Look on qrz.com and you will see my 80m tower/verticals. They are
insulated by placing solid fiberglass rod inside each tower leg.
Using Rohn steel tower, you MUST guy it, so torque should not be a problem.
The fiberglass rod is available at most livestock/feed stores ...
usually being sold as 'fence posts'.
Be very careful as the fiberglass 'flakes' off and can enter your
eyes/skin, etc. Wearing gloves to handle it is very good planning!
You can 'seal' the fiberglass by coating it with a clear lacquer, but
the rod I use does NOT flake and was purchased in 8-foot lengths many
years ago.
Remember to drill holes just above the insulators so water/ice does
not accumulate inside the tower legs.
73
Don
N8DE
Quoting w7xu@iw.net:
> I'm looking for some suggestions on how to insulate the base of
> Rohn 25 tower so
> it can be series fed. This is for a 4-square on 80 meters. I
> already have the tower
> on hand, so I'm not really looking for alternatives to using tower
> as the radiating
> elements. I've looked through the archives of TowerTalk and Top
> Band, but I'm
> wondering if anyone has some other ideas.
>
> The options I've found are:
>
> 1) Base insulators carried by DX Engineering, with one insulator in
> each leg of the
> tower. They go for about $450 pertower. I've seen the arguments
> that having
> an insulator in each leg is less than ideal, due to torque, etc.,
> but each tower will
> only be 60 some feet tall. This is the lowest cost commercial
> alternative I've found.
>
> 2) Commercial AM tower insulator. I did some investigating and was
> quoted about
> $1100 per insulator, with of course just one insulator per tower.
> I've been looking
> locally for several years and can't come up with 4 used ones, so the
> used route
> hasn't proven to be a viable option.
>
> 3) Power line insulators. I checked with my power company and they
> won't sell
> these.
>
> 4) Rohn insulated tower section -- These cost about $2000 each now,
> plus shipping.
> Ouch.
>
> 5) Home made insulator? I'm willing to go this route if it doesn't
> involve finding some
> one-of-a-kind items that I probably won't be able to locate locally.
> Also, for those that
> have made insulators with Teflon sheet, etc., I also wonder how the
> shunt capacitance
> introduced into the system affects performance.
>
> Thanks in advance,
>
> Arliss, W7XU
>
>
>
>
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>
>
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