Mechanical Issues with EFHW Antenna (
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- čas přidán 9. 09. 2024
- Rolf, KE1Y, has a EFHW 80 - 10 and it's wire has broken near the loading coil. He wants to know if there is a better way to have the loading coil so it would be so likely to break and Dave's view of the EFHW.
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Hey Dave, You just need to wobble your drill in a big circle to get what he was looking for in the hole shape. Good day Dave!
This would also work lol
As for that PVC pipe coil form, I have used a counter sink bit or a bigger drill bit to take the cutting edge off the hole. And at the big box stores is a metal drawer with an assortment of rubber grommets that could be fitted into a larger sized hole and that rubber will protect even better than chamfering the edge of the hole as it's protecting the wire inside as well as the outside edge of a already thin pipe hole. Before anyone says the rubber will rot, well nothing lasts forever. But this may last longer before it has to be rebuilt again.
My 80-10 has been up for 2 years and went through an F1 tornado. From what I have experienced, My Antenna has great build quality and I have been able to talk to the world with my 991 barefoot. I use it in a 130 plus foot horizontal orientation that is pulled as tight as a banjo string and well above 20' off of the ground. I have taken it down a number of times to use while camping, for POTA, to change the configuration and to let people borrow it. The transformer has gotten beat up real bad and all of the mounting points are broken off of it. I keep it strung real tight with ropes and weights connected to the eye loop and I STILL will tell everyone that they should own one of these antennas. Hands down the best setup available for someone just starting out or a seasoned veteran. Awesome reception and remarkable reach. Many of my friends have this antenna and we all love it and have never had a problem. I wholeheartedly feel like this was an isolated incident somehow. As usual, great video and thank you for all you do for our awesome hobby.
KD2TCM
I'm glad you mentioned that that transformer is technically an UnUn. Many amateurs are lazy and call ANY transformer a BalUn. 73, from the Netherlands de PD0PSX.
The metal thing inside then end loop of wire is called a thimble. Confusingly, not the same as a sewing thimble, but routine for making eye splices in ropes and cables.
Darn, beat me to it! ;-) And the "solder circular thing" is a ring tongue lug. :-)
Putting up this antenna soon, and became concerned after viewing this. My solution is to use a zip tie through the plastic spool ID and form a loop around the
two wires. If you adjust the length of the loop carefully , you end up with the two wires enntering the Id of the spool almost vertically. The stress is now taken by
the zip tie which has no sharp edges, rather than the holes. The zip tie can also flex a bit presenting more surface area to the face of the wires.
BTW no need to take the wire off the spool. Done in place in five minutes. Remember to cut off
the excess zip tie flush to the tie head. The second problem of coil seperation can be addressed using a second zip tie thru the spool id
and over the wires on the outside. The guy that invented the zip tie should have got a nobel prize. I would post pics if I knew how to do it.
It's not a design fault, it's an installation fault. Your friend Rolf did not think the installation through. I used to make the same mistakes back in the 80's. I used to have my wires taught with no sag. It makes no difference in the performance of the antenna by having the wire a little loose, but it will last years or decades longer. Take the strain off the wire and use a pulley and counterweight.
Yeah we gotta be careful about the details. You do a marvelous job of explaining such issues. Great video.
I have a different but related EFHW issue. FINALLY - able to get around to putting this up. This will be my first HF antenna.
A Home brew 80-10 EFHW.
== Scenario: Had an arborist come out to put my flange with pulley about 60' up in a 100+' douglas fir - the other end of which will be mounted to the top of a 21' steel extension mast (easy up mast) extending from a stout 5' steel tripod mount on my back porch, which I plan to guy with 2 sets of 3 rope guys (@ 12 & 20') . Total distance from top of mast to tree about 150'.
I will be putting a free weight - along with springs along the line - and a bungee from the bottom of the weight.
Antenna is the 14 gauge copper coated hi-strand count steel (forgot the name - but was well spoken of).
== Question: Regarding the 20' tower -- ALL the pull is the direction of the Tree.
(EFHW is unlike a dipole - in which you get antenna pull in both directions)
Wondering if I should I add extra guy(s) opposing the direction of the tree. This then would make the guy system assymetric.
