Lol I'm a plumber. I had a little chuckle when you said you're pretty good at soldering. I understand there is a huge difference in soldering copper pipe and wires, but i did look at that antenna just before you said that and I thought , looks like he had some trouble soldering. Lol
If you are a plumber, why don't you mention to clean the solder areas with sandpaper, use flux on both ends, heat the joint then heat the opposite side where you touch the solder and it will flow to the heat, then wipe the excess with a damp rag?
@@nupss4710 A little late to the party, but that looks like the first time I tried to use my Hakko on a jpole. Had to get a blow torch, and some silver solder to do the trick.
Anybody watching this now make sure you waterproof your coax ends. Water will go down the jacket of your coaxial cable and short out your transceiver. J poles make great antennas and cost almost nothing but your labor. I made my first using aluminum. Pushed one end into the ground and tuned it. I was amazed at what it could do.
PARTS LIST: 1 ten foot 1/2 inch copper pipe...1 1/2 inch elbow...3 1/2 inch caps... 1 1/2 inch T connector. a really hot soldering iron or a torch and plumbers solder (preferably) i prefer a so-239 connector soldered to the ground radial pipe (longest tube) and extend the center connector to the shortest tube (driven element).
If you build one of these, a piece of cardboard cut to the gap size makes a great construction alignment jig. Tape the tubes to the cardboard and then fold back from the areas you are soldering while all the components are secure to the cardboard sheet spacer. The jig would be nothing more than a piece of cardboard 19-1/4 X 1-3/4 inches. Assemble the components with tape. Fold out the bottom for the solder job. This holds the driven element and stub in align for the soldering.
It’s been my experience that if you hit a kind of SWR barrier (in this case can’t get it below 1:1.4) its because the elements that make up this antenna are out of tune (incorrect dimensions) or something is de-tuning them. Your video did not show you actually making the adjustments but was just showing it laid on a table with a SWR meter connected. Putting the antenna upright to keep interaction between the stub and radiator with the ground is needed to prevent such de-tuning, its also important to keep anything conductive away from the antenna (including yourself) during measurements for the same reasons. The adjusting section on the top of the stub is a neat idea but I would also put one at the top of the antenna as well, as with a fixed attachment point of a stub lengthening the stub will also have the effect of electrically shortening the radiator and therefore de-tuning it a little. A caveat I’ll put on the use of a silicone sealant is to only use a neutral cure type as the acetic acid in non neutral types can promote corrosion. If a silicone sealant is used wait for it to completely cure before using as wet sealant can be conductive and can upset SWR measurements. Apart from all that I’d say nice video.
I moved the coax up and down to get the 50 ohm's then add or remove some on the long part to get It to resonate at the frequency I want . And as Always a Ballanced antenna fed with unbalanced coax needs a choke . This is an end fed 1/2 wave antenna.
This is also how I do it. although I use a spectrum analyzer and a coupler to see Return Loss. The coax is adjusted to balance the near and far lobe into balance. Adjusting the center end will shift the right lobe, while the shield side will shift the left lobe. The balance of the two will suppress the center lobe.
Hi, by my calculations, to get the antenna shown to 'center' around 145Mhz the long upward section (A) should be increased from the dimensions given,... in length by 57mm & the short upward section (B) should be increased by 28mm. For 144Mhz value (A) should be increased by 63mm, and (B) by 31.5mm. For 146Mhz (A) should be increased by 60mm, and (B) by 30mm. . The 'balun-loop' length, is to match the unbalanced coax feed-cable, to the 50-Ohms balanced impedance position of the antenna,... and should be reasonable as given. The position of these two points of contact, for the coax, should be moved slightly up or down in parallel to the short horizontal stub, to obtain 50-Ohms balanced impedance while testing.
I think you would have to be very quick as you don't want to melt the inner insulator sheath or your SWR will be around 30:1 not good and will burn out your power stage so you want a 1:1 SWR.
