[TowerTalk] 40 mtr dipole spacing above tribander

[Robert Harmon]

Dave,

Good info on testing for interaction Dave !  I will check the F/B before and after 
as you describe.  


thanks,

Bob
K6UJ




On Feb 6, 2011, at 8:02 AM, Dave Hachadorian wrote:

> The D40 is not resonant on 10, 15 or 20 meters, so the dipole should be ok 
> parallel to the C3.  I have a 40-2CD six feet above a KT-34XA, elements 
> parallel, and all is ok. Those antennas have been there for 30 years, and I 
> do pretty well in contests, considering that the XA is at 48'.
> 
> The D40 has a broad resonance around 18 MHz, so if the C3 is supposed to 
> work there, there will be a problem.  The D40 should be a pretty good 18 
> MHz antenna, swr about 2.5, well within tuner-by-Eimac range.
> 
> The best way to determine if there is any degradation in the C3 is to do 
> front-to-back measurements with a local ham (0.5 mile to 20 miles distant). 
> Have him transmit, while you do the front to back.  Procedure is here:
> http://lists.contesting.com/archives//html/Towertalk/1998-11/msg00502.html
> 
> Do the f/b on the C3 before and after installing the D40 to see if there is 
> any change.  F/b is the most sensitive measurement of interaction.
> 
> If f/b is degraded, add six feet to the 40 meter feedline and see if it 
> helps, or short the 40M feedline while testing the C3.
> 
> If that doesn't work, then put the D40 orthogonal to the C3.  If that 
> doesn't work, take it down, or add more separation.
> 
> 
> Dave Hachadorian, K6LL
> Yuma, AZ
> 
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