Welding Rod J-Pole Possible?
Chuck James
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
jimbo
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
Bob Miller
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
John Smith I
> ...
>
Why not just through together a 1/2~ monopole with a simple gamma match
and 1:1 current balun?
Regards,
JS
Sal M. Onella
"Bob Miller" <NOS...@neosoft.com> wrote in message
news:2jl7p2hn91q562tth...@4ax.com...
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.)
Chuck James
"John Smith I" <assembl...@gmail.com> wrote in message
news:en13or$pgh$2...@aioe.org...
John Smith I
> ...
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
RST Engineering
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" <c456...@sbcglobal.net> wrote in message
news:TDMkh.7702$yC5....@newssvr27.news.prodigy.net...
Cecil Moore
> (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
John Smith I
> 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
RST Engineering
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" <myc...@hotmail.com> wrote in message
news:G9ulh.27784$hI.1...@newssvr11.news.prodigy.net...
RST Engineering
along with it.
Jim
"John Smith I" <assembl...@gmail.com> wrote in message
news:Ntxlh.96$lb7.2...@news.sisna.com...
Cecil Moore
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.
John Smith I
> ...
> 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
Bryan
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
John Smith I
> ...
>
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
Chuck James
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" <j...@rstengineering.com> wrote in message
news:_Znlh.59$lH6.1...@news.sisna.com...
Chuck James
Any more details anywhere?
"Bryan" <bryan.swad...@comcast.net> wrote in message
news:KNSdndriU-A-tgrY...@giganews.com...
Bryan
Hi John,
I found the image here: http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up. There're more links to bazooka antennas here:
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative.
73,
Bryan WA7PRC
Bryan
> This looks like what i am asking for, but the picture is not very clear.
> Any more details anywhere?
>
I found the image here: http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up -- not much more info available on that page. It's
basically a dipole turned vertical. With the feedline going thru the bottom
half and connecting at the top of that section, it becomes a "bazooka"
vertical.
There're more links to bazooka antennas here:
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative. I don't think you'd need to use RG-8 as described -- just about
any 50-ohm feedline would work fine.
73,
Bryan WA7PRC
RST Engineering
sources and you can't figure out how to do it.
Go away. Just go away.
Jim
"Chuck James" <c456...@sbcglobal.net> wrote in message
news:f_Glh.56759$wP1....@newssvr14.news.prodigy.net...
RST Engineering
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" <c456...@sbcglobal.net> wrote in message
news:4TGlh.56758$wP1....@newssvr14.news.prodigy.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
RST Engineering
rods.
STOP TRYING TO CONFUSE THE GUY. It is a simple ground plane with removable
radials. STOP POSTING ABOUT THE STUPID BAZOOKA.
Jim
"Bryan" <bryan.swad...@comcast.net> wrote in message
news:kpmdnQp0SaYpoArY...@giganews.com...
John Smith I
> ...
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
Bryan
> 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
Bryan
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
Sal M. Onella
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.
Jimmie D
>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
>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..
Cecil Moore
> 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.
John Smith I
> ...
> 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
jake
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
Chuck James
"Bryan" <bryan.swad...@comcast.net> wrote in message
news:kpmdnQp0SaYpoArY...@giganews.com...
Sal M. Onella
> 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"
Bryan
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
Richard Clark
<salmo...@food.poisoning.org> 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
Chuck James
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" <j...@rstengineering.com> wrote in message
news:VRHlh.130$ZG6....@news.sisna.com...
Jimmie D
"Richard Clark" <kb7...@comcast.net> wrote in message
news:aafip25f45fevobkd...@4ax.com...
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.
Cecil Moore
> 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.
Chuck James
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" <jimm...@bellsouth.net> wrote in message
news:Eggmh.17315$%e7....@bignews2.bellsouth.net...
Cecil Moore
> 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.
Jimmie D
No kidding!!!!!
John Smith I
Yeah, but tape a couple of ne-2 bulbs there and you can get that kool
old cb look when they light up on key down!!! <silly grin>
Regards,
JS
Sal M. Onella
< snip >
"Bryan" <bryan.swad...@comcast.net> wrote in message
I'm not
> sure I follow your line of thinking in regard to moving the shield
up/down.
> Bryan
>
Perhaps I am over-analyzing it. Here's what I meant:
To make the antenna, a quarter wave section of shield is exposed, then
inverted and pulled down over the outside of the coax jacket. If it's
pulled down TIGHT, it has maximum length and minimum spacing to the part of
the shield under the jacket, hence the greatest decoupling takes place, if I
understand the principle of the antenna.
However, what I alluded to earlier was moving the end of the shield up and
down as a tuning method. I said this because another poster said you tune
the thing by changing the length of the coax section and/or the shield
section; I was looking for a non-cutting method to change the length of the
shield portion and merely pushing the end upward seemed to be viable. (I'm
sure the shield is sufficiently flexible to allow this.) If the end of the
shield is pushed upward, it shortens the shield and should shift resonance
up.
