The old world way of doing it. Based on the formulas posted earlier.

10-23-25 Project on hold.

I must take a break from the bench. Maybe I will get back to it soon??

RF Amp and antenna input circuit

The input should be matched to the antenna and the amp input. I will use a bandpass filter for 80 meters. First the page from the book.

and the results.

The sweep.

Needs a Local Oscillator and some bandpass filtering

The direct conversion unit can cover any portion of the HF spectrum by simply tuning the LO as desired. Some filtering may be required to keep the signal clean. I am in the fringe area of the two closest AM stations so not much concern about that. Anywho the next step is the LO. We could keep it simple and just build a Lamda Diode oscillatoe or be a little more adventerist and buils an oscillator with Vcap and coils? We need to look at stage interaction. It is easy to build a single stage and get good gain. Not so easy when we tie stages together and they interact. It seemed some folks would see a new schematic and start declaring this that and the other were not needed. Maybe we could try removing a part here and there to see what happens but most every piece of this set has a purpose.

The radio less the LO

Now we apply the signals across a non linear device and see a much different output. The readout measure a signal of 1Khz. How does a 1000khz and 1001khz produce a 1khz outout. The non linear action of the diode procuces 4 output posibilities. They are the sum, difference, and 2 orignials signals.

In this circuit I simply apply 2 signals to a resistor and the produce an algebraic sum or difference of their amplitudes. The resistor being a linear device it has no effect on the signal phase or frequency.