[AMPS] input Q upgrade

[nospam4me@juno.com]

Hi Charlie,

Glad to see you going with the g-grid circuit. You'll find the 4-400
amplifier 
slightly harder to drive vs the similar 3-400/3-500Z.

I have most of the input circuits for the common tubes, the trouble is
the 
paperwork was done before solid state final exciters. The lower Q of the 
older designs plays havoc with some exciters. I've seen a real
interesting 
oscillator made from an early SS exciter final where one wasn't wanted. 

I'm in process of rebuilding my personal SB-220 with all the current
fix's, 
during last nights late night tune up into a termination, I measured the 
factory SB-220 swr using my TS-940.  The best obtained was about 1.6 to 
1 sweeping the entire 80/40/20 meter bands. Although my 940 seems to 
drive it fine, "your results may vary."

I hoped to avoid rebuilding the input for a higher Q, but it looks like
it 
should be a "must include" for a new project. 

Rich mentions the SB-220 input factory Q about 1.6 and suggests more. 
I agree with that opinion.  His web site probably has the information 
you need.  I can scan the 4-400 inputs I have (better than nothing) here 
for the sonic server, but it'll have to wait until next week.  I'm in the

middle of another server upgrade process. 


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