Bill, AC hum that begins spontaneously is sometimes due to an audio cable that is loose, breaking the shield connection.
Another possibility is the failure of a filter capacitor inside a power supply feeding the IRLP device. Ideally, all sources of audio feeding the repeater and/or the controller should have just one DC power source. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Bill Sent: Saturday, August 09, 2008 7:37 AM To: [email protected] Subject: [Repeater-Builder] Hum on MSR200 Receiver Howdy group. I have a Motorola MSR2000 repeater on the ham bands that I maintain. VHF 147.32 in Austin (Oak Hill)Texas. It has developed a hum on the receive signal. I know it's the receiver as there is no hum when the machine ID's with no input from the receiver. The hum has been getting worse and now I need to take a look. I have schematics and instruments. I'm asking to see if anyone has seen this kind of issue before. I run a 114.8 PL but it sounds more like 60Hz not 114 hz I'll have to look at the audio and measure. The machine is on IRLP if anyone wants to take a listen the node is 3364. Any input would be helpful. Jim K5VPW monitors the machine and runs the IRLP node so he may be listening and is willing to assist. Bill N5ZTW
