[TowerTalk] station grounding question

[James C. Hall, MD]

Hi Frank:

Ouch ! Seems I hit a nerve there. Now, I have used insulated copper wire on
several occasions and things like copper water piping as a common bus on
which you could connect copper flashing. But now you have me confused on one
point - how can the pressure of insulation (or lack of it) decrease (or
increase) RF impedance ? If it is a simple 'lack of appropriate contact'
without the pressure, it would seem to me that linear stretching  would
provide adequate contact - at least intuitively.

Just trying to learn something here. Grounding sometimes gets into the Karma
of Ham Radio ! HI

73, Jamie
WB4YDL

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of
donovanf at starpower.net
Sent: Tuesday, November 22, 2005 6:48 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] station grounding question

Braid is a suitable RF grounding conductor only when 
alternatives such as stranded wire or copper strap are subject 
to flexure failures, such as grounding of swinging metal doors, 
fence gates or movable components in vehicles.

Braid from RG-213 is a suitable RF grounding conductor only if 
you do not remove the jacket from the cable.  After you 
remove the jacket, the RF impedance of the braid increases 
dramatically because all of the braid crossovers are no longer 
under pressure.

A more appropriate equipment grounding conductor would be 
stranded copper wire, 16 AWG or larger would be suitable.

Braid is something little girls do with their hair, it's completely 
unsuitable as an RF grounding conductor except when no other 
alternative is practical.

73!
Frank
W3LPL



---- Original message ----
>Date: Tue, 22 Nov 2005 18:22:53 -0600
>From: "James C. Hall, MD" <nwtcc at earthlink.net> 
>Subject: Re: [TowerTalk] station grounding question  
>To: "'Richard W. Harris'" <Richard_Harris at byu.edu>, 
towertalk at contesting.com
>
>Richard:
>
>Got some old 213 coax(or similar RG-8) lying around ? Take 
the jacket off a
>chosen length of this coax and push up the braid until it simply 
slides off
>the dielectric. Use two large solder eyes - one on each end 
and give the
>braid a half twist around the solder lug. Clamp and solder the 
eyes to the
>braid and you have instant ground strap ! This you can use to 
flexibly
>connect your gear to the copper flashing or SPG panel. I've 
used this method
>for over 25 years without a single problem.
>
>73, Jamie
>WB4YDL
>
>-----Original Message-----
>From: towertalk-bounces at contesting.com
>[mailto:towertalk-bounces at contesting.com] On Behalf Of 
Richard W. Harris
>Sent: Monday, November 21, 2005 9:19 PM
>To: towertalk at contesting.com
>Subject: [TowerTalk] station grounding question
>
>Hi,
>A simple question on station grounding.  I have a copper wall 
plate for
>common grounding of all of my station equipment.  I have 2" 
wide copper
>strap to connect each piece of gear to the copper panel.  Most 
pieces of
>equipment have a simple bolt for grounding.  Seems to me 
that a single/small
>bolt connection to the copper strap is not a very good 
connection. Any
>suggestions here?  Should I simply be connecting the 2" 
copper strap to the
>grounding bolt of each piece of gear or is there a better 
method?
>Thanks,
>Richard Harris - KJ7CU
> 
>Also, thanks to all those that gave me advice on my 160M 
shunt-fed tower.
>Working great.  A lot of work but well worth the effort
>_______________________________________________
>
>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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>http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________

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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