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Re: [TenTec] Static blow-up

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Static blow-up
From: Randy Russe3ll <lord_russell53@yahoo.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 14 Feb 2006 09:05:47 -0800 (PST)
List-post: <mailto:tentec@contesting.com>
I've experienced serious potentials from my open wire
line, which I believe to be much more prone to static
discharge than the flat strip ladder line.  When any
storm front crosses my Qth, even a minor one, voltages
would start discharging sparks across the cap plates
of my link coupled tuner.  I believe these caps to be
rated  @3500V.  They are certainly rated well above
1000V. I would immediately flip the switch to
disconnect the antenna, but through emperical testing
I observed some interesting phenomena.  First, with
insulated pliers, I could get a 1 inch spark to
ground.If I left the leads disconnected, they had to
be set in a glass Jar, or sparks would jump to any
nearby surface of even slight conductivity. If I
GRABBED the leads, sometimes I could just BARELY hold
on.  More often than not, it just shocked the holy
livin' Heck out of me! I invite the incredulous to try
this experiment at home for themselves.  Well, I
solved it by a 2.5 mH (cut-off frequency is 1 MHZ and
below), and a 1 Mega Ohm resistor in parrellel. I run
a pair of these off each antenna terminal and to
ground.  I still have a knife   switch to disconnect
antenna when not in use.  I guess my point is antennas
can definetly develope over 1000V if there is not some
static bleed off to ground. For those using coax, an
in-line suppressor is cheap insurance.  I've had
similar experience with coax fed longwires (380 ft.). 
With the increasing computerization of modern gear
protecting gear from static build up is a real issue. 
Some of these newer semi-conductors just don't do well
with static-voltage surges. ICOM blames problems they
are having with a semiconductor going out on their
746pro, to static discharge.  Of course, just because
the manufactorer tells you that's the problem, doesn't
make it so.  

--- Mike Hyder  -N4NT- <mike_n4nt@charter.net> wrote:

> Sometimes we would put an RFC (radio frequency choke
> for those of you in Rio 
> Linda) across the aerial inputs to the rig to get
> rid of DC.
> 73, Mike N4NT
> ----- Original Message ----- 
> From: "Larry DiGioia" <listacct@longwire.com>
> To: "Discussion of Ten-Tec Equipment"
> <tentec@contesting.com>
> Sent: Sunday, February 12, 2006 8:57 PM
> Subject: Re: [TenTec] blow-up number 5
> The PIV is 1000V per Paul. I put a neon tester light
> across the end of
> the ladderline, I am going to leave it on each one
> for a few days and watch.
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec

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