[TowerTalk] Station Ground

Fri Jan 14 22:20:49 EST 2005

> You should focus your efforts on designing and constructing a low
> impedance grounding window at the location where your cables
> enter your home.  All cables entering your home should be bonded
> to the grounding window either directly or through suitable lightning
> protection devices.
>
> There is no need whatsoever for any further grounding of your station
> equipment, other than the green wires from your equipment to your
> AC power receptacles.

In that case, explain this:

My cables come in through a bulkhead. Each cable goes through a PolyPhaser 
(bulkhead connector type) in that bulkhead.  The radio station is on a large 
desk that sets against the West wall.  To the left of that desk is a 
computer desk with the computer that serves as control, packet, and 
sometimes logging.

I had the cable to the 440 array disconnected from the Alpha-Delta coax 
switch for the UHF/VHF antennas.  The end of the cable with the PL-259 
attached was laying on the desk top, below and a bit to the side of the 
antenna switch for a total distance of about 10 inches.  Both duo-band 
144/440 rigs set on top of the hutch above the antenna switch.  The switch 
was in the 144 MHz position.

Remember, all these cables and others go back through that grounding 
bulkhead.
I was at the computer keyboard on the main computer which is on a desk 
against the South Wall which is directly to the East of the other computer 
desk. Both Duobanders (the second connects to a colinear vertical side 
mounted low on the tower) and the 756 Pro were operating as well as all 4 
computers on the Cat-5e (hard wired) network.

Lightening struck the tower and there was a briliant flash from a very 
bright arc accompanied by a lound "bang" from the end of that cable up to 
the antenna switch.

Other than Both UPSs resetting and the network reconnecting there was no 
indication that anything had happened.
However it's only 8 feet at most back to where the cable laying on the desk 
and the cable tied to the switch connect together.  There was no damage to 
any polyphaser.

It must have been a very rapid rise time to that strike, but with all rigs 
bonded together externally as well as through the cables there was no 
damage.
>
Maybe that low inductance ground doesn't do anything, but after that, I will 
certainly continue using them in all my installations.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
www.rogerhalstead.com
> 73!
> Frank
> W3LPL
> donovanf at erols.com
>
>
>
> ----- Original Message -----
> From: N6KJ <n6kj at yahoo.com>
> To: <towertalk at contesting.com>
> Sent: Friday, January 14, 2005 7:44 PM
> Subject: Re: [TowerTalk] Station Ground
>
>
>> At the moment, my rig and amplifier ground lugs
>> are not connected to anything.  I have no stray
>> RF problems or RFI that I am aware of (except a
>> little bit of TVI when operating 40/80 which I've
>> never been able to solve).  The manufacturer always
>> says you should connect up the ground lug.  So far, I
>> have not done that but I WILL do it if-and-only-if
>> it doesn't make things worse.  My assumption is that
>> the ground lug is there for a reason Maybe this is a
>> bad assumption, but ....
>>
>> The primary reason for my questions today is:
>> I am going to start on a home addition soon.  As of
>> today, my rig is located in the basement next to an
>> outside wall.  I can easily get to a ground rod
>> that is located only about 5 feet from my
>> rig.  This will no longer be true once the addition
>> is built.  Once the addition is built, my rig
>> will still be in the basement but the wall will
>> no longer be an outside wall, SO if I ever want a
>> good ground system with a short connection to ground
>> then I need to do it now.  I don't have to hook it
>> up to my rig/amp, but I have to at least drive in
>> the ground rods and run a wire from the ground rods
>> into the shack.
>>
>> I'm not worried about safety ground.  I can use the
>> existing safety ground OR add one later, but a good
>> RF ground needs short leads to ground and that means
>> building the grounding network NOW.  I think I now
>> have enough info from everyone to do that.  Thanks.
>>
>>
>> --- Jim Lux <jimlux at earthlink.net> wrote:
>>
>> > At 01:39 PM 1/14/2005, you wrote:
>> > >How do people attach their rigs to a bus-bar (or
>> > >similar)?  The bigger the ground wire the better,
>> >
>> > WHy would you necessarily want a huge wire?  How
>> > much current do you expect
>> > to be carrying through that wire?  Hopefully not
>> > much. Sure, bigger is
>> > (slightly) lower inductance, but presumably, the
>> > wire is fairly
>> > short.  Also, is the rig chassis ground common with
>> > the power supply return
>> > (if 12V powered)?  What about the electrical safety
>> > ground (the greenwire
>> > ground)?
>> >
>> > [ Stuff Deleted ]
>> _______________________________________________
>>
>> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any
> questions and ask for Sherman, W2FLA.
>>
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> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any questions and ask for Sherman, W2FLA.
>
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