Welding Rod J-Pole Possible?
 

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

Welding Rod J-Pole Possible?
 

Chuck James wrote:
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



There are mny plans available on the Internet for free standing
J-poles made out of 1/2 -3/4 inch copper tubing.

Good luck, jimbo

Welding Rod J-Pole Possible?
 

On Thu, 28 Dec 2006 10:03:31 GMT, "Chuck James"
wrote:

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


You might get some design ideas looking at the j-poles at
http://www.arrowantennas.com/

I personally have a j-pole made from a small length of 450-ohm line,
which could be made self-supporting with a wood dowel and stand.

Lotta ways to do this...

bob
k5qwg

Welding Rod J-Pole Possible?
 

Chuck James wrote:
...


Why not just through together a 1/2~ monopole with a simple gamma match
and 1:1 current balun?

Regards,
JS

Welding Rod J-Pole Possible?
 

"Bob Miller" wrote in message
...
On Thu, 28 Dec 2006 10:03:31 GMT, "Chuck James"
wrote:

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


You might get some design ideas looking at the j-poles at
http://www.arrowantennas.com/

I personally have a j-pole made from a small length of 450-ohm line,
which could be made self-supporting with a wood dowel and stand.

Lotta ways to do this...

bob
k5qwg

Agree. I have made copper pipe j-poles for 50,144, 220 & 440 bands. They
match well; sometimes I can hit 1:1 at the sweet spot. They are virtually
indestructable and very cheap. Gonna do one for 10M next. (It'll be about
24 feet tall and will likely need guy ropes.)

Welding Rod J-Pole Possible?
 

Any instructions on just how to do that? I'm relatively new to this hobby.

"John Smith I" wrote in message
...
Chuck James wrote:
...

Why not just through together a 1/2~ monopole with a simple gamma match
and 1:1 current balun?

Regards,
JS

Welding Rod J-Pole Possible?
 

Chuck James wrote:
...

Chuck:

I have been tearing apart this place. About a year ago I had
constructed one for 10 meters and had all my notes, etc. Now can't find
a thing.

This link:
http://www.cebik.com/trans/gamma.html

will show you details of a gamma match. It is being used on a dipole
element. Basically, you just use the top half of the element, the half
with the gamma match. Just below the gamma match, you chuck in a 1:1
current balun to choke off the rf which might go to the outside of the coax.

A counterpoise of wire, cut to 1/2 wave at the center freq. of the band
can be attached to the outside of the coax (or coax connector) at the
antenna.

The monopole radiator is a simple 1/2 wave and the length can be
computed from the standard formula: 5904/(frequency in mhz) = length.

The link above contains a basic program to compute the gamma match
dimensions. You should be able to tear the formulas out of the text and
use them manually.

I will see if I can't find the material on dimensions, etc. I had put
together here, still looking.

Regards,
JS

Welding Rod J-Pole Possible?
 

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

Welding Rod J-Pole Possible?
 

RST Engineering wrote:
(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.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.
--
73, Cecil http://www.w5dxp.com

Welding Rod J-Pole Possible?
 

And I did not mean to imply that you couldn't use brazing (not welding) rod,
which is nothing but brass and a little more to make the elements. IT
certainly makes a STIFFER antenna, but copper wire is a lot easier to work
with.

Jim



"Cecil Moore" wrote in message
et...
RST Engineering wrote:
(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.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.
--
73, Cecil http://www.w5dxp.com

Welding Rod J-Pole Possible?
 

Cecil Moore wrote:
RST Engineering wrote:
(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.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.

Hmmm. In some cases, would be nice to keep more of that signal terrestrial.

Regards,
JS

Welding Rod J-Pole Possible?
 

That's why you bend the radials down at a 45. It bends the pattern right
along with it.

Jim



"John Smith I" wrote in message
...


Hmmm. In some cases, would be nice to keep more of that signal
terrestrial.

Regards,
JS

Welding Rod J-Pole Possible?
 

John Smith I wrote:
Cecil Moore wrote:
RST Engineering wrote:
(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.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.

Hmmm. In some cases, would be nice to keep more of that signal
terrestrial.

