Spider
Antenna
Project Using
Ham
Sticks
Eugene
Bradeen, KX1C
This
project came about after seeing an advertisement for a multi-band
antenna made from ham sticks. There are several on the market, from
MFJ and Chameleon, among others. The antenna looks like a spider when
all four bands are installed. Presently, I have only three bands
installed, 6M, 10M, and 20M. On the Chameleon website they had a
decent picture of the internal construction, along with the name of
the company making the octagon box. I ordered a box from Newark. The
ham stick mounts, 3/8-24 thread, were ordered from Quicksilver Radio.
A chassis mount SO-239 connector is also needed. A parts list with
sources is shown below.
The
box that I purchased is 5 inches across by 1 ½ inches deep. I
drilled holes that were centered in height and symmetrically located
round the perimeter. Four of the mounts are wired together and go to
the center pin of the SO-239. The other four are wired together and
connected to the chassis. I flattened the ends of the ring adapters
that came with the mounts to make a wider spot to solder the #12
wire.
I
offset the chassis mount SO-239, so that there was room for the mast
mount and for tightening the PL-259. Also, a small hole was added to
let moisture out, since the box is not waterproof.
The
mast mount was made from a piece of bent scrap stainless steel, 3”
X 8 ½”. Holes were drilled to attach the mount on the box,
allowing clearance for the SO-239 connector and centering the mast on
the box to balance the antenna. I drilled two sets of holes in the
mount for use with two different sizes of masts. Stepped drill bits
worked great. Drilling the holes left a little rough edge. Just a
touch more with the bit cleaned up the edges with a slight chamfer!
Two
ham sticks are required for each band you want to use. They are
mounted in a dipole configuration directly opposite from each other.
I put the 10M sticks perpendicular to the 20M ones and the 6M set in
between. The antenna balances quite well in this configuration.
Tuning
the ham sticks takes a little patience. I started with 20M and
adjusted to less than 2:1 SWR. I found the 10M and 6M ones interacted
a little. More patience. Tuning back and forth between them got the
SWR to around 1.7:1. The auto tuner will take care of the rest.
Using
my KX3/KPA100 running at 70 watts on 20M, I made a contact in
Maryland. He gave me a 5/4 signal report. Not bad for having the
antenna on a 12 foot mast mounted on the back deck!
Watch
where you put the antenna. The close proximity to my Davis anemometer
caused RFI to give me a high wind speed of 92MPH! Oops…
I
think the antenna went together fairly easily. It will be good for
portable use, camping, SOTA, or just about anywhere you go.
Parts
List:
3/8-24
Antenna mount w/ring lugs Qty. 8, Purchased from www.qsradio.com
Newark
P/N 61T5010, Octagon Die cast box, Mfg. Hammond, P/N 1590STPC
Purchased from www.newark.com.
Waterproof version P/N 1590WSTPC
SO-239
Chassis mount w/hardware
#12
wire – 12”-14”
Ham
Sticks 2 for each band. Purchased from www.qsradio.com
Hardware
for mounting to mast, L-bracket with U-bolts or pipe flange.