FWIW
I have two C31JK-XR tribanders - one at 90', the other at 55' - fed via a
DXE phasing box (U/L/BIP/BOP). The lower C31 is on a swinging gate that
rotates from 350 degrees and around through 0 degrees to about 235 degrees.
My experience is as follows:
Whether or not I get some gain from running both antennas in phase to EU
for example depends on a number of factors including conditions, time of
day, and distance from me (I'm in NH). The noticeable gain in received
signal might be a db or two in general. Nothing to write home about. 20 is
a wash with 15 and 10 being the bands that seem to benefit the most from
running the stack in phase. But there are two more important reasons why
I'm happy I did this.
1. As the opening to EU on any of the three bands progresses given current
SF, the opening starts to favor the lower antenna. This is most pronounced
on 10 but is definitely a factor on 15 as well. I can run EU on 10 on the
lower antenna well after the upper antenna can't be heard in EU.
2. The fact that I can rotate both antennas gives me the ability to point
in two directions at once. When in S&P mode I can cover EU and SA without
rotating an antenna. I tune the radio and call. In run mode I can cover EU
and JA callers. In contests where US stations also count for points and
multipliers (like CQWW RTTY or WPX), I can cover EU and the US
simultaneously. This setup can be very effective on all three bands.
Would I do this again? Absolutely yes.
For pictures, see my QRZ page.
73,
John
NN1SS
On Mon, Apr 7, 2025 at 11:31 AM Jim Lux <jim@luxfamily.com> wrote:
>
>
>
>
> True, but I think that's also, to a certain extent, an artifact of the
> simple phasing, switch network (BIP, BOP, Top, Bottom): which sort of gives
> you 4 different patterns in the elevation axis. If you have a variable
> phase shift, you can steer the beam quite a bit.
>
> It is unclear how much this would buy you (for significant increased
> complexity) - the beams are broad. Probably more useful is the ability to
> put a null on a take off angle that is giving you interference. (and on Tx,
> to avoid sending Tx power to an undesired elevation angle).
>
> On receive, doing this is pretty easy with modern SDRs, but on Tx, it's
> more challenging - you can't just generate multiple signals that are phased
> differently and run them into a PA, because the antennas interact, and
> power from amplifier N couples into the output of Amplifier N-1 and N-2.
> For large HF arrays (think Over The Horizon Radar) they do this, and
> there's a whole lot of modeling and testing that goes into forming the
> beams correctly.
>
>
> On Mon, 7 Apr 2025 09:05:55 -0600, Tom Hellem <tom.hellem@gmail.com>
> wrote:
>
> Ron-
> The reason stacked tribanders don't work as well as monobanders is
> that you can only optimize the stacking distance for one band.
> I have used a stack of tribanders, though, and I can attest they
> are better by far than a single yagi.
>
> Tom
> K0SN
>
> On Sun, Apr 6, 2025 at 8:02 PM Ron WV4P wrote:
>
> > I am very surprised to learn that multi-band antennas do not work well in
> > stacks.
> >
> > Ron, WV4P
> >
> > On Sun, Apr 6, 2025 at 8:48 PM Mike Fatchett W0MU wrote:
> >
> > > He could have used 20m monobanders and saved a ton of
> > > money......Obviously money was not an issue. 4 80 ft towers as the
> > > supports.....etc.......And then when it broke you were SOL.
> > >
> > > W0MU
> > >
> > > On 4/6/2025 7:34 PM, Richard (Rick) Karlquist wrote:
> > > > A stack in 2 dimensions like that only works well on one band.
> > > > It won't be anything great whether SteppIR's or any other tribanders
> > > > are used. W6BH tried a stack of KT34's (only vertical stacking)
> > > > and it didn't work very well, which should have been obvious without
> > > > building it. As was said, more cents than sense.
> > > >
> > > > 73
> > > > Rick N6RK
> > > >
> > > > On 4/5/2025 9:27 PM, john@kk9a.com wrote:
> > > >> K9LTN became a silent key in 2009. It would be interesting to know
> > > >> if that
> > > >> system ever worked and what happened to it.
> > > >>
> > > >> John KK9A
> > > >>
> > > >>
> > > >> David Gilbert AB7E wrote:
> > > >>
> > > >> I wonder what happened to it. K9LTN is an expired callsign.
> > > >>
> > > >> Dave AB7E
> > > >>
> > > >>
> > > >>
> > > >> On 4/5/2025 7:23 PM, john at kk9a.com wrote:
> > > >>> Imagine this maintenance headache:
> > > >>> https://www.kkn.net/dayton2006/K9LTN.pdf
> > > >>>
> > > >>> John KK9A
> > > >>
> > > >>
> > > >> _______________________________________________
> > > >>
> > > >>
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