>From: K7LXC@aol.com
To: <towertalk@contesting.com>
>Date: Mon, 12 Apr 1999 11:57:13 EDT
>
>In a message dated 99-04-12 11:32:51 EDT, you write:
>
>>> Don't forget that a crank-up has cables connecting all the
>>> sections. It's one big lump of steel as far as being a
>>> conductor is concerned.
>>
>> Yes, but I'd be concerned that the sections are electrically
>> bonded only via the contact area between the steel cables and
>> pulleys. Wouldn't dirt/lubricant on the cable and in the
>> pulley grooves tend to make that contact unreliable?
>
>I'll bet you a nickel that there is still an adequate electrical
>connection. If you look at the races of the pulleys, they are
>generally bare metal. Running the tower up and down with the
>cables under pressure does a pretty good job of keeping
>oxidation off of those parts.
I'll bet you two nickels that little if any of the current flows
on the support cable anyhow. The tower sections usually make
good enough contact (judging by the lack of observable damage on
several local crankups that I know have been hit). Also, the
relatively high inductance of the support cable compared to the
tower structure would cause the fault current to flash over at
the tower connection points even if the connection there was
open.
>
>I'll try to remember to take a DVM with me the next time I'm on
>a crank-up and measure some of those points.
>
>Lubrication? What lubrication? 98% of hams have never lubricated
>their cables so that's kind of a non-issue.
>
>> I've seen recommendations on bonding crankup tower sections
>> together for the purposes of improving lightning protection,
>> but always felt that was not really feasible.
>
> You're right - it's not.
AMEN!
>
>Cheers, Steve K7LXC
73, Eric N7CL
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