John
?Glad to hear you made some progress. Sounds like the replacement YTO was
?too sensitive (degraded phase margin and increase in loop BW due to
increase in overall loop gain), correct? I wonder if the best way to fix
that would be a shunt resistance across the tuning coil. There's a lot to
be said for not altering the loop filter itself, if possible. It has to
work over a rather-wide range of conditions as the analyzer sweeps across
the band.
Thanks for that thought. I can't argue with your logic! I'll try it when I
next summon-up the physical strength to lift the analyser off the shelf where
it lives!
FWIW I did look for a change in loop performance, using the shape of the noise
pedestal across the tuning range of the analyser, and it seemed pretty
consistent at both of the band edges and at its centre. I didn't have the
time or energy to look at the loop using more formal methods...
Vy 73
Chris
GW4DGU