Does the DIAMETER of the copper tubing matter? For example, could I use tubing half that diameter, or even one quarter that diameter, without negatively impacting the antenna's performance characteristics? I need an antenna with a very low footprint visually. Smaller tubing would obviously help.
You can use any diameter tubing. A larger diameter tube will increase the resonance and a smaller conductor will decrease the resonance. This is due to the skin effect.
@@TheOKBluseman .. Thanks. But what does that mean? I obviously want to maintain as much performance (bandwidth, range, etc) as possible. You talk about "resonance," which means very little to me. At what point does smaller tubing have a detrimental effect on performance? Does quadrupling or more the diameter (4-6 inches or more) greatly improve performance?
@dwightstewart7181 Copper pipe gas gotten very expensive and you see a lot of J-poles these days made with twinlead or ladder line. The larger conductor diameter gives a slightly better bandwidth in theory but probably not practice. 2-6m is the sweet spot for a copper pipe j-pole. When you get into UFH you can't get the copper pipes close enough even using a street elbow. The gap needs to be very small compared to the wavelength. Parallel transmission line J-poles really shines in UFH. As a practical matter power is the only concern when it comes to wire diameter. Ladder line can support about 75W.
man i made 2 of them i even added brass tunning stubs but i am just unable to get it to perform any better then my. 1/2 wave 2 meter antenna.. I got the swr down like yours..
It will have about the same performance as a half wave antenna because electrically this is a half wave antenna. The part below the open end of the stub is just an impedance matching feed line.
Hi, shango066 is it You? I found this channel because I am also building same j-pole antenna for 2m, and I am also a subscriber of You "shango066" channel
Most important overlooked item.. The dielectric constant is different than air. Insulators in this gap will affect tuning as it changes the capacitance. Dielectric constant of air is very close to 1.0006. Polycarbonate is 3.0. Some materials will have dielectric absorption.
looks like he didn't clean, didn't flux, and because of that overheated the pipe causing it to warp like it did. You can see how discolored and gold the fittings turned, they are baked way past where they should have been heated for solder to evenly flow. First thing to learn when building an antenna like this is how to sweat pipe.
Clean joints are a little difficult considering the tubing may have to adjusted several times before the antenna is complete. The goal here is a working antenna, not show-quality soldering joints. If you want looks, sand and polish the entire antenna to a high shine afterwards. Sure to impress your friends & neighbors.
My SWR is really high...like 3 + on both 146 and 147. Any thoughts on how to fix. I have the same set of plans, so mine is probably too long too. What is the finished length of the long radiator?
Caidyn Edlund You would want to use a grounding rod with any antenna like this. Also Ive been told terminal clamps work better than solder for the cable and wire connections because lightning will melt the solder in a split second.
This antenna is out of balance. You should be able to get a return loss of < -25dbm RL across the band. while you were concentrated on shifting the frequency, you paid no attention to the bandwidth or the lack of suppressing that center null. When you see it on a spec an, or an antenna analyzer, it is pretty clear how everything plays together. You need to be able to see the spectrum in order to tune properly. Much respect for those who use these techniques. I would go mad before I could get what I wanted.
hi, i don't understand the J Antenna Model you short the signal power to the Ground !please explain , if i have 65 watt power output and i short it to the ground by the J antenna. thanx. all my antenna its depole. signal positif top and the ground down
It’s not shorted to ground at the design frequency, the J section forms a kind of resonant feed line that has an impedance transformation function. Basically the impedance changes from low to high as you move away from the shorted part of the J so you need to find the point where it is 50 Ohms.
Will work with 2 inch if thats what you got as long as you keep the lengths and spacing right. Most people use 1/2 because it's cheaper and easy to find.
