My first Moxon was a single band 30-meter Moxon,
in the spring of 2008 and it broke in the
summer of same year. For my construction I used
fishing rod 10 meters long, I used support aluminum
angle ( 2 mm) but it could not resist a summer’s
storm as you can see below:
and below the twisted remnants of Marco's original moxon.
last autumn, I decided, with the help of ik2bcp and
ik2ded, to build a new, more resistant moxon for 2 bands--
Easy….in less than 2 weeks, the moxon was on my
house roof, ready to set up. Nice bandwidth, nice
ROS, Nice FB in 30m. , less in 20 m. but antenna was
low (3 meter above roof) and not free from other tv
I supported the fishing rods by 2 iron TV pipes (3
meters long), Impossible to break or twist. I used only
half of fishing rod, so no need wire rods for fishing
Woot! Antenna was ready, but it was really too perfect…
in my opinion adding about 2 meters to rod, it should
be less resistant, more awry but works for the fantastic
40 M band…
This is the story…
- 4x 10 meter fishing rod (delta) removing last
- 2 TV antenna support pipe Galvanized iron, 3
- Copper wire PVC covered ( common electrical
civil installations) 1 mm Dia
- A piece of tv sat 75 ohm cable.
- Water pvc pipe (red) (support wire at centre
and system match) 3 meters
- Moxon software
First moxon resonance (for 30 meter in 2008) was
9.9 mhz using 10.100 mhz and 1 mm wire in the moxon
software. Maybe the wire I used produced an electrical
stretch, because antenna was too long .
So I decided to recalculate the two moxons 300khz
higher than the original center frequency.
Testing it on the roof during set up, the resonance
7.200 (1.4:1 Ros) [Ros means SWR]
10.280 (1.5:1 Ros)
But the antenna must lay above a 30 meters (100ft)
tower, last experience teach me that the resonance
decrease about 50 khz when put antenna a top of tower.
IK2DED with Moxon ready for assembly
on the 30 meter tower
Moxon installed on the tower top.
Rotor is a prosistel 3 D.
Connection two dipoles was made with short
75 ohm tv sat cable, so, we do not modify correct space
between each dipoles. I try to feed dual band with symmetrical line ( like
a spiderbeam feed) but I prefer coaxial 75 ohm because , in my opinion, is
better for the 40 meter tuning.
The finally ROS resonance result are:
- 7.000 - 1,2
- 7,130 – 1,1
- 7,200 – 1,8
- 10,100 – 2,1
- 10,150 - 1,9
- 10,230 -1,4
- 10,400 - 1,9
40 meters is great! F/b ratio is really about 30
db, low radiation angle and nice gain over dipole.
30 meters Fb not more of 15 db, low radiation
angle, gain over dipole, but not same performance like
40 meter… Maybe its resonance is too high, next spring
we will do fine set up.
The 30 meters tower is above a 700 meters hill, and
we have a nice drop till south-east to west direction,
perhaps the trick is that! But during autumn and winter,
EU season, we contact usa west coast daily via
long path, both 30 and 40 with only 100 w. and gets
nice reports from VK and ZL (about antipodes for Italy),
now 40 meter is open for the dx all day long…
is 30 meters high, (about 100 ft) from the ground, it
is above a hill, and in some directions ( south , east
and west ) there is a gradient ground, the antenna in
south east ( w6 Long path) looks more then 40 or 50
Ciao de ik2clb Marco
Brescia North Italy.