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Voltage dropping resistor question
#1

I think that I know the answer to this question, but here goes. With the typical high line voltage here, I noticed that some of my voltages were a little high on my Philco 18. So I did what I occasionally do and installed a 50 watt Dale dropping resistor after the switch. It's a 23 ohm (all I had on hand) and it dropped the incoming voltage a little more than usual and it is something like 104 volts. The "tuning eye" is now not as responsive, but working. Is this because of the lower voltage? What would be a better choice resistance? (Yes, I know a bucking xformer is better.)
#2

Well, think of it this way: the equivalent of what you do by adding a 23 Ohm resistor in the primary is top add more or less 210 Ohm resistor in both halves of the centertapped winding of the rectifier circuit, if your half-winding to primary ratio is about 3:1. (300V)

Is it good? Never tried, but my gut feeling, a bucking Xcfmr is better, as it does not change the impedance of the Mains.
#3

The obvious answer is something less than 23 ohms, but of course you already know that! Without knowing a little more, like what your line voltage was to start all we could do is guess at what lesser value you could try.

As to the shadow-meter performance, the lower line voltage could very well be a problem, but have you replaced all the caps and any resistors that are out of range, especially in the shadow-meter/a.v.c. circuit? If so I would run the set on a variac at 110-115 and see how the set and shadow-meter perform. Below are a couple of helpful links on shadow-meters, the first one will help you visualize how the meter works in relation to the a.v.c.:

http://www.philcorepairbench.com/tips/svctip01a.htm

http://www.philcorepairbench.com/tips/svctip01.htm

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"




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