[Amps] 4cx25ob amp for hh

Jameshickox5 at wmconnect.com Jameshickox5 at wmconnect.com
Wed Jan 29 09:46:30 EST 2003


Hello all,

I am beginning to work on a HF amplifier using 2 of the 4cx250b tubes.  I am 
starting with the June 1975 QST article "the LKA-1 Linear Amplifier".  This 
amp uses a tuned grid input.

I am wondering if anyone has tried to place a 450 ohm resistor at the grid, 
then feed it with a 1:9 transformer.  I am hoping this will allow very low 
drive from the exciter, and reduce or eliminate the need to neutralize the 
tubes, and most of all, eliminate the need to tune the grid every time I 
change frequency.

Any ideas on the subject would be appreciated.

James Hickox, AA5AO


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