Batboard

I have a GP300 that when I turn up the volume above 3/4 open, it becomes distorted and squeals. Any suggestions ? Works fine otherwhise.

Jay

Two things come to mind, one is a weak battery with high internal resistance.
The other is loose and/or dirty shield connections to the frame and poor grounding on the main board to the chassis frame.
Then there is the more diffacult problem of a bad bypass cap in the receiver and audio section. Most of these I fix for $25.

Opps.. need new glasses.. I read GM300 here at first!!
On GP300's... if tightening the retainer clips on the main shield doesn't cure it, its likely a VCO problem... and that is very bad news as a VCO is a very touchy circuit and naturally microphonic. Check the shield cover on the VCO for any cracks in the solder joints.. otherwise I'd stick a speaker/mic on it to get the speaker audio away from the VCO. Good Luck!

oh well here is the GM300 speaker howl fix too
That is a very common problem we see. Open the radio and take the shields off on the main RF board side. Then simply tighten all the torx head screws that fasten the board to the radio frame. You will notice that several if not all are loose.
Carefully re-install the shields.. pay close attention to the fingers on the VCO shield.
Thats all there is to it.. Crank the volume and go!
Bruce




<font size=-1>[ This Message was edited by: perthcom on 2002-01-04 21:49 ]</font>