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I'm now working on my second one of these, a Model 44F. F means its for 25 Hz.
I got the stuff in the power supply out of the tar yesterday and measured
the capacitors. The ones which are not filter capacitors are roughly
the same values as usually listed for the plain 44. The three filter
capacitors are much larger, physically and in capacitance.
They measure differently on my capacitance meter and by
measuring the response of an RC filter using them. The latter is
usually accurate. All three are in the 3.5 to 4 uF range, and
all look to be identical size. I plan on using values of 1.5, 10 and 10
uF for the recap values. I don't want to go too high on the first
one as this raises the B+ voltage ... and of course the set will be used
normally on 60 Hz. Those values will still work fine
at 25Hz of course, the B+ will just be a bit low, assuming the
same turns ratio on the monster transformer.
I also rebuilt the ballast, which was broken. I used 0.005 inch
Alumel wire and needed roughly the same number of turns
to get the same value, though I made it in fact 33 Ohms
due to our higher AC line voltage. Alumel is nice since
you can solder to it. The wire was reglued to the ceramic
core using a product called Red Devil Furnace Mortar.
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