Don't know much about antennas yet. What's the purpose of the coiled up cable? Is that part of the antenna design or just extra cable in case you need it?
not bad.....you're on the right track.....old timers like me use baluns for HF dipoles.....the coiled up coax makes a quick and nasty air-choke balun (?)....and for this antenna, it's the cheapest and best option, and cuts down on line loss and stray RF....the famous G5RV HF antenna uses an air choke balun, but for diff. reasons, cuz it's a multi-band that's made to use with an antenna matcher/tuner and with two types of feedline (50 ohm, and 450 ladder line) before it gets to the wire, which is 51 ft per side I think....at higher freq's, the antenna can be shorter....whole idea of ham radio...tinkerers...all of my antennas are made form scraps, and donated stuff whenever possible, and I have worked 100 countries in a weekend is some of the bigger contests, just using garbage and donated materials for antennas at 28-39 feet AGL(above ground level)....old zipcord stuff, like flat ext.cords for 120vac, is good for 300-500watts on hf...excellent for portable dipoles for QRP or barefoot (100-150W) use....maybe a tad more, but not really gud for running 1000-1500watts....old romex is excellent for hf dipoles/inverted vees.....they can handle the Kw plus input power at the feedpoint...thicker/heavier gauge wire the better.....12/14 gauge is common..hope this helps....
I'm going to make a "Thunderpole" Coaxial Collinear using a carpet stair rod (steel tube) for the 1/4 wave and half inch pipe for the lower section for 2m. Made one MANY years ago for CD - it was over 17 feet long with an SWR of 1.1 through the band - when it was away from a chain link fence! That one was all copper - a huge brute :) Point is, yes, tinkering with scrap is the way to go!
Newer timers use UHF powered iron toroidal cores. They don't radiate the same as an air coil balun does. Works very well. 2 or 3 just larger than the coax jacket and designed for the frequency are ideal. Don't confuse a ferrite suppression torrid. They are very lossy to attenuate RFI. You want the inductor choke for this application.
J Pole antennas are very hard to tune to get to 1.1 to 1 I have never heard any one get a J Pole to a really good tune. when someone does let us all know
I have built many J poles for 2m & 10m from aluminium tubing and got swr down to 1.0 ....... The trick with tuning j poles , is adjusting the feed point and also adjusting the element lengths as well ....... I use an Analyzer , so I also look for 50 ohms with lowest fragrance ........ de 9z4bm
Good job on the build, Next time you might want to invest your time in building a better antenna design. You might not know this but the Slim Jim and the J-pole are are variants of marconi style antennas and are nothing but snake oil whose performance has been massively over exaggerated. The over exaggerated gain claims of these antennas has been thoroughly debunked by some of the most well respected antenna experts in ham radio. In the real world and contrary to their fanboyz both these antennas have less gain then a simple 1/4 wave ground plane antennas. If you are using one of these antennas then your coax shield is actually acting like the antenna and not the so called Slim Jim or J-pole part of the antenna. That's why the performance of these antennas drops when you use a choke balun at the feed point Unfortunately inaccurate antenna modeling by a few unethical hams produced exaggerated gain figures that still persist to this day. Unfortunately these lies have persistent primarily because the average person building these antennas holds an entry level licence with little understanding of the math and science behind feedlines and antennas and as such they are easily sold snake oil. By the way you never way to use normal silicone to waterproof coax, Not only is it make a poor dielectric It's releases acidic compounds as it cures
Isn't the appeal of slim jims the space and weight that they don't take up? A quarter wave ground plane antenna isn't exactly a low weight, low volume item.
