[Amps] Henry 4K Ultra Mods

Bob Maser bmaser at tampabay.rr.com
Tue May 30 14:58:03 EDT 2006


I'm coming down the home stretch on my modifications to my 4K Ultra and I 
have some questions.  What is the recommended zener diode for the bias 
circuit?  The original 8877 design used a 1N2810 12V @ 50W zener.  This 
seems a bit high for the 3CX1200D7 that I an using.  Also, the bias circuit 
in the 4KU has the 10K resistor in front of the zener.  In my modified 
circuit I am going to connect the bias circuit to the center tap of the 
filament transformer.  In all the circuits I've seen, the zener is connected 
to the CT and then the resistor is in series but behind the zener.  Does the 
circuit care which component is connected to the CT?

Thanks,
Bob  W6TR 



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