Also worth noting:
The stock firmware shuts down the bfo and local oscillator to the second mixer
when transmitting CW.? So all RF on the uBitx main board is at the operating frequency.?
Forks of the code should take care to do the same.
This will avoid any unexpected products, also?avoids having mike audio sneak through
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On Mon, Jun 4, 2018 at 09:25 am, ajparent1/KB1GMX wrote:
A reminder:
* Generating CW
?* The CW is cleanly generated by unbalancing the front-end mixer
?* and putting the local oscillator directly at the CW transmit frequency.
?* The sidetone, generated by the Arduino is injected into the volume control
?*/
Straight from the source code.? CW TX is not prone to the SPUR issue as it is a clean
signal at the operating frequency with no mixing.? We still have to have low pass
filters to remove harmonics but thats easy and works.
SSB we involve two IFs two FIlters and three Mixers.? Much more going on and?
with far more complex interactions.
Allison
