Earl Andrews VE3AB - busy today Sept 21-08 building and working on my SHORT
VERTICAL ANTENNAS. I want to use a home brew short vertical antenna in my back yard
for 160, 80 and 40 meters (swl and Broadcast band listening as well!!!!)
--Testing the antennas is being done on my truck with a magnetic mount and on a tin
roof of my 10 by 10 shed. I hope to develop something that works well and I would
ideally like to invent a better short antenna. (perhaps a short vertical dipole..who
knows????)
I also like to listen to the LOW FREQUENCIES and broadcast band from time to time. I
want my antenna to be capable of being adjusted to those frequencies as well. A coil
loading system (adjustable)  for a short vertical antenna is what I will be working on.
I picked up some old Hustler coils (without the
windings) at a ham radio flea market several
years ago.

Here I took an old 80 meter resonator and
soldered on an airwound coil I had in my
junkbox. It resonates at around 5.5 mhz or so
with the hustler mast on my truck. A starting
point.
Here is the magnetic mount that I am
experimenting with.

Unfortunately..this assembly is giving me
problems. It seems to have some sort of
intermittent problem and I am going to rebuild it.

I used copper foil to surround a magnet and then I
homebrewed a circuit board on top for the
connections to the antenna and ground.

IT seems to work fine for awhile then the epoxy
heats up in the sun and the SWR goes crazy.

I may end up rebuilding it who knows..but I have
set it aside for that reason!
I found it resonated on about 5.6 mhz with my
hustler mast. I will have to do some work on it
either tapping it down to get it on 40 or adding a
top hat to get it near 80.
MY NEW AND IMPROVED
MAGNETIC MOUNT FOR MY
MOBILE STATION.
My target frequency for my mobile whip
was 3.755 mhz. This is a very popular
frequency for nets and is close to some
popular ragchew frequencies.

The Hustler whip (without the top hat)
was resonant around 3.860 mhz.

I put on this top hat (made of copper
plumbing strap). The resonant frequency
dropped way down below the 3.5 mhz!

More adjustments were necessary.
These short vertical antenna pages are currently being worked on (as is the antenna itself).

I want to develop a short efficient (small city lot friendly) antenna system for the low bands
without extensive ground radials and without unsightly wires in the sky.

click here to see page 2 of this presentation.
NOTE of caution!!

This big mechanical
assembly will be
safety strapped to the
vehicle.
early development work in the yard
This coil is around 75 uh.
To get an 8 ft whip on 75
meters you need 120 uh or
so. The ARRL handbook
has a chart for 8 ft long
vertical mobile antennas
and the inductances
required.  I have since,
used this coil at the base
of my HF2V vertical to get it
to resonate on 160. I
needed about 65 uh so I
tapped it. Worked well.
June 7 2010..I am updating these MOBILE
antenna pages.

This airwound coil has actually been set
aside for use with my Butternut HF2V
vertical.

It is the right inductance to make that
80/40 vertical to resonate on 160 meters
with this coil at the base of the antenna.
NOTE the homemade sliding top hat made with copper
plumbing strap.
june 2010 note: spring/summer
are antenna building times.

I am working on the short
vertical/mobile/portable
antenna(s) that I have and will
be updating and improving
these pages as I go along.
A capacity hat will lower the resonant frequency of the
antenna.

A movable capacity hat is what I am working at
developing.

It can tune an antenna perhaps even be motor driven
for remote tuning.

One fellow in Sault Ste Marie Ontario has a mobile
antenna with a sliding capacity hat for tuning. He had
his car at our picnic one year at the Elliot Lake Amateur
Radio club.
JUNE 2010 NOTE;

i AM WORKING ON THIS MAGNETIC
MOUNT CURRENTLY.

I am improving its LOOKS.

The 3 big springs have been taken
off.

I will post some pics when I get it
finished.