Not sure whether the asymmetry is worse than not having a directly opposing support guy.
[ In many places it might not matter. Here near mt. St. Helens in Washington we can get some nasty winds as we are on the side of a 600' hill over the Columbia river. Once a few years back got 120 mph tore off our whole porch and much other damages - I pray to never see that again, but 60-70 mph is not uncommon. Figure to unextend the mast if any such winds are forecast.]
Perhaps you have had experience with this unbalanced force using an EFHW.
I am really anxious to FINALLY get on the air on HF, ...but I want it to be a joy and not an accident waiting to happen - LOL.
Any thoughts would be appreciated.
Regards,
RH W6VU
Very useful, thanks again
I've found that bungee cord will deteriorate if left out in the open. Modern bungee cord is generally not as good as it used to be, for sure. However, the same farm store I can get bungee cord from also stocks tensioning springs for electric fences. I'd be inclined to use one of them at the tree end, making sure it's well enough isolated from the antenna wire by at least 6ft of rope, to avoid de-tuning.
I used two screen door springs to hold up the ends of my carolina windom antenna and it has survived multiple hurricanes over the 20 years it has been in place held up by the topmost branches of the tree. My biggest worry is that the cord holding it up has been incorporated into the tree itself so I won't be able to lower it to replace the coax.
Dave this is the second time I watched this one thing I do is to leave enough slack in the wire to negate the motion of the tree during high winds. As you know we get hurricane force winds here on the front range. 73 ki0ad/Jim
From an engineering point of view on using a pulley and weight on one end. There is a constant weight on the wire. As a tree sways in the wind the wire moves through the pulley. The weight never flys around and puts any more tension on the wire. I've got 45' palm trees that sway in heavy winds. The weight sits there gracefully and keeps a constant tension on the wire.
I have an MFJ version of this design antenna. The skinny 20AWG wire broke three times in the mid-span before I ripped it all apart and replaced everything except the toroid and the SO-239! I used 16AWG THHN wire and wrapped it around the PVC pipe coil exactly like it was before with no issues. I have the wire threaded through a PVC pipe standoff with refrigerator ice maker hose around it at the apex, so the wind does not allow much movement and strain on the goofy loading coil... The other end is connected to polymer cord and tied to a tree. It works exceptionally well and I am a big fan of EFHW antennas now!
Epoxy over the holes, so they are not chafe points and the wire can be lead straight off the coil form. And change the antenna wire to the type Chameleon uses, with an internal Kevlar strand to take the load off the wire itself.
Use a deburring tool to bevel the edges of the holes. What is really needed is a redesign of the coil mount with strain reliefs like the unum has.
If you elongate the holes by drilling at a shallow angle in line with the tension there are two beneficial results. The sharp edge is eliminated and equally important the bend 'radius' will increase. Both lower the stress concentrations in the wire.
A countersink drill bit that is used to drill a hole for flush screws can provide a hole that is angled and not a 90° edge.
A chamfer in the coil would be advantageous because like you mentioned Dave, the movement of the tree has incredible power it would be better if some form of strain relief on the coil would be much better , perhaps an insulator could span the gap, and letting the coil droop or lay along the side , something to allow the torque off from the PVC because it will eventually saw through either the wire or thin tubing wall. I really like the idea of the bungee, when I was a lad my dad helped me with my HF wire , he used a pulley and a bag of sand on our setup , when I removed the antenna years later, that brass pulley was polished as glass, from extreme movement, the rope was similar to the type you'd use on a lawn mower pull start. And it was worn almost completely through. So yes you need a good shock absorber, if you lash an antenna to a tree.
You could countersink the hole with a larger bit to provide a taper to relieve the sharp edge... maybe?
Yes, or use a countersink bit if you have one.
Well Dave you've done it again, you debunked, distroyed, and informed me. For years I bragged about my ingenious weighted connection at the tree end of my HF dipole. The "inertia thought" never occured to me. (oh snap) If it had I might have still used the 3 window weights hanging from a rope that went through the brass pulley but I wouldn't have bragged so much. I regularly give a hardy AMEN while taking in the multi-discipline approach you bring to this hobby.
