[TowerTalk] RG179 Chokes For TX 4-Squares

Jim Brown jim at audiosystemsgroup.com
Tue Feb 19 14:26:08 EST 2019


That's a judgement call that I wouldn't argue with. Choke guidelines for 
RG400 would apply.

73, Jim K9YC

On 2/19/2019 8:48 AM, john at kk9a.com wrote:
> I think RG-302/U would be a better 75 ohm PTFE coax choice.
>
> John KK9A
>
>
> Jim Brown K9YC wrote:
>
> After some discussion on one of the reflectors about chokes that could
> be used in 75 ohm phasing lines, Grant, KZ1W, sent me some. I wound a
> bunch of chokes using the same methods, and on the same cores, used to
> produce the new Cookbook, and added winding guidelines for these chokes.
> They have been added to the latest version of k9yc.com/2018Cookbook.pdf
> Refresh your browser to make sure that you've got the latest version. If
> you have the latest, you'll a a photo of a choke wound with white
> miniature Teflon coax on page 3.
>
> Note that RG179 has much more loss than RG400, so they have a lot more
> differential mode dissipation for the same power level. They MUST be
> exposed to air so that they don't overheat. If used in this manner, they
> are probably sufficient for use in a 4-square in which power is equally
> divided between the four antennas, running at legal limit.
>
> What looks like new old stock RG179 is plentiful and cheap ($0.35 -
> $0.50/ft) on the big auction site from vendors with 100% ratings.
>
> 73, Jim K9YC
>
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