That's the subtle point I was trying to make. To keep
the TOA low, the antenna should not exceed 5/8 WL.
6/8 WL raises the TOA. That's not optimum for hitting
repeaters unless they are on very high, very close
mountains.
--
73, Cecil http://www.w5dxp.com

Welding Rod J-Pole Possible?
 

Cecil Moore wrote:
...
That's the subtle point I was trying to make. To keep
the TOA low, the antenna should not exceed 5/8 WL.
6/8 WL raises the TOA. That's not optimum for hitting
repeaters unless they are on very high, very close
mountains.

Cecil:

OK. No problem, subtle is all yours ...

But, remember, I get sarcastic and blunt! evil grin

Regards,
JS

Welding Rod J-Pole Possible?
 

Jim wrote:
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

I agree -- Chuck isn't looking to work big DX so, a complicated antenna is
not needed. Another simple concept is a vertical dipole. Here's an
illustration from "Simple, Low Cost Wire Antennas for Radio Amateurs", by
William I. Orr and Stuart D. Cowan: http://tinyurl.com/yzydbo
The bottom section connects to the shield of the feedline. If made from
tubing, it will act to decouple the outer surface of the shield. If cut for
144-148MHz (38-39" overall length), it will work at 432-444MHz as well. To
make it portable, use stiff wire (welding rod, etc) for the top half, and
schedule-40 ½" copper tubing for the bottom half. An insulated coupling can
be fashioned from wood or plastic dowel or plastic pipe. More dowel or
plastic pipe can be used as a carring handle. Like the ground plane, it can
be suspended from an overhead support. It can also be slipped into/onto a
baseplate if you don't have an overhead support available: nonmetallic
umbrella stand, heavy flower vase, etc. With the exception of the feedline,
your home improvement box store will have all the parts you need.

Bryan WA7PRC

Welding Rod J-Pole Possible?
 

Bryan wrote:
...


You remind me. I have built those antennas, long ago, in the past for
10M+ bands.

If I remember correctly they were termed "bazooka antennas." I kind of
remember there was a recommended ratio of coax shield dia. to inside
diameter of the sleeve--possibly the ratio of the radiating element
figured into securing a 50/75 ohm match also?

You have any more data on that antenna?

Warmest regards,
JS

Welding Rod J-Pole Possible?
 

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

Welding Rod J-Pole Possible?
 

This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

"Bryan" wrote in message
...
Jim wrote:
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

I agree -- Chuck isn't looking to work big DX so, a complicated antenna is
not needed. Another simple concept is a vertical dipole. Here's an
illustration from "Simple, Low Cost Wire Antennas for Radio Amateurs", by
William I. Orr and Stuart D. Cowan: http://tinyurl.com/yzydbo
The bottom section connects to the shield of the feedline. If made from
tubing, it will act to decouple the outer surface of the shield. If cut
for
144-148MHz (38-39" overall length), it will work at 432-444MHz as well. To
make it portable, use stiff wire (welding rod, etc) for the top half, and
schedule-40 ½" copper tubing for the bottom half. An insulated coupling
can
be fashioned from wood or plastic dowel or plastic pipe. More dowel or
plastic pipe can be used as a carring handle. Like the ground plane, it
can
be suspended from an overhead support. It can also be slipped into/onto a
baseplate if you don't have an overhead support available: nonmetallic
umbrella stand, heavy flower vase, etc. With the exception of the
feedline,
your home improvement box store will have all the parts you need.

Bryan WA7PRC

Welding Rod J-Pole Possible?
 

John Smith wrote:
Bryan wrote:
...


You remind me. I have built those antennas, long ago, in the past for
10M+ bands.

If I remember correctly they were termed "bazooka antennas." I kind of
remember there was a recommended ratio of coax shield dia. to inside
diameter of the sleeve--possibly the ratio of the radiating element
figured into securing a 50/75 ohm match also?

You have any more data on that antenna?

Warmest regards,
JS

Hi John,

I found the image he http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up. There're more links to bazooka antennas he
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative.

73,
Bryan WA7PRC

Welding Rod J-Pole Possible?
 