knupder actually a quarter Wave 2 meter ground pkanr antenna is significantly smaller than any J-Pole style antenna. The fact that J-poles are constructed almost exclusively of copper plumbing pipe and that quarter waves can be made out of 12 gage wire makes the J pole significantly heavier than the quarter wave. The only value j Pole style antenna offers is the Practical experience of learning to build a slightly more complex antenna design. by complex I don't mean better or more efficient just more complex to build A quarterwave ground plane antenna is exceptionally simple the build with so-239 panel mount and some copper 12 gauge wire. so it's nowhere near as much fun to build but it is a much more efficient antenna
You can make a slim jim out of ladder line though. You ever move through terrain that wasn't manicured for an easy walk? I wouldn't want to lug a ground plane antenna through actual bush. That would just be an exercise in wasted calories and frustration. I'm not saying that the technical aspects of one is necessarily superior to the other, but there's a time and a place for compromise. There does come a point where space and weight are at an absolute premium (and where things just snag on every errant branch that you encounter). For whatever the difference is between the volume and the weight that your ground plane antenna takes up (versus one of those roll up slim jims) that's as much food or medical kit that you aren't going to be carrying. It might not matter in a great many number of cases, but there does come a point where you're cutting the handles off of your toothbrush because the damned thing is just too big otherwise.
knupder 》》 thats true, but keep in mind that's a portable antenna and not something you would want to put on top of a 70-foot tower subject at 60 mile an hour winds or for that matter even on top of a 50-foot guide mast on your roof. So we kind of got to compare apples to apples and oranges to oranges. the one place where a Slim Jim or J- Pole shines is as a roll up portable emergency antenna.
I don’t believe a 1/4 wave gp would outperform this antenna, the j pole is a variant of the end fed dipole and should perform as such. I know there is some snake oil out there regarding what part of the antenna radiates and therefore how much gain is obtained but once it’s current distribution is understood ie only the part above the j section radiates then it should be understood its performance should be about the same as any other form of 1/2 wave antenna.
Lol I'm a plumber. I had a little chuckle when you said you're pretty good at soldering. I understand there is a huge difference in soldering copper pipe and wires, but i did look at that antenna just before you said that and I thought , looks like he had some trouble soldering. Lol
That's a real bad solder joints looks like he used soldering iron
I thought the same and I'm not a plumber. That solder didn't flow into the joints, or he couldn't tell that it did and just kept adding more.
If you are a plumber, why don't you mention to clean the solder areas with sandpaper, use flux on both ends, heat the joint then heat the opposite side where you touch the solder and it will flow to the heat, then wipe the excess with a damp rag?
@@nupss4710 A little late to the party, but that looks like the first time I tried to use my Hakko on a jpole. Had to get a blow torch, and some silver solder to do the trick.
Anybody watching this now make sure you waterproof your coax ends. Water will go down the jacket of your coaxial cable and short out your transceiver.
J poles make great antennas and cost almost nothing but your labor. I made my first using aluminum. Pushed one end into the ground and tuned it. I was amazed at what it could do.
I made this with just a U at the bottom and set it on my work bench. Made contact with a repeater about 15 miles away on 5W power. I am thrilled.
That SWR meter that you're using is for C.B. radios bro. Try using ones for 144MHz VHF.
PARTS LIST: 1 ten foot 1/2 inch copper pipe...1 1/2 inch elbow...3 1/2 inch caps... 1 1/2 inch T connector. a really hot soldering iron or a torch and plumbers solder (preferably) i prefer a so-239 connector soldered to the ground radial pipe (longest tube) and extend the center connector to the shortest tube (driven element).
If you build one of these, a piece of cardboard cut to the gap size makes a great construction alignment jig. Tape the tubes to the cardboard and then fold back from the areas you are soldering while all the components are secure to the cardboard sheet spacer. The jig would be nothing more than a piece of cardboard 19-1/4 X 1-3/4 inches. Assemble the components with tape. Fold out the bottom for the solder job. This holds the driven element and stub in align for the soldering.
