I am seeing similar indications out of IC503 with my just completed QMX+.?
It was working fine for a couple of hours on 20m at 4.3w. Tried tuning up on 10m and power out went to 0w. Switched back to 20m and still no output.
Having been through this and with a handful of spare BS170s, I just clipped them out and started looking at IC503. I'm getting a wonky output from one pair of the gates (C&D) and only 2v P-P. Good and bad traces attached..
The output of IC501 is also a bit weird compared to IC502 but I'm thinking this may be caused by a bad gate within IC503.
I will be replacing IC503 tomorrow. If all looks well I'll plug in a new set of BS170s and see how it goes.
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Randy, N4OPI
