I have a little OB7-3 that I bought never assembled, still in the box, from a
contester friend who was going to use it for a "multiplier" antenna. He changed
his mind and sold it to me for half what he paid for it, which was still pricey
IMHO.
I had an issue with QC and wrote a review on eham documenting it. I immediately
got an email from "blue ocean", not trying to rectify the issue, but accusing me
of improperly storing the antenna. Since it had been in my friend's garage
(along with several German cars), in the still strapped carton, I disagreed. He
continued to give me so much grief, I asked that the review be removed.
Even with the very short boom, there is a bit if sag at the joint, and yes, the
boom to mast clamps are similar to muffler clamps. The way the elements are
assembled in my opinion makes swaging unnecessary and the loose fit makes it
easy to telescope the tubing for shipping purposes. I can't fault the
operational performance and it models well, but I wouldn't buy another OptBeam.
Wes N7WS
On 5/6/2018 11:31 AM, john@kk9a.com wrote:
On my OptiBeam 40m antennas there is no swaging, just a bolt that goes
though the element. The square boom mounts to the aluminum plate with a
square u-bolt and it's impossible for the mast to spin. The boom to boom
joints were just a couple of internal plates. I have had no issues with any
of these things but perhaps they are with larger beams. Momobeam uses a
similar square boom except they have slots in the boom for coupling and I
have recently seen one that moved out of alignment. I agree that finding
metric tubing in the US is very difficult. Since DX Engineering now sells
OptiBeam perhaps they can obtain replacement parts. I always found OptiBeam
owner, DF2BO to be a pleasure to work with.
John KK9A
Jim Thomson VE7RF wrote:
## Several folks have had severe issues with the way optibeam splices
their square boom sections together. I dont like their boom to mast
assys, it uses 2 x muffler clamps for the mast. Nobody uses muffler
clamps for anything these days, esp the types with sheet metal saddles, as
depicted. https://www.dxengineering.com/parts/dbo-ob12-4w-p JKs
version wont budge or slip on any mast. Optibeam uses METRIC tubing
sizes for the elements..and also the square and also their round booms.
Unlike 6063-T832, 39 ksi yield strength...... or 6061-T6, which uses 40
ksi yield strength..and both using standard tubing sizes and wall thickness,
METRIC tubing does not telescope with a snug fit. They make a sloppy fit
and have to be either shimmed, or swaged.... pita. The deal breaker for
myself is that METRIC tubing is a bitch to find in Both Canada..and the
USA. A buddy finally found one source for metric tubing in the usa....and
it was special order, and expensive. That may have changed. So even if
you can find replacement METRIC tubing in the usa, next up you will have to
get the ends carefully swaged. Any swaging process has to be done dead one.
Too little or too much, and you are in trouble..esp if too much.
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