ARRL

Secure Site Login

Forum Home - Rules - Help - Login - Forgot Password
Members can access, post and reply to the forums below. Before you do, please first read the RULES.

Windom antenna. How to design the choke.

Feb 14th 2019, 15:40

N1AUP

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I built an 80 meter Windom antenna following these instructions.

http://www.hamuniverse.com/k4iwlnewwindom.html

As I understand things, I have to build a choke to keep RF off of the coax feedline. I bought 1 foot worth of ferrite cylinders, and am going to put them on a piece of RG8X cable.

The plans suggest that I need ten feet of coax between the antenna balun and the beginning of the choke. I've also read that you don't need the 10 foot section.

Does this antenna need a choke? What distance from the antenna feed point does the choke have to start? Is 10 feet the right length? I think the 8x that I bought at HRO has a foam dielectric.

Thanks
N1AUP
Feb 14th 2019, 20:39

N5CM_John

Joined: Sep 6th 2017, 16:13
Total Topics: 0
Total Posts: 0
In the 23rd edition of the ARRL Antenna Book on page 10-7, there is a reference to the "Carolina Windom", which sounds like what you built. For their 80m antenna, they used a 22-foot section of coax below the feed point balun and inserted a 1:1 choke at that point. The feedpoint balun was a 4:1 voltage balun which, per the Antenna Book, does not act like a current choke. So, the 22-foot section of RG8X between the 4:1 voltage balun at the feed point and the 1:1 choke 22 feet down, radiates and fills in nulls. I have an old Carolina Windom (10m-40m) that I resurrected in Februaru 2018 after my 10+ years QRT. It is my only "store bought" antenna and it works fairly well. I use it with a tuner in the shack on all bands, 10m through 40m. I've worked a lot of states and DX with that antenna on CW. I would think the 1:1 choke down on feed line would be a good idea.

Back to Top