Date: Wed, 8 Sep 2010 21:18:24 -0500 (CDT)
From: ac9s@mchsi.com
Subject: [TowerTalk] Antenna Swittch - Grounded or Open Unused
Contacts
To: towertalk@contesting.com
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I am about to replace my 30 year old Ameritron antenna switch with a DX
Engineering unit. It will be placed at the top of the tower to select between
the various antennas - wire slopers for 160 and 80, inverted vees for 75 and
40, and the Steppir ( currently under repair) for the rest of HF. I will not
have multiple antennas selected at the same time. What is best - to wire the
switch so that unused ports are normally grounded or open? My inclination
would be to ground all the unused antennas, but since the switch is shipped
normally open I have an element of doubt.
Thanks --
Keith
AC9S
## My Array Solutions remote switch box is wired so that all the DE-energized
ports 1-6 have their center conductor's grnded.
With the 12 vdc shut off.. OR if the rotary switch is switch is sitting on
positions 7-12... all 6 x relays are De-energized.
The AS box is a 1 in, 6 out remote switch box. The control box for it uses a
12 x pos rotary switch....and the 1st 6 are used.
The AS box uses 6 x DPDT relays...with all contacts in parallel. [ double the
RF current capacity + redundant contacts]
## The COM [moveable contact] goes to the hot side of the coax connector for
each ant port. NC goes to the grnd buss strap.
NO goes to the hot 2 kw buss [ bonded to the hot side of the input connector].
As you can see, the de-energized ports are all grnded, via the
NC grnded buss. All 6 x braids are grnded to top of tower... via the
metal box. In the event of an electrical storm...and with
all relays De-energized... both the center conductor's AND the braids of all
6 ports are grnded to the top of the tower.
## I'd install a lightning arrestor at the base of the well grnded tower..and
a 2nd on on your SPG. Then you are covered.
later... Jim VE7RF
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