Re: how to set bfo

Dave Bottom <ars.kd6az@...>


That's an interesting  idea to use the audio output.  Typically you set the Carrier Oscillator/BFO 20 dB down the skirt.  I have lots of spectrum analyzers, but actually I mostly now use RTA Audio on my iPad as it has >100dB dynamic range.  I'm going to make a a cable breakout box from the TRRS input to play with that.  

It turns out for me I found the offset is exactly the same as on my Collins 2.1KC Mechanical Filter (ooops KHz filter) for good sounding SSB and also lots more output from the Balanced Modulator.  This is a long way from the default BFO setting.

On Wed, Jan 10, 2018 at 9:50 AM, Gordon Gibby <ggibby@...> wrote:
The software for automatic link establishment also turns out show you a spectrum analyzer in bar chart form.  Just by watching the waterfall in FL DGI or other software you probably got a intuitive understanding as well.

Sent from my iPhone

On Jan 10, 2018, at 12:41, Rod Self <km6sn@...> wrote:


Thanks. I dug into the software and  found out how to get into setup. OK now.

r.e. the BFO - as you know, the receiver on a ubitx is a 12 MHz fixed-frequency receiver. USB/LSB switching is done in the previous mixing stages. Using band-noise as a wideband signal source, if one views the ubitx audio output on an audio spectrum analyzer, it should be quite easy to set the BFO frequency to a desirable setting.

On Linux there is a great open-source audio spectrum analyzer called JAAA. On garden-varitey USB sound cards you can see at least an 80 db range. I will use JAAA to view the ubitx audio spectrum and set the BFO accordingly. Then, in the ubitx.ino code, one can tweak the SECOND_OSC_USB and SECOND_OSC_LSB constant definitions to achieve balance when switching sidebands.

I am sure there are useful audio spectrum analyzer programs for Windows and Mac, which would work equally well.

That is my plan for today; I will travel to my shop and will let you know how it works out.



On 01/10/2018 08:59 AM, Dave Bottom wrote:

When in SETUP keep turning the knob clockwise and finally BFO Set will appear.  It always starts at the same default frequency (this should be fixed and display the current frequency setting) but then you can change the BFO.  Record your setting so you can try different values, but listening while adjusting on a SSB station works (sort of).

Dave WI6R

On Tue, Jan 9, 2018 at 1:55 PM, Rod Self <km6sn@...> wrote:

Hi All,

How does one get into setup to set the BFO frequency? The instructions on the web site appear not to work.


73 Dave WI6R

73 Dave WI6R

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