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New J-pole for the barn workshop

SOTA

SOTA

Solder Splash Goalie
Since moving my workshop last summer I have been suffering with an old boombox for tunes:puke: but now with the weather getting nicer the shop will be set up with an Onkyo TX-850 rec, Polk RT35i spkrs and a Panasonic DVD to play CDs. Being in the boonies I have never had much luck with a twinlead dipole so I opted to make a j-pole that will mount right inside the barn so that it can be up high but still out of the weather...

jpole.jpg


I decided to fit it with an f connector and make it tuneable instead of soldering the coax to a fixed point.
fconn1.jpg

fconn2.jpg


On the stub is a grounding screw which I can use in the event it ever gets mounted outside.
base.jpg


The testing was done in the house and the results were amazing, (we live in an fm "hole") pulling in signals all across the band with really good strength when normally the home receivers are on cable to be usable at all. The barn is 5 miles down the road on higher ground so it should be just fine in there. The pole is designed for 98mhz which suits the local signals very well. I don't know why I didn't do this sooner:rockon:

J.R.
 
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I learn something new on this forum every day. Very interesting. How do you go about figuring out how to construct it ( i.e. dimensions) and tune it ??
 
I got my calculations here...http://www.hamuniverse.com/jpole.html. The connector/tuning part I just brained it out myself using parts I had on hand. I have a sheet of 1/4" phenolic, a piece of which holds the connector and the rest is ring terminals, 14ga solid wire and a couple of copper pipe straps attached to the phenolic plate with 8-32 bolts/nuts and the same bolt/nuts used in the stub for a grounding point. Pretty much a "parts drawer" project.:yes:

J.R.
 
SOTA. Thanks for the information. I was just considering pulling a tuner or two out of retirement. And I'm in an area that could make good use of a better antenna. This just may be the ticket.
 
As a amateur radio operator, I have built several J-poles for transmitting on 146 mHz. They are rugged effective antennas with good reception.

Before building one of 98 mHz, I think I will try one of 2 meter (146 mHz) poles to see how it does. I bet I will be better than the little cheap dipoles.
 
I've never heard of using one as a receiving antenna. I thought they were designed as a transmitting antenna only. Not that you couldn't use it for receiving, of course. Made of metal and all...

Very interesting regarding FM. I've got about a 12' ceiling up in the attic. This could be interesting!
 
wonder if it conscan be used for horizontal pick-up or if it is to be used vertical only?

Fantastic truction/assembly work.

I wonder how the grounding below the 20" effects it? I understand you clamp it to a steel pipe or such.
 
Sansui Louie said:
Wow...pretty cool. Care to share *your* plans? (dimensions, supplies, etc.)
Click to expand...

Hardly "my" plan, j-poles have been around a long time. I have a copy of The Radio Handbook and it covers just about any kind of antenna you may want. That's where I got the idea from and I just added a couple of twists of my own to it. I did add an upper clamp to it today to stiffen up the whole assembly...

PICT0017-1.jpg

PICT0016-1.jpg


Earlier in the thread I posted what I used to make the hookup section and where I found the online calculator...the rest is just 1/2" copper pipe and fittings. Having the right tools helps a lot and I have a very complete wood/metalworking shop:D

J.R.
 
Mark, very nice work on the antenna. I particularly like the mounting bracket you made and may just have to steal the concept to mount mine to one of the barn beams. As I stated in my OP, mine will be inside the barn out of the weather so I don't know that I will need anything quite so heavy duty but your execution of the bracket is ideal:thmbsp:

J.R.
 
Great idea on the f-connector. If you turn your head just a minute, I'll steal it! (the idea) :D I built a J-Pole a few months ago and I am very happy with it's performance.
 
SOTA said:
Mark, very nice work on the antenna. I particularly like the mounting bracket you made and may just have to steal the concept to mount mine to one of the barn beams. As I stated in my OP, mine will be inside the barn out of the weather so I don't know that I will need anything quite so heavy duty but your execution of the bracket is ideal:thmbsp:

J.R.
Click to expand...

I like your F connector idea. Makes a nice clean connection. The little blocks in my mounting bracket are a material called Micarta a Phenolic resin with canvas fabric composite. Totally impervious to weather and tough as nails. For an indoor application a good solid wood like some Maple or Oak would work great.

It's not in these photo's but I also shoved a 3/8" D fiberglass temp fence post up the inside of the main tube and used wraps of black electrical tape every foot to make a real tight fit. the idea was to stiffen the tube as we get up to 45 mph winds around here and being my house is the only full 2 story around and the antenna is mounted 18' off the ground at the highest peak of the house I wanted to keep it as ridgid as possible I figured the less vibration the longer the mount would last.
 
Disappointing...

Built a J-pole tuned to 94.7 FM, wife's favorite station that just barely comes in above the FM mute level. Used 1/2" copper and built to the specs in the plan and found that it was slightly worse than the cheap dipole we had been using and wasn't exactly omnidirectional...mostly, but not quite.

Double checked all the specs, I don't think I screwed up, but it's possible.

This kind of confirms my suspicions over the years that FM antennas are a voodoo science. I've tried 'em all...amplified powered antennas, beam boxes, various miracle antennas claiming this or that for gain and now the J-pole. Results are always the same...its' more about having decent electronics than about what hunk of wire you throw on the back of them, so it would seem.

I can always turn the J-pole into a nice set of copper wind chimes for Mother's Day... heheheh.
 
Hey Louie.......... the wire that connects the antenna to your Sansui is essential. :D, Chuck
 
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