My 2 C31XRs (14 elements each) are stacked at 40 and 80 feet. I added a F12
"custom" 5 element 10 at 23 feet. I feed the tribanders with separate
feedlines, so I essentially have 3/3 on 20, 4/4 on 15, and 5/5/5/ on 10.
Each band has equal length feedlines from the same roll of coax.
This will be the first year I will be using the stacks, so it will be
interesting to see a) if it works b) how good the setup is
Tom, N2SR
From: "john@kk9a.com" <john@kk9a.com>
To: towertalk@contesting.com
Sent: Sunday, July 17, 2016 8:14 PM
Subject: Re: [TowerTalk] Tribander Stacking
Have you modeled this in NEC2? The antennas are really close together, even
for 10m. I think a two stack would be a better option. Yes they should be
fed with equal length coax.
John KK9A
To: towertalk@contesting.com
Subject: [TowerTalk] Tribander Stacking
From: Filipe Lopes <ct1ilt@gmail.com>
Date: Sun, 17 Jul 2016 18:50:29 +0200
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hello guys,
I have read quite a few posts here but I still am not sure about the
distances I should use to stack my tribanders.
I am rebuilding my contest station CR6K in Portugal from scratch, meaning
all antenas are gone, new antennas are being constructed and also a new
self supporting cranck up tower 20m high is being built by my dad CT1CJJ.
For this new tower I want to make a stack of 3 x tribanders (10 15 20m) 11
elements each. I tried a few simulations with MMANA and HFTA and what I
found is that my stacking distances are best at 5.4m (+- 17 feet) from each
antenna, meaning I would have the 3 antennas at 11.4 m / 16.8 m / 22.2 m (
37 / 55 / 73 feet). I then read one post from someone who says that HFTA
has some sort of bug that considers maximums at < than 0.5 wl.
For info the top antenna will rotate when necessary and the other 2 will be
fixed to USA and my QTH slopes down a lot towards USA. Also this is mainlly
a USA tower because there is another tower dedicated to EU/ASIA.
So my questions are:
- Is a stack of 2 tribanders @ 60/90 feet enough?
- If I consider the 3 tribanders the top one might be a lot towards EU
and so the other 2 towards USA
- Is 9 m (30 feet) the optimum stacking distance for tribanders?
- Will it hurt having for example 30 feet stacking between the 2 bottom
antennas and 17 feet between the second one and top one?
- I know the coax lines between the antennas and the power splitter need
to be electrically the same but does it matter how long they are, for
example 3x 25m is ok?
All comments and suggestions are welcome.
Thank you so much.
73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|