Hey Y'all,

My QMX has been doing well for a few days and quite a bit of use after fixing some solder joints, but now I notice something that bothers me.

The power will stay up for a while until it gets really warm. Then power will reduce somewhat, I expect hot finals will lose some power, that's normal in regular rigs in my experience, however after a while it will lose even more, up to a watt and a half, sometimes more. Cool things off and it's back up.

Measuring the drive to the finals I get 2.505v on one pair and a 2.534v on the other pair. This isn't at the maximum heat, but was showing low power when I shut it down to test.

Obviously the drive should be the same on both sides, and it has other times. Could the issue be the driver IC or one set of BS170s?

Maybe some before the driver? I'm wondering if this is a clue to my issue of blowing finals far too often.

I can change both the IC and the finals, but before I do I wanted to get opinions from the experts in case we can find the "real" issue.

Thanks all for your comments.

73,
Cliff, AE5ZA