[ARC5] Collins xfmr ratings

[Dennis DuValll via ARC5]

For the same total current and voltage values the same amount of power will be dissipated (wasted) in either a bleeder resistor or a string of VR tubes. Elementary power supply parameters and calculations are covered in the ARRL (and other) handbooks all the way back into the 1930s and probably earlier.

I (crit) = DC voltage/L (choke inductance in henrys)

Dennis D.  W7QHO
Glendale, CA

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On Aug 15, 2014, at 10:22 AM, Dennis Monticelli <dennis.monticelli at gmail.com> wrote:

> I like choke input power supplies, but the critical inductance issue is a
> serious one for CW usage as Ken noted.  You either have to find a high
> value "swinging" choke or put up with wasting a lot of power in the form of
> bleeder heat.  I would like to share a workaround.
> 
> In lieu of a high wattage bleeder, use a VR tube stack to maintain the
> requisite minimum load current.  Then pick off the appropriate voltage
> points for feeding the Osc and PA screens for the ARC-5.  This is what I do
> in my setup so my bleeders are not power hungry and less power gets wasted.
> You only need 150mA total (not 200mA) at 500V for this scheme to power an
> ARC-5.  Your keying note will improve as well.  A fringe benefit is the
> attractive glow of the VR tubes.