I checked a few of the other big repeaters, and they have just as much side channel noise as mine did. I adjusted the deviation and it's now narrowed down to around 10 kc either side of the transmit frequency, and not as bad as it was.
Mathew At 1/17/2005 01:09 PM, you wrote: >I had something brought to my attention yesterday on my 2 meter >repeater. ABout 15 miles away, I'm being told that my repeater can >be heard on the output for about 20 to 25 Khz away. From what I am >told, it is not legible, but it's there. The transmitter is a >Magiorrie Hi-Pro running about 2.5 watts and the PA is a Vocom 200 >Watts. I'm getting right about 165 watts out of the duplexer, fed >through 7/8" hardline 160' to the top of the tower into a Diamond >Dual Band Antenna with a vsr of 1.1 with 1/10 of watt reflected. Is >this normal, or is there a problem. Depends on the radio being used to receive your repeater, but generally no. Most amateur-grade equipment has enough selectivity to completely "lose" anything 20 kHz away unless the received signal is driving some stage into overload. 2 things to check on your repeater TX: deviation, & modulation spectrum. Deviation can be checked with a service monitor or deviation meter. Modulation spectrum is a little trickier & as such is often overlooked. The easiet way to get a rough idea of your modulation spectrum is to connect the 9600 BPS output of a receiver to the line input of your computer's soundcard & run an audio spectrum analyzer program (lots of shareware out there plus I'm working on one but it's not quite ready for "prime time"). Then make your repeater blow squelch & see if the resulting noise is flat out to 3 kHz compared to the noise you see with no signal present on your monitoring RX. Above 3 kHz it should start to roll off & above 4.4 kHz it should be down 10 dB (that is what I see on all my G.E. radios when TX audio is fed to the mic input). Ideally in a 15 kHz world the rolloff should be steeper. The audio processing boards Kevin has made available (<http://www.repeater-builder.com/products/audioprocessingorder.html>) would be ideal, but if you don't have a 15 kHz "neighbor" that's close by then 10 dB down @ 4.4 kHz should be good enough. Bob NO6B 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/
