On Fri, Apr 4, 2025 at 03:52 PM, pgramsey, N9LFF wrote:
I've sort of convinced myself that I have a shorted Q504, drawing too much current and heating up Q507
I think you are correct, based on the evidence stated.? Did you perhaps leave your QMX in tx mode when you turned away??? Extended tx time could have burned one or more finals at full voltage/power.? You can try measuring resistance between the leads of Q504 (and the other three BS170s).? Mine shows in-circuit S-D resistance of about 6.8k.? The resistance between G and S or D varies depending on which polarity I connect the probes - but always over 150k.
?
