[Amps] SB220/221 - won't load on 80

[Dana Roode <K6NR@ARRL.net>]

Amp folks -

I'm also working on a SB221 that belonged to my father (K6VO).  He had this 
Amp out on his workbench for several years before he passed away in 1999.  I 
have studied it to see what its status is - it has the parasitic suppresser 
mods, the Harbach filter capacitor and meter boards installed.  Looks like 
he was all done.

I fired it up, no HV.  I found that the multi-meter's negative lead was not 
connected to ground - fixed that, there is HV after all.  The Amp seemed to 
tune up, but no power output.  The problem turned out to be a missing wire 
to carry the RF from the load capacitor to the antenna relay.  It goes from 
above the chasis through a hole to a lead on the relay that also has a 
RFchoke to ground.  I can't imagine why this wire would have been removed, 
unless it was for some planned modification.  Are there any mods that might 
require removing this wire?

The Amp works well on all bands except 80 where it doesnt want to tune up 
into my dummy load.  It works OK at 3.9mhz, but musters only a 100watts or 
so at 3.5.  I see there is a 500pf capacitor added in the circuit for 80, 
the bandswitch seems to be working OK, I doubt the capacitor would go bad, 
but who knows.  That's what I'll check, any other suggestions?

  Dana


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