Drill the hole on a tangent. And a hot glue gun wouldn't be without it
You say at time 6:37 'I don't know of any tool that would make a hole like that'. But that's easy. If one could get to that box without the wire coming out of that hole, one could just take the tip of a pocket knife blade and cut into that plastic and turn that cylindrical hole into a conical one. And then make sure to e.g. use a chain saw file to make sure the plastic is smooth. If one could get in there, one could also try to attach the edge of the wire to the side of the unun downstream of that hole.
last weekend I bought a Chameleon Emcomm 3 EFHW and an FT891 on a little overnight radio expedition with the club into Uwharrie National forest in central NC. All of my previous experience was with 2m repeaters. The antenna went up easily in an inverted v and had contacts across the eastern half of the country in a half dozen nets and one weak contact in Germany. I got a lot of complimentary signal reports. Pretty good for a first time HF use.
My EFHW8010 has been up as a sloper going from 20' to about the 75' level of an 80' pine tree has been up for seven years now with a pulley in the tree and a 20 lb downrigger weight hanging about 8' above the ground. Maybe I've been lucky, but it's survived several rounds of 50-60 mph winds. One thing that mitigates the stress on the hole is that the other hole is on the opposite side of the short little tube. That tends to pull it to an angle and make the entrance more like 45 degrees than 90. Did he have the end tied directly to the tree? Almost any antenna would break somewhere if it's not allowed to move with the wind.
On my homebrew Antenna's Coil I drilled the holes in the PVC at a 45* angle so the wire is NOT on a sharp cutting edge.
Another way uses added hardware is to put the same type metal clamp as the connection point uses and a piece of Dacron rope with knots tied in each end so ALL the stress is OFF the Coil form and lets the PVS just float like you would to build a splice.
Strain-relief on the coil. Put small clips or rings like a key ring on each end of the tube, and install the same type of strain relief that's used on the UNUN. Then the antenna wire will be pulling on the strain reliefs.
I have used that very antenna for the last 3 years with zero issues. I’ve been amazed with how it has performed.
73
de WA9SWW
I've seen designs for that coil where there's strain relief before and after the chunk of PVC pipe, which would solve this issue. It can even be done with a couple pieces of paracord. It also allows the coil to be made out of a different material, like some enameled magnet wire, which could make it smaller for the same inductance.
Replacing that piece with your own inductance coil can be tricky, since the dimensions of the wire and coil form, the number of turns and the insulation on the wire all change the inductance. While most multimeters can't read inductance, a nanovna can, with the help of a known-value capacitor, provide enough data to deduce inductance.
Mine has been up for 4 years in various configurations. All my wire antennas float, The efhw isn't mounted solid to a tree or post but hangs away from tree by a length of dacron. Then up 30 feet through an insulator on limber limb which is like a spring. Then to 80 foot into a pine. I like pulleys because my pines can sway 6 feet easy. I've watched the weights go up and down as if monkeys were in the tree pulling em up. I use a heavy chain as a weight. 10 pounds is usually enough to keep antenna with good tension. As the trees sways it pulls up more chain adding resistance. Better than springs and bungee cords. 3 location of mounting that can give some play.
You can use a countersink to deburr the hole. You shouldn't have to do that considering how much these cost. The fact that they don't deburr that when they assemble them is disappointing to say the least.
Can't do that on the inside
@@DonHavjuan yes you can, but it's a different tool. Look up noga back side deburring tool.
hey Dave on phone in hospital so didn't read all post ... but on my builds on items like this i drill the holes at an angle (about 60 deg or so ) pointing towards ends of pipe so no sharp turns wire is near straight pulling mostly on wire itself
Good idea!
@@davecasler Hey there . You are my hero ..I,ll donate when I can Im 63 and bad health issue restarted back into "Hamming" about 9 months now . I watch all your videos. I'll explain more later . but wanted to tell you how valuable you are !!! thanks Robin N5sfv (kb5oop)
To create a chamfered hole...wobble the drill bit after you drill the hole!😱👍
😁 Figured it out regarding my question below - about whether to add a guy in opposition (180 degrees from ) the antenna connection and its concomitant forces.
Not another 'guy' at 180 degrees opposed the singular direction of the EFHW antenna, but extending the rope through a pulley at/near top of mast to a tie up point (think I'll use a cogged takeup reel) at about the same radius as the guys. Realized it is best if I can lower this from both ends - initially had it fixed at the mast side.
