[Elecraft] OT - Toroids for Stereo RFI?

[John, KI6WX]

Hi;
For blocking HF into cables, you want the highest mu ferrite material you
can get.  I often use #73 material for this purpose, but there are higher mu
ferrites available.  As for size, you have two choices.  You can buy a big
toroid and wind a number of turns on it, or you can buy one that just barely
fits over the wire (this sometimes requires removing connectors).  If you do
the second, you do want a tight fit around the wire.  Also, some
manufacturers make split ferrites which can be clamped around the cables
using the plastic housing that contains the ferrite material.  These work
great when you don't want to remove the connector when sliding the ferrite
over the cable.
-John
 KI6WX


> Greetings:
> Last weekend the new KPA-100 module and a 70m horizontal loop at 12 feet
> (effectively QRP in terms of ERP!!!) knocked the states needed for
Elecraft
> WAS from 17 down to 4 hard ones (all in the "1" call zone). But the 100w
on
> 15m and 20m is getting into the family entertainment system bigtime (15w
> never did; the RFI was from the TV on 15m), making the quest less than
> popular in the household and pinching operating time. (With the "Priority
> Mail" box that arrived today from Elecraft, band changing is soon going to
> be much, much faster!)
>
> So, what are the best toroids (size and mix identifier) for winding audio
> input cables, speaker wires and AC power cords onto, how many turns and
> where's the best place to get em?
>
> Tnx and 73,
> John, K7JG.