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Windom Trouble

D

datsun66

Active Member
Apr 10, 2005
251
15
48
Lewistown, Montana
I put up a Windom antenna in my tree in the back yard and it has a 4:1 balun.
On 10,20,40 bands the antenna does a fair job but when i go to 80 meter the trouble starts.
I re did all of the station grounding with copper ground strips and grounded all of the equipment according to ARRL standards. When I go to 80 meters I start by tuning up 80 meters with a Yaesu 857d and turn the power all of the way down to 5 watts on am.
Load and tune the antenna for the lowest swr on the antenna tuner. When everything looks good I start turning the power up and watch a FS meter I have in the shack so I can monitor any stray RF. As I get close to 25 watts then the GFI breaker in the house that powers up the shack trips. I was watching the FS meter and I did see some RF coming back into the shack. With this kind of trouble there is no way I am going to fire up the amps and I do really want to check out the Swan Mark 11 for operation. Any Ideas, Oh BTW I was going to build a coax choke balun to put inline.
Any ideas
 

Never have problems with my Fritzel FD-4 with AMA 83 balun, 1:6 with 1:1 choke in one for 1500 watts.

My own build OCF's have mostly a 1:4 current balun followed by a choke to be sure no rf gets on the coax.
These homebrew are on 30/40 feet high, if you go higher, use the 1:6 balun.
 
I'd put the station on a circuit NOT protected by a GFI, first of all.

Then, if that didn't fully cure the problem, I'd switch the 4:1 balun with a 1:1 for comparison. The windom might be presenting a low feedpoint impedance (like 20 ohms or so) on 80, and a 4:1 would be transforming it by a factor of 4, down to ~5 ohms. Matching networks don't like that.
 
Thanks for all of the ideas, It's time to make a 1:1 balun. Would you mount the balun close to the feed point or mount it where the coax comes out of the radio shack? amd are you talking about a coax choke or a true balun.
Bob.,
Rats, went looking into the ugly balun and answered my own question.
http://www.hamuniverse.com/balun.html
Great web site for of my questions. Off to the shop to build one.
 
Last edited:
What's the length of your 'Windom' antenna, or OCF doublet? Is it a 1/2 wave on 80 meters? If not, then expect for it to be not very easily tuned.
As 'Beetle' said, it's not a balanced antenna so a balun is unnecessary. Where's the 'balanced' part? If you just have to use something like that, then use an 'unun'. Or if it's just to reduce the RF back into the shack, a coaxial choke. I'm assuming you're using coax for the feed line?
Without getting into a bunch of theory, the reason for the dipole being fed 'off center' is to find the feed point which produces an input impedance close to 50 ohms. That's typically about 33% from one end. That '50 ohms spot' is not 'fixed' at all, it varies according to how/where the antenna is positioned and how high off the ground. It will be somewhere between 25% and 50% from one end.
Have fun looking...
- 'Doc
 
Hi Doc.
I received a large book with a CD in the back. Yep you guess it. the ARRL Antenna book.
Next I am going to order the ARRL Wire antenna book. This should be good reading when the -30 degrees temps hit Montana. Thanks for all of the info and I have never herd of a unun.
the OCF has a coax feed and a 4:1 balun to the coax and I believe 90 ft on one leg and 20 feet on the other or something like that. Kinda hard to get around right now. 2 Weeks ago I had a total knee replacement and it will be another 2 weeks before I can get out and do some work on the antenna. Time to study for my extra.
Bob.
 
datsun66 said:
Hi Doc.
I received a large book with a CD in the back. Yep you guess it. the ARRL Antenna book.
Next I am going to order the ARRL Wire antenna book. This should be good reading when the -30 degrees temps hit Montana. Thanks for all of the info and I have never herd of a unun.
the OCF has a coax feed and a 4:1 balun to the coax and I believe 90 ft on one leg and 20 feet on the other or something like that. Kinda hard to get around right now. 2 Weeks ago I had a total knee replacement and it will be another 2 weeks before I can get out and do some work on the antenna. Time to study for my extra.
Bob.
Click to expand...

Hey Bob - while I can't completely empathize with you over the knee, my wife had her port-side knee replaced in June, about a year and a half after she had the starboard-side done. She's not bouncing back quite as quickly with the second one, but she's coming along one day at a time. Good luck with yours.

Google "unun". Lots of information out there.
 

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