[Amps] RF in the Audio

Commander John crazytvjohn at yahoo.com
Sat Sep 24 10:32:58 PDT 2011

Suggest you wind a choke with Mix 31 RF suppression cores using RG 8u or Equivalent.
Place it between the tuner and the radio or Amplifier.  I made one with 5 fair rite 
2631803802 rf suppression cores.  They look like toroids.  Mine has 7 turns.
 john W9ZY   

              .... Commander John ....

From: Rob Atkinson <ranchorobbo at gmail.com>
Subject: Re: [Amps] RF in the Audio
To: amps at contesting.com
Date: Friday, September 23, 2011, 8:03 PM

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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