On Sun, Mar 16, 2025 at 10:39 PM, lars anderson wrote:
i scoped the gates while pressing T on the diagnostic menu & all had square waves so the 7408 & XOR are ok
Lars, square pulses are not enough. You need also 5 V for high. Last time I had a QMX on my work banch with a partially broken IC503. Both outputs had square pulses but one side 5 V for high and the other 4.5 V for high. When sending the IC drew an excessive current.
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?i don't exactly know how to test if Q507 is fried, but a friend of mine says that's the same control point that's used for the reduced voltage setting used for teh SWR sweep & tuning.?
Yes. But you have to check if the output is reduced using SWR sweep & tuning. A simple way to check Q507 is to use Terminal diagnostics and observe the PA voltage. Without "T" pressed it should be 0.x V and with "T" depressed a voltage a bit below the supply voltage.
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But nice to read your QMX+ is back to life.
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73 Ludwig
