Re: [TowerTalk] 80m 1/4wave vertical construction

[tongaloa <tongaloa@alltel.net>]

Can't help on the tubing size but am also working on a 1/4 wave vertical 
for 80 and
plan to make it a little short and put a 20m trap in the middle for 2 x 
1/2 waves
in phase on 20 as a bonus to the 80. Trimming feed to odd multiple of 
1/4 waves
on 20 should get a decent match on 20...looking at a piece of fiberglass for
the center. Had not thought about guys yet but will probably telescope 
the glass
section in a few extra inches and run some 3/16" eye screws into it.

Want to compare with the 80m, rectangular, vertically polarized, loop. 
3/8 wave
top and bottom and 1/8 wave verticals.

http://www.ee.surrey.ac.uk/Personal/D.Jefferies/slotnotch.html
talks a little about this sort of antenna as related to a slot antenna
but I've not been able to find any analysis of it.

-Bob


Dave N0RQ wrote:

> I am hoping to build an 80 meter 1/4 wave vertical, but have several practical questions.
>
> Size of aluminum tubing?  I don't want to waste $ and buy too big, but obviously
> don't want it too small either.  http://www.texastowers.com/aluminum.htm
> shows what TT sells (and thankfully they are local to me).  I plan to get the 
> 12'
> lengths (unless that is a bad idea for some reason).  Do I start with 1.75" and 
> step
> down ending up with 1.25" on top?  Bigger/smaller?
>
> What about a guesstimate on the length, using tubing like this?  If a wire 
> dipole leg
> would be 61.25' (468 / 3.82MHz / 2), what would be a good starting length for 
> tubing?
>
> Also need an idea on making some sort of attachment point a little over halfway 
> up
> to attach some dacron "guys" for support.  Simple smallish eye-bolts?
> Should I be concerned about dacron getting wet and affecting SWR/performance?
>
> And what is the best way to attach the bottom of the antenna to a 4x4 post, 
> maintaining insulating properties from the post but yet very strong.  Perhaps
> grey PVC over the aluminum and some sort of bracket?  I'm having problems
> visualizing it...
>
> Dave N0RQ
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>  



_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk