Another QCX almost working #t1 #qcx #lpf #alignment

Richard G4TGJ
 

I've been building my 30m QCX  over the last few days. Unfortunately I put a 33k resistor in one of the 47k positions. I discovered that removing components from double sided boards is quite tricky. In removing it I destroyed it. Annoyingly I didn't have any 33k resistors in my collection but a pack arrived from RS yesterday so I was able to finish it last night.

Alignment went well up to the IQ balance stage. But the Phase Low and Phase High adjustments don't give a proper minimum - the pots just adjust right to the end of their range. But it does receive and I couldn't find the unsuppressed sideband so it is at least usable. 30m seemed surprisingly busy last night.

The output power is lower than I would expect. With 12V I am getting about 1.5W instead of the expected 3W. Transmitting at 8MHz into a dummy load gave higher output so it looks like the LPF needs tweaking. I did put it on the air and although I didn't have any QSOs my signals were picked up by a few RBN stations so it looks very promising.

I won't get chance to look at it again until the weekend and it seems I need to revisit all the coils. But at least my soldering appears to be OK and I haven't fried any components!

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