So, I imagine I can cut the shield section for slightly more than a quarter
wave, then tune it as I described. The upper section can be tuned with
dikes and/or a soldering iron, as necessary.
"Sal"
Bryan
>
> < snip >
I "groc" you, now. Sure, why not?!
Bryan
Sal M. Onella
"Cecil Moore" <myc...@hotmail.com> wrote in message
news:Wnhmh.14258$Gw4....@newssvr23.news.prodigy.net...
I have 160 watts available. ... about 90 volts at the feedpoint, so a
whopping 1800 at the end of the shield. (Might want to keep the mike gain
throttled back.)
OR ... use a larger braid over a spacer of some kind and solder it to the
coax braid at the feedpoint. The spacer could be a piece of plastic pipe
slipped over the coax at the outset. Actually, the braid doesn't really have
to be braid. It could be a piece of copper pipe. The tuning operation
would need to be slightly different; I'll need to keep a few inches of the
original coax near the feedpoint. I'll tune it by sliding the pipes and
bunching up the coax at the feedpoint. Or tune it by adjusting the length of
the center conductor element.
I wonder ... if the pipe were sufficiently large, it would tend to broadband
the antenna. I know of this effect at UHF. How about 10m???
I'm looking forward to this. <g>
Chuck James
stationed in the City Health Department Conference Room, which is Downtown
and practically under the local repeater towers. This is also why I was not
TOO worried about obtaining a particularly high gain antenna, and was more
concerned with being unobtrusive. However, inside that building, the rubber
ducky antenna worked, but just barely, so I took the mobile antenna off my
Tahoe and screwed it onto my HT, using an SMA to Coax adapter. That
received much better, but was a little unwieldly, plus it puts a little more
strain on the little SMA connector than I like. This little "TV Antenna
Feed Line" J-Pole should be just the ticket for any situation like this in
the future.
"Cecil Moore" <myc...@hotmail.com> wrote in message
news:qcimh.55949$qO4....@newssvr13.news.prodigy.net...
Jimmie D
.
>
> I wonder ... if the pipe were sufficiently large, it would tend to
> broadband
> the antenna. I know of this effect at UHF. How about 10m???
>
> I'm looking forward to this. <g>
>
>
Yes it does, solves some of the problem you have with the all coax type of
sleeve antenna. stuff some pieces of styrofoam inside the pipe to center the
coax. Wind a choke in you coax and it is a pretty decent antenna. Consider
this, make the sleve out of 2 inch conduit, at the middle of the antenna put
a cap on the pipe with a hole drilled to accept a mount for a whip, RS and
truck stops sell these. Bottom end screws into a 2inch PVC pullbox, other
side of the pullbox screws on another piece of pipe used as a mast. There
should be enough room in the pullbox for the choke.
John Smith I
Or, just lengthen it out to a full wave dipole, provide a matching
circuit of your choice, add a 1:1 current balun and end up with a MUCH
more desirable antenna ...
Oh yeah, you still can use the ne-2 bulbs at either end (or both) of
this dipole and end up with that kewl "cb look!" <satisfied look>
<moving on>
JS
Sal M. Onella
That's a clever idea. I am recalling four turns as the spec for the
feedline choke at 2m. However, at 28 MHz, there's a lot less inductive
reactance in those same four turns. How many turns are we looking at for
the choke?
Sal M. Onella
"Sal M. Onella" <salmo...@food.poisoning.org> wrote in message
news:BFGmh.53728
I am recalling four turns as the spec for the
> feedline choke at 2m. However, at 28 MHz, there's a lot less inductive
> reactance in those same four turns. How many turns are we looking at for
> the choke?
< snip >
... answering my own question: 4 feet of RG-58, coiled into 6 - 8 turns.
[ARRL Antenna Handbook]
"Sal"
John Smith I
> ...
In my travels about the net, I chanced upon this antenna--a rather
unique one and is a good conversation piece ...
http://www.orionmicro.com/ant/ddrr/ddrr1.htm
Regards,
JS
Jimmie D
"John Smith I" <assembl...@gmail.com> wrote in message
news:hbVnh.33$lz1.6...@news.sisna.com...
Yes it would be the subject of much conversation if you had one.
Jimmie
John Smith I
> ...
<chuckle>
JS
Bryan
> In my travels about the net, I chanced upon this antenna--a rather
> unique one and is a good conversation piece ...
>
> http://www.orionmicro.com/ant/ddrr/ddrr1.htm
>
> Regards,
> JS
I've seen the same antenna called a "Directional Discontinuity Ring
Radiator" (a rose by any other name). Lots of Google hits for that phrase.
73,
Bryan WA7PRC
cliff wright
in a hurry.
Came up with a good old Kiwi #8 fencing wire solution. using an old
ceramic "choc block" connector for the feed I madea 2 element cubical
quad on a bit of 2x1 timber. (Usual formulae out of the ARRL and RSGB
books). Despite being made out of galvanised Iron wire it showed a 7 dB
gain over a dipole at the same height on the local 2M beacon!
Where there's a will there's away!
Regatds Cliff Wright ZL1BDA ex G3NIA