A Home
Brew HF Vertical From Copper Pipe
by John Reisenauer Jr., KL7JR/KL7USI
Use it portable or for fixed station operation!
Interchange lengths for 5 band HF fun in the Wild!
In my younger days on portable
island activating adventures, I used a homebrew multi-banded quarter-wave
vertical antenna that was easy to assemble and disassemble and didn't take up a
lot of space in my canoe.
The antenna was not only lightweight, but cheap and easy to construct, (I
didn't want to lose any more expensive ham gear the next time I'd tip my canoe
over!).
I'm still using this antenna over a decade later, and I sure have logged a lot
of DX from all over the lower 48, Alaska and Canada with it! It's great for
portable use or set it up for permanent station operation.
BILL OF
MATERIALS 1- 10'
length 1/2" copper pipe (top section)
1- 10' length 3/4 inch copper
pipe (base)
1- 3/4" male sweat fitting
threaded
1- 3/4" female sweat fitting
threaded
1- 3/4" by 1/2"
reducing coupling threaded
1- 1/2" male sweat fitting
threaded
1- 1/2" female sweat fitting
threaded
70' #14 or #16 wire (ground
radials) and various nuts, bolts and clamps from the junk box
Below is a simple drawing of the 20 meter version:
CONSTRUCTION:
Now cut both pipe sections in
half and solder the appropriate fittings on. (5 foot sections
makes for easy portability)
Total cost around $25.00 and two
hours to build.
If you've never soldered copper
tubing before, perhaps a little help from someone who has; would be nice.
Pipe lengths plus appropriate tip
= band of your choice:
PIPE
LENGTHS TIP
LENGTH BAND
3 @ 5 feet*
18
inches
14 MHz
See note
2 @ 5
feet 36
inches
18 MHz
2 @ 5
feet
12 inches
21 MHz
2 @ 5
feet
none
24 MHz
2 @ 5
feet
none
28 MHz
NOTE: * 2 @ 3/4" and 1 @ 1/2". Use the two
3/4" sections of pipe for the other bands. )
The same ground radials were used
on all bands.
I used 5 foot lengths only because it packed well in my truck and
canoe. You may want to use shorter or longer lengths depending on your
situation (ie- instead of one 5 foot length, perhaps
you want to go to a more transportable length of 2 at 30 inches long).
To secure the antenna I built an "H frame" structure from 2"
PVC pipe and used 1" PVC for the riser. The H frame breaks down to two
pieces for transporting.
You'll need to isolate the antenna from ground. A piece of PVC pipe stuck
in the ground would work too but many islands that I want to activate back
home are mostly giant rocks.
I used a 3" long piece of scrap 1/2" PVC glued inside the T fitting
of the riser.
The antenna sits on this piece to maintain the 3" distance from ground.
Cut a 1 inch square hole in the riser and on the bottom section of the copper
pipe (the one without a fitting on one end) to accept the coax connection.
For a great photo of the H frame base, see the most interesting ham website
of N0LX www.n0lx.com- click in "antennas" category
for "Mini Antenna
Mast and PVC base" and in "Portable" category
"Islands of Colorado"
for a heavier duty version photo).
I used heavy duty alligator clamps for both the center coax and braid connection.
Since I operate mainly on 20meters, I cut four lengths of wire at 16.5 feet
long (1/4 wavelength formula 234 divided by Freq. in MHz) out of #14 insulated
wire.
Then bare one end and tie all four together. I used a 1/4" bolt with
a couple nuts and washers as the connector.
The alligator clamp on the coax braid clips easily on the 1/4" nut as
does the clamp on the center conductor of the coax to the pipe.
I keep the ground radials permanently attached to the PVC H frame with ty-raps and when transporting, I simply coil the wires and
stuff in each PVC leg.
When I'm set up, I simply throw out the radials in each direction. I put as
many in the water as I can. I'm sure it helps cut down on the "noise"
verticals are known for.
Additional tips and notes:
I highly recommend using a tuner with this antenna since background and ground
conditions affect SWR and will differ from set up locations and the 24 and
28 MHz lengths are a bit long "electrically speaking".
You may want to cut tips of the correct lengths for 10 and 12 meters.
Also, very important, do not use a wrench to tighten the pipe sections as
it's easy to strip the pipe threads! (I only had to do that once!). Hand tighten the copper pipe sections only.
I can honestly admit this antenna is easy to tune on many bands, is not noisy
and works DX! 73 and happy hunting! John Reisenauer Jr., KL7JR/KL7USI