Re: [Repeater-Builder] Repeater upgrade needed
I have one of the micors like you are using, same gas-fet, dci 4 bay filter and duplexor also. The gas-fet is the single biggest item of gain, and would mention if you have easy access try changing just that to a bi-polar and do only one thing at a time because without being there it is hard to say what one or 2 things will have the biggest effect on filtering your signal in and the others out. You might want to snoop the new paging company tx and offer a low pass filter to them to try as an experiment. I had to use a 5 bay helical from a mastr2 to suppress the inner-mod with the gas-fet and at times it still gets some noise, I am about to build the ramsey pr10 that Kevin suggests on the repeater builder and see if that can run just a 2 bay helical with it having it's own tunable circuit. The antenna spacing sounds close, is there another high band antenna you can move to for a few weeks to test with, the micor is a great radio for selectivity and I wonder what the attenuator pad is for? [EMAIL PROTECTED] wrote: > > A question to all you repeater guru's out there. Have a repeater in a high > noise environment at a large TV tower site. Lots of pagers, FM transmitters, 2 > ways, etc on this tower. My Super Stationmaster 2 meter antenna is just 5 > feet > away from a bed spring style 45 kw FM transmitter on 101.5 MHz. My repeater > is a Canadian mobile Micor along with Wacom duplexer and a circulator on Tx > side. Have a DB 4062 cavity can tuned to bandpass Rx between duplexer and > receiver. Works OK but the 1000 feet of 7/8 hard line has a great effect on > the Rx > side of the repeater. Also a new paging tenant might be blanking the Rx out > of my repeater. Putting the repeater at the base of the antenna is not > possible. I would like to improve the receive side of the repeater. Have the > following > equipment available: > Advanced Receiver Pre amp GaAsFET P144VDG > Telewave TWPC-1005-1 pass cavity 88 - 108 mhz > DB 4062 WC-B 143-156 mhz 6 can duplexer > Wacom 641 duplexer 4 can (second set) > Kay switchable attenuator pad > DCI bandpass 144-148 filter > DB 4048 cavity cans (2) from disassembled duplexer > What would be the best choice and hook up to increase the Rx sensitivity and > keep the noise out of the receiver? Any help would be really appreciated. > Gary K2UQ > > > Yahoo! Groups Links > > > > -- 73...Clark Beckman N8PZD Pursuant to U.S. Code, title 47, Chapter 5, Subchapter II, ß227, "Any and all nonsolicited commercial E-mail sent to this address is subject to a download and archival fee of $500.00 U.S.". E-mailing denotes acceptance of these terms. 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] Repeater upgrade needed
Gary, Before a solution can be discussed, you need to define the problem. Connect a spectrum analyzer to the end of the hardline and determine the frequencies and relative amplitudes of the signals you see. You may discover that your receiver is being desensitized by a harmonic or other spurious emission from another transmitter at the site. If this is the case, the owner of the offending transmitter has the responsibility to fix the problem. It is also possible that intermodulation is occurring, either due to problems at the site, or within your own receiver. Such problems can be a bear to resolve. My gut feeling is that one or more notch filters may be part of the solution. You can only do so much with bandpass filters; when you have very powerful transmitters that are close- such as the 101.5 MHz signal- a very sharp notch cavity may be needed for each one. That's why I suggest using a spectrum analyzer to identify what it is you have to notch out. You might be able to create some effective notch filters with quarter-wave lengths of 7/8" or 1.25" hardline. There's also the possibility that some inexperienced technician has left the shields off a UHF station, and its exciter (which is normally a VHF exciter followed by a tripler) is radiating a signal close to your image frequency. Spurious signals originating in the equipment building may become much more pervasive when the victim's feedline is not properly grounded. Finally, keep in mind that paging systems frequently use backhaul or control links in the 72-76 MHz band. If such a link is at your site, it probably has a ferrite isolator to protect it from other transmitters. Such a device requires a harmonic filter to block the second harmonic, which will be in the 144-152 MHz band. Hmmm... 73, Eric Lemmon WB6FLY [EMAIL PROTECTED] wrote: > > A question to all you repeater guru's out there. Have a repeater in a high > noise environment at a large TV tower site. Lots of pagers, FM transmitters, 2 > ways, etc on this tower. My Super Stationmaster 2 meter antenna is just 5 > feet > away from a bed spring style 45 kw FM transmitter on 101.5 MHz. My repeater > is a Canadian mobile Micor along with Wacom duplexer and a circulator on Tx > side. Have a DB 4062 cavity can tuned to bandpass Rx between duplexer and > receiver. Works OK but the 1000 feet of 7/8 hard line has a great effect on > the Rx > side of the repeater. Also a new paging tenant might be blanking the Rx out > of my repeater. Putting the repeater at the base of the antenna is not > possible. I would like to improve the receive side of the repeater. Have the > following > equipment available: > Advanced Receiver Pre amp GaAsFET P144VDG > Telewave TWPC-1005-1 pass cavity 88 - 108 mhz > DB 4062 WC-B 143-156 mhz 6 can duplexer > Wacom 641 duplexer 4 can (second set) > Kay switchable attenuator pad > DCI bandpass 144-148 filter > DB 4048 cavity cans (2) from disassembled duplexer > What would be the best choice and hook up to increase the Rx sensitivity and > keep the noise out of the receiver? Any help would be really appreciated. > Gary K2UQ > > > 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] Repeater upgrade needed]
It seems like you were on here about a month ago telling us the same story and asking the same questions.. Anyway, the BEST thing you could do is to move the repeater antenna BELOW the 45KW of FM broadcast. The micor receiver and band-pass filters are good & there is probably nothing better you could do. [EMAIL PROTECTED] wrote: > A question to all you repeater guru's out there. Have a repeater in a high > noise environment at a large TV tower site. Lots of pagers, FM transmitters, 2 > ways, etc on this tower. My Super Stationmaster 2 meter antenna is just 5 feet > away from a bed spring style 45 kw FM transmitter on 101.5 MHz. My repeater > is a Canadian mobile Micor along with Wacom duplexer and a circulator on Tx > side. Have a DB 4062 cavity can tuned to bandpass Rx between duplexer and > receiver. Works OK but the 1000 feet of 7/8 hard line has a great effect on the Rx > side of the repeater. Also a new paging tenant might be blanking the Rx out > of my repeater. Putting the repeater at the base of the antenna is not > possible. I would like to improve the receive side of the repeater. Have the following > equipment available: > Advanced Receiver Pre amp GaAsFET P144VDG > Telewave TWPC-1005-1 pass cavity 88 - 108 mhz > DB 4062 WC-B 143-156 mhz 6 can duplexer > Wacom 641 duplexer 4 can (second set) > Kay switchable attenuator pad > DCI bandpass 144-148 filter > DB 4048 cavity cans (2) from disassembled duplexer > What would be the best choice and hook up to increase the Rx sensitivity and > keep the noise out of the receiver? Any help would be really appreciated. > Gary K2UQ > > > > > > 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/