It’s been my experience that if you hit a kind of SWR barrier (in this case can’t get it below 1:1.4) its because the elements that make up this antenna are out of tune (incorrect dimensions) or something is de-tuning them. Your video did not show you actually making the adjustments but was just showing it laid on a table with a SWR meter connected. Putting the antenna upright to keep interaction between the stub and radiator with the ground is needed to prevent such de-tuning, its also important to keep anything conductive away from the antenna (including yourself) during measurements for the same reasons. The adjusting section on the top of the stub is a neat idea but I would also put one at the top of the antenna as well, as with a fixed attachment point of a stub lengthening the stub will also have the effect of electrically shortening the radiator and therefore de-tuning it a little. A caveat I’ll put on the use of a silicone sealant is to only use a neutral cure type as the acetic acid in non neutral types can promote corrosion. If a silicone sealant is used wait for it to completely cure before using as wet sealant can be conductive and can upset SWR measurements. Apart from all that I’d say nice video.
Notice the SWR meter he is using. Made for use in 11 meters (an HF band) not 2 meters (VHF)!
Xlnt! My 'J' is now SPOT-ON. Thanks for the information.
I moved the coax up and down to get the 50 ohm's then add or remove some on the long part to get
It to resonate at the frequency I want . And as Always a Ballanced antenna fed with unbalanced coax needs a choke . This is an end fed 1/2 wave antenna.
This is also how I do it. although I use a spectrum analyzer and a coupler to see Return Loss. The coax is adjusted to balance the near and far lobe into balance. Adjusting the center end will shift the right lobe, while the shield side will shift the left lobe. The balance of the two will suppress the center lobe.
Helpful. Easy to understand. Not excessive. Clean technique. Thanks!
LOL!
Hi, by my calculations, to get the antenna shown to 'center' around 145Mhz the long upward section (A) should be increased from the dimensions given,... in length by 57mm & the short upward section (B) should be increased by 28mm. For 144Mhz value (A) should be increased by 63mm, and (B) by 31.5mm. For 146Mhz (A) should be increased by 60mm, and (B) by 30mm.
.
The 'balun-loop' length, is to match the unbalanced coax feed-cable, to the 50-Ohms balanced impedance position of the antenna,... and should be reasonable as given. The position of these two points of contact, for the coax, should be moved slightly up or down in parallel to the short horizontal stub, to obtain 50-Ohms balanced impedance while testing.
Your FRS & 2-Meter vids are great!😉 I'm just getting into HAM -& your helping me get into it alot deeper! Thanx!☺
"ham"
I think you would have to be very quick as you don't want to melt the inner insulator sheath or your SWR will be around 30:1 not good and will burn out your power stage so you want a 1:1 SWR.
That MICRONTA (Radio Shack) SWR meter is made for CB (27 MHz), not for 2 Meter frequency's. I doubt your'e getting accurate SWR readings.
You're right bro, I thought I was the only one who notice it. 27MHz is way way off from 146MHz with that SWR meter he's using. 73's.
Rainman makes a J Pole?
If the copper pipe isn't equal higher up, what about some PVC with T junctions on each end?
Copper is quite ductile, you could probably just bend the short side out a bit until the sections are parallel.
Does the DIAMETER of the copper tubing matter? For example, could I use tubing half that diameter, or even one quarter that diameter, without negatively impacting the antenna's performance characteristics? I need an antenna with a very low footprint visually. Smaller tubing would obviously help.
You can use any diameter tubing. A larger diameter tube will increase the resonance and a smaller conductor will decrease the resonance. This is due to the skin effect.
@@TheOKBluseman .. Thanks. But what does that mean? I obviously want to maintain as much performance (bandwidth, range, etc) as possible. You talk about "resonance," which means very little to me. At what point does smaller tubing have a detrimental effect on performance? Does quadrupling or more the diameter (4-6 inches or more) greatly improve performance?
@dwightstewart7181 Copper pipe gas gotten very expensive and you see a lot of J-poles these days made with twinlead or ladder line. The larger conductor diameter gives a slightly better bandwidth in theory but probably not practice.
2-6m is the sweet spot for a copper pipe j-pole. When you get into UFH you can't get the copper pipes close enough even using a street elbow. The gap needs to be very small compared to the wavelength. Parallel transmission line J-poles really shines in UFH.
