[Collins] Another 516-F2 PS Question

[Dr. Gerald N. Johnson]

On 11/10/2015 6:59 PM, Al Parker wrote:
> once agn, thanks Jerry,
> Tnx for your always great technical explanations.
> I'll try the 2x 5v fil. winding bucking arrgt., probably next wk. I've
> used bucking b4, and agree that it's better than Variac. I've worried
> about the HV values to the KWM-2 & S-line for a while. Haven't done it
> in the Halli rigs due to their internal problems. Our line voltage is
> pretty steady at 125vac. I oughta use a big 12v xfmr to buck the whole
> shop and shack supplies.
> tnx, 73,
> Al, W8UT

There was an old time electrician and ham in Ames Iowa that installed a 
bucking transformer at his home's service entrance. He claimed to have 
cut his electric bill and lengthened the life of lamps and appliances. A 
decade or so he retired and moved and I don't know if the transformer 
moved. His son KI0Q is running the electric company now. A third 
generation of hams and electricians.

An incandescent lamp's life is definitely lengthened by lowered voltage. 
A rule of thumb from a lamp catalog I have studied is that a 5% 
reduction in voltage causes a 10% reduction in light and a doubling of 
lamp life. A 5% increase causes a 10% increase in light and cuts lamp 
life in half. You'd benefit by hunting for 130 volt lamps for longer 
lamp life. Fluorescent and LED lamps that have a ballast, magnetic or 
solid state (RF noise generators) if they work good hold the lamp 
voltage constant even with high line voltage. That's there job because 
the fluorescent lamps and LEDs have a fixe voltage drop and need 
external control to hold the current constant. Lots of LEDs have used 
series resistors for that but the resistor is simple but not energy 
efficient.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.
>
> On 11/10/2015 5:33 PM, Dr. Gerald N. Johnson wrote:
>> I like to lower the line voltage with a bucking transformer taking it
>> down 6 or 12 volts. That service bulletin says the PA bias will have to
>> be readjusted and that the load should never have a SWR over 2:1. A 6
>> volt bucking transformer would drop the voltage enough to account for
>> the different in drop between vacuum and silicon rectifiers, I'd like
>> another 6 volts because the power companies have raised line voltage
>> from 115 to more like 124 to allow for big loads to drop the voltage
>> without it going under 110 that regulators would call bad. Typically the
>> pole pig has about 4% impedance so there's a potential for 4% change in
>> voltage if its primary voltage holds steady. Its usually not regulated
>> at that voltage, though but is regulated at a higher voltage so there's
>> another transformer with that 4% impedance so the load voltage varies at
>> least 8% and regulators want it to stay above 115 or 110 depending on
>> the jurisdiction and that high line voltage makes for high power supply
>> voltages when the power supply was designed for 115 volts input, so a
>> variac or bucking transformer helps keep voltages under control. I
>> prefer a bucking transformer to a variac because its not going to get
>> the knob turned by a visitor who has no idea what it smokes. And a
>> bucking transformer is usually cheaper than a variac. Any filament
>> transformer can be used as a bucking transformer if it has enough
>> current rating. I think W5USI uses the two rectifier filament windings
>> in the 516F-2 for bucking when converting to silicon rectifiers.
>>
>> 73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.
>
>