There is a problem with getting the phase shifts equal.
First of all, the triplexers need to be equal delays,
when tested in a 50 ohm system. Then the mismatch
of the 3 tribanders must be low or at least the
same. Depends on the individual tuning of the triplexers.
Seems like a lot of moving parts to get right.
Rick N6RK
On 3/21/2017 8:29 PM, Rudy Bakalov via TowerTalk wrote:
Mike,
Option #3 can be executed slightly differently and it is what I am pursuing.
You don't need 9 HP BPFs, only 3. The sequence of devices, starting from the
tribander and going to the shack is:
1) 3 x Tribanders with single feed line each
2) Each feed line goes into a triplexers and you get separate lines for 20,15,
and 10. In total, you get 3 x 20, 3 x 15, and 3 x 10
3) You take all the individual band lines and stack them using 3 stack matches
4) Now you have 3 feed lines again- for 20, 15, and 10
5) Install HP BPFs on each feed line, for a total of 3 BPFs
Haven't built it yet. It's a summer project, along with expanding the remote
SO2R switch.
Rudy N2WQ
Sent using a tiny keyboard. Please excuse brevity, typos, or inappropriate
autocorrect.
On Mar 21, 2017, at 8:50 PM, Mike DeChristopher <mfdechristopher@gmail.com>
wrote:
I know some of you are using (or have used) a triplexer with your
tribander. Having very limited experience with triplexers and
tribanders, I'm hoping you can assist with a thought experiment we're
working through.
For the purposes of this discussion, we'll ignore the pitfalls of
stacking tribanders themselves, at least where it comes to pattern,
elevation, separation, etc. -- let's assume we have that all worked
out.
Phase 1: Take a three -high stack of identical tribanders, each single
feed. We want to do the reasonable thing and use a stack match of some
sort. This probably works OK.
Phase 2: Now we want to host a multiop. We'll need to separate the
feeds with a triplexer (BPF's included) between the stack match and
the shack. Now we have three feeds coming in and a shared stack for
10, 15, and 20. The obvious downfall is that three operators are
chained to the same stack configuration; for example, the 10m op wants
to use only the top beam while the 20m op wants to run EU
simultaneously on the full stack -- fisticuffs break out as operators
fight for the stack control box.
Phase 3: The next logical step is to put a triplexer and the BPF's per
tribander. So we now have three feeds per antenna, which can then be
run into three stack matches (one each for 10, 15, and 20). At this
point, we'd truly have three independently-controlled stacks. The only
shared controls would be rotors.
[Given the cost of nine HP BPF's, three triplexers, three stack
matches, other assorted hardware, the nearly-logical suggestion might
be "build another tower and use monobanders" -- but that's why this is
a thought experiment, after all.]
Question 1: Has anyone done this (Phase 3 above)?
Question 2: If one used tribanders with separate feeds for each band,
could one forego the triplexers and simply use BPF's between each
feedpoint and the stack match?
73,
Mike N1TA
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