Page 1 of 1

GM300 TX Power Problems

Posted: Mon Jun 02, 2008 1:34 pm
by RADIO43
Guys,

Having a problems with a 45 watt 146-174 Mhz GM300. Placed the radio on the service monitor the other day and it TX's at full power for about a 1/2 second and then the power cuts down to what appears to be exciter power. here is the weird part. The radio is still pulling about 10 or 11 amps during this process.

I am performing these test using the General Dynamics 2670 Service monitor and have tested that numeous times to make sure that is working properly, which it is. I would think the radio has a bad power amp but looking for other suggestions. Any help ideas would be great.

radio43

Re: GM300 TX Power Problems

Posted: Mon Jun 02, 2008 2:13 pm
by Max-trac
I have had some bad PAs do that (not sure it they still drew current though).
Measure the control voltage going to the PA. (pin 2 of the 5pin connector going from logic board to PA).
If it drops off, try jumpering the 9.6volts (T) to it while transmitting.
If power out stays good, then you can add a manual power control bypassing the feedback circuits.

Re: GM300 TX Power Problems

Posted: Mon Jun 02, 2008 6:24 pm
by RADIO43
Thanks Max-trac for info.....