[Milsurplus] Super Pro Help! - Transformer Needed

[Bruce Gentry]

The commercial SPs had very good audio. I have an SP-400, and it sound 
great, I just wish there was something good to listen to on AM around 
here:( .  I fear an AudioPhool got the transformer from yours.  I faced 
the same problem with an HRO someone had converted to one chassis, 
ripping out the push-pull to make room for a power supply.  I solved it 
with a phase inverter autotransformer from an old early 50s tube car 
radio (Buick or Cadillac are the best bet) and an output transformer 
from a table radio or  car radio. The center tap of the autotransformer 
goes to ground or bias, whichever is used, and the ends to the grids of 
the output tubes. The drive is applied to one of the grids, and the auto 
transformer inverts and drives the other grid.  I used the primary of an 
output transformer from a table radio as a coupling choke in place of 
the driver transformer primary, and coupled the audio from the 6F6 
driver plate to one of the output grids with a .2MFD condensor. It 
sounded very good, and certainly better than silence.  If you make a 
bracket, you can mount the two transformers and the condensor in the 
same place as the original and preserve the chassis for the time when 
you might find an original driver transformer.

       Bruce Gentry, KA2IVY


On 9/25/14 9:32 PM, Robert Goff wrote:
> Picked up a Hammarlund Super Pro with PS at the last hamfest.  I'd
> really like to get this one up and running since it is the 200X
> version covering the BC band and 160m.
>
> The one thing missing, strangely enough, is the audio INPUT
> transformer.  This is single 6F6 to push pull 6F6's.  A look through
> my junk box yielded nothing even close.
>
> Anybody have a junker Super Pro with this transformer?  It's T-7 on
> the schematic in TM 11-866.
>
> Thanks,
> de Robert W7MKA
>
> PS.  This particular receiver, although it has civilian markings does
> have orange Signal Corps stamps and MFP varnish - applied (as the
> stamp says) Jan '52.  Panel is black and that seems to be the original
> color.  I'm guessing this was a very late pre-war production?
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