[Collins] Bucking Voltage

[David Knepper]

Yes, it is possible to buck the voltage with the unused 5 volt filament =
windings if the 516F-2 is converted to solid-state rectifiers for the =
5U4 and 5R4.

I did an experiment, using clip leads,  with a 516F-2 power supply to =
see if I could reduce the A.C. voltage.  With the right combination,  I =
was able to reduce the voltage to 115 volts.  This is no rocket science =
as they say.

 However, I am not sure that both 5 volt windings would carry the =
primary current of the transformer.  Therefore, I abandoned the project =
since this transformer can be expensive to replace.  No sense pushing my =
luck. =20

The measured A.C. voltage to the input of the primary with one 5 volt =
winding doing the bucking was about 117 volts but with both windings in =
series, the voltage dropped below 115 and the filament winding was below =
6 volts - not good on the tubes in the KWM-2!

It would seem that one 5 volt winding would work but the current =
capacity is way too low and would overheat the winding.

I would recommend a separate 12 transformer or a variac as some have =
suggested.

Yes, it can be done but I am not a risk taker with such expensive a =
transformer in the 516F-2.


Dave, W3ST
Secretary to the Collins Radio Association
Publisher of the Collins Journal
www.collinsra.com
  ----- Original Message -----=20
  From: Bill Haselmire=20
  To: David Knepper=20
  Sent: Monday, November 17, 2003 11:05 AM
  Subject: Re: [Collins] Bucking Voltage


    Dave....
    Did you ever get an answer to this...I never saw one.

    Thanks,

    Bill WX8S




    Subject: [Collins] Bucking Voltage


    Someone mentioned that they use the unused 5 volt secondary winding =
to buck
    the primary voltage in an HT-37.  I wonder if the same could be done =
with
    the power transformer in the Collins 516F-2.

    I wonder why this trick circuitry has not been discussed before to =
reduce
    the A.C. voltage on the primary, thus, giving some relief to the =
transformer
    from the over 120 volt line voltage in many areas.


    Thank you.

    Dave, W3ST
    Secretary to the Collins Radio Association
    Publisher of the Collins Journal
    www.collinsra.com

    ...




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