In the past 18 years I have owned a variety of Optibeam yagis, including two
OB2-40 2el yagis and an OB4-40 4el. I also have an OB3-40 in the process of
going up on a tower.
Mechanically, they are all good designs, and are fabricated well. My QTH is on
the coast of Maine where, suffice to say, we have plenty of wind (all year
round) and a LOT of ice in the winter. The use of square tubing, for the boom,
as well as trussing for the elements, keeps the whole thing co-planar and true.
The OB2-40 does not use a boom truss, while the OB3-40 and OB4-40 do use a
boom truss. My only complaint pertained to the boom-to-mast plate and I
fabricated my own (out of quarter-inch steel plate) rather than sticking with
Optibeam’s aluminum part.
Performance has been excellent. If I can hear it, I can work it. Maybe not
always on the first call, but usually.
I have also compared the OB2-40 to all kinds of other 40m beams – to include
the M2 40M4FS, a W6NL Yagi-Moxon (long boom), an NW3Z vee-beam, a Cushcraft
XM240, an M2 40M3LDD, and a few others I can’t recall. On many occasions (not
always) I had the luxury of doing A/B testing between an OB2-40 and other 40M
options, so I have a feel for how they do against one another. There is,
absolutely, a material difference between a 2el yagi on 40m and a 3el. You
will hear stuff with the 3el that’s either marginal or unreadable on a 2el.
But IMO the single best option for a compact 40m beam is the OB2-40. There may
be something about a Moxon architecture that has your attention (more
broadbanded) but if I was you’d I’d get myself an OB2-40 and never look back.
Could you do better? Sure, the full-sized 4el M2 was nice. But the extra
effort in supporting it and maintaining it was unwelcome and I suspect you’d be
quite happy with the OB2-40. It helped, in my case, that I didn’t care that
much about the OB2-40 performance in the phone portion of the 40m band so it
may be the case that the Moxon architecture offers you a better shot at that.
Vy 73,
Mike, W1MU
From: TowerTalk <towertalk-bounces@contesting.com> on behalf of Ignacy Misztal
<no9e@arrl.net>
Date: Thursday, May 20, 2021 at 1:55 PM
Cc: "tower and HF Antenna Construction Topics." <towertalk@contesting.com>
Subject: Re: [TowerTalk] OptiBeam OB2-40M
OB40-M weighs 35 kg (77 lb) and by specs it covers all of 40m with SWR < 2.
A shortened Moxon from JK Antennas: JK 402-Piccolo with coils weighs 88 lb
and covers only 250 KHz. A full size Moxon JK420T weighs 125 lb and covers
all of 40m. Both antennas have 100 mph ratings.
Judging by the size, OB40-M uses coils but has higher bandwidth than the
equivalent JK. Not sure why.
OB2-40m is about $2100 from DX Engineering and JK 402 Piccolo
around $1700.
Ignacy NO9E
On Thu, May 20, 2021 at 4:26 AM David Gilbert
<ab7echo@gmail.com<mailto:ab7echo@gmail.com>> wrote:
I have owned an OB2-40 (the non-Moxon version) for ten years and it has
held up just fine to ridiculous wind gusts on my southern Arizona
hillside. The antenna is built like the proverbial tank and I've
measured wind gusts as high as 100 MPH. The wind gusts are brutal here
for about three months every spring, to the point that I usually can't
bring myself to even look at my antennas when I hear one of those
mini-tornadoes come roaring down the side of the mountain. I even
watched one lift my teenage son about two feet off the ground while he
was weedwacking part of the lot. It picked him up vertically (with the
weedwhacker still in his hands), moved him about three feet laterally,
and set him back down. This is no exaggeration ... I saw it with my own
eyes.
The OB2-40M is listed as having the same overall weight as my OB2-40 and
the construction looks identical, except of course for the Moxon
wingtips. The wind area of the OB2-40m is 5.9 sq ft versus 6.8 sq ft
for the OB2-40 and I would think that the Moxon configuration adds a bit
of additional stability, so I don't see why it wouldn't hold up as well
or better than my antenna.
73,
Dave AB7E
> On Wed, May 19, 2021 at 7:34 PM Michael Tope
> <W4EF@dellroy.com<mailto:W4EF@dellroy.com>> wrote:
>
>> One of the radio clubs I belong to is interested in buying an OptiBeam
>> OB2-40M two-element 40 meter Moxon Yagi. Optibeam is kind of vague on
>> wind survival specifications. Their website indicates "Windload at 130
>> km/h 430 N / 0,54 m² / 5,9 feet²". To me that implies the
>> antenna is designed to survive 130 km/h winds (80.7 MPH), but it doesn't
>> actually say that. The antenna is going to be installed at a Southern
>> California QTH at a fairly low elevation, so icing is extremely
>> unlikely. However, the antenna will be installed on a high narrow ridge
>> that lend itself to very high uneven (shearing) winds when we get the
>> occasional winter storm or Santa Ana wind condition.
>>
>> Anyone out there using one of these antennas? I am curious what you
>> think of it in terms of performance and reliability?
>>
>> Thanks and 73,
>>
>> Mike W4EF.................
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