Dave,
The input impedance of the SB-200 is a strong function of the output tuning,
i.e. lots of feedback from the output to the input via the tube's capacity.
Not that tuning the input is that difficult but only saying that you probably
need to do it with the amplifier up and running (e.g. with a VSWR meter between
the exciter and the SB-200).
73
Bob Groh, WA2CKY
________________________________
From: david sutton <sootydave@yahoo.com>
To: amps@contesting.com
Sent: Tuesday, April 7, 2009 9:07:27 AM
Subject: [Amps] still working on SB-201
hi group,
i have a SB201 that was modified to 11 meters. i have rebuilt the amp from
scratch all new components. the tuned circuit had been butchered so the 20 and
15 meter coils need to be re-wound. does any one have any idea how many turns
each coil requires. the 20 meter coil needs rewinding due to having been smoked
this has 9 turns on the former, i think this is the right amount. the 15 meter
former has 3 turns +padding (removed), this I'm thinking is way off.and would
be correct for the 11 meter band. if any one has a SB201 they are willing to
open up and count these windings for me i would be most pleased.
also i need to know what the driving impedance of the 572b tubes are, so as i
can re-tune the coils
73's
Dave
Brits with a southern call? how strange, only when you hear the accent.
see kg4uxr on :-
www.qrz.com/callsign/kg4uxr
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