TRC-458 runs REALY hot esp in SSB mode, then power drops off

[mr_fx]

My TRC-458 runs really hot, when it gets hot the power out REALLY drops off...

I have since backed it off a little and that seemed to help...

the power supply heat sink gets hot and so does the driver/final heatsink

any ideas? besides running a fan?

 

[binrat]

How high is the SWR??

 

[mr_fx]

How high is the SWR??

almost flat on the low side of the CB band, around 1.4-1.6 on the high side of the CB band

I need to adjust my A-99, it's close, but not quite right

 

[Robb]

The driver/final transistor insulators on the 458 are large ceramic pads that need to be replaced with the thin mica insulators and a generous portion of heat sink compound. No doubt that your radio may also need other refinements. It is a fine radio, but its potential for problems are present if they aren't dealt with.

Your bias voltage on the driver and final transistors may need adjusting. But if you do not know what you are doing, then you might damage the radio. Time to consider shipping it off to DTB Radio and let them do some upgrades and give it a real alignment. Otherwise, I fear that your own efforts might be the radios failing if you don't have the experience and knowledge to give this radio what it really needs.

Attempting to tell someone how to fix a radio can be likened to explaining how to do minor brain surgery, and I wouldn't want to do that. Don't want that responsibility. However, here is a link from a forum member that will give you an idea what you are up against. Once again, remember if you don't know how to do this - then by all means don't:

Http://unit399.fortunecity.com/858ssb.html

 

[ExitThirteen]

Two problems would cause it to run hot and the power to drop off. First make sure your power supply is putting out anywhere from 13.7~14 volts, no more than 14. Also, if the Driver and Final bias pots are cranked wide open, that will also cause those symptoms. Check to make sure the Driver and Final bias are set properly. The radio will run warm normally, as my President Washington has always ran warm, but doing those two checks will reduce heat and power output drop. Hope this helps!


~Cheers~

 

[mr_fx]

I was running 14.4 ish... also cranked down the juice a little bit