I know that's been done before, at least with fairly short verticals (1/4 w.
80 m.; maybe even 1/4 w. on 160) but since a top section is really made to
handle holding a mast I do not know how much downward compression force it
can take as you mention, so I would really try to find a genuine rohn bottom
taper for what is going to be a taller AM tower. The other thing is that
it would be made to mate with the insulator hardware, the other point which
you rightly bring up.
73
rob / k5uj
From: "jeremy-ca" <km1h@jeremy.mv.com>
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>,<towertalk@contesting.com>
Subject: Re: [TowerTalk] re 25G base insulator
Date: Mon, 6 Aug 2007 12:59:58 -0400
How about using a pointed top section at the bottom? I know that Rohn has
made adaptors to reverse the sex for those who erected a tower the wrong
way. Would it be able to support the tower weight? And adapt to an
insulator?
Carl
KM1H
----- Original Message ----- From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
To: <towertalk@contesting.com>
Sent: Monday, August 06, 2007 12:31 PM
Subject: [TowerTalk] re 25G base insulator
>Hi,
>
>AM broadcast stations don't use 25 all that often so insulators for it are
>kind of unusual. Rohn used to make a bottom taper and insulator so you
>might give them a try, or whoever is making the R25 hardware these days.
>
>Because the station wants to use 25, I'm making a few assumptions--the
>tower
>is going to be around 90 degrees and in the higher part of the band so it
>isn't very tall; maybe not even lamped and painted. You say the f/p I is
>5.5 amps. Assuming a f/p Z of around 36 ohms it looks like a 1 KW station
>(this has nothing to do with the insulator--I'm just having some fun). I
>would be a bit uncomfortable with separate leg inulators at the base. Any
>AM R25 tower is still gg to be pretty tall for the face width. I'd look
>into Austin insulators for a single point ceramic insulator and see if they
>have anything. They took over making the Lapp line I believe. A small 7
>inch long Austin might be the ticket depending on the download.
>
>http://www.austininsulators.com/radio/product.html
>
>btw, AM tower sections are often tac welded together.
>
>73,
>
>rob / k5uj
>
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