As a practical matter power is the only concern when it comes to wire diameter. Ladder line can support about 75W.
How is it not shorted out ? The ground shield and center conductor are touching the same pipe basically
Radio frequency behaves nothing like DC (and 60Hz is essentially DC compared to RF). Most of RF "resistance" is impedance not ohmic resistance.
man i made 2 of them i even added brass tunning stubs but i am just unable to get it to perform any better then my. 1/2 wave 2 meter antenna.. I got the swr down like yours..
It will have about the same performance as a half wave antenna because electrically this is a half wave antenna. The part below the open end of the stub is just an impedance matching feed line.
Shango is that you? Came across this in a search.
Seriously, I half expected a repair of a vintage television from 1958!
Pas de vidéos en France 'bien dommage'
Dude sounds just like Shango....
Yes
Great simple and nice effective way to make one.
How long did it last
disini banyak ilmu yang kami dapat.
terima kasih semua nya.
what's all that stuff on the floor boards?
Dear sir if i do then its handle 500watt power for vhf
Hi, shango066 is it You? I found this channel because I am also building same j-pole antenna for 2m, and I am also a subscriber of You "shango066" channel
Why not use a non-conductive spacer at the top of the tuning stub
to keep it the right distance ?
+Jon Biddell can you show an example of non-conductive spacer at the top of the tuning stub?
+Dan Eriksen Something like a piece of lexan or plexiglass, cut to fit between the two elements to hold them at the right spacing
+Jon Biddell It doesn't need it, very rigid once soldered. Also it doesn't effect the swr much, the length of the tuning stub is whats critical.
Most important overlooked item.. The dielectric constant is different than air. Insulators in this gap will affect tuning as it changes the capacitance. Dielectric constant of air is very close to 1.0006. Polycarbonate is 3.0. Some materials will have dielectric absorption.
looks like he didn't clean, didn't flux, and because of that overheated the pipe causing it to warp like it did. You can see how discolored and gold the fittings turned, they are baked way past where they should have been heated for solder to evenly flow.
First thing to learn when building an antenna like this is how to sweat pipe.
IF you flux those copper joints before solder it will come through much cleaner, just sayin'
And, of course, if you polish the copper people will sound more polished!
Clean joints are a little difficult considering the tubing may have to adjusted several times before the antenna is complete. The goal here is a working antenna, not show-quality soldering joints. If you want looks, sand and polish the entire antenna to a high shine afterwards. Sure to impress your friends & neighbors.
Can you give measurements in civilised numbers?
My SWR is really high...like 3 + on both 146 and 147. Any thoughts on how to fix. I have the same set of plans, so mine is probably too long too. What is the finished length of the long radiator?
HAVE PROJECTS WITH NEURT OR CABLE LAND IN LARGER ELEMENT AND OTHERS IN LOWER ELEMENT
just curious if lightning is a concern with this?? sorry for stupid question.
Mine got hit a few years back, did do some damage. Remember to disconnect before a storm, if you're worried about it.
Caidyn Edlund You would want to use a grounding rod with any antenna like this. Also Ive been told terminal clamps work better than solder for the cable and wire connections because lightning will melt the solder in a split second.
These articles are very helpful and informidable need more put on google ke8hfu keep up the good work
This antenna is out of balance. You should be able to get a return loss of < -25dbm RL across the band. while you were concentrated on shifting the frequency, you paid no attention to the bandwidth or the lack of suppressing that center null. When you see it on a spec an, or an antenna analyzer, it is pretty clear how everything plays together. You need to be able to see the spectrum in order to tune properly. Much respect for those who use these techniques. I would go mad before I could get what I wanted.
Question: For concealment purposes I'd like to put the entire thing inside a length of 4" PVC pipe. Problem??
