Ham Radio - A 2 meter Slim Jim from window line.
Вставка
- Опубліковано 22 лип 2024
- Details on the slim jim I just made to use outside on my RV. Super easy to make, performs well.
Link to design web site:
www.m0pzt.com/slimjim/
Link to discussion on slim jim vs J-pole:
www.hamradio.me/antennas/slim...
If you like my videos, please subscribe here: ua-cam.com/users/loughkb?s...
If you want me to keep making more videos like this, consider becoming my patron at Patreon: / kb9rlw
Discuss this and other videos on Facebook:
/ kb9rlw - Наука та технологія
I got the same model from N9TAX on my roof in NYC installed on PVC mount & work awesome. Using 50w mobile radio with this antenna, I cover Tri State area in NYC.
Another good "rainy day project". These inexpensive builds are fun. The club I belong to has been helpful to get me started. So, when make something like this I gift it to someone to help them. It's a great hobby. Thanks for sharing ideas!
Pro tip cut your .8 inch gap first so that you have that gap with the insulation for strength, then cut the rest of your antenna
Great video Kevin! What a simple, nice, and portable design to use. 👍📻⚡️Thanks!
Again a well presented video. Your attention to detail (except for the 3/8 - 3/4 blip) makes it easy for the beginner to follow along. Several friends have the Slim Jim and one has it mounted about 25 feet up and gets into several San Antonio repeaters with 5W. He's about 20 miles south of SA.
I just received my N9TAX 2M/70CM Slim Jim today. SWR is 1:1.01 on 146.520 and 446.000. There are other stock antennae and custom order available. A bargain for $30.
I did some testing of the antenna with Fred, G2bcx when he was developing it, he claimed it had a slight gain over a J pole which was due to it having a lower radiation angle mostly. It became very popular here for many years. I enjoy your videos Kevin, have a safe trip. G4mqk
Thanks for the build tips, I've just got the bits together to make this antenna.
Another great simple video, i really like the current format...
N. Davis/WB4BKO
About six years ago, I constructed a similar antenna for two meters, but I inserted the antenna into the PVC pipe. It was suspended from a pipe cap using a zip tie. Inserting the antenna into the PVC had negligible effect with SWR below 1.25:1.0 across the entire band. It is still in use as my primary 2-meter antenna and delivers good results with the top just squeaking above the roof line of my single story home. Eventually, it will be placed higher in the air at 40 feet when I mount it to the side of my telescoping tower. Good video and instructions are very clear. 73
3:57 What I did was to cut it centered in the solid area - for strength - and then measured down for the rest. I did have to strip away some of the solid at the base to make the soldered short and also at the feed point, but that was no problem at all.
Another great video. It's the perfect blend of practical antenna theory, construction article and motivational video to get people building and enjoying the hobby.
I think I'll make some Slim Jim antennas for friends looking to get into personal emergency communications on the cheap. I'll put the ladder line in rigid 3/4" PVC with caps on each end with the strain relieved coax in the lower cap with a #60 weep hole to save a couple of RF connectors - cheaper, easier, more reliable, slightly better performance. A coax choke also adds more strain relief and I'll cut the coax just long enough to reach the radio. Simple, easy, cheap and good enough. I can cut the PVC pipe longer to get a bit more elevation without a tower while having a fairly unobtrusive antenna.
I purchased my slim jim (many years ago). I used it for a while as my base antenna until I got a copper j pole. Now I have it hanging from the ceiling of my shack with a UV5R connected to it for monitoring. No PVC pipe or anything. Still works great! Since I have my base radio disconnected, most of the time, to avoid lightening storms, I have replied to people using the UV5R with no problem.
Your a hit with the “Ham Heads”
Kevin. 👍🏻
Thanks for a great presentation, and actual lab results. I find that my 1/2'' copper pipe slim jims have a much broader bandwidth, typically 144 to 153 Mhz. Indeed, using 3/4'' copper pipe for 70 cm slim jim, it is good forl 430 to 470mhz. I believe my Slim Jims have a 2 Mhz broader bandwidth than my J-poles made of the same diameter materials. I also believe that these antennas will have a lower take of angle and improve performance the higher that they are mounted.
Thanks for the tip, the linked article was extremely interesting! 73
Great stuff Kevin, as always thanks for the time to do these. I'm always looking for different antennas to build so this is just another that will be on the future build. These videos do get people motivated so again thank you.
