> A 1.5 volt battery may not be enough to breakdown any contact
> 'resistance' in the tower joints. I'll bet a KW of RF (or even 100W)
> does a lot better :-)
>
[Steve Katz] Actually, my DVM uses 4.5V. At 20 Ohms, that's 225 mA
through the circuit. Still, not very much. Your suggested experiment might
be useful, I'll try it next time -- although the 70' R25 I was writing about
is long gone (at least for me!). R45 and 55 are pretty common AM BCB
antennas, as I see just driving around. I wonder if the BC stations do
something special to enhance conductivity? They probably do. -WB2WIK/6
> Someone suggested using a CURRENT SOURCE set to 1 AMP
> and then measure the Voltage across the antenna joints. Sounds
> like a better solution to me.
>
> Tom N4KG
>
> On Tue, 19 Nov 2002 11:05:40 -0800 Steve Katz <stevek@jmr.com> writes:
> > Interesting subject.
> >
> > I'm sure this varies a great deal, but I measured the resistance
> > from the
> > top to the bottom of 70' of R25 that had been up for a couple of
> > years, and
> > it was very high. (Measurement made by attaching #12 insulated
> > copper wire
> > to the top plate of the tower, running that wire to the bottom of
> > the tower,
> > and measuring the resistance from "top" to "bottom," assuming that
> > 70' of
> > #12AWG pure copper is zero. It's not zero, but it's damned close.)
> > In that
> > case, I measured more than 20 Ohms through the tower. Banging hard
> > on the
> > guy wires could change it very slightly, but not as much as I
> > thought it
> > would.
> >
> > I don't think I'd want 20 Ohms in series with my 50 Ohm antenna, but
> > that's
> > just me!
> >
> > -WB2WIK/6
> >
> > "If everything seems under control, you're just not going fast
> > enough." -
> > Mario Andretti
> >
> > > -----Original Message-----
> > > From: Pete Smith [SMTP:n4zr@contesting.com]
> > > Sent: Tuesday, November 19, 2002 8:21 AM
> > > To: towertalk@contesting.com
> > > Subject: Re: [Towertalk] tower joint Conductivity ???
> > >
> > > At 10:45 AM 11/19/02 -0500, k7lxc wrote:
> > > > > Should I use conductive grease?
> > > >
> > > > I would. But hard to predict the conductivity of the whole
> > tower.
> > >
> > >
> > > I may be living in a fool's paradise, but I figured that with 2
> > bolts per
> > > leg per joint, plus the zinc-on-zinc contact of the legs on top of
> > one
> > > another, pressed together by the weight of the tower and guy
> > forces, the
> > > conductivity between sections ought to be pretty decent.
> > >
> > >
> > > 73, Pete N4ZR
> > > Sometimes a tower is just a tower
> > >
> > >
> > >
> > >
> > > _______________________________________________
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>
>
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