[Amps] B&W FC-30 Filament Choke: EPILOGUE

[TexasRF at aol.com]

Hi All, is there no possibility of having the input matching network  
resonate with the FC30 filament choke to allow 160m operation?
 
With the low impedances present it seems that the loaded Q would still be  
fairly low. Seems that the rf related currents would be much lower than the  
filament currents in the choke.
 
What parameter actually establishes the lower frequency rating of choke  like 
this?
 
Not suggesting using it this way; just wondering.
 
73,
Gerald K5GW
 
 
In a message dated 3/4/2007 6:57:38 A.M. Central Standard Time,  
gswynar at durham.net writes:

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 at contesting.com
http://lists.contesting.com/mailman/listinfo/amps




<BR><BR><BR>**************************************<BR> AOL now offers free 
email to everyone.  Find out more about what's free from AOL at 
http://www.aol.com.