[TowerTalk] TowerTalk Digest, Vol 234, Issue 1

[Pete Smith N4ZR]

I think these lessons Hank explained so well aren't just for KT-34 
variants or tribanders.  In WV I had a stack of Force 12 C-3Es, with a 
Force 12 2-element short 40 above the top one.  Performance on 15 was 
much degraded from that before the 40m antenna was added, until I turned 
the 40 90 degrees to the stack, at which point all 3 antennas played 
much better.

73, Pete N4ZR
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On 6/3/2022 3:16 PM, hp via TowerTalk wrote:
> I do not have a 36XA but have a KT34 rebuilt to latest M2 specs and mechanics.
> It had never been quite right on 15 so when I rebuilt I spent a LOT of time on
> what was going on on 15.SWR was always taking off below 21025 and F/B was lousy
> in CW portion. Long story short - problem was the 15 meter cap tubes were slightly
> oversize ID and the 3/8 tubing was undersize by a few mils on each such that you
> could not get the capacitance you needed . So after I resolved that - I could get
> good swr and F/B over the band . Look up N6MW on the internet he has published a lot o
> of what both he and I and others did on KT34 15 meter problems.
>
> Now to interaction.
> I was doing the work on a tripod on roof peak about 30 feet under a 40M1L rotatable dipole.
> I would get everything just fine (running F/B with a friend about 2miles north of me. )
> Then I would finalize everything and recheck next night and it had gone to hell. I was using
> the 40M1L at night and was not attention to where it was left.What was happening is that
> the F/B and low end SWR were massively affected by the coupling to the 40M1L dipole some 30 feet higher .
> I could move F/B 100khz -150khz by changing orientation of the two antennas. (I suspect that one might
> be able to "open" the dipole and reduce the coupling but with the dipole in line with the KT34 boom
> it was not an issue )
>
> Once I nulled the remote 15M sig on the dipole (end on to the signal) then adjusted the KT34 15M traps - everything
> was solid and would stay just fine. My signal source buddy and my Grandson armstrong rotator who both thought I was
> crazy as hell were relieved.
>
> See Bill N6MW comments on KT34 he and I were working on same issues at the time and has other data
>
>
> Hank K7HP
>
>
>
> Message: 1
> Date: Thu, 2 Jun 2022 14:14:59 -0600
> From: Steve London<n2icarrl at gmail.com>  
> To:towertalk at contesting.com  
> Subject: [TowerTalk] Why does KT34XA/KT36XA stink on 15 ?
> Message-ID:
> <CAB7zQ=386x5CB2ymYN1iRy7qrM3Bj1W4+KkX2ySrO40XLNjx0g at mail.gmail.com>  
> Content-Type: text/plain; charset="UTF-8"
>
> I know I'm not the first one to observe this...
>
> I have a KT36XA on one tower, and reference monobanders for 10, 15 and 20
> on other towers. On 10 and 20, the XA always performs within a few dB of
> the monobanders (sometimes, even better than the monobanders). On 15, the
> XA is always down about 6 dB from the monobander. This is consistent
> regardless of distance, direction, skip length, etc. Even the "band noise"
> is down by this amount. The SWR on all 3 bands is reasonable. Long ago, I
> also measured the resonant frequency of each element. See
> http://www.kkn.net/~n2ic/kt36xa.xls  . There is a 40 meter beam about 30
> feet above it, but the 15 meter SWR does not change when either the XA or
> 40 is rotated, so I don't think there is significant interaction.
>
> What did KLM/M2 do wrong on 15 ?
>
> Before you tell me your KT36XA works great on 15, what are you comparing it
> with ?
>
> 73,
> Steve, N2IC
>
>
>
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