also, please advise what model number of MaxTrac you began with. There may be some aspect of the conversion that makes your receive radio especially vulnerable. If you have already tried bandpass cavity filters on the receiver input, with the radio inside a shielded box and all penetrations suitably filtered, and not seen any reduction in desense, then the offending signal must be on or very close to your desired receive frequency. That brings us back to a spurious or harmonic signal being generated by the FM broadcast transmitter, or perhaps there is an IM product being created between the FM station carrier and another transmitter that has yet to be identified. It may be instructive to use a good (i. e., well-shielded) spectrum analyzer with a bandpass cavity on its input to filter out everything but signals very close to your 900 MHz input frequency. This technique once helped me track down a alarm system motion detector that was operating around 900 MHz. Some spectrum analyzers are poorly shielded, and are practically useless when immersed in a high-RF environment. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of David Epley Sent: Thursday, November 22, 2007 9:17 AM To: Repeater-Builder@yahoogroups.com Subject: RE: RE: [Repeater-Builder] Receiver overload It is linked but there is only an STL link receiver at the site From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of n9wys Sent: Thursday, November 22, 2007 12:08 PM To: Repeater-Builder@yahoogroups.com Subject: RE: RE: [Repeater-Builder] Receiver overload Is the FM broadcast studio located at the transmitter site, or is it linked? If the studio is remote to the transmitter, it could be a harmonic of the studio uplink freq. But now I:m shooting in the dark. Mark - N9WYS From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley Analyzer was connected to the receiver port of the duplexers. The noise floor looked good. The amount of degradation does not seem to change. There are 900mhz pager transmitters on site but none are on full time and I do not see any change as each one transmits. I can also have my transmitter turned off and the degradation is still here. From: Repeater-Builder@yahoogroups.com On Behalf Of Ron Wright David, Your problem might be harmonic related. Might do some calculator work. I can see no muliple of 104.9 related to your 2 frequencies or IF related. There are other 900 MHz stuff around. Would be good to get a spectrum analyzer on your receiver port, but know spectrum analyzers are not easy to come by. Might be noise floor emissions from the FM station which could be on your receiver input. Now this one would be a real problem. 73, ron, n9ee/r From: David Epley Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com On Behalf Of Jim Brown David,try using one or two band pass only cavaties in the receive side instead of the BpBr type. The BpBr filters often do not discriminate against signals far off the pass frequency, and you may not be getting enough rejection out of your input cavities. 73 - Jim W5ZIT --- David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
RE: RE: [Repeater-Builder] Receiver overload
The conversion was done per the repeater builders page on maxtrac conversions. I first used the standard 2 pole gigifilters you can for 900mhz later replaced with 3 pole filters. This improved the site degradation by about 5 db. I remove the PA and install a female N connector on the back of the maxtrac. I also pull the DC power connector from the PA and install it on the back of the Maxtrac. I have one maxtrac that I installed in a 19 rack extruded aluminum box with an N RF connector and all inputs\outputs going thru feed thru caps. This showed no improvement. I do not believe I am dealing with a signal on the input frequency but with a very high level of RF energy at the receiver input that it is affecting the sensitivity of the Receiver. David N9CZV _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Thursday, November 22, 2007 12:59 PM To: Repeater-Builder@yahoogroups.com Subject: RE: RE: [Repeater-Builder] Receiver overload David, This is definitely an interesting thread! I cannot think of a more suitable topic to discuss in this forum. You mentioned in your original post that you are using a converted 800 MHz MaxTrac mobile radio as your 900 MHz receiver. Could you please elaborate a bit on what you did in this conversion? Also, please advise what model number of MaxTrac you began with. There may be some aspect of the conversion that makes your receive radio especially vulnerable. If you have already tried bandpass cavity filters on the receiver input, with the radio inside a shielded box and all penetrations suitably filtered, and not seen any reduction in desense, then the offending signal must be on or very close to your desired receive frequency. That brings us back to a spurious or harmonic signal being generated by the FM broadcast transmitter, or perhaps there is an IM product being created between the FM station carrier and another transmitter that has yet to be identified. It may be instructive to use a good (i. e., well-shielded) spectrum analyzer with a bandpass cavity on its input to filter out everything but signals very close to your 900 MHz input frequency. This technique once helped me track down a alarm system motion detector that was operating around 900 MHz. Some spectrum analyzers are poorly shielded, and are practically useless when immersed in a high-RF environment. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of David Epley Sent: Thursday, November 22, 2007 9:17 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: RE: [Repeater-Builder] Receiver overload It is linked but there is only an STL link receiver at the site From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of n9wys Sent: Thursday, November 22, 2007 12:08 PM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: RE: [Repeater-Builder] Receiver overload Is the FM broadcast studio located at the transmitter site, or is it linked? If the studio is remote to the transmitter, it could be a harmonic of the studio uplink freq. But now I:m shooting in the dark. Mark - N9WYS From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of David Epley Analyzer was connected to the receiver port of the duplexers. The noise floor looked good. The amount of degradation does not seem to change. There are 900mhz pager transmitters on site but none are on full time and I do not see any change as each one transmits. I can also have my transmitter turned off and the degradation is still here. From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of Ron Wright David, Your problem might be harmonic related. Might do some calculator work. I can see no muliple of 104.9 related to your 2 frequencies or IF related. There are other 900 MHz stuff around. Would be good to get a spectrum analyzer on your receiver port, but know spectrum analyzers are not easy to come by. Might be noise floor emissions from the FM station which could be on your receiver input. Now this one would be a real problem. 73, ron, n9ee/r From: David Epley Date: 2007/11/22 Thu AM 07:32:46 CST To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Receiver overload I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable improvement. David N9CZV From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com
Re: RE: RE: [Repeater-Builder] Receiver overload
900 MHz is used for STLs. Might consider looking at this as some image or other freq problem. The STL is low power, but probably dish high gain antenna pointed directly to your site. Too bad you cannot turn off the FM for a bit, but good way to loose your site. 73, ron, n9ee/r From: n9wys [EMAIL PROTECTED] Date: 2007/11/22 Thu AM 11:26:10 CST To: Repeater-Builder@yahoogroups.com Subject: RE: RE: [Repeater-Builder] Receiver overload I was thinking that maybe yourinterference might be a harmonic of their uplink freq⦠Back tothinking some more. ;-) From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley It is linked but there is only an STL linkreceiver at the site From: Repeater-Builder@yahoogroups.com On Behalf Of n9wys Is the FM broadcast studio located at the transmitter site, or isit linked? If the studio is remote to the transmitter, it could be aharmonic of the studio uplink freq. But now I:m shooting in the dark⦠Mark â N9WYS Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: [Repeater-Builder] Receiver overload
Muncie Indiana _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Sent: Thursday, November 22, 2007 9:32 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Receiver overload Are you sure that 104.9 (WINN?) is the only FM station near your repeater? Looking at the data, it looks like 100.3 WYGB is possibly on the same tower. This is assuming that your repeater is in Columbus, IN. 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
Re: [Repeater-Builder] Receiver overload
Are you sure that 104.9 (WINN?) is the only FM station near your repeater? Looking at the data, it looks like 100.3 WYGB is possibly on the same tower. This is assuming that your repeater is in Columbus, IN. 73, Joe, K1ike David Epley wrote: I have a repeater receiver overload problem I am trying to cure. The repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast station 100 yards away 104.9mhz. The repeater works fine at another site. My transmitter is a Motorola Purc 5000 running 75 watts the receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 different antennas on the tower. When I use a 900mhz dish antenna pointed away from broadcast tower I only have 3 db degradation. I have tried 3 different maxtrac receivers, added 2 more BpBr cavities in the receiver side and used 3 pole filters in the receivers with no improvement. Today I looked at the signal level getting to the receiver at 104.9. To my surprise I was getting -8 dbm at the receiver. I believe this level is overloading the front end of my repeater. I was wondering if a stub cut for the broadcast frequency would work. Any thoughts would be greatly appreciated. David Epley, N9CZV Winchester, Indiana