Chuck James wrote:
This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

Hi Chuck,

I found the image he http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up -- not much more info available on that page. It's
basically a dipole turned vertical. With the feedline going thru the bottom
half and connecting at the top of that section, it becomes a "bazooka"
vertical.

There're more links to bazooka antennas he
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative. I don't think you'd need to use RG-8 as described -- just about
any 50-ohm feedline would work fine.

73,
Bryan WA7PRC

Welding Rod J-Pole Possible?
 

Bull****. It is NOT a bazooka, it is a simple ground plane with bent over
rods.

STOP TRYING TO CONFUSE THE GUY. It is a simple ground plane with removable
radials. STOP POSTING ABOUT THE STUPID BAZOOKA.

Jim




"Bryan" wrote in message
...
Chuck James wrote:
This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

Hi Chuck,

I found the image he
http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up -- not much more info available on that page. It's
basically a dipole turned vertical. With the feedline going thru the
bottom
half and connecting at the top of that section, it becomes a "bazooka"
vertical.

Welding Rod J-Pole Possible?
 

Jesus Christ, I give you step by step directions with part numbers and parts
sources and you can't figure out how to do it.

Go away. Just go away.

Jim




"Chuck James" wrote in message
. net...
This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

Welding Rod J-Pole Possible?
 

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

Welding Rod J-Pole Possible?
 

RST Engineering wrote:
...

For years now I have had an alarm on the wall of the shack; its' meter
needle has never moved.

I built it for an old-old magazine article issued on April 1 of some
past year, written by a Dr. Kuku I believe.

I surely thought I must have made an error in its' construction, as,
like I say, the meter needle has NEVER moved.

But, darn it, when I opened up your post--the damn meter needle went
clear off scale!

Darn ku-ku meter works!!!

JS

Welding Rod J-Pole Possible?
 

Jim exclaimed:
Bull----. It is NOT a bazooka, it is a simple ground plane with bent over
rods.

STOP TRYING TO CONFUSE THE GUY. It is a simple ground plane with
removable
radials. STOP POSTING ABOUT THE STUPID BAZOOKA.

Jim

Jim:

Alright, it's not a bazooka; it's a decoupling sleeve (thank you for the
enlightenment). Semantics aside, it will do what the OP wishes it to, and
in a physical representation that will work within his constraints.

Regards,
Bryan

Welding Rod J-Pole Possible?
 

Jim demanded:
STOP POSTING ABOUT...
Jim

Jim:

AFIK, usenet is open to anyone to post anything that does not transcend
legal limits, and I have not come anywhere close to that limit. Until I
cross that line, you (or anyone) is welcome to challenge anything I may post
in a *non-confrontational* manner.

Regards,
Bryan WA7PRC

Welding Rod J-Pole Possible?
 

"Cecil Moore" wrote in message
t...
John Smith I wrote:
Cecil Moore wrote:
RST Engineering wrote:
(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.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.

Hmmm. In some cases, would be nice to keep more of that signal
terrestrial.

That's the subtle point I was trying to make. To keep
the TOA low, the antenna should not exceed 5/8 WL.
6/8 WL raises the TOA. That's not optimum for hitting
repeaters unless they are on very high, very close
mountains.
--
73, Cecil http://www.w5dxp.com

Yup, the peak of the main lobe is elevated. ... but my 144 copper pipe
j-pole does put sufficient 440 energy toward the horizon that I am often
able to hit a repeater more than 70 miles away (Santiago Peak in Orange
County CA from southern San Diego County). Power out is around 4 watts from
a Yaesu FT-530.

Just now I tried Santiago and didn't hear back, so I tried 449.08 on Palomar
Mountain, 45 miles away, with a half watt and bought it up. Antenna is only
20 ft above ground; house is around 510 ft above sea level on a small rise.

Welding Rod J-Pole Possible?
 

"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



Yes you should be able to build one out of welding rod. I built mine out of
brazing rod and an N connector. It is an open stub design where the bottom
end of the matching section is open instead of shorted like most designs and
is fed from the bottom. 3/4 wl part is connected directly to the center pin
of an N connecter, short side is connected to the outside of the N
connector. Seems to work OK but it got to be a real pain and probably a
saftey hazard "put your eye out kid". Finally made an in-door antenna
modeled after a 60s 70s style pole lamp. SImplest version was a piece of PVC
pipe about 8 ft long that you wedge between ceiling anf floor and tape a
dipole to the antenna. I think I still have a wooden one around somewhere
that uses pieces of a tape measure for elements..

