.....the story continues....
dear Tony
casually I discovered that the micro was blocked I think because the start-up did not happen correctly and then to the
micro did not get the reset. There will be some problems in the U12A, U12B and U21A circuit of the A13 board (controller).
Waiting to resolve the anomaly I gave a manual reset putting for a moment on the ground the pin 3 of U12A (RST).
As a miracle, the display appeared correctly indicating 1000000 Hz and a level of -86.98 dbm.
I tried to change the level and everything was ok. On the output connector, with 0 dbm on the oscilloscope we could see one
beautiful sinusoid. Changing the level the sine wave changed size, perfect everything ok. I thought I had solved everything, except
of the small problem of reset ..... but no !!!!
As soon as I tried to change the frequency, even a few hz, both from the keyboard and manually with the tune knob,
while the display indicated the new frequency on the output connector the marked disappeared. This even if I set
the frequency again at 1 MHz. Nothing went out anymore !!!
The only way to review an output signal was to reset the micro. In doing so, outgoing one had to
new the signal of 1 MHz and the level of -86.98 dbm, but as soon as we tried to change the output frequency
the signal disappeared and instead the display indicated the new frequency and the level that had been set,
but outgoing nothing !!!!
Strange thing by scrolling all frequencies with the tune knob (but also with the keyboard) at some point, when
the display indicated 14 MHz (approx.) in the output a signal of about 22MHz appeared and continuing to change frequency
at 44 MHz (approx.) a lower level signal was again (maybe a 2nd harmonic?).
I hope I have clearly illustrated the anomaly and ask for your opinion.
Excuse me if I disturb you continuously but given your experience I'm sure you can give me good advice.
Best wishes