PVC pipe will effect resonance.
hi, i don't understand the J Antenna Model you short the signal power to the Ground !please explain , if i have 65 watt power output and i short it to the ground by the J antenna. thanx. all my antenna its depole. signal positif top and the ground down
It’s not shorted to ground at the design frequency, the J section forms a kind of resonant feed line that has an impedance transformation function. Basically the impedance changes from low to high as you move away from the shorted part of the J so you need to find the point where it is 50 Ohms.
Will this work with 3/4" pipe? I only ask because I have a ton of 3/4" pipe laying around, I could go get 1/2" if it isnt possible
Will work with 2 inch if thats what you got as long as you keep the lengths and spacing right. Most people use 1/2 because it's cheaper and easy to find.
I need to repeat 3 G phone signal (900-2100 mhz), can I use this design ? if yes, what are the sizes to use ? thnx
No.
Yes
Over that frequency range, no. But I have seen a j pole made for the 23 cm amateur band (around 1280mHz) work reasonably well.
Don't know much about antennas yet. What's the purpose of the coiled up cable? Is that part of the antenna design or just extra cable in case you need it?
not bad.....you're on the right track.....old timers like me use baluns for HF dipoles.....the coiled up coax makes a quick and nasty air-choke balun (?)....and for this antenna, it's the cheapest and best option, and cuts down on line loss and stray RF....the famous G5RV HF antenna uses an air choke balun, but for diff. reasons, cuz it's a multi-band that's made to use with an antenna matcher/tuner and with two types of feedline (50 ohm, and 450 ladder line) before it gets to the wire, which is 51 ft per side I think....at higher freq's, the antenna can be shorter....whole idea of ham radio...tinkerers...all of my antennas are made form scraps, and donated stuff whenever possible, and I have worked 100 countries in a weekend is some of the bigger contests, just using garbage and donated materials for antennas at 28-39 feet AGL(above ground level)....old zipcord stuff, like flat ext.cords for 120vac, is good for 300-500watts on hf...excellent for portable dipoles for QRP or barefoot (100-150W) use....maybe a tad more, but not really gud for running 1000-1500watts....old romex is excellent for hf dipoles/inverted vees.....they can handle the Kw plus input power at the feedpoint...thicker/heavier gauge wire the better.....12/14 gauge is common..hope this helps....
I'm going to make a "Thunderpole" Coaxial Collinear using a carpet stair rod (steel tube) for the 1/4 wave and half inch pipe for the lower section for 2m. Made one MANY years ago for CD - it was over 17 feet long with an SWR of 1.1 through the band - when it was away from a chain link fence! That one was all copper - a huge brute :) Point is, yes, tinkering with scrap is the way to go!
Oops - CB not CD :)
Newer timers use UHF powered iron toroidal cores. They don't radiate the same as an air coil balun does. Works very well. 2 or 3 just larger than the coax jacket and designed for the frequency are ideal. Don't confuse a ferrite suppression torrid. They are very lossy to attenuate RFI. You want the inductor choke for this application.
Are you Shango 066 your voice sounds like it
John the electron man ensor uy
Очень хорошо!!
Why do you need the four turns coiled at the top?
what is the web link for the drawing?
Haz mas antena j pole gracias
wot gives the frequency distance!!!!!
the wavelength. a 144mhz signal has peaks about 2 meters apart.
Nice video. Thought your voice sounded familiar! Your radio and tv videos are awesome! Are you a ham or just tinker with radios too.
👍
73
Dave
на обычный провод так же ловиться будет!
Shango 666?????
I'm pretty sure
@@hotsauce2446 Gotta be
And a razor blade to cut a couple of lines. I'll cut the first, you cut the second and then we will get started! lol!! Just kidding. Neat build man!