Welding Rod J-Pole Possible?
 

Sal M. Onella wrote:
Yup, the peak of the main lobe is elevated. ... but my 144 copper pipe
j-pole does put sufficient 440 energy toward the horizon that I am often
able to hit a repeater more than 70 miles away (Santiago Peak in Orange
County CA from southern San Diego County).

Yep, paraphrasing Roy:
All antennas emit energy at all angles.

I just don't like to waste 10m/VHF/UHF energy
at high angles.
--
73, Cecil http://www.w5dxp.com

Welding Rod J-Pole Possible?
 

Cecil Moore wrote:
...
I just don't like to waste 10m/VHF/UHF energy
at high angles.

Cecil:

And, neither do I. (well, 11m band--sometimes. Just for medicinal
purposes, mind you. evil grin)

I have pursued the "Ultimate 10M Antenna", and a yaga or quad is/are
great. However, I like a omni to listen for traffic on. And, when
there are high winds, I like to point those directional antennas into
the wind. (have stripped too many rotor gears and suffered too much
damage in past decades)

Like you point out, and I concur, the perfect Omni which throws no rf to
the sky is elusive ... strange too, we can do it with light.

I have gotten used to the "RF GODS" extracting their portion of my rf
field to their realms in the sky :( (sometimes they toss a bit back to
australia though, I like the women there :) )

Regards,
JS

Welding Rod J-Pole Possible? (alternate antenna)
 

hi

don't want to talk you out of the jpole but have you seen the

Moxon for 2m ? Direct fed with 50 ohm coax.

http://www.cebik.com/moxon/moxbld.html

has gain similar to a 2 element yagi but takes up less space,
and no radials to worry about.


73 jake

Welding Rod J-Pole Possible?
 

Yep, this is exactly what I'm looking for. Thanks!

"Bryan" wrote in message
...
Chuck James wrote:
This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

Hi Chuck,

I found the image he
http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up -- not much more info available on that page. It's
basically a dipole turned vertical. With the feedline going thru the
bottom
half and connecting at the top of that section, it becomes a "bazooka"
vertical.

There're more links to bazooka antennas he
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this
construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative. I don't think you'd need to use RG-8 as described -- just
about
any 50-ohm feedline would work fine.

73,
Bryan WA7PRC

Welding Rod J-Pole Possible?
 

"Bryan" wrote in message
...
Jim exclaimed:
Bull----. It is NOT a bazooka, it is a simple ground plane with bent
over
rods.

STOP TRYING TO CONFUSE THE GUY. It is a simple ground plane with
removable
radials. STOP POSTING ABOUT THE STUPID BAZOOKA.

Jim

Alright, it's not a bazooka; it's a decoupling sleeve (thank you for the
enlightenment). Semantics aside, it will do what the OP wishes it to, and
in a physical representation that will work within his constraints.

Regards,
Bryan


Either way, do we know the impedance? That is an "easy build" and I want to
try some single-band, no-tuner HF antennas. I cut one for 350 MHz
receive-only some years back (for the Blue Angels' radios at an air show)
and it worked fine.

One more thing: Assuming a nominal 50 ohm match can usually be made, is
there any drawback to tuning the thing by making the braid a little longer
than calculated, moving the end of the braid up and down to find the best
match and then securing the end? I mean, if you don't mind a somewhat
lumpy-looking sleeve. (I'm a bit lumpy-looking, myself.) The decoupling
capacitance would be reduced by both the decrease in length and the increase
in spacing, but the changed value would be, in effect, part of the tuning.

"Sal"

Welding Rod J-Pole Possible?
 

Sal M. Onella wrote:

Bryan wrote:
Jim exclaimed:
Bull----. It is NOT a bazooka, it is a simple ground plane with bent
over
rods.

STOP TRYING TO CONFUSE THE GUY. It is a simple ground plane with
removable
radials. STOP POSTING ABOUT THE STUPID BAZOOKA.

