Picking the "right" 40m beam is hard. So I appreciate the struggles the
OP is going through.
I went through this same process when putting up a 40m tower a couple of
years back. 40m seemed the toughest of all the bands to work on because
there are good arguments to be made for just about any solution. Here
in the midwest, wind and ice are a persistent issue and monster beams
are tough to keep up. My final solution was a stack of the 2-element
moxon-looking JK beams. Lower is fixed on EU; top rotates. It seems to
work a lot better than my 40m 4SQ reference, and the best part is that
despite a lot of bad wx since putting them up, they remain operational,
intact and work just fine. Fingers crossed!
Some compare & contrast of the various performance metrics (these are
JK) is on my web page where I talk about some of these decisions. While
this is JK-centric, the general discussion is applicable to whatever
your favorite brand happens to be.
https://www.ac0c.com/main/page_acc_towersantennas_40m_stack.html
Good luck OM!
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 5/22/21 11:08 AM, k1ttt.dave@gmail.com wrote:
I had stacked 40-2cd's years ago. Both exhibited intermittent connections on
the reflector coil connections resulting in fluctuating swr. I 'assume' the
driven element didn't show that problem because it would likely arc over the
thing oxidation layer at any reasonable power level. The fix was to take off
the end of the shrink wrap that covered the connections, remove the sheet metal
screws and drill through for a machine screw... clean and add noalox, tighten
well and trim off excess length of screw, then cover with shrink wrap that had
the meltable sealant. I know others who had similar problems with the older cc
40's, not sure if they changed the design on later versions or not.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: telnet://k1ttt.net:7373
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of k7lxc--- via
TowerTalk
Sent: Saturday, May 22, 2021 11:43
To: ab7echo@gmail.com; towertalk@contesting.com
Subject: Re: [TowerTalk] OptiBeam OB2-40M
Sorry, but I don't believe any of that.? It sounds purely anecdotal.
Anecdotal?!? Ha - most of the stuff you get here is anecdotal along with lots
of different opinions. Here's more anecdotal. I had an original KLM 4L 40M
beam that always seemed to break during the winter and require a major effort
to repair every summer. I bought a CC 402CD to replace it and set it to the
Secret LXC dimensions. The KLM never played like I thought a big 3L yagi should
have. (I didn't count the dual driven elements.) Anecdotally I was much happier
with the CC performance plus it didn't have to be repaired every year! My
budget dream 40M array? A 2 stack of CC antennas. You don't need big bucks or
rotators to turn the danged things plus you have a choice of arrival/takeoff
angles and 2 different potential headings at the same time. IMO there's no
downside and you save LOTS of money. I'm just saying. Cheers,Steve K7LXC
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