I guess I'm pretty randomly asking but do anyone know of a good website to stream newly released movies online ?
@Alexzander Maximo Meh I would suggest flixportal. just search on google after it:D -briggs
@Briggs Tristan Thanks, I went there and it seems like a nice service :D I really appreciate it!
@Alexzander Maximo You are welcome =)
I built something similar, except instead of your PVC pipe backer, I zip tied mine to an 4-wheeler whip flag I had laying around. It's been holding up nicely so far and I didn't see a SWR shift.
Great video.
It’s a roll up, most use it for emergency use anyway. As long as it’s at or below 1.5:1 I’m good!
Just made one in about a half hour, lol including tuning it 1.2 swr at 50w! Thank you Kevin!
on which frequenzy?
@@hubsi5263 2m also tuned ok at 70cm
I put mine inside of a piece1 inch PVC with a cap on the top and bottom then so-239 on the bottom works great I have also installed an eye bolt in the cap where I can string it up over a tree or anywhere
Thank you for your fine details sir 👍🏾
You can Make this Window line into a 2 Meters Slot Antenna, 39 Inchs, with the Feed Point on 4 inchs from the End of the Window line, this Antenna is Vortical Polarize with is in the horizontal Position,
Hi Kevin, nice build & test!
Would love to see a Rhombic build with an a/b switch comparison to dipole & "pro" built 70cm. It would be nice to see how far out you can hear & talk.
73 - John - N7GHZ
Your explanations are really commendable. Excellent presentation
73
New Delhi
Certainly a useful item to have in your travel bag.
As always, a great video
Thank you sir !!
Most everyone I know calls it ladder line. If yer cut falls on a space (window) you could make a small hole in the top solid piece and bottom solid piece and sick a wire tie through the holes and zip it up to where both halves are even. You'd have to use plastic wire ties though. That would strengthen the antenna. There's no link in the description.
1/4 inch fiberglass rod works better as a mast and won't affect the radiated angle of the slim jim. Apparent gain is the advantage of a Slim Jim over a J-Pole. Anecdotally, my SlimJim performs incredibly well portable/SOTA ops and I have complete confidence in this great design.
Great video just on with making it wish you had told us at the beginning about how better it would be to have the cut at 19inches on the stronger part of the line ..already done the other parts ..lol..never mind easy and cheap enough to make another if need be ..👍😉👍
I get a better SWR on my 2m Slim Jim if I don't connect the wires at the top, but bend them to face each other, leaving a small gap of 1-2mm. No idea why...
Have you ever tried a flower pot antenna? I'm curious how it compares to J-pole and Slim-Jim. I've got loads of coax and no ladder line :) The flower pot antenna can be dual band VHF/UHF using only coax and some pvc pipe. Worth a look when you get the 3/4 PVC pipe.
Thanks Kev, very interesting, regards, carl.
Just put one to gather. To night. August. 25, 2020. Still have to tune as I ran out of light. Seems to be a little high. But it will be used for scanner mostly. Tks for good show. Cheep. Sturdy and if pinched no Biggie got about 80" more feet to go. Kv4li
kx4o is a great reference for j-pole stuff. I wrote to him about the patent on his groundable version. It's still in limbo (and the patent would belong to the U.S. government of all things...) but I may have to build one for my own experimentation purposes.
Great Video Kevin, I already got suscribed.
I'll try out this project and the YAGI one.
Among several 450 windows: 14, 16 or 18 and solid or stramd
What is the best one?
Thanks
I noticed that you have Fig Newtons stacked up to your right. ;-) Bob- KN4UUT
You could superglue a length of non conductive material to bridge that gap, then use some adhesive lined shrink tubing to reinforce that gap.
Or just cut your line so the gap is in the middle of one of the spacers. Less work that way.
@@loughkb Yes, that's exactly what you do. I have made them for 27Mhz and the FM broadcasting band and that is how I've made every single one of them
Window line has almost the perfect dimensions for a 2M Jpole or SlimJim.
Thanks for the video!
Love this setup!!! Great explanation and details, good blog article as well.
Where do you get the window line?
DXengineering.
Hi Kevin.....love your videos. I have a question in regards to the slim jim that you built. I can see that you intend to mount it to the outside of some pvc tubing. If the antenna were to be mounted inside the tubing/pipe with an end cap on ( to protect from the weather etc ) do you think there would be much loss ?.....I intend on building the same antenna but had thoughts of mounting the ladder/window line inside the tube....what do you think ??....Many thanks and keep up the good work...Mark, m0mco.
