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Re: [TowerTalk] Quick Disconnect Suggestion

To: "'Roger \(K8RI\)'" <K8RI-on-TowerTalk@tm.net>, "Jerry" <grf@uneedspeed.net>, "Tower Talk" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Quick Disconnect Suggestion
From: "Dick Green WC1M" <wc1m73@gmail.com>
Date: Thu, 11 Jun 2009 07:41:44 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
> > What do you use for your rotator, antenna switch, etc. connectors at
> > your SPG boxes?
> In one word, Nothing!  I do not normally disconnect the cables coming
> into either station (shop or house) which are also interconnected.
> There are just too many cables.

That would have been my answer before the big disaster. Went 10+ years
without a problem. Then the big one struck.

I suspect part of the reason for my good luck was that one tower was a
crankup with a single antenna that was never above 22 feet during a storm
and the others were AB-577s with single antennas, ranging from 50 ft to 75
ft. All of the antennas were well below the level of nearby trees. Also, for
most of that time, the equipment connected to the control lines was
relatively robust: Hy-Gain rotor controllers, 4-square controller, etc.
These devices don't have semiconductors directly connected to the control
lines. For about two years I did have one SteppIR controller, which does
have sensitive chips attached to the control lines, and it was connected to
the computer, but I guess I was just lucky it never got hit.

Things changed when I put up a 110' tower with four antennas on it, three of
the SteppIRs. 

I believe the shack was greatly protected during the big strike by the
suppressors at both ends of every wire entering the shack. I'm certain the
Polyphaser coaxial suppressors did their job and protected every radio that
had coax connected. I believe the problem was that the MOVs in the control
line suppressors, which were of the typical 82V or 64V variety, allowed the
voltage to rise far too high for the semiconductors in the three SteppIR
controllers and Green Heron rotor controllers. The chips were fried. Some
evidence of this is that K5FD suppressor boards I use have 5A fuses which
were blown, indicating a fair amount of current flowed before the MOVs
activated. The surge also found its way from the SteppIR controllers to the
computer, the motherboard of which was destroyed, and from there to many
devices connected via RS-232, almost all of which were damaged (typically
the RS-232 level converter and the attached CPU.) However, there were no
burn marks, no singe marks, no flames, etc. No visible damage at all. I
suspect the MOVs kept much worse damage from happening. I have since lowered
the value of the MOVs to the minimum possible for the operating voltage
ranges of the attached devices.

> A point that is often neglected is when lines from the tower are
> disconnected to protect equipment in the shack/house/shop the external
> lines should be grounded and not left floating.  

Wouldn't do any good with my coax lines because the Polyphaser coax
suppressors at both ends don't pass DC. Would be good for the rest of the
stuff, but it would be a major project to build cables to ground the nearly
200 wires and would double the time it takes to unplug everything. One of
the reasons I built the panel the way I did was to make everything
accessible in one place, quick and easy to disconnect, so there would be no
disincentive to do it. Hopefully, the suppressors will do their job and
clamp the voltage of the surge below the level where it would jump from the
panel to nearby ground.

73, Dick WC1M

> -----Original Message-----
> From: Roger (K8RI) [mailto:K8RI-on-TowerTalk@tm.net]
> Sent: Thursday, June 11, 2009 1:40 AM
> To: Jerry; Tower Talk
> Subject: Re: [TowerTalk] Quick Disconnect Suggestion
> 
> 
> 
> Jerry wrote:
> > What do you use for your rotator, antenna switch, etc. connectors at
> > your SPG boxes?
> In one word, Nothing!  I do not normally disconnect the cables coming
> into either station (shop or house) which are also interconnected.
> There are just too many cables.  I agree the safest and surest
> protection is to disconnect and unplug everything, but I rarely even
> unplug anything.
> 
>  From the house to the tower are rotator, 2 remote antenna switches, the
> 6-pack control , 3 LMR-600 feed lines (soon to be 5), two RG-6 to the
> UHF TV antennas at roughly 90 feet and two RG-6 from the satellite dish
> through underground conduit to the tower. There are also 3 CAT-6 network
> cables from the house to the computers in the shop.  There will be as
> many as 7 RG-6 feedlines from the splitters in the house to the shop,
> from the satellite HD receiver to the shop, and AV lines from the system
> in the house to the shop.
> 
> In the shop there are also 3 LMR 600's underground to the tower, control
> lines to the remote antenna switches, another to the 6-pack, and the
> rotator as well as RG-6 to a satellite dish and another to a TV receive
> antenna just under the AV640. There are also feed lines to the 40' tower
> on the West end of the shop.
> 
> BTW there are 4 state of the art quad core and one dual core computer on
> the CAT 6 Gigabit network
> 
> It's just too many things at 3 different locations that would need to be
> disconnected. To top it off the house and shop are different electrical
> feeds with their own meters even though all the grounds on the property
> are tied together along with 32 or 33 8' ground rods
> 
> BTW since finishing up the ground system I've not had any damage from
> lightning with a total of 15, visually verified strikes to the tower.
> >  I like to disconnect my antenna feed lines and control
> > lines when thunderstorms approach, etc.  I've looking for ideas with
> > respect to SPG box connector and the line connector plugging into the
> > box.
> A point that is often neglected is when lines from the tower are
> disconnected to protect equipment in the shack/house/shop the external
> lines should be grounded and not left floating.  Floating they can
> become antennas for inducing current into wires inside the structure or
> even arching into the structure.
> 
> 73 and good luck,
> 
> Roger (K8RI)
> >   Hope that makes sense!  I have use a mike connector and a Cinch
> > Jones, but these seem to have problems over time.  Thanks for your help.
> > Jerry France
> > K7LY
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> >


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