A 500 watt tactical HF vertical antenna system
An interesting assortment of military suplus gear mixed with a bit of ingenuity can go a long way.
I've had a Shakespeare AT-1011 antenna (or two) for quite a while. I've had various Harris remote antenna couplers for quite a while. It seemed like the two were meant for each other and, in fact, they are commonly used together by our field troops - primarily as mobile setups.
But, what I wanted was a means to quickly deploy a portable antenna system that could take 500 or more watts with good efficiency over most of the HF spectrum. The key word being "quickly".
I didn't need back-pack portability; there are other solutions for that problem. But, I needed something that one ordinary guy, a guy like me, could easily put up in a short amount of time.
So, one of my Ham Radio buddies, David McGinnis (K7UXO), and I got together and started working the problem. What we came up with fit the bill perfectly!
Before I go on for hours, blathering about how cool this thing is, let's have a look. A picture is worth considerably more than my blathering..
The picture shows what it's like to do Field Day in Montana! That's I-90 a few thousand feet below. But, the point of all this is the antenna system over there on the right side of the picture. It's hard to see due to the flora and all the green CARC paint but what you're looking at is a really beefy tripod, a Harris RF-382 remote antenna coupler and the bottom of a Shakespeare AT-1011 32' vertical antenna. I guess I need a wide angle lense to show the antenna itself.
Here's a picture that shows the antenna better. In fact, there are two of these setups in this pic. One in the foreground and another off to the right, on top of the generator building. (Yes, we had permission from the site manager for such shenanigans.)
There wasn't much of a breeze at the moment that picture was taken even though we were at 7,014 feet above sea level. So, the antennas sort of disappear up into the Big Sky.
Here's what the AT-1011 looks like with a fresh, mountaintop breeze. It just bends over in a very graceful manner and comes back to vertical when the breeze dies down. It's a very pretty sight!
So, what keeps the antenna upright? What keeps it from blowing over? That, dear reader, is what this article is all about.
Here is an overview that shows (from front to back) a bagged AT1011 antenna, a mount plate for the RF-382 antenna coupler and the components for a tripod upon which the entire assembly will rest.
The key to this whole thing is the tripod iteslf. It is made up of a tripod adapter (available from this guy on ebay) and three legs which are standard aluminum military surplus four foot mast sections (also commonly available on ebay). A fourth mast pole is used to couple the coupler / antenna mounting plate to the tripod.
As they say in American Football, here's the "reverse angle" view.
It's all lightweight aluminum and trivial for an ordinary guy, such as myself, to carry the thing around. At least in it's broken down state as shown here. The coupler / antenna mount plate is 1/2" thick aluminum plate although a thinner piece of stock would be fine -- it's just what I had in hand on the day I decided to build this thing. At the top of the plate is a "sugar scoop" antenna mount off a HMMWV. On top of that is the base for the AT-1011 and a RF-1980-AT001 Tilt Whip Adapter both of which are generally available from this guy on ebay.
The first step is to insert the three legs into the tripod adaptor. That takes about 30 seconds and a decidely non-herculean effort.
The next step is to drop the coupler / antenna mount plate into the vertical hole in the tripod adaptor. Usually, the RF-382 is already mounted to the plate for this operation. Which is still an easy enough thing for one ordinary guy to accomplish on his own.
The next steps would be to assemble the AT-1011 and mount it to the tilt over adapter that is already mounted to the mount plate.
Oh, yes, please notice the 3/4" braid hanging down from the mount plate. That attaches to both the mount plate and to the RF-382 ground terminal. I always drive a metal ground stake into the ground directly under the center of the tripod. I attach the braid to that ground stake which gives the antenna extreme stability. Pulling straight down from the center of the tripod to a good anchor makes this thing stand up in even harsh weather. And, the braid makes for a very convenient place to clip on radials!
Above you can see the 30 radials I typically deploy. They're 33 feet long and have a big alligator clip on one end and a 3" diameter PVC spool on the other. To deploy I clip the aligator clip onto the braid and toss the spool off into the weeds. It's easy, quick and 30 radials is enough to be pretty effective.
So, that's it in a nutshell. Here are some more pictures with various detailed views. There's not much more to say - if you have questions just shoot me an email.
I've run this antenna system during Field Day for the past five years with great success. If you've worked the Field Day CW op at either K7UXO or W7KF you were hearing this antenna.
It's simple, it works and it serves me well. I love this thing!