Jim

Alright, it's not a bazooka; it's a decoupling sleeve (thank you for the
enlightenment). Semantics aside, it will do what the OP wishes it to,
and
in a physical representation that will work within his constraints.

Regards,
Bryan


Either way, do we know the impedance? That is an "easy build" and I want
to
try some single-band, no-tuner HF antennas. I cut one for 350 MHz
receive-only some years back (for the Blue Angels' radios at an air show)
and it worked fine.

One more thing: Assuming a nominal 50 ohm match can usually be made, is
there any drawback to tuning the thing by making the braid a little longer
than calculated, moving the end of the braid up and down to find the best
match and then securing the end? I mean, if you don't mind a somewhat
lumpy-looking sleeve. (I'm a bit lumpy-looking, myself.) The decoupling
capacitance would be reduced by both the decrease in length and the
increase
in spacing, but the changed value would be, in effect, part of the tuning.

"Sal"

It's a dipole, so it should look like 50-75 ohms to the feedline. I'm not
sure I follow your line of thinking in regard to moving the shield up/down.
Bryan

Welding Rod J-Pole Possible?
 

On Sun, 31 Dec 2006 22:31:41 -0800, "Sal M. Onella"
wrote:

Either way, do we know the impedance? That is an "easy build" and I want to
try some single-band, no-tuner HF antennas.

Hi OM,

The sleeve dipole makes for a pretty tall HF radiator and puts one end
quite close to ground where a ground plane design, if you matched the
heights of the feed points, would probably show less loss.

As for impedance, it would be close to a conventional dipole - 70 to
75 Ohms. However, the proximity of earth (for HF) would alter that.
Further, the jacket material that covers the outer braid is notorious
for being rather lossy in its own right. When you draw the braid back
over it, it creates a lossy transmission line with that material
between the drawn back braid, and the jacketed braid it is covering.
This does not normally concern most who build this style of antenna as
it is one of those "precious" details that is argued endlessly while
others put it to good use.

One more thing: Assuming a nominal 50 ohm match can usually be made, is
there any drawback to tuning the thing by making the braid a little longer
than calculated, moving the end of the braid up and down to find the best
match and then securing the end?

It'll work just fine.

The decoupling
capacitance would be reduced by both the decrease in length and the increase
in spacing, but the changed value would be, in effect, part of the tuning.

This is the first I've heard of "decoupling capacitance." The lower
arm of the vertical dipole is just that, the lower arm. It's
proximity to the feed line will certainly impact the state of tune,
but there is no claim to decoupling built into this design. You will
have to provide for the usual considerations in that regard (but most
neglect that too to no particular pain).

73's
Richard Clark, KB7QHC

Welding Rod J-Pole Possible?
 

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

Welding Rod J-Pole Possible?
 

"Richard Clark" wrote in message
...
On Sun, 31 Dec 2006 22:31:41 -0800, "Sal M. Onella"
wrote:

Either way, do we know the impedance? That is an "easy build" and I want
to
try some single-band, no-tuner HF antennas.

Hi OM,

The sleeve dipole makes for a pretty tall HF radiator and puts one end
quite close to ground where a ground plane design, if you matched the
heights of the feed points, would probably show less loss.

As for impedance, it would be close to a conventional dipole - 70 to
75 Ohms. However, the proximity of earth (for HF) would alter that.
Further, the jacket material that covers the outer braid is notorious
for being rather lossy in its own right. When you draw the braid back
over it, it creates a lossy transmission line with that material
between the drawn back braid, and the jacketed braid it is covering.
This does not normally concern most who build this style of antenna as
it is one of those "precious" details that is argued endlessly while
others put it to good use.

One more thing: Assuming a nominal 50 ohm match can usually be made, is
there any drawback to tuning the thing by making the braid a little longer
than calculated, moving the end of the braid up and down to find the best
match and then securing the end?

It'll work just fine.

The decoupling
capacitance would be reduced by both the decrease in length and the
increase
in spacing, but the changed value would be, in effect, part of the tuning.

This is the first I've heard of "decoupling capacitance." The lower
arm of the vertical dipole is just that, the lower arm. It's
proximity to the feed line will certainly impact the state of tune,
but there is no claim to decoupling built into this design. You will
have to provide for the usual considerations in that regard (but most
neglect that too to no particular pain).

