John, What is the CTCSS tone frequency? You might use a service monitor to see if some of your repeater users have excessive CTCSS deviation. Yaesu, Alinco, and Icom radios seem to have way too much tone deviation, and- unfortunately- the tone deviation cannot be adjusted separately from the voice deviation. Some samples of the above radios have CTCSS deviation above 1200 Hz! CTCSS deviation in the 400-500 Hz range is plenty.
Another hum source, especially if you're using an Astron power supply, occurs when the power supply's negative terminal is grounded internally to the case. As I reported in an earlier posting on this list, that situation is almost always going to inject an AC hum into the repeater audio. Check to ensure that the DC power supply negative terminal is not grounded. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of W3ML Sent: Sunday, November 08, 2009 5:43 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] repeater problems solved Hello, I wanted to thank everyone again for the recommendations on how to fix our system. I made several of the changes posted and we replaced the antenna and hardline with new ones. The system is working right now. The problem with the radio power going up has stopped and the noise is all gone when people talk. Only one thing to figure out is a low hum coming across on transmit. We have ruled out the power supply. From what I have read on here today in old messages, I feel it may be the CTCSS coming through. But, it is nice to have the power up high and to be able to understand people when they talk instead trying to make it out through the noise. Thanks again for all the help. 73 John, W3ML
