Re: calibrate v4 ubitx
Hi Jim,toggle quoted messageShow quoted text
The easiest way I have found to set the BFO is to use something like the graphical display in fldigi or Spectran - I prefer spectran. Set the display to show the audio frequency as opposed to showing you the radio frequency. The waterfall or spectral displays of the background noise will show a 'shadow' of your "system" pass band and that will be largely determined by the xtal filter passband. Be sure to disable or bypass any audio filters. My passband with my uBitx is about 1900 Hz wide. I see a broad, mostly flat curve with a slope at either end. Changing the BFO up and down will move the slope up and down the frequency scale. I adjust the BFO so that the low frequency slope starts to roll off at about 300 Hz. Thereafter, tuning SSB and AM signals (using synchronous AM detection) gives me clear voices. Music is not going to be good through that filter no matter what we do with the BFO. The master oscillator (25 MHz) must be calibrated first.
I hope this helps.
On 07/20/2018 11:32 AM, Jim Sheldon wrote:
bark less - wag more