[RFI] #73 beads

[David Hale]

How would a series of five #73 beads over RG400 work as a common mode
choke? I have a cobweb antenna from MFJ which covers 6,10,12,15,17,20m and
their supplied choke is as described. I didn't trust it so I built a proper
choke according to KY9C's cookbook for 10-20m, consisting of 10T RG400
wound on 2631803802 #31 toroids, two in series. The tables for K9YC's
chokes stop at 10m but I wonder if they don't still supply some resistive
choking impedance at 50MHz.

After doing that I got to thinking, I wonder if leaving the five #73 beads
is maybe good for 6m? Or maybe I should follow the guide here
http://k9yc.com/ChokesVHF.pdf and include a series of 2T through #31
clamp-ons? Are the #73 beads detrimental for the other bands?

What else might I use #73 beads for?

I have seen Jim Brown's slides here,
http://audiosystemsgroup.com/NCDXACoaxChokesPPT.pdf and here,
http://k9yc.com/CoaxChokesPPT.pdf, which refer to a W2DU choke which
consists of 50 0.2 inch #73 beads spanning 10 inches. The charts on the two
presentations don't quite seem to agree with each other, one suggesting
that Rs departs significantly from Z at 50MHz and the other showing them
almost the same.

My #73 "beads" are actually 1.125 inches in length so I have 5.625 inches
of #73 material (though I have another 5 of these same beads on hand so I
could come up with 11 inches worth).

I guess I'm trying to determine whether or not I should be using some
number of these #73 beads, along with my two "K9YC" chokes, or not.

Thanks,
Dave N3WTK