Hi Bill, The only thing I have heard about stacking tribanders was at W7GG. The
had a 3 stack of KT34s and found that a 2 stack would work better for most
bands. I don't know any of the details, only that he did change to the 2
stack. That was on a 195 ft tower.
73
Jim Cassidy
KI7Y
> Date: Tue, 23 Feb 2010 22:30:46 -0800
> From: wycpublic@gmail.com
> To: towertalk@contesting.com
> Subject: [TowerTalk] 3-Stack Tribander Issues
>
> I’m thinking of building a 3-stack of tribanders. Folks who are familiar
> with stacked monobanders give me doubtful looks. I’m wondering who on the
> list has actual experience stacking tribanders, and what practical
> observations they can offer.
>
>
>
> By way of background, I was an EE in a past life, with a bit of professional
> experience with phased arrays for VHF/UHF and shortwave broadcast, and
> radar. So I appreciate the phased array concept.
>
>
>
> My contemplated stack has 8.6m spacing between antennas (with the top
> antenna at 130’). I recognize that half wave spacing has certain desirable
> attributes, and that my spacing is a bit large for 15m and a bit short for
> 20m. But modeling suggests that’s not a big deal. (I may cover 10m
> separately.)
>
>
>
> I expect to turn the top two antennas in tandem, and have the bottom antenna
> independently rotatable.
>
>
>
> I recognize that tribanders are, themselves, compromises. However, current
> designs seem a vast improvement over the designs of 30 years ago. (I’m
> thinking of using one of the interlaced models, e.g., with 2 or 3 full sized
> elements per band.)
>
>
>
> I’m not interested in longer boom yagis – narrow in azimuth and broad in
> elevation pattern (e.g., beaming Europe only to put a null on Africa, or
> beaming Japan only to put a null on NZ/Australia). I’d rather have a
> broader azimuthal pattern, and a selection of different elevation patterns –
> depending on whether I drive antennas #1+#2+#3, or #1+#2, or # 2+#3, or
> #1+#3, or #1, or # 2 or# 3.
>
>
>
> What issues/observations can folks with experience relate?
>
>
>
> Tnx/73,
>
>
>
> Bill, K2PO/7
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