Built my first beam this weekend
Finally built a beam for 20m. I ended up building a moxon out of pvc and fiberglass crappie poles.
I think I have around $50.00 in it.
first shot was too low in the band. I figured out that using insulated wire changed the resonace point.
I ended up calculating for 14.735mhz and it ended up at 14.225mhz at 1.1:1
I think I'll try the multi-band design I found on a moxon site for my next build.
any one know any tricks to building a multi band beam?
This is great, I love making antennas.
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why 14.735 when the band for us ends at 14.350?
center would be 14.175........
I thought I could get rich in the stock market by investing in
Viagra, Geritol, And Ginseng but my stocks didn't rise to the occasion.
Hell, I figured that there was always somebody somewhere either trying to
Get it up
Get it going
Trying to remember what to do with it.
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Good deal, antennas are fun and what makes it all work.
Not only does insulation on the wire lower the resonant frequency, but so does height above ground if the antenna's not "high enough." My 20m beam is perfect 1:1 at 14.200 when it's up 55 feet and resonance shifts to about 14.000 if I lower the tower and the beam sits at 25 feet. If I could get it even lower, it would resonate down below the band.
A government which robs Peter to pay Paul can always depend on the support of Paul.
-- George Bernard Shaw
I know that's a fact but I have to say that I have never experienced that kind of shift. I always adjust about 10' above ground (I also use 14. 200 as the target) with the antenna pointing straight up and it does change when up on the tower but it may go from 1:1 to 1:3 to one, at least this is what I have found on a TA33SR, CL33, TH6DXX and my quad stays rock solid at 1:1 between 30' and 55' (it was tuned 8' above ground pointing straight up). I have to admit I don't get it but that's been my experience with those antennas, perhaps a mono bander beam is a different animal but all 3 bands on the quad did not change at all. Of course I am always putting them up in terrible weather so maybe the old "gotta do it in bad weather" has something to do with it!! Anyway, nothing beats the satisfaction of a home brew antenna. Just about to raise a 8 element 6 meter home brew quad for 6 meters.
Originally Posted by WB2WIK
Last edited by WA8UEG; 07-10-2012 at 02:56 AM.
In response to the original question I would suggest avoiding adjacent bands with your multi-band Moxon. Instead, try 10 & 15 and 12 & 17 or 15 & 20M---otherwise you might run into some serious interaction problems.
Maybe it was via the Moxon Project website or a link from there but I have run across some very nice dual band Moxons made with aluminum angle stock and wires run through the insides of fiberglass poles attached to the angle stock; truly inspiring antenna builds.
Please post a pic or two when you're done, OK? I never tire of seeing a nice homebrewed design.
Got the 20m on the air last night.
I was able to work Argentina and Italy, all with 100w.
These are my very first qsl's out of North America.
I'm going to start on the 15-20m this weekend and do some design changes to it to make it lighter and order a
rotor so I dont have to run outside to change the heading when I want to work a different area.
here's a quick picture of the 20m moxon. I'm going to work on a x pattern multi band 15-20m this weekend to try and make it a little lighter. The PVC beam section is kinda heavy.
Nice job on the structural bracing!
Author of: Mr. Fred, Nuke This Forum (Danger Close)
He used insulated wire, that changes the game plan when it comes to length for dipoles etc compared to bare copper wire.
Originally Posted by KD8DEY
I use it here, always have to do some trimming on dipoles, or adding. But I like insulated wire as he cuts down the snow static in the winter.
To the OP congrats on your new antenna.