73's
Richard Clark, KB7QHC

I made one of these sleeve antennas for 10M with the folded back shield,
put a KW on it and it arced through the black vinyl.
Not exactly what I would call a "precious detail". Many years ago Shakespear
antennas were made this way and they changed there design because of the
same problem. Now they replace the folded back sheild with 4 or 5 wires
imbeded in the fiberglass shell putting a good bit of air dielectric between
the folded back part of the dipole and the sheild.

Welding Rod J-Pole Possible?
 

Jimmie D wrote:
I made one of these sleeve antennas for 10M with the folded back shield,
put a KW on it and it arced through the black vinyl.

It's a standing wave antenna. The voltage at the end
of the shield is approximately 20 times the voltage
at the feedpoint. For a KW, that's more than 5 kV,
too much for ordinary coax.
--
73, Cecil http://www.w5dxp.com

Welding Rod J-Pole Possible?
 

Well, I finally took the time to work on the "TV Antenna Feed Line" J-Pole
someone suggested. I got it down to less than 1.6 SWR, on 2 meter, and less
than 1.2 on 70 cm, by trimming it down 1/8 inch at a time. So now I have a
VERY portable dual band antenna, I can just roll up and stick in a small
"go bag". I tried it on my Yaesu VX-6R and was able to hit several local
repeaters, some, of them even on low power.

Thanks again to all that helped.

"Jimmie D" wrote in message
.. .

"Richard Clark" wrote in message
...
On Sun, 31 Dec 2006 22:31:41 -0800, "Sal M. Onella"
wrote:

Either way, do we know the impedance? That is an "easy build" and I want
to
try some single-band, no-tuner HF antennas.

Hi OM,

The sleeve dipole makes for a pretty tall HF radiator and puts one end
quite close to ground where a ground plane design, if you matched the
heights of the feed points, would probably show less loss.

As for impedance, it would be close to a conventional dipole - 70 to
75 Ohms. However, the proximity of earth (for HF) would alter that.
Further, the jacket material that covers the outer braid is notorious
for being rather lossy in its own right. When you draw the braid back
over it, it creates a lossy transmission line with that material
between the drawn back braid, and the jacketed braid it is covering.
This does not normally concern most who build this style of antenna as
it is one of those "precious" details that is argued endlessly while
others put it to good use.

One more thing: Assuming a nominal 50 ohm match can usually be made, is
there any drawback to tuning the thing by making the braid a little
longer
than calculated, moving the end of the braid up and down to find the best
match and then securing the end?

It'll work just fine.

The decoupling
capacitance would be reduced by both the decrease in length and the
increase
in spacing, but the changed value would be, in effect, part of the
tuning.

This is the first I've heard of "decoupling capacitance." The lower
arm of the vertical dipole is just that, the lower arm. It's
proximity to the feed line will certainly impact the state of tune,
but there is no claim to decoupling built into this design. You will
have to provide for the usual considerations in that regard (but most
neglect that too to no particular pain).

73's
Richard Clark, KB7QHC

I made one of these sleeve antennas for 10M with the folded back shield,
put a KW on it and it arced through the black vinyl.
Not exactly what I would call a "precious detail". Many years ago
Shakespear antennas were made this way and they changed there design
because of the same problem. Now they replace the folded back sheild with
4 or 5 wires imbeded in the fiberglass shell putting a good bit of air
dielectric between the folded back part of the dipole and the sheild.

Welding Rod J-Pole Possible?
 

Chuck James wrote:
Well, I finally took the time to work on the "TV Antenna Feed Line" J-Pole
someone suggested. I got it down to less than 1.6 SWR, on 2 meter, and less
than 1.2 on 70 cm, by trimming it down 1/8 inch at a time. So now I have a
VERY portable dual band antenna, I can just roll up and stick in a small
"go bag". I tried it on my Yaesu VX-6R and was able to hit several local
repeaters, some, of them even on low power.

A little trick I learned in AZ - It will work better
on 440 if you slant it toward the repeater.
--
73, Cecil http://www.w5dxp.com