[Amps] RF in the Audio
dj2001x at comcast.net
Sun Sep 25 04:06:01 PDT 2011
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
I can say for my own experience that this technique does work. I have a Palstar BT1500A double L network balanced line tuner and I added a choke balun as per your suggestion above, about 4 feet from the tuner posts, the tuner now is tuning entirely different than before and much wider range of bands and I now no longer hear the two local radio stations S-9 mix at 3790 and a S9+10db third harmonic 3990, which was my original reason for adding the choke. The choke balun works on open wire feedline using a balanced L network tuner. BTW, this "trick" was suggested by Paul at Palstar.
I'll check out your tutorial Jim. Thanks.
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