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Re: [TowerTalk] 2 el 40m beams

Subject: Re: [TowerTalk] 2 el 40m beams
From: Paul Staupe <>
Date: Fri, 25 May 2012 11:20:39 -0500
List-post: <">>
Last summer I joined a group of YCCC club members in a project to rebuild
my XM-240 into a Moxon (Grant's V2).  Several of us built this version, and
Tony, K1KP decided to build the V3. We've all been very pleased with the

It took a lot of time, a lot of SS nuts and bolts and a good drill press to
get the job done, but I finally was able to get the antenna up in the air
in January, thanks to a mild winter here in Minnesota.  Since I had too
many trees near the base of the tower, I had to assemble the Moxon piece by
piece on the tower so it went up without testing.  I was shocked that it
worked perfectly, had the published SWR and real gain.

The Moxon sits 18' above a 4L SteppIR which is at 77' so it's totally
exposed. We've had some severe winter gales and recent straight line winds
combined with thunderstorms here that I no longer worry about.... the Moxon
is rock solid, and sheds the wind "gracefully."  I can't say enough good
things about this antenna.

Best regards,

Paul W0AD

Date: Thu, 24 May 2012 21:28:35 -0700
From: Grant Saviers <>
Subject: Re: [TowerTalk] 2 el 40m beams
Message-ID: <>
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The W6NL 40M  Moxon has several design iterations.  As far as I know
there are 4 versions, in time sequence I think they are

V1 - 2006 original Cushcraft modified XM-240
V2 - 2007 center of element strengthening of V1, also known as the
"K3LR" version
V3 - 2010? the "120 MPH" design, a scratch build from raw stock, no
antenna is modified
V4 - 2012 "100 MPH" design for W2SC, modified from the XM-240

K6KR and I opted to parallel build two V3's in my garage.  I cannot
attest to any relative comparisons since I haven't owned the other
Moxons or commercial 2L alternatives.  However, I've done some basic
mechanical analysis of the V3 and can confirm it is in the strength
ballpark as specified.  One reason we decided on the scratch build is we
could buy known alloys whereas starting with the now MFJ built Cushcraft
has some unknowns, and neither of us had one.  Also, as the build
progressed, we became convinced that Dave's element segment connections
are superior.  In rebuilding and strengthening a used F12  EF120C to use
a Tornado variable center coil I found many loose or missing rivets and
changed to the V3 bolting technique.  YagiMech predicted structural
failures at about 70MPH and it had damage where predicted.

Performance wise, the V3 Moxon was exactly as expected, testing at 92'
with an AIM4170.  Observed pattern seems about right.  Measuring gain
and elevation pattern is not feasible for me (who can? :-( ).  I've had
some 1/2" icing and all was ok, but it has been on the tower for only 7

There is nothing particularly difficult about building this antenna, but
there are many parts and it does take considerable time and
concentration to build it (we made a little scrap).  Getting all the
tubing sizes is a bit of a challenge.  The ballpark material costs for
us, going first class with all DXE element saddle clamps and SS hardware
was around $1700 per antenna.  W3TX emailed me that he may be interested
in commercially building it.

I doubt there is anything commercial that is stronger.  Dave in a recent
QSO (Moxon to Moxon) said "it is the largest antenna I can keep together
at my QTH"  I think he has recorded 160MPH gusts.  At my Redmond, WA QTH
the wind so far has been negligible, I'm back from the ridge edge and
100'+ trees all around make a huge difference.

Grant KZ1W

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