Author Topic: Power variations between bands  (Read 382 times)

G3EJS

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Power variations between bands
« on: June 01, 2018, 04:37:28 PM »
Maybe it is not the "driver to output" that is the main power problem.
I have tried various ways of making T10, and various devices for Q92, 93, 96 and 97, some were better than others, but one thing remained constant, and that was the relative different power levels, ie 3.5 high, 7 lower than 3.5, 14 higher than 7, 21 much lower than 14, then 24 and 28 higher than 21.
Doesn't matter what I changed, or what the actual output was, this trend was constant.

I measured on the hot side of C200 and C204, and the trend is exactly the same.
Measuring the CLK2 level at R100 shows it is constant across all bands.
Tests were om CW, so the preceding circuits had no effect.
The only thing between the CLK2 level and C204 is the T1/T2 mixer circuit, so I suggest this is where the major power variations are originating. (I did not isolate the LPF from the output of T2, so that may come into the picture)
I would expect a smoother decline in power from 3.5 to 28 as the gain pf the amplifiers declined as the frequency rises.
I'm also thinking of increasing the values of R97 and R98 to 100Ω or even a bit more. (may make no difference, as)
Critical comments welcome :)
« Last Edit: June 02, 2018, 08:21:33 AM by G3EJS »