Good Morning All...
...And many thanks to the SEVEN respondents who took the time to address my
query yesterday re. the whys & wherefores of my old Barker & Williamson type
"FC-30" filament choke...
For benefit of any interested parties who may one day chance across one of
these assemblies at a Hamfest, etc., here's what I learned on the PLUS side
(file it away on the back-burner --- it may prove to be useful at some time):
-The FC-30 is, in essence, TWO type FC-15 filament chokes in ONE enclosure;
-Each of these FC-15 chokes is rated at 15-amperes: to safely pass 30-amperes
through them, you simply parallel the two, and,
-The unit has the flexibility of feeding two separate tubes from two separate
filament transformers via its two separate chokes (maximum 15-amperes per
filament, of course), or, one tube / paralleled tubes requiring 30-amperes
maximum.
Now, on the MINUS side:
-The FC-30 is specified for operation from 3.5-MHz to 30-MHz, inclusive:
because each FC-15 rod is only 3-1/2" long, it does not have enough inductance
for 160-meters;
-Even if I elected to SERIES-connect the two interior FC-15's to secure twice
the inductance for possible use on Topband, I would be robbing it of its
ability to handle 30-amperes of filament current...and my hoped-for 4-1000A
requires 21-amperes to make it glow (sigh!).
I've always been curious as to the possible effectiveness of employing the
ferrite core from a TV picture tube deflection yoke / coil assembly as the
foundation for a robust torroid-type filament choke...I have an inordinately
LARGE example of one here, which was removed from a junked early colour TV set
many years ago: maybe this is an opportunity in disguise, waiting to be
realized...
I have no knowledge of anyone ever having tried this latter trick, but I can't
see why it wouldn't work.
~73~ Eddy VE3CUI - VE3XZ
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