[Amps] RF in the Audio

Rob Atkinson ranchorobbo at gmail.com
Fri Sep 23 18:03:16 PDT 2011

You don't wind your balanced feed on a torroid for crying out loud, a
method I find preposterous, and probably subject to heating and loss;
you employ a link coupled balanced tuner and float the balanced feeds
so their connection to the unbalanced line is via capacitive and
inductive coupling and not a direct electrical connection.  The link
(think of it as both a variable balun and isolation transformer) stops
common mode RF.



On 9/23/2011 3:08 PM, Robert Kirkland wrote:
> I think your quite right in "seriously choking off your feeders". But
> please tell me how to use toroids on a 600 ohm open wire line.

>Wind a bifilar choke using 12-14 bifilar turns of #12 THHN on a #31
>2.4-in o.d. toroid. It introduces a small mismatch (Zo approx 100 ohms),
>but only about two feet of line. Photos and details in the latest
>version of my RFI tutorial. http://audiosystemsgroup.com/RFI-Ham.pdf

>73, Jim K9YC

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