Send TowerTalk mailing list submissions to
towertalk@contesting.com
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.contesting.com/mailman/listinfo/towertalk
or, via email, send a message with subject or body 'help' to
towertalk-request@contesting.com
You can reach the person managing the list at
towertalk-owner@contesting.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of TowerTalk digest..."
Today's Topics:
1. Re: Arrestor placement (Gary Schafer)
2. Identity of DowKey relay (John King via TowerTalk)
3. 40/80 stub (Tom Osborne)
4. Re: 40/80 stub (Dave Hachadorian)
5. Re: Identity of DowKey relay (Jim Brown)
6. Re: Identity of DowKey relay (Jim Lux)
7. 275W EFJ Matchbox for sale (k7mks@comcast.net)
----------------------------------------------------------------------
Message: 1
Date: Mon, 29 Dec 2014 11:33:52 -0600
From: "Gary Schafer" <garyschafer@largeriver.net>
To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Arrestor placement
Message-ID: <5F5939907F3649F589CABEE9138D94CE@garyPC>
Content-Type: text/plain; charset="us-ascii"
Part of the reason for the arrestor on the coax line is because the center
conductor is going to have a voltage different from the shield.
The tower and all of the lines coming down the tower share any strike
current. Even if the center conductor is bonded to the shield at the top of
the tower you will still end up with energy on the center conductor.
Because of the high current on the shield during a strike, the resistance
of the shield allows voltage drop over the distance of the cable. Energy is
induced onto the center conductor.
Because the propagation time on the inside of the cable is slower than on
the outside you end up with a voltage difference at the end of the cable
between center and shield. For more information on this look up "transfer
impedance".
This center conductor voltage can be induced on the cable even if the cable
is on the ground. Anywhere there is current on the shield some of the energy
ends up on the center conductor.
This is why you want the protector close to the shack. The length between
the tower and the shack can allow the energy to be induced onto the center
conductor.
This current can come from the tower strike or ground currents from another
direction.
One other important thing that no one has mentioned, although most here
know, is that your AC power must also be protected and bonded to your
entrance panel where the coax suppressors are installed.
You do not want any difference in potential between the AC power and your
coax lines. The easiest way to accomplish this if your power panel is not
close to your coax suppressor panel is to run an AC line (large extension
cord is fine) over to the coax entrance panel. Install AC protectors on that
line with them bonded to the coax panel.
Feed all of your power and antennas from only that panel. This will insure
that everything stays at the same potential. Of course include any phone
lines, rotor cables etc the same way.
73
Gary K4FMX
------------------------------
Message: 2
Date: Mon, 29 Dec 2014 11:46:53 -0800
From: John King via TowerTalk <towertalk@contesting.com>
To: towertalk@contesting.com
Subject: [TowerTalk] Identity of DowKey relay
Message-ID:
<1419882413.37167.YahooMailBasic@web160301.mail.bf1.yahoo.com>
Content-Type: text/plain; charset=us-ascii
I have a REMOTE DoiwKey relay with the nomenclature P/N 71 on it. It has seven
female connectors on it. There are 6 connectors in a circle and 1 in the
center which indicates to me that the feed line connects via a PL-259 to the
center connector and the relay switches through the 6 in the circle to select
the desired output feed line.
It has a round female multi pin control receptical where the control attaches.
I do not have the control or selector box so I have no idea as to voltage to
operate. It appears to be a SUPER multi-coax selector switch.
Is anyone familiar with this remote antenna selector switch? I need data
regarding voltage required and a diagram if I can get one.Your help will be
greatly appreciated. 74, John, K5PGW
------------------------------
Message: 3
Date: Mon, 29 Dec 2014 13:23:44 -0800
From: Tom Osborne <w7why@frontier.com>
To: towertalk@contesting.com
Subject: [TowerTalk] 40/80 stub
Message-ID: <54A1C660.1020906@frontier.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Hi All
It is possible to make a ~23' stub with a switch in the end to open and
short for 20/40. Can you do this with 40/80 by making an 80 meter stub
and put a switch on the end like the 20/40? I've never seen this done.
I have a 40/80 elevated vertical I'd like to put a stub on. Thanks and 73
Tom W7WHY
------------------------------
Message: 4
Date: Mon, 29 Dec 2014 14:41:39 -0700
From: "Dave Hachadorian" <k6ll.dave@gmail.com>
To: "reflector Towertalk" <towertalk@contesting.com>
Subject: Re: [TowerTalk] 40/80 stub
Message-ID: <8C79B933354A407BBF5C26898CCCE772@Toshiba>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=response
I have done this at 100 watts, with a dinky little panel-mounted
toggle switch. You could probably use a wall switch or a relay
at high power. I have used a 3-way wall switch to make a
2-position antenna switch for high power.
Dave Hachadorian, K6LL
Yuma, AZ
-----Original Message-----
From: Tom Osborne
Sent: Monday, December 29, 2014 2:23 PM
To: towertalk@contesting.com
Subject: [TowerTalk] 40/80 stub
Hi All
It is possible to make a ~23' stub with a switch in the end to
open and
short for 20/40. Can you do this with 40/80 by making an 80
meter stub
and put a switch on the end like the 20/40? I've never seen this
done.
I have a 40/80 elevated vertical I'd like to put a stub on.
Thanks and 73
Tom W7WHY
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 5
Date: Mon, 29 Dec 2014 20:28:16 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Identity of DowKey relay
Message-ID: <54A229E0.6050904@audiosystemsgroup.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
I have one that comes close to that description that came from the junk
box an SK. It's 120VAC.
73, Jim K9YC
On Mon,12/29/2014 11:46 AM, John King via TowerTalk wrote:
I have a REMOTE DoiwKey relay with the nomenclature P/N 71 on it. It has seven
female connectors on it. There are 6 connectors in a circle and 1 in the
center which indicates to me that the feed line connects via a PL-259 to the
center connector and the relay switches through the 6 in the circle to select
the desired output feed line.
It has a round female multi pin control receptical where the control attaches.
I do not have the control or selector box so I have no idea as to voltage to
operate. It appears to be a SUPER multi-coax selector switch.
Is anyone familiar with this remote antenna selector switch? I need data
regarding voltage required and a diagram if I can get one.Your help will be
greatly appreciated. 74, John, K5PGW
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 6
Date: Mon, 29 Dec 2014 20:43:02 -0800
From: Jim Lux <jimlux@earthlink.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Identity of DowKey relay
Message-ID: <54A22D56.2060906@earthlink.net>
Content-Type: text/plain; charset=windows-1252; format=flowed
On 12/29/14 8:28 PM, Jim Brown wrote:
I have one that comes close to that description that came from the junk
box an SK. It's 120VAC.
I'd get a variac and slowly ramp the voltage up and see where it pulls in.
The coils could be 12V, 24V, or 120V
------------------------------
Message: 7
Date: Tue, 30 Dec 2014 05:02:30 +0000 (UTC)
From: k7mks@comcast.net
To: towertalk <towertalk@contesting.com>
Subject: [TowerTalk] 275W EFJ Matchbox for sale
Message-ID:
<1637810143.11473798.1419915750843.JavaMail.zimbra@comcast.net>
Content-Type: text/plain; charset=utf-8
Excess to my needs. 275W Johnson Match box w/o SWR meter/coupler. Cosmetically
excellent. Decal on back of tuner is unblemished. Can provide photos. $85 +
shpg from W WA. joe k7mks
------------------------------
Subject: Digest Footer
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
End of TowerTalk Digest, Vol 144, Issue 66
******************************************