J Pole
 

I don't have any 300 ohm twin leed and really(at this time) don't feel like
doing the copper pipe thing .Is there another easy way to make one.My
thoughts were to maybe take and attach some wires to a board say a 1x4 and
just make it work accordingly.It's only for a temporary scanner antenna for
in the back yard on my patio. The stock rubber duckie antenna doesn't
recieve anything as I'm kinda out in the boonies and an antenna with some
gain would work.I tried a magna mount CB antenna and believe it or not it
was pulling in signals that weren't even resonant to the frequency it was
designed for.
So,in a nutshell there it is. Thanks in advance for any comments or
suggestions.
Best regards,
Will

--
Humble to the humble , inflexible to the arrogant .

J Pole
 

In article YoGKg.3053$CL6.2183@trnddc06,
Amerigo Vespucci wrote:

I don't have any 300 ohm twin leed and really(at this time) don't feel like
doing the copper pipe thing .Is there another easy way to make one.My
thoughts were to maybe take and attach some wires to a board say a 1x4 and
just make it work accordingly.

Sure, you can make that work. You'll need to fiddle with the lengths
of the elements, and the attachment point of the coax to the matching
section to get the best match. Using an MFJ or similar antenna
analyzer will make the job easier.

I built a J-pole somewhat like this by taping ordinary insulated
hookup wire to the fiberglass shaft of a bicycle safety flag. It took
a while to get the lengths and feedpoint position adjusted correctly,
but once it was done I had an antenna which was 1.5:1 or better across
the entire 2-meter band, and works very nicely when I ride "bicycle
mobile" at a public-service event.

If you aren't planning to transmit, you probably will have an easier
job of it - your scanner will work acceptably even with a significant
amount of mismatch at the antenna feedpoint.

I'd suggest thoroughly waterproofing whatever piece of wood you use -
treat it well with marine spar varnish or a similar outdoor-rated
polyurethane or other varnish. This will ensure that the wood doesn't
soak up rain moisture and change its electrical characteristics and
de-tune the antenna.

As another alternative, since you're scanning and would presumably
prefer a wide antenna bandwidth, would be to make yourself a skeleton
discone. A chunk of wood with holes drilled in it, and a dozen pieces
of stiff wire, and a bit of simple soldering and you'd end up with an
antenna which would probably receive acceptably over a very wide
bandwidth.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

J Pole
 

"Dave Platt" wrote in message
...
: In article YoGKg.3053$CL6.2183@trnddc06,
: Amerigo Vespucci wrote:
:
: I don't have any 300 ohm twin leed and really(at this time) don't feel
like
: doing the copper pipe thing .Is there another easy way to make one.My
: thoughts were to maybe take and attach some wires to a board say a 1x4
and
: just make it work accordingly.
:
: Sure, you can make that work. You'll need to fiddle with the lengths
: of the elements, and the attachment point of the coax to the matching
: section to get the best match. Using an MFJ or similar antenna
: analyzer will make the job easier.
:
: I built a J-pole somewhat like this by taping ordinary insulated
: hookup wire to the fiberglass shaft of a bicycle safety flag. It took
: a while to get the lengths and feedpoint position adjusted correctly,
: but once it was done I had an antenna which was 1.5:1 or better across
: the entire 2-meter band, and works very nicely when I ride "bicycle
: mobile" at a public-service event.
:
: If you aren't planning to transmit, you probably will have an easier
: job of it - your scanner will work acceptably even with a significant
: amount of mismatch at the antenna feedpoint.
:
: I'd suggest thoroughly waterproofing whatever piece of wood you use -
: treat it well with marine spar varnish or a similar outdoor-rated
: polyurethane or other varnish. This will ensure that the wood doesn't
: soak up rain moisture and change its electrical characteristics and
: de-tune the antenna.
:
: As another alternative, since you're scanning and would presumably
: prefer a wide antenna bandwidth, would be to make yourself a skeleton
: discone. A chunk of wood with holes drilled in it, and a dozen pieces
: of stiff wire, and a bit of simple soldering and you'd end up with an
: antenna which would probably receive acceptably over a very wide
: bandwidth.

The skeleton discone sounds like a neat idea.Do you have a diagram or
something for that? Oh BTW I am a ham I am just working with limited
resources at the moment. Call hre is Kilo Alpha 3 Victor India Delta . Nice
to make the aquaintance.



:
: --
: Dave Platt AE6EO
: Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
: I do _not_ wish to receive unsolicited commercial email, and I will
: boycott any company which has the gall to send me such ads!

J Pole
 

In article KLHKg.1381$xh4.656@trnddc04,
Amerigo Vespucci wrote:

The skeleton discone sounds like a neat idea.Do you have a diagram or
something for that? Oh BTW I am a ham I am just working with limited
resources at the moment. Call hre is Kilo Alpha 3 Victor India Delta . Nice
to make the aquaintance.

Take a look at the discussion at

http://www.radioreference.com/forums...hp/t-8000.html

You'll see a bunch of different homebrew discone designs there,
including both traditional (solid sheet-metal disc and a sheet-metal
cone) and skeleton (radial rods to make both the disc and the cone).

The Diamond D130J is a commercial version of the latter.

One simple way to put together a discone "on the cheap" - use a block
of wood perhaps 2" in diameter and 2" high as the center insulator.
Drill a 3/4" hole in the center, insert a piece of 3/4" dowel (the
mast) and glue into place. Take 3 or 4 pieces of stiff copper wire
12" long, twist them together in the center, and the ends apart so
that they form a flat disc of radial-like elements, solder the twisted
section together, and mount on the top of the wood block with a couple
of wire staples. Drill a set of 8 holes, angled upwards into the
block at a 45" degree angle, and insert 12" wires or rods (forming the
skeleton cone). Run a length of bare stranded wire around the inner
ends of these wires or rods (right where they enter the block) and
solder. Drill a hole upwards through the block, right beside the dowel.

Now, run your RG58 (or whatever) feedline up the mast/dowel and
zip-tie it into place. Remove a few inches of insulation, separate
the braid from the center conductor, strip the end of the center
conductor, run the stripped end up through the small hole you drilled
and solder it to the junction of the six radiating spokes, and solder
the coax braid to the wire which connects to all of the skeleton-code
wires. Waterproof the end of the coax somehow (paint-on electrical
"tape", perhaps).

You now have a garage-built skeleton discone, akin to the Diamond D130
but a lot less expensive. [Probably a lot less rugged, too, but if
it's just a temporary it should serve you well enough.]

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

J Pole
 

"Amerigo Vespucci" wrote in message
news:YoGKg.3053$CL6.2183@trnddc06...


snip

I'm kinda out in the boonies and an antenna with some
gain would work.

snip

Best regards,
Will


The j-pole won't give you much gain. It yields the standard "donut" pattern
of a single vertical element. The gain is about 2 dB over a theoretical
isotropic (point source) antenna. You lose power in the up and down
direction and get an increase toward the horizon.

Whatever you finally decide to use, if you can put it up high, that will
improve its performance. If you do the wires-on-a-stick design, make it on
one end of a long stick (8 -10 ft) and lean it up against a building or
fence. It should be better that that rubber duck!

I have built about two dozen j-poles, all of copper pipe , and I really like
them.