|Etched, Solder Wiped and Drilled,|
Ready for Cut and Parts
|The Completed Mixer|
The Two J310 JFETs are located in the Center
JFET Bias Circuit is on the Left
The Two Coils are, of course, Obvious
I spent some more time with LTSpice. I changed the LO from a small sign wave to a 70mV square wave, it works much better. Then I could correctly observed the results via an FFT plot. For the simulation I used a frequency of 27MHz for the LO and 7MHz for the input signal. As can be seen in the FFT plot, the output contains the desired 20MHz signal and lots of higher harmonics. The 20MHz peak is the difference (27 - 7 = 20) and the 34MHz peak is the sum (27 + 7 = 34), the 27MHz LO is suppressed, as it should be.
|Lower Left is the Farhan Mixer Circuit|
Upper Left is the Full FFT Plot
Upper Right is the Expanded FFT Plot Centered on 27MHz
Lower Right is the Output Plot at the 50 ohm Load
I really like working with LTSpice.