Transponder ID function inop
I had suspected it since acquiring it, and it has now been confirmed by a kind lady at Brussels information: my KT77 transponder works nice in modes A and C. But when they ask me to ident, I turn the knob to its furthest and non-locking position "TST", and the poor radar operator doesn't see a difference.
Is there something I have misunderstood about how to ident?
Or would there be a defect? I always understood the "ident" is no more or no less than an extra (13th?) bit in the squawk code. I have some soldering skills, enough to connect a cable to a plug (and yes, I know they should be crimped rather than soldered, in aircraft use) and I think I could isolate a defective logic gate in the transponder electronics. What would be my chances of locating the source of trouble? If a defect there is, my suspects are (in order) the switch, cabling, electronics.
I do consider HF-electronics like a less evil variant of black magic, though, and am very reluctant to touch anything on the HF-side.
Or could anyone recommend a decent avionics workshop in Belgium? There's one I've heard of at Zwartberg EBZW, but am afraid they might be expensive, as they mostly work on certified planes (mine isn't).