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On Fri, Aug 2, 2019 at 11:03 AM, JT Croteau wrote:

Could someone please point me in the direction of how to calibrate the uBITX with a PC audio spectrum analyzer?

?JT,

Here's what I did, and it seems to work well. Note: I am using KB8CEC v1.2 firmware. I don't know if this applies to the stock firmware since I have never used it.

I downloaded Spectrum Lab from here:


Install it and run it and go to Options->Audio Settings and select your sound card for the device input. Click Apply, and then you should see the spectrum display. If you don't you might have to click Start->Start Sound Thread. And if you're using some spectrum analyzer software other than Spectrum Lab then things will be different, but that's the gist of it.

Now connect a 1/8" stereo cable from the uBITX headphone jack to the audio input jack on your PC. Then turn on the uBITX and select USB. I did this on 20M but I don't think it matters. Slowly advance the volume control until you see the audio passband rise up from the noise floor.? If you advance the audio too much you won't be able to distinguish the passband from the noise floor.

Now turn on Setup Mode in the radio firmware, and then select "Set the BFO." Now adjust the VFO knob until the upper corner of the passband is at 2300 to 2400 Hz. The lower corner will be around 300 to 400 Hz. Press the PTT button to save the values. Now select CW mode and then select "Set CW RX BFO" and repeat the process for CW.

I posted a screen capture of the Spectrum Lab program after I finished adjusting the BFO. Thanks to Adrian KK6VQK and others for this idea.

73,
Doug K4DSP