[RFI] Re: Common mode

pmarkham@newsguy.com pmarkham@newsguy.com
Mon, 22 Nov 1999 11:12:32 -0500

I made a detailed post to this "reflector"? in late 1997? concerning my use of 
tv yolk and flyback transformer cores for common mode chokes. If anyone saved 
that post, I would appreciate a copy as it is not in the reflector archives and 
my copy was lost with a massive computer crash last  month.

I suspect a large core from a large tv, or maybe several in series, may be a 
cure for what ails. The cores are cheap enough (free from junk tvs), and you 
can have several on hand for immediate use by winding x feet of the coax of 
your choice through the core of your choice and terminating the ends with 
pl259s. I have in use many smaller cores on a variety of cables from phone and 
computer lines to the largest core around which I have 15 turns of RG8U to 
shunt feed my tower. 

The core mixtures vary markedly depending on the technology/age of the 
tv/monitor. If you are more interested in the effect than the core composition 
and its theoretical limitations, don't let my ignorance get in the way... ;-)


On 20 Nov 99, at 3:56, Blackburn wrote:

> 1. Introduce a high impedance in the RF path, i.e., a common-mode
> choke.  In this case, I don't think this is a realistic approach because
> of the large amount of inductance required to have a significant effect
> at broadcast frequencies.

Eschew obfuscation.

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