[Elecraft] WSJT K2 Unreliable Output with WSJT

[Michael Carter]

Hi Lenny,

Have you operated SSB recently or only FT8?

I would remove the RigBlaster interface to the K2 (audio, PTT and RS-232) and try a known good microphone directly to the front panel connector on the K2.  If you can activate PTT from the microphone pushbutton and see (or hear on a separate receiver) the RF when you whistle into the microphone, then the KSB2 module is likely working correctly.

You verified the presence of audio on the output of the compressor IC (U3, pin 13) with your existing interface, which is encouraging.  The RF SSB signal is generated by filtering the output of the DSB modulator, U5 pin 4.  I would check (if your scope has at least 10 MHz bandwidth) for that RF output, which will be a DSB modulated carrier at 4.915 MHz.  If that is reliably present when the microphone PTT button is pressed, then that narrows the search a bit more.

The seemingly anomalous measurements you made on the DAC PWR CTRL output, if present when using a microphone directly connected to the front panel connector, may be helpful.  However, until you verify the reliability (or not) of RF output with a microphone (or external audio tone generator and a separate PTT switch), I wouldn't focus on the DAC outputs.

73,
Mike, K8CN