[TowerTalk] 80m 1/4wave vertical construction

[Jerry Muller]

Dave,

I constructed a four square for 80 out of tubing from Texas Towers. I 
used the 6 foot sections (UPS shippable) and constructed it with eleven 
6 foot pieces telescoping from the largest size they have. The overall 
vertical is 61 feet. My construction uses a 3 foot section of 2" 
electrical conduit at the base mounted to a 4 X 4 in a mailbox mount. A 
1/2 inch lag bolt makes the hinge. A second 1/2 inch lag bolt could be 
used to brace it, but I don't think it's really necessary. You'll need 
three sets of guys total. I also used three 10 foot pieces of DAVIS RF 
Flexweave as the first 10 feet of the top set of guys making a capacity 
hat. The top set of guys is two sections down from the top at about 50 feet.

I use four elevated radials 68 feet long constructed from #14 stranded 
wire from Home Depot (or was that Home Despot :-) ). The antenna as 
constructed direct feeds and covers the CW portion nicely. The best SWR 
is at 3.6 MHz. I add a series capacitor of 1000pf (be sure to use one 
rated for enough RF current) to put the antenna up into the phone band.

I used one of these last year in the ARRL DX SSB weekend for something 
like 267Qs in 67 countries. I now have four of them up in a four square. 
I can't wait to see how they do this year.

GL es 73, Jerry, K0TV

The man who brought you (or at least paid for) the Marchand decision....


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 at contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>