On Feb 28, 8:58*pm, Mike Coslo wrote:
On Thu, 28 Feb 2008 09:18:53 -0800,DVoeltzwrote:
I'm new to this and need your help in selecting which antennas to use on
my railroad motorcars.

How doggone cool! I saw a group of cars going through the bald eagle
valley in central PA last fall. I didn't know there was a big organized
group.

The radio will be moved between two pieces of equipment. *One cab has a
flat metal roof and the other has a fiberglass cab. *I would like an
antennathat I can unscrew from the cab when traveling the equipment
down the road on a trailer. *The radio will be using the NARCOA licensed
frequency of 151.625 MHz. I understand that this frequency is in what is
known as the VHF-High Land Mobile Radio (LMR) Service band, and uses a
modulation known as narrow band (5 kHz deviation) FM. *I will be using a
Vertex FLT 2011 40 Watt radio.

Based on the little I know about this, I understand a specialantenna
will be needed for the fiberglass cab since there is no ground plane.
Bothantennawill be mounted directly to the roof through a hole. *The
radio will be mount within 2 feet of where this hole will be drilled so
I only need a short wire to connect from theantennato the back of the
radio.

*Ideally there would be a ground plane for both, but it seems that mostantennamounts of the mag mount variety are getting their ground from the
electrical system, then the body of the car. If the whole body is
fiberglass, you could run some wires to use as ground plane under or on
top of the roof. They won't be very long.

You might want to get anantennathat has a removeable mast so that you
can just unscrew theantennaand leave the coax cable in place. If the
whole thing has to go with the car, you'll probably want a clamp on.

re you averse to building your ownantenna? a 1/4 wave ground plane would
work very well, is easy to construct if you have some soldering skills,
and is very inexpensive. Rough details are that it would take around
18.and a half inch wire for the vertical section, and 4 wires of that
length for the radials.

If you are interested in that route, let me know and we can fill you in
on the details.

To see pictures of what this equipment is, go to:

www.narcoa.org

where does one get hild of one of those cars?

--
-73 de Mike N3LI -

Mike, I would like more details on building the antennas. I have the
skill to do so.

These speeders are getting hard to find but if you look under the for
sale link on www.narcoa.com you will see where some are for sale from
time to time. They could be purchased for $300 20 years ago, now the
same car costs $3,000. Wished I would have bought a 100 of them :-)

Thanks!

Dave in Pierre, SD