[AMRadio] Johnson trannies...


Kim Elmore cw_de_n5op at sbcglobal.net
Sat Jun 4 11:19:10 EDT 2011


I noticed the same thing with a transformer that Dahl designed for me 
many years ago. It's a replacement for the original AL-80A 
transformer designed to generate about 3.6 kV B+ under load using a 
FWB instead of a doubler. This was the result of a question that went 
like "I wonder how much I'd get if I ran the 3-500Z right up against 
its voltage rating limit?" I had to alter the output network values 
because this changed the output impedance (something I had not 
considered until I tried tuning up the amp) but with the appropriate 
changes it's well-behaved. All the effort bought me a bit over 1 dB, 
and so wasn't worth it from the standpoint of increased output, but 
the knowledge gained was far beyond price.

Kim N5OP

At 08:04 AM 6/4/2011, you wrote:
>yeah but the big question is do they still sell it and for how much.
>
>The Dahl drop in replacement for the B+ transformer in the Ten Tec
>Centurion amp mysteriously disappeared from their list a few years
>ago; I have no idea why but I'm sure glad I got mine before that
>happened.  It is far and away better than the stock transformer.
>
>73
>
>Rob
>K5UJ
>
>On Fri, Jun 3, 2011 at 10:41 AM, Kim Elmore <cw_de_n5op at sbcglobal.net> wrote:
> > Hi Jim,
> >
> > I do believe that you pulled that right off of the Peter Dahl/Harback
> > web site :) It's pretty handy for stuff like that. It's amazing how
> > many different transformers they've re-engineered for the old rigs!
> >
> > 73,
> >
> > Kim N5OP
> >
> > At 09:11 PM 6/2/2011, you wrote:
> >>I think this is what you are seeking:
> >>
> >>JOHNSON VALIANT DRIVER XFMR
> >>P/N 22.1286, T4
> >>CORE) EI-062 X .75           STYLE #) 01  E-I LAMINATED CORE
> >>PR) 230 OHMS DC (12AU7 AUDIO DRIVER PLATE)
> >>
> >>S1) 800 OHMS CT (PP 6146 MODULATOR GRIDS)
> >>
> >>DM) HT =  1.643 WT =  1.955 DT =  1.438 MD =  0.000 MW =  2.375
> >>
> >>
> >>
> >>----- Original Message -----
> >>
> >>
> >>
> >> > Thanks, Darrell. Do you, or anyone else on the list, happen to know
> >> > the
> >> > specifications of the driver transformer in the Valiant?
> >> >
> >> > -----Original Message-----
> >>
> >> >
> >> > Not the same transformer. The Ranger uses an interstage transformer
> >> > (step-up). The Valiant uses a driver transformer (step-down).
> >> >
> >> > Darrell, WA5VGO
> >>
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