Yes, a bit of loss. Tuning might shift a little too.
Hi Kevin, I Know M0PZT, Charlie, he lives about 7 miles from me...Fred in Uk
Yo Kevin!:
GREAT video again! Great you admit to a "brain fart"! Ok I wanna make a request. 160 mtrs end fed wire to a balloon! You might be surprised! : )
I've actually looked into those large real estate advertising balloons, always thought it would be cool to have a big bad balun balanced blimp-based broadband antenna.
Is the coax shield on the gap side of the antenna? Thank you
Yes.
Great video. Gotsta bust out my hot iron
Clear cilcone when wet will conduct it dryies outside in i put some on a 400vdc diode bridge and it blewup kg6mn
Good job he used black silicone then.
You should have waited for it to cure! ;-)
Did your clear silicone smell vinegary when you were applying it?
Have try this
hey brother do you have 450 ohm ladder line slim jim plans for 2m 70 cm 145mhz/440 mhz combined with good match ? adding coax part of the way up for matching ?
I've been told that if you cut the length to 58 inches instead of 59 inches, it will work well on both. I haven't modified mine since I rarely, if ever, find myself needing 70cm.
Hi, Kevin.
How about folded dipole for 2m, using the window line? It is much shorter than the slim Jim.
But, we need 4:1 balun with correct toroid mix., for more optimum performance.
Thank you. :)
If I ever build a yagi, I'll use a folded dipole for the driven element.
something I've wondered is can you shorten a j-pole, not to just get a smaller antenna, but to alter the radiation pattern, maybe?
No, the length is important for resonance.
Newb here, won’t putting the antenna inside the PVC “hinder” performance? I thought the antenna had to be outside of any type of tubing to get the best performance. Pls educate me, I’m learning. Ty for your time.
I mounted mine on the outside of the PVC. You can put them inside, but that will alter the tuning of the antenna slightly. You'd have to adjust the wire length a bit to compensate. Other than that, the plastic won't block RF at all, it won't affect sensitivity.
Nice little antenna Kevin. How many watts would you be comfortable using?
40 should be fine, with the heavier wire in the window line, even more is probably fine.
I wonder how that pole set up would work on a metal cargo trailer conversion. Would the roof ground plane change it a lot? In a good or bad way! 73, W1ECM Eric
The slim jim does not rely on a ground plane. But you'd probably want it up above the metal roof by at least a half wavelength or more.
What would happen if I followed this but had 10 meters worth of coax and soldered it the same way as in the photo would that receive anything or wouldn't it work mew to making my own stuff
The longer the feedline, the more loss, especially at VHF. But 10 meters is not too much. It should work fine.
I understand that the Slim Jim has a lower take-off angle than the J-pole.....8 deg vs 20 deg.....if this is correct, the Slim Jim may be useful for longer range on flatter territory.....the J-pole might be more useful from a valley to a repeater sitting up higher......?
I don't think there would be a noticeable difference. I ran across many claims about the slim jim vs j-pole. Most were not backed up with any data and just seemed to be hearsay.
If there were that much of a difference, by the time you get further away from the antenna, with the diffusion of the field outward, it would be a very very small difference.
Does it matter which side the center coax is attached? One way is farther from the gap.
The diagram shows it on the long side, I put text on the screen when talking about the gap that said, "shield side of coax". Sorry if it wasn't clear. Should I do something different?
Yes! It does! The shield always goes to the cut side on either J-pole or Slim-Jim. The "hot"/center conductor goes to the long/un-cut side.
73
Kevin Loughin it was the photo that confused me. In one we’re the center melted the center went to the left. When that was corrected it’s shown go into the right. I understand now. Thanks for the reply.
@@TJVergerII ahhhhhh! I wouldn't have thought about the orientation like that.
Can you make a 2m 70 cm version?
Yes. This one gave a low SWR on some parts of 70cm already, but I think I remember a few designs that specified dual band. Search for 2m 7cm slim jim and you should find them.
Got to love a good brain fart. I must have exactly the same wires crossed in my brain because I often say 3/8 when i mean 3/4 and j-pole when I mean slim jim.
Are you using 300 ohm or 450 ohm ladder line?
