[HBR] Restoring old receiver

[hbr@mailman.qth.net]

In a message dated 8/2/03 4:08:56 PM Eastern Daylight Time, ak0b@swbell.net 
writes:

> I recent acquired an old receiver from the late 1940s that is not
> collectable grade.   

What model?

Every cap in it needs replaced plus several  tubes.
> 
> It is a National and the  basic design was no doubt state of the art for
> a AC/DC receiver in that era.  I am considering redoing all of the caps
> and rewiring the tubes for a filament transformer and also using a
> reverse filament transformer to generate the DC.   Other choice is what
> to do about the detector stage.   My first thoughts were to replace the
> 6H6 with a 6BE6 product detector, but after consideration think maybe
> the better choice is to restore everything electrical with the improved
> power supply circuit and add a RF connector to go to an external Q5er.  
> 
> 
> After all of the rework it will still not be a collectable quality
> receiver, however, it will look original, and be an excellent test
> receiver (and safe with the isolated power supply) for my work bench
> that I can also use to listen to SSB activity on the bands or the local
> AM stations.
> 
> 

Always good to have a general-coverage "bench" receiver for listening to 
oscillators, side-by-side comparisons, dipper checks, etc. My current bench 
receiver is a BC-342-N by Farnsworth. 



> 
> Wonder what others have done in similar cases ?  Have you used a oldie
> as the foundation for a HBR or improved one ?
> 
> 
> 

I used to do stuff like that but nowadays I favor simply building from 
scratch. Any manufactured rx has some custom parts that restorers need. 

I suggest first restoring the rx to original electrical condition to see how 
good/bad it really is. From that evaluation you can decide whether to restore 
it, use as-is, or sell it.

If you are concerned about safety, just use an external isolation 
transformer. 

As for Q5er operation, a BC-453 preceded by a crystal-controlled converter 
makes an excellent, stable receiver for HF up to 10 MHz or so (two tuned 
circuits for image rejection) or even 15 MHz (three tuned circuits). 

73 de Jim, N2EY 


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