The Comtek 4 square box has been wrongly used with two verticals (I know
there are old manuals with this idea).
Quite simply - it doesn't work - or better said, it doesn't work very well.
This is the box for two verticals - done correctly - with outstanding
results:
https://www.dxengineering.com/parts/dxe-dva-40b-p
Available for many bands
73
Tim K3LR at DX Engineering
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
k1ttt.dave@gmail.com
Sent: Wednesday, August 11, 2021 10:16 AM
To: 'Tower Talk'
Subject: Re: [TowerTalk] Terminate unused ports on remote antenna switch?
Ok, the supported 2 vertical configuration won't work in your case as it is
designed to have a 1/4 wave spacing between the verticals... it also calls
for 50 ohm phasing lines instead of the normal 75 ohm for the 4 vertical
case. I would be very careful about what you do with the phasing box as you
may damage it with the wrong impedances if you use high power. As I said
before the comtek boxes are designed for nominal 100 ohm loads when using
all 4 verticals, but only 50 ohm loads on 2 ports with the others open for 2
verticals.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: telnet://k1ttt.net:7373
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Raymond
Benny
Sent: Wednesday, August 11, 2021 04:04
To: Wes <wes_n7ws@triconet.org>
Cc: Tower Talk <towertalk@contesting.com>
Subject: Re: [TowerTalk] Terminate unused ports on remote antenna switch?
I did not detail my situation at all, sorry.
And, I do understand not needing to terminate the unused port on a remote
coax switch.
In my case, I am building an 80m 4 SQ TX antenna system. I have a Comtek 80m
4 sq phasing controller switch and remote box, and have 2 of the diagonal
verticals working independently.
Soon, I plan to connect the two verticals so to get correct 2 way phasing
and matching. And, so I don't possibly mess anything else I plan connect
1kw dummy loads to the the ports that do not have a corresponding antennas.
In doing this, no matter where phasing box is set, there should be no
possible damage anywhere.
However, I do like the idea using high wattage incandescent bulbs. They are
less critical to weatherproofing.
Knowing my full situation now, are there any other thoughts or ideas?
BTW, I have done much research on designing and building of my 80m 4 sq tx
antenna system. There is a lot to read. The two most beneficial for
building; first, is a write by Gary, WA60, on their rebuild of the 80m 4 sq
at N6RO, a very big west coast contest station. 2nd, is a write up for
1:1 baluns by Jim, K9YC specifically for 4 sq antenns systems.
Tnx and 73,
Ray,
N6VR/W7YA
On Tue, Aug 10, 2021, 6:29 PM Wes <wes_n7ws@triconet.org> wrote:
> Bingo.
>
> Wes N7WS
>
>
> On 8/10/2021 6:22 PM, Earl Morse wrote:
> > Terminating multiport devices in their characteristic impedance is
> desired
> > when those ports are still part of the circuit. In the case of the
> antenna
> > switch, which disconnects the undesired ports and either just leaves
> > them hanging or shorts them to ground, termination with a dummy load
> > doesn't really do anything except to prevent you from transmitting
> > into an unused port that is either open or shorted and not properly
> > terminated. It
> would
> > probably be cheaper to use a switch with the proper amount of
> > connections rather than buying dummy loads for each unused connection.
> >
> > It is common to terminate unused ports in various multiple port
> > devices
> but
> > really doesn't apply to the coaxial switch as the unused ports are
> > physically disconnected or shorted or both.
> >
> > Earl
> > N8SS
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > 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
>
_______________________________________________
_______________________________________________
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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|