On Oct 8, 2023, at 19:24, Evan Hand <elhandjr@...> wrote:

?Gordon,

Here is the "ideal" filter response based on simulation:



It looks like -26DBc is the best to be expected from the filter.? I would look at the drive to see what it is doing.? If the push-pull is balanced, the 2nd harmonic should be significantly less than the 3rd.? If you have a high Z input for your SA, you could use it to see the spectrum at the secondary of T5.? The other option would be to look at the two waveforms with your oscilloscope at each driver stage emitters.? Compare R20 to R48 and then to R19 and R47.? With a dual trace scope, look at r20 vs R19 and R45 vs R48.

73
Evan
AC9TU