Minta sekema nya mister
J Pole antennas are very hard to tune to get to 1.1 to 1 I have never heard any one get a J Pole to a really good tune. when someone does let us all know
Mine is 1:1.17 on the low end and 1:1.27 on the high end, pretty happy
I have built many J poles for 2m & 10m from aluminium tubing and got swr down to 1.0 ....... The trick with tuning j poles , is adjusting the feed point and also adjusting the element lengths as well ....... I use an Analyzer , so I also look for 50 ohms with lowest fragrance ........ de 9z4bm
Very nice
Nice this video
Good job on the build, Next time you might want to invest your time in building a better antenna design.
You might not know this but the Slim Jim and the J-pole are are variants of marconi style antennas and are nothing but snake oil whose performance has been massively over exaggerated. The over exaggerated gain claims of these antennas has been thoroughly debunked by some of the most well respected antenna experts in ham radio.
In the real world and contrary to their fanboyz both these antennas have less gain then a simple 1/4 wave ground plane antennas. If you are using one of these antennas then your coax shield is actually acting like the antenna and not the so called Slim Jim or J-pole part of the antenna. That's why the performance of these antennas drops when you use a choke balun at the feed point
Unfortunately inaccurate antenna modeling by a few unethical hams produced exaggerated gain figures that still persist to this day. Unfortunately these lies have persistent primarily because the average person building these antennas holds an entry level licence with little understanding of the math and science behind feedlines and antennas and as such they are easily sold snake oil.
By the way you never way to use normal silicone to waterproof coax, Not only is it make a poor dielectric It's releases acidic compounds as it cures
Isn't the appeal of slim jims the space and weight that they don't take up? A quarter wave ground plane antenna isn't exactly a low weight, low volume item.
knupder actually a quarter Wave 2 meter ground pkanr antenna is significantly smaller than any J-Pole style antenna.
The fact that J-poles are constructed almost exclusively of copper plumbing pipe and that quarter waves can be made out of 12 gage wire makes the J pole significantly heavier than the quarter wave.
The only value j Pole style antenna offers is the Practical experience of learning to build a slightly more complex antenna design.
by complex I don't mean better or more efficient just more complex to build
A quarterwave ground plane antenna is exceptionally simple the build with so-239 panel mount and some copper 12 gauge wire. so it's nowhere near as much fun to build but it is a much more efficient antenna
You can make a slim jim out of ladder line though. You ever move through terrain that wasn't manicured for an easy walk? I wouldn't want to lug a ground plane antenna through actual bush. That would just be an exercise in wasted calories and frustration.
I'm not saying that the technical aspects of one is necessarily superior to the other, but there's a time and a place for compromise. There does come a point where space and weight are at an absolute premium (and where things just snag on every errant branch that you encounter). For whatever the difference is between the volume and the weight that your ground plane antenna takes up (versus one of those roll up slim jims) that's as much food or medical kit that you aren't going to be carrying. It might not matter in a great many number of cases, but there does come a point where you're cutting the handles off of your toothbrush because the damned thing is just too big otherwise.
knupder 》》 thats true, but keep in mind that's a portable antenna and not something you would want to put on top of a 70-foot tower subject at 60 mile an hour winds or for that matter even on top of a 50-foot guide mast on your roof.
So we kind of got to compare apples to apples and oranges to oranges.
the one place where a Slim Jim or J- Pole shines is as a roll up portable emergency antenna.
I don’t believe a 1/4 wave gp would outperform this antenna, the j pole is a variant of the end fed dipole and should perform as such. I know there is some snake oil out there regarding what part of the antenna radiates and therefore how much gain is obtained but once it’s current distribution is understood ie only the part above the j section radiates then it should be understood its performance should be about the same as any other form of 1/2 wave antenna.
Good,Day This is 7HDB JR=JULIET ROMEO -J.R
MY CLUB HRC
HAM RADIO CEBU INC,APOLOGIZE to share diagram every Ham radio
Know you are doing this for us ... but set up camera and show each part. This "magic cut" stuff is not helpful.
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good73
If its so critical, why don't you use millimetres? Wtf
Looks like a dead short to me.!!!!!!