|[AMRadio] Negative Bias Supply on Viking II|
navy.radio at gmail.com
Sat Mar 27 09:42:11 EDT 2010
I don't have a Viking II any more, but the schematic certainly shows
the two negative leads of C12-C13 (dual 15uf/150v) going to either
side of the bias supply choke and the positive lead to ground. In the
photo in the manual it looks like this dual cap indeed has two black
(negative) leads and a single red (common positive) lead.
Nearby is a dual 15uf/450v (C10-C11) in the B+ line, with a single
negative lead to ground and maybe that's confused someone?
Manual at http://bama.edebris.com/manuals/johnson/viking2(2)/
On Sat, Mar 27, 2010 at 7:29 AM, Arnie Adelman
<arnie.adelman at infosec-consultant.com> wrote:
> I've begun recapping the Viking II I'm working on. The dual 15Uf/150V cap connected to the 6AL5 has the positive sides of the cap going to the 6AL5 and choke and the negative side going to ground. Since this guy is intended to produce negative voltage and the connection is to the plates of the 6AL5 rather than the cathodes, shouldn't the filter caps (I'm using two 22Uf/450V) positive side be going to ground and the negative sides going to the 6AL5 plates?
> I'm reasonably certain this is correct, but the original design used a dual (two caps in one package with a common ground lead) cap and I've never seen one where the common lead wasn't the negative sides of the electrolytic cap.
> Thanks for your advice.
> arnie - W1GCI
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