Yeah mate. FIIK?.
Pair of 3-500Z and the cap was 4700uF/50V. When the amp was
keyed, the reed relay contact shorted the 15k resistor in series
with the diodes. The idle current would take a full second or so
to come up to the 150mA I wanted. The miniature reed relay failed
after many years and now there's a pink Opto22 job in its place.
I can test it again? soon, as I want to take my GS35B 6m amp out
of the rack for a modification. I'll stick a thumpin big cap in
there and see if I was dreaming all those years ago.
Cheers, Alek.
On 2/03/2025 12:10 am, Jim VE7RF via
groups.io wrote:
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On Sat, Mar 1, 2025 at 01:31 PM, Alek Petkovic wrote:
>Hi Jim.
>I tried a large value electrolytic across the bias
string and every time I keyed up, the ZSAC would take a
while to stabilize at the set level. When I stuck something
like a 22uF in its place and it seemed to be better.
>Without trying to work out time constants and such, I
figured that the 22uF would still provide the good dynamic
regulation during speech and CW transmissions. Dunno if I
did something wrong that initial time but for >better or
worse, I've always settled on the lower value caps since
then.
>Cheers and thanks, Alek VK6APK.
##? what tube were u using ?? ?This makes no sense at all.? The
string of diodes and the parallel? cap are in the circuit at all
times...and in series with the 50-100K? cutoff resistor.? We
used 7000 uf on buddy's 3x6 amp...and when 200 ma idle current
drawn, it was rock solid.? ?I have also tried as much as 45,000
uf? (3" diam lytic with mounting bracket)....same deal...doesn't
budge.? ?The V drop across the string of diodes is constant,
whether the cutoff resistor is shunted or not.?
This one baffles me.?
