View Single Post
  #10   Report Post  
Old April 26th 06, 08:46 AM posted to rec.radio.amateur.antenna
 
Posts: n/a
Default mobile loading coils

There are quite a few ways you can match them. You can use a
coil at the feedpoint, IE: like the "dollar special" matcher in the
handbooks, or you can use an L tuner, or sometimes just a cap alone.
A few turns of the loading coil can be applied as part of the matching
too
if needed. Most of the "stick" antennas have the matching coil wound
at the base of the antenna. Most any old tuner would match it. Even a
cheap random wire tuner would work fine. You just reverse the
connections
for low Z use if you need to.
With the 6 ft stick I have, I put the coil at the top, and then added 5
ft of
stinger on top of the stick. So it came out center loaded, being the
coil
is a few inches long. The first one I built had the coil about 2.5 ft
above
the base. I still use it on the truck when I'm whacking a lot of low
trees.
I use the tall coil version when I more out in the clear. On my play
truck,
the mount is up on the cab at 64 inches from the ground. I hit trees a
plenty,
but have never hurt one of the antennas yet. The stinger just bounces
off
most of the time, and if I do hit the glass part, it just bends and
snaps
back. I don't use a spring. On the higher HF bands, even a loaded
antenna will still work real well. Even most hamsticks unmodified
will do ok. Both mine use fairly large coils. About 2.5 -3 inches
dia...
So electrically, about the same as a bugcatcher as far as performance
without all that heavy weight that the average bugcatcher entails.
I use the 3 ft mast at the base when parked, and on the low bands.
The coil is nearly 8 ft above the cab and the tip of the antenna at
about
19 ft. Kicks butt, even on 80m..
MK