When I attempted to answer someone’s PSK31 CQ I noticed my RF power was averaging about 30 watts, but peaking at 70 or so.

I doubled checked various knobs on the US Interface Navigator, software, etc. Everything looked fine.

I transmitted again. The peak power was still there.

I knew this was not right and I was frustrated. I then recalled the power meter correlated very well with the sharp clicks coming from my kid’s air hockey table in the next room, but how could that noise be getting in and if it was, why was it having any affect from so far away.

Aha… the “MIC GAIN” on my Icom 746 was still up meaning the microphone on my Hail headset was still live and mixing with the audio from the Navigator.

Plus, the staccato noise from an air hockey puck smacking against the handle is a lot louder than it might seem because it is so short.

I turned the mic gain down and all is well.

I have not found an automatic way of muting the microphone input during sound card transmit with my IC-746. Have any of you found a way to do this?

73
kx4o

It was not even two minutes before a ham came back to my Olivia 16/500 call on one of the 40 meter calling frequencies.

The ham was patient with me as he noticed he had to swing his receive calibration value down quite a bit to copy me. He mentioned he had to adjust the ppm value for his sound card receiver down a full 5000 ppm to pull me in. We chatted a while and I decided to put +5000 ppm in my soundcard TX calibrate attribute. It worked. We could now have an Olivia QSO with no adjustments.

Discussing this further, he suggested I run the WWV Calibrate procedure described in the MixW documentation. After the QSO was over, I did this for the RX and TX values using the 5 MHz WWV frequency. I found my RX adjustment was -160 and the TX adjustment +6689. Wow.

The ham mentioned sound card calibration is very important for the multi-tone modes including:

• Olivia is more tolerant
• MFSK16 is more sensitive
• MT63 is very sensitive

Thinking back to some PSK31 QSOs I did notice my transmitting frequency was just a little different than my receive frequency. Using “lock” I was able to avoid the leap-frog up the band thing that happens when two unlocked PSK31 systems try to constantly lock onto each other and pull their RX frequency along.

This could be my Icom-746 drifting in frequency too, but this sound card caliburation is clearly an issue.

By the way, this is the sound card in my US Interface Navigator, not my PC.

So judging by the values, the calibrate procedure for your sound card and software combination may be just the thing to finalize your digital mode exploration.