Hi Chris !
The first screenshot shows an un-symmetrical square-wave that will
generate two frequencies to the 1:4 divider and Tayloe-mixer. An FFT of
this signal (R17-to-pin3) should show two peaks and not only one as
expected. A standard frequency counter will show only the arithmetic
mean value of both frequencies, as it is just adding zero-crossings
during gate-time.
The Softrock series 6.x had a different type of I/Q divider that used
three flips-flops. They did not have a problem with such an
un-symmetrical square-wave, as there was an inherent divider by two,
which forced the oscillator signal to be symmetrical to the mixer.
You could try to move the bias-level of Q2 transistor to a voltage where
the output (square-wave) signal of Q2 will be almost symmetrical.
If the oscillator at Q1 is not running smoothly, this is where to look
for variations of C's or R's to make it run stable.
73 de dg3lv Tobias
Am 26.01.2018 um 20:36 schrieb Chris Wilson:
I just completed two scope measurements at R17 to pin 3 of the divider
IC. One of the faulty LF Softrock, and one on my MF one that works
fine. the resultant wave forms are quite different. But I am not
clever enough to say if they hold the clue, so will post them here.
Thanks again.
Faulty LF oscillator or divider first
http://www.gatesgarth.com/R17-to-pin3.jpg
Working MF Softrock, same place
http://www.gatesgarth.com/mf-R17-to-pin3.jpg
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