[Hallicrafters] HT-37 problem

[David C. Hallam]

Are you sure it was L15 that smoked.  While shorts in 5V4 do happen, the 
most common problem in the HT32/37 series of transmitter is a short of 
the 5R4 filament to HV winding.  Most owners of these transmitters 
replace the 5R4 with a solid state rectifier and disconnect the 5R4 
filament leads from the 5R4 tube socket.  This keeps the HV off of the 
5V filament windings.  The increase of HV resulting from 5R4 replacement 
will have no effect on the 6146's. They can easily withstand up to 900V.

David
KW4DH


On 1/13/2014 10:28 PM, K4PRF - Burton Pratt wrote:
> Happy New Year,
>
> I'll cut to the chase.  The filament choke (L-15) feeding the heaters 
> in the 6146s in my HT-37 overheated while I was in a QSO on forty 
> meters.  Saw smoke and shut it down.  I know about the plate to 
> filament PT transformer problem usually caused by a shorted 5V4.  I 
> think I put a 5R4 in place of the 5V4 and changed the bias rectifier 
> long ago.  The resistances on the 6146s are right on.  I will check 
> the tubes tomorrow and start the usual diagnostics soon but thought 
> some of you might have a suggestion.
>
> Thanks and 73,
>
> Burt Pratt,  K4PRF
>
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