Thanks. I appreciate the suggestion, but I have built the antenna you
described, using welding rod, plus a 440 MHz (smaller version), but in a
crowded room the radials stick out farther than I want. I tried building a
TV antenna line J-Pole today, but the SWR was higher than I expected. I
haven't tried shortening it yet, but will when I get time. But I would
still have to find some way to hang it from the ceiling or something. I
really want something small, unobtrusive and cheap and easy to build.

"RST Engineering" wrote in message
...
You are not asking for the moon. What you want is a simple, compact,
reliable antenna for both 144 and 440 MHz.. Having done a fair amount of
that sort of RACES/ARES stuff, here's what I'd advise you.

Go down to your local radio parts store, Rat Shack if that's all you've
got and get yourself a female BNC chassis connector (UG-1094, RS #
278-105). Get a couple of quality male BNC cable connectors while you are
at it. Unfortunately for you, RS doesn't sell anything but that twist-on
solderless crap for male BNC, so you may wind up buying them mail order.

Get yourself four 3/8" solder lugs and five 19" pieces of solid #14 copper
wire (strip house romex if you have to).

To each of the four solder lugs, solder one end of the #14 wire. These
will be the four ground plane wires. THe fifth piece of #14 will connect
to the solder cup on the bottom of the female BNC chassis connector to
become the radiating element.

Now put those four solder lugs over the radiating element and over the
threads on the connector. Use the nut that came with the connector to
fasten the solder lugs, each at approximately 90° from each other (a small
crescent wrench or dedicated 1/2" wrench needs to be part of your
permanent tool kit). Bend them down at about a 45° angle.

Take the two male connectors and make an RG-58 cable to run from your
radio to where you want to put your antenna. Connect one end of the cable
to your radio and the other end to the UG-1094 connector.

You want to move the antenna? Disconnect the cable. Grab your wrench and
pull that nut off. Take off all 4 ground plane wires. Bundle them up
around the radiating element. Reassemble in the new location. Ten
seconds up, ten seconds down.

You want to use it in the field outside? Bend a small hook (no more than
1/4" long) in the radiating element. Tie a roll of heavy twine to the
hook and bend the hook shut. Take the roll of twine and throw it around
the highest tree limb you can find. Hoist that sucker up and you are on
the air.

We can dick around with a mounting bracket on the UG-1094 threads if you
want to make a permanent installation out of it.

(By the way, you are operating close enough to the third harmonic of 144
on 440 that the antenna will perform quite well on both frequencies.)

Jim









"Chuck James" wrote in message
t...
I know I could just go buy a mag-mount mobile antenna, but would it be
possible or even practical to build a J-pole type or vertical (without
long radials) antenna for 2m/70cm, out of welding rod, which could be
small enough to be easily portable and used inside different rooms? Our
local RACES is trying to set up a volunteer communications network inside
several different city and county offices to assist in emergencies. I
have searched (a little) for such a design, and found something similar,
made out of TV line, but would prefer something that could be made free
standing and as small as practical. The Welding Rod antennas made with 45
degree radials are a little bulky to move through congested hallways. The
idea is to make it portable enough to move from room to room as needed.
Long radials would impede moving through hallways.
Thanks in advance, KE5GEO

I'm sure you know what you want, and I'm sure you have all the lab equipment
necessary to calculate VSWR on an antenna inside a conductive structure.
I'm also sure you have built antennas for emergency and portable use for
fifty years, so you are on your own so far as I'm concerned.

Cheap, easy, small. Pick two.

Best of luck; write if you get work.

Jim



"Chuck James" wrote in message
. net...
Thanks. I appreciate the suggestion, but I have built the antenna you
described, using welding rod, plus a 440 MHz (smaller version), but in a
crowded room the radials stick out farther than I want. I tried building
a TV antenna line J-Pole today, but the SWR was higher than I expected. I
haven't tried shortening it yet, but will when I get time. But I would
still have to find some way to hang it from the ceiling or something. I
really want something small, unobtrusive and cheap and easy to
build.standing and as small as practical. The Welding Rod antennas
made with 45
degree radials are a little bulky to move through congested hallways.
The idea is to make it portable enough to move from room to room as
needed. Long radials would impede moving through hallways.
Thanks in advance, KE5GEO

One of the other posters in this thread gave me the solution to my quest,
and it was cheap, easy, small, and less than 1.3 SWR. It was a simple
dipole, made of a wooden block and welding rod. I took a piece of 3/4 inch
wood dowel, cut it to about 4 inches in length, drilled one hole in each end
(lengthwise). I left about 1/2 inch of wood between the holes I drilled, so
the welding rods would not touch. I inserted a 19 inch piece of welding rod
in each end. The overall length is about 38 and 1/2 inches. Then, in the
center of the dowel, I drilled two intersecting holes so that I could put
screws into the wood which would press against each piece of welding rod.
This kept the welding rods in place, and it also gave me a place to attach
the center wire and braid from an RG-58U Coax cable. I soldered two small
alligator clips, on the coax, so that I could just clip the coax to the
antenna. To take it apart, or put it together, all I need is a phillips
screwdriver.

I'd like to thank everyone for their help, in pointing me in the right
direction!

"RST Engineering" wrote in message
...
I'm sure you know what you want, and I'm sure you have all the lab
equipment necessary to calculate VSWR on an antenna inside a conductive
structure. I'm also sure you have built antennas for emergency and
portable use for fifty years, so you are on your own so far as I'm
concerned.

Cheap, easy, small. Pick two.

Best of luck; write if you get work.

Jim



"Chuck James" wrote in message
. net...
Thanks. I appreciate the suggestion, but I have built the antenna you
described, using welding rod, plus a 440 MHz (smaller version), but in a
crowded room the radials stick out farther than I want. I tried building
a TV antenna line J-Pole today, but the SWR was higher than I expected.
I haven't tried shortening it yet, but will when I get time. But I would
still have to find some way to hang it from the ceiling or something. I
really want something small, unobtrusive and cheap and easy to
build.standing and as small as practical. The Welding Rod antennas
made with 45
degree radials are a little bulky to move through congested hallways.
The idea is to make it portable enough to move from room to room as
needed. Long radials would impede moving through hallways.
Thanks in advance, KE5GEO