Eddy, I recall an article in QST many years ago about TVI elimination in
which fly back TV cores were used. I believe there was a comment that these
cores are low frequency jobs and, in the TVI function, are operated well
above their normal frequency range. I believe the article said that the
impedance created in the hf range is primarily resistive rather than
inductive and they would be very poor candidates for a filament choke. 73,
Dan, N5AR
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of EP Swynar
Sent: Sunday, March 04, 2007 4:56 AM
To: topband@contesting.com; amps@contesting.com
Subject: [Amps] B&W FC-30 Filament Choke: EPILOGUE
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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|