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previous: david I've caught bits and pieces of how ... -- 8/19/1999 2:36 PM

Re: Using zeners to lower B+ voltage

8/19/1999 7:19 PM
dave r.	Re: Using zeners to lower B+ voltage David, I have a feeling you might end up needing to lower it to get in the 400 volt dc range of B+. Why don;t you put it all togther, fire it up with tubes and all, get the bias voltage close to spec and see what B+ you get. Then fire off another querstion to the BBS to find out which value diode you might need. You'll need a 'reversed polarity' zener diode that has to be mounted flush on the chassis so that it acts as a heat sink. You connect the center tap of the PT secondary to the top of the diode and the contact with the chassis is its ground connection. To minimize hum, you should mount it close to the chassis ground connection (or close to the first filter cap ground if you're grounding everything to the chassis).

8/19/1999 7:19 PM

dave r.

Re: Using zeners to lower B+ voltage

David,

I have a feeling you might end up needing to lower it to get in the 400 volt dc range of B+. Why don;t you put it all togther, fire it up with tubes and all, get the bias voltage close to spec and see what B+ you get. Then fire off another querstion to the BBS to find out which value diode you might need. You'll need a 'reversed polarity' zener diode that has to be mounted flush on the chassis so that it acts as a heat sink. You connect the center tap of the PT secondary to the top of the diode and the contact with the chassis is its ground connection. To minimize hum, you should mount it close to the chassis ground connection (or close to the first filter cap ground if you're grounding everything to the chassis).

Replies:

Gil Ayan How about using power resistors to ... -- 8/19/1999 7:32 PM
Mook I just put a reverse Zener in my Ho... -- 8/23/1999 11:55 AM