MICOR VHF 110W REPEATER XMIT AUDIO WENT DOWN

[telemetryguy]

I have a MICOR VHF 110w repeater (not a conversion, came from the factory as a PS repeater). I converted it to two meters and it was running fine (at 35 watts reduced power because of the notch-only duplexer).

A few weeks ago I was notified that "the audio seems low". It is. 5Khz deviation on the input signal yields only about 2.5 to 2.8 Khz out of the transmitter.

I tried another exciter board with my channel element with no success. I injected a 1Khz audio tone into the exciter, bypassing the cards in the card cage to rule them out. No help.

Since this is true FM, I wonder if something could have gone bad in the channel element and/or the crystal itself. It sounds strange I know, but there are quite a number of components in the element and anything can happen.

Have any of you folks seen this or something like this happen? I am ready to start checking components in the element. Just wondering what any of you may have found along these lines.

Thanks in advance for any info anyone may have. PM if you like. Or reply here.

[jackhackett]

Modulation is done in the channel element with a varactor diode, so your problem is most likely with the element. Was it off frequency at all? Also, what is the part number of the element?

[telemetryguy]

Was not off frequency. KXN-1019B is the channel element number.

[jackhackett]

If you don't already have one, there's a schematic for that element on the Repeater Builder site.

[telemetryguy]

I already have it. I am checking components now. Thanks though.

[telemetryguy]

It was the channel element. I checked every component I could find the value for and none of them were bad. I couldn't find values for the two varistors so I sent it back to International Crystal and they fixed it. Works fine now. Thanks to all for the help.