Common 450 ohm, purchased from DXengineering.
Thank you.
Hi Kevin, I'd heard that a Slim Jim is electrically a folded dipole. Is that a valid statement?
Not entirely. A folded dipole is connected all the way around and fed at the center. Kind of a loop that's been squashed almost flat. It has a feedpoint impedance around 200 ohms.
This antenna is partially folded back on itself, but not connected. It's also fed very near the end where the impedance comes down to 50 ohms. A folded dipole has a higher impedance near the end.
So, lot's of differences electrically.
It is an end fed folded dipole. It has to have one end open like that and fed only on one side because of the phasing. Think about this: if it's connected at both sides, you're trying to force the antenna to radiate with opposite phase, because the end of the 1/4 wave matching stub has high voltage and impedance rf of opposing phase at its end. The end of the folded dipole should be IN phase at that point. That's what the end break and gap on the slim jim allows
How about doing a three or four element yagi for SSB and CW?
Where would I store it? I'm tripping over things in here now. Remember, I live in a 25 foot by 8 foot box.
Kevin, you are very resourceful, design a 3 or 4 element 2 meter beam that you can fold up!
@@JimN5QL make one out of rabbit ears.
@@loughkb ...a quad you could snap together using 1/4" diameter fiberglass rods which flex when you slide them into a boom complete with short tubing hubs wherein the fiberglass rods slide, the 4th rod bending the rest until all in straight & tight, a Dacron cord in physical parallel with the wire to absorb the stress and remove it from the wire for longevity.
When done using it, flex out the rods, roll it up & put it on a shelf somewhere, maybe above the upper pop-out railing.
I thought the PVC didn't cause problems until you'd been transmitting for a few seconds?
I haven't had any problems from the PVC at all.
Great video! de WQ1I 73'S
Can you support /bridge the gap with a little piece of your $0.88 cutting board ??? Does it still fit in the pvc radome???
You could bridge the bap with just about any non-conductive material.
It would take a bigger piece of pipe to put the window line inside. Tuning would shift and need to be adjusted and it would be too big around, I think. Weatherproof and strain relieve the coax as I did and it's fine to have it out in the elements.
Just for curiosity's sake, wouldn't it be better to put a small set of alligator clamps on the coax shield and center conductor to facilitate finding the correct location to solder them on? How does this compare with the antennas that Ed Fong sells on Ebay? I have two of them, both bought some time ago at $35 each. So just curious. If you're in the Kingman area I'd be happy to let you borrow one of mine for testing and comparison. KK6LOP Also looking forward to hearing you on our Thursday night ragchew run by Bruce, WC7W of the Mohave Amateur Radio Club.
www.ebay.com/itm/DBJ-1-Dual-Band-VHF-UHF-2-meter-70cm-ham-base-antenna/113516146770?hash=item1a6e16f052:g:cA0AAOSwpHlZbVuC:sc:USPSFirstClass!86409!US!-1
I think that was you on the net that asked this question last Thursday. But I'll respond here as well for the benefit of others reading the comment.
Using alligator clips would not be my first choice. It's likely that after finding the sweet spot, you'd miss it my a millimeter or two after soldering the wires on.
Just lightly soldering the wires first, using the dimensions in the diagram will get you very close. Then it's just a quick touch of the iron and slight move to tune it. Then just adding more solder once you're there. Easy.
@@loughkb Thanks, yes it was me. I had no idea how much you would have to move it. So a millimeter or two would certainly be easy peasy.
From the article: "For you copper pipe 2BCX Slim Jim manufacturers out there claiming a gain over a traditional j-pole, isn’t it time you quit revealing to the planet your obvious lack of antenna design capability? It’s well worth your while to research the product you sell. If you want to manufacturer an antenna that uses more materials than a traditional J-pole with no measurable benefit, fine, but don’t mislead your customers about nonexistent gain advantages."
3/4 (3/8) what.
Inch. I'm in the U.S. where it's a common presumption, sorry for the confusion.
An Dr. Edward Fong antenna pisses on this one and costs less to make.
Put it inside a PVC pipe....
If you put it inside a PVC pipe it won't tune correctly. KN4BHS
Well, it might shift a bit. So you could tune it to compensate. I.e. if it shifted 500khz down, tune it 500khz high when out of the pipe.
@@loughkb thanks Kevin great video.
Spielzeug