Hello Evan
Thank you very much for the help, I really appreciate it.
The antenna connector, as well as TP1 and TP2 are both 'hot': with a small antenna connected to the signal generator, I can receive the generator signal with a 30 cm piece of wire, and even with my ...finger. I don't have an idea on the output power of the generator: it is an antenna analyser, that can be used a generator. So I would assume that the signal chain to TP1 or T1 are fine. The audio part is ok: touching the volume pot gives hum, and the side tone on CW is fine.
Then I checked Q90. On transmit I measured (with the oscilloscope) collector 12 V, base 4V, and emitter around 3.5 V. Seen the resistor divider on the base 1k/470E that looks fine to me. I also measured once again supply currents: on receive 230 mA, in SSB 630 mA (modulation doesn't barely change this current), and in CW key down some 1.2 Amps.?
I just tried something else: the antenna input is connected to the dummy load. With the generator at 48.6 MHz, and the uBITx at 3.6 MHz, I receive the generator loud and clear. But when I touch TP13 and/or TP14, absolutely nothing changes: no cracks, no hum, signal doesn't become weaker or stronger - nothing happens, no matter if I touch TP13 or 14 or not... Is my conclusion correct: the first DBM works fine, but there is something wrong around Y1... ?
Thanks again !
Tony ON6NT
