[W8ZV]

We got you working.  The crystal oven takes 1/2 hour to stabilize.  But you would still be able to use the counter immediately, it just won't be accurate.  As for the 400 hertz tone, you need an unmodulated signal to drive the counter anyway.  You can't read the RF signal with the modulation on.  It will be modulating the RF output and the counter will be reading all over the place.  I haven't tried the mod suggested by the other poster, but if you are running across the generator to use the AF input for an output to drive the counter, you may be introducing noise back into the AF section, unless you used shielded cable to wire that connector.  The best way to get direct drive for the counter is to put an output from the cathode of the RF oscillator.  That way, you get the signal, without affecting the RF output and modulated signal.  It's how HP did it with their older tube based generators.  I don't know what would be required to do that in the Heath SG-8.