[RFI] Please comment this picture

[Jim Brown]

On 1/4/2023 12:40 AM, Martin Kratoska wrote:
> The beads used for the W2DU style balun are Laird LFB095051-000. This 
> stuff has a crossover frequency R=X slightly above 1 MHz.

Martin,

The W2DU balun is FAR more than style -- the design DEPENDS on a 
particular Fair-Rite part with an impedance characteristic that exactly 
fits most of the HF spectrum. I've described his design here, beginning 
with slide #53. With any bead except that specific part, it's NOT even 
close to a W2DU choke, nor is it a good design. Indeed, for good noise 
suppression and good power handling, AT LEAST 200 beads must be used. 
Fair-Rite part number 2673002402. The i.d. is 5 mm, 0.197 in. It fits 
coax with a form factor like RG142, RG400.

http://k9yc.com/CoaxChokesPPT.pdf

73, Jim K9YC