On 01/19/2021 08:22 PM, Evan Hand wrote:
It is not clear to me what you are asking. If you have a uBITX then the
method that Bob describes is the easiest. If your question is how to do
that, then here is the way that it is done in the v3 and later,
displaying the v6 schematic:
The way that works is that the first mixer (T1 and T2) is being
unbalanced by a 5 volt signal from the Nano on the CW-KEY line. This
forward biases 2 of the diodes in the mixer and allows the LO signal
that has been changed to the frequency that is to be transmitted to be
applied to the amplifier stages.
It should be noted that the power output will be the full power for that
To get less than full power out, you can vary the voltage from 0-5v. TP13 (it looks like TP13 anyway) would be a good place to inject that variable voltage, you'd probably want to use a diode and resistor in line.
I did that on my B40 and it worked well. I put the pot right on the front panel.
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