[TowerTalk] OptiBeam OB2-40M

[Jeff Blaine]

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 at 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 at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: telnet://k1ttt.net:7373
>
>
> -----Original Message-----
> From: TowerTalk <towertalk-bounces at contesting.com> On Behalf Of k7lxc--- via TowerTalk
> Sent: Saturday, May 22, 2021 11:43
> To: ab7echo at gmail.com; towertalk at 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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