[AMRadio] Smoothing Choke & ART-13 supplies

Mark Foltarz Foltarz at rocketmail.com
Thu May 4 13:51:03 EDT 2006


    This discussion re the power supply filter has got me thinking.

    This stuff has been done both ways.

    I have built a power supply for my TBW using the  swinging  / smoothing
choke arrangements.

    However, I also have in operation a 115 vac power supply for the ART-13.

    It was made by the R.L. Drake Company - yup, the same one that is (was) in

    Oddly enough, it is not that heavy. Perhaps 40 lbs.

    When I got the unit the filament supply transformer was dead.

    I replaced the (4) 866jr with silicon, all the electrolytics have been
replaced and I reworked the filament supply.

    I removed the giant selenium rectifier in lieu of a full bridge rectifier
that was now mounted to the chassis.

    I placed some large computer grade 35 volt cap across the output.

    The filament transformer was replaced by a 19 volt 30 or so amp transformer
( 19 X 1.41 = 26.79 volts -  close enough. ) 

   The filter for both the hv supplies is a choke input followed by the
electrolytic.  Presumably, it is pure smoothing.

   The only thing I did to the ART-13 was remove autotune functionality by
desoldering a field winding. 

Apparently, the fields are energized the entire time filament was supplied
making for a warm front panel and unnecessary load on the power supply.

   By the way, I understand there is a mod to get around this "continuous field
on" situation besides my approach of desoldering the field connection. 

If anyone has the dope on that pleas let me know.

   de KA4JVY




--- Rick Brashear <rickbras at airmail.net> wrote:

> Jim,
>     I appreciate your take on the power supply and agree for the most 
> part.  Even though this particular ART-13 will see little if any CW 
> operation I would like the supply to be as stable and clean as 
> reasonably possible.  You are absolutely correct about the difference of 
> availability of capacitors and chokes in today's world versus the days 
> of W.W.II.  I considered using more modern components and at one time 
> even thought about an all solid state power supply.  It would be much 
> easier and cheaper to construct and less expensive to operate with less 
> heat.  However, the lure of the olden days kept calling me back to 
> glowing tubes and swinging chokes.  So, even though I agree that with 
> modern technology applied I could have a cleaner, lighter and less 
> expensive supply, I will likely stay with the old school thinking on 
> this one.  That is IF I can get the ripple to a low enough level so as 
> not to cause problems on the transmitted signal.
>     Thanks again for your advice and explanation, you make a very valid 
> point and one which would serve my project well.
> 73,
> Rick/K5IZ
> Jim candela wrote:
> >Rick,
> >
> >   Sorry but I am going to throw a wrench into this discussion. Those
> >swinging choke power supplies, although useful, have been out of favor for
> >years...
> >
> >  
> >
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