Batboard

I just had the Maxtrac transmitter in my Desktrac repeater replaced. Afer about 5-6 min of exchanges in air traffic the PA simply SHUTS OFF. (Not gradual decrease in power) When it sits for awhile or if the radio is turned off then back on again immediately it is back up to full power.

I have one fan blowing into the housing and two fans directly on the heatsink. The radio does not feel like it is getting all that hot. It is a 40w radio turned down to 20w.

I am running the exact same setup with a 40w GM300 tuned to 20w as the transmitter and have never had this problem and I only have one fan on the GM300. Are the Maxtracs more sensitive to the heat than GM300? (I know essentially the same radio) Is there a bad component that could cause this? I thought it was strange that the radio would simply go from 20w on the meter to nothing (but there is still a slight signal coming out...probably the exciter stage)

could be the pre-driver or driver stage, to many possible causes to narrow it down without actually troubleshooting the radio..
you say you just had it replaced, I'd take it back to whoever did the work.

Hummm.I think I will. In the meantime I have a "good" GM300 that is the 10w model. I will swap radios and see what happens! Thankks for the reply!

I would go into the service/replace transmitter section and do an alignment...
Or if you select logic board replacement, you can check all the settings....You will need a setup to inject audio, a watt meter , freq counter and service monitor..
I have had radios behave like you said that had logic boards blanked and no alignment was done.
Don't forget when you are done, to read the radio and save the file and never use an old file to program it....