[TowerTalk] 40m optibeam de-coupling stubs

[john at kk9a.com]

Dave's model was for the 2el 40m coil loaded OptiBeam and I concur with his
post.  The 40M4LLDD is a different animal, its 15m resonance was previously
posted by N2IC.
http://lists.contesting.com/archives//html/Towertalk/2015-09/msg00315.html

John KK9A


To:	"tower" <towertalk at contesting.com>
Subject:	Re: [TowerTalk] 40m optibeam de-coupling stubs
From:	"StellarCAT" <rxdesign at ssvecnet.com>
Date:	Mon, 16 Nov 2015 21:06:50 -0500

Dave.... please send me that file if you don't mind (and if it is ok with 
Optibeam). 

I asked Richard, N5ZC to test his 40M4LLDD recently .... I asked him to
check 
to see what the SWR was on 15 (and 20) meters. I have plans on having
stacked 
6/6 on 15 with the top antenna 30' from this 40 meter beam... 

he got back to me ... the 20 seems fine ... but on the 15 check: sure enough
- 
1.3:1 at 21.2! OUCH! That concerns me a bit. 

I modeled it - but I didn't want any issues related to modeling the linear 
loaded 40 and instead modeled a 2 element full size... with that resonating 
properly on 40 I tested it on 15 and found it was not resonate on 15 but
rather 
higher up - maybe around 22 Mhz. And likewise had no effect on
SWR/FB/gain.... 
I'm not sure if this is the case and the LLDD because of its altered design
is 
indeed resonate lower .... or what. 

I know a good deal use the antenna, the 4LLDD, alone - I can't afford to
have 
yet another tower just for it... 

Gary 
K9RX