Batboard

This may have been asked before but due to the nature it seems to be difficult to search for.

The problem was first noticed when there was fan noise when the fan was running. When the fan is not running it is quiet. I was doing some trials and when you tap on the repeater case or even the radio it picks up these taps and put over the air when the repeater is transmitting. What is the cause of this and what would be the cure? This is a GR1225 repeater. This happens whether the mic is plugged in or not.

As a 2nd question..... I actually have had a similar issue when a 2 meter repeater that was hooked up by a local dealer using 2 Kenwood TK-762 mobiles but this actually only happens of the microphone is plugged in.

Thanks!

Try searching this board on +microphonic + repeater. Sounds like something is causing the transmit VCO to shift frequency in accordance with mechanical vibration.

Tear it apart, clean the connectors between the boards, reassemble it, align it, see what happens. It's not an unknown problem, but it can be tricky to resolve sometimes.