[Elecraft] RF Chokes (renamed)

[Ron D'Eau Claire]

> I've been looking for a pair of RFC's to bleed the static off of my 
> parallel
> feedline to ground. Have a couple of resistors, but would prefer a lower 
> resistance DC path to ground. The antenna is used for the 160 through 6
meter 
> ham bands and general coverage receiving so having something that would
have 
> a high impedance from 10 kHz to 100 MHz would be great.
>
> Would this type of choke be suitable?
>
> Darrell  VA7TO  K2 #5093

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I'll add to Jack's comments that, whatever choke you use, it is important
that they have *no* series resonances on any frequency of interest. 

A choke exhibiting a series resonance becomes an RF "dead short" at that
frequency. 

Virtually *all* chokes show series resonances. That's why non-inductive
resistors are generally used to bleed the static off of an antenna. (That's
not for lightning grounding, of course, but just to avoid the build up of
snow and rain static that can cause QRN in a receiver). 

Where wide frequency ranges are needed, such as in the high-impedance plate
circuits of vacuum tube amplifiers, you'll normally see what amounts to
several chokes in series. The first one will have relatively few turns for
adequate inductance at the highest frequency, the next choke (or section of
one choke) will have more turns, etc. That way, there is still adequate
inductance even when one of the sections hits a series resonance. 

Ron AC7AC