DXE Catalog is the “Erector Set” for Antennas
DX Engineering makes it fun to prototype antenna ideas with their parts.
They deal with aluminum tubing in a big way. I love my 43 foot antenna from them. It was a natural
first place to go for a supply of antenna components.
Pleased with my experience using the Resin Support Blocks for my Hex Beam and TV Antenna, I
made sure to consider them for this project.
DX Engineering also sells rectangular plates for use in the junction points of beam antenna elements
and boom. Thinking their small version was 1/4 inch aluminum plate, I added that to my wish list.
After some time with simulations and with their web catalog handy, I came up with this design…
Figure 1 – Asymmetrical Hatted Dipole Antenna
KX4O-000049.pdf
Full size prints available.
Contact kx4o@hamradio.me for details.
Brand new parts for this antenna assembly, including the $50 speaker stand, will set you back about
$250… more than a little, less than a lot. Those with existing aluminum stock can likely reduce
cost.
Tripod for the Portable HF Antenna
One major premise of this design is the use of a commercial speaker stand from the music/sound
reinforcement industry. A tripod with its various angles, stress points, etc. is not an easy thing to
design and make. You don’t have to because the music industry offers quite an assortment of sturdy
models. Speakers are heavy things so these speaker stands already include engineering to make
them plenty strong enough for this lightweight aluminum antenna. A speaker stand was a
“nobrainer” for this project. Fortunately, I still have a couple stands from the “rock band” days.
With the prototype design more or less complete I made an order to DX Engineering and dug out
my speaker stand. This stand, by the way, is the same make and model used in the Hoverman
“Superbowl” TV Antenna.
Many speaker stands have 1-3/8 inch (~35mm) masts plus an optional plastic sleeve to
accommodate speakers with 1-1/2 inch (~38mm) sockets. The key feature of my stand is the unique
reversible upper section. This is 1-1/2 inches diameter for most of the length with one end narrowed
to 1-3/8 for about 6 inches. This allows the stand to interface with either size speaker socket simply
by flipping this upper shaft over. This is a big advantage for us because it provides a nice long 1.5
inch mast to interface with the rest of the antenna. Here is a link to the manufacturer of this stand…
Manufacturer information on SS7761B Speaker Stand
Other nice features of this stand are adjustable height, up to 80 inches, and a locking pin to secure
the mast. The antenna’s weight is much less than most speakers so you can rest assured the locking
pin isn’t really necessary, but is there for the cautious. The adjustable height is a great feature to
have for any antenna.
Shop around. Despite the news to the contrary, the economy is not in good shape and the various
music equipment suppliers are in savage competition for your dollar. Amazon reveals this quite
well…
On Stage SS7761B Music People SS7761B Tripod Speaker Stand
You should be able to get this stand for a very good price and with little to no shipping costs.
Note, the On Stage stand is made of aluminum and will resist corrosion. However, the small
hardware parts are steel and will quickly rust outside. You can replace the parts with stainless steel
or coat them with something like oil, WD40 or maybe paint. I am eager to hear how others handle
this.
Parts arrival day
When the DX Engineering order arrived I opened the package to find aluminum tubes, resin support
blocks and one rectangular plate. I was very interested in the plate so I picked it up first. Wow light.
Wait… this wasn’t aluminum. It’s a piece of black plastic.
Oops… in my haste I did not read the description on DX Engineering’s web site closely. Sure
enough I ordered a plastic plate. However, it was 1/4 inch thick and seems quite sturdy. After some
thought I decided to use it as the back bone of the antenna. Here is the drill drawing to convert this
piece for use with this antenna design…
Figure 2 – Vertical Dipole Antenna Support Plate
KX4O-000050.pdf
Thinking it was 1/4 inch aluminum I was prepared for quite a drilling task. I even purchased a
special bit.
It all turned out reasonably well. Let’s have a look…
Portable HF Antenna Prototype in Driveway
The driveway became my test area.
Figure 3 – Asymmetrical Hatted Dipole Protoype
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