I've done this with PVC pipe with the appropriate size hole and then a circular file that simply rotates around at a 45 degree angle in a circle and makes exactly the shape that you showed in the picture with smooth edges on the inside of the tube and on the outside of the tube.
Might have been mentioned, but use some skinny fuel line as a protruding grommet thought the holes. Won't fix the overall problem, but will get rid of the sharp edge concern.
My EFHW 4010 1k is 6 years old and still works fine still. Put in an inverted V with apex at 22 feet up from the ground, I haven't seen any issues mentioned above.
I have both an 8010 and 4010 My Antenna EFHW up as inverted Ls for 3 years with no problems. I have counter weights and pulleys at the far ends everything is mounted on & in trees. The loading coils are in the 35' up legs of each antenna which probably eliminates back and forth wear & tear on the wire......... 73 Mike K1FNX near Boston
You could use a counter sink drill to round the corners of the holes or a step drill will some what help the sharp corners
I am using EFHW-8010 since 2017 and it seems no issue since then..
- Mangesh
VU3OUM
I might try model airplane fuel line. You would have to make a larger hole though.
I used a countersink drill bit to taper the holes in the plastic pipe I used for my clone of this...
The metal thing to prevent chafing of the insulation at the strain relief is called a thimble. I agree completely that the coil needs a proper strain relief similar to what the unun box has. Droop in something like a cable is called catenary. There are tables used for the breaking strength of wire according to diameter that are used by industry all the time. So i'm afraid this study is false. 16 AWG copper is not exempt from the laws of physics. Absolutely I am a subscriber to your excellent videos.
Counter sink bit I worked machine shops and that what we use
You can chamfer the hole on the outside of the pipe, but the inside has a sharp corner too. This inside is impossible to chamfer. In a similar problem with a different antenna I chamfered the outside hole and passed a short length of vinyl tubing through the hole. I passed my antenna wire through the tubing. The tubing protects the wire and the antenna lives on!
I chamfer the inside by drilling a larger hole on the opposite side use the same drill bit to countersink by hand the underside of the small hole regards Ei7gg
I'm using the Hyendfed 5 band efhw that has the loading coil terminated with stainless steel screws and ring terminals connecting the wire and it appears stronger than this design.
You can take a hot pencil iron and melt a rounded hole , easy peasy .
if you search for marine grade bungee cord you can find it if various lengths, usually black in color and UV resistant which equals longer life.
Running a strain relief through the pvc choke with a non conductive line and clamping it to the antenna on either side of the choke would be a fix.
But obviously the antenna should have a tensioning spring or counterweight at one end to relax the load when under harsh conditions.
Drill hole at an angle to relief the inside then chamfer the outside. Easy peasy.
The Un-Un in the MyAntenna's EFHW is a tuned transformer with a specific graphite toroid and a capacitor. The loading coil moves the resonant frequency on 80 meters. There is a fair bit of engineering in the specifics to get that antenna to match well in the ham bands to work well with minimal tuning at the radio. There is a channel on YT where the presenter explains it in detail and shows how to build one for a small fraction of the brand name cost.
Whatever you built, it is nowhere near the transformers we make. We do not use cheap FT-240-43s in our transformers like EFHW-8010-1K+ Also, the coil does not do anything on 80m, it is made for 10/12 and 15M bands as a matching device.
@@danielhorvat4340 I'm sorry if I misremebered some of the details. My point still stands that the brand antenna has more design/engineering than the typical EFHW antenna design. That work provides a better match and energy transfer at the frequencies in the Ham bands.
DX Engineering sells premium 14 gauge antenna wire made for this purpose. Their wire has a 92.5# breaking strength ...... order on-line, DX Engineering will make sure it is shipped promptly to your home.
The 14ga XLPE wire use in question is 200# breaking strength
@@danielhorvat4340 Amateur Radio Supplies sells stealth antenna wire. Their POLYS-13 is made from 13 AWG wire, and with a break strength of 370-lbs. The company was founded in 2012 and ships to 65 counties around the world.
@@kevingary7018 Actually it was available more than 10 years ago by DavisRF. Great wire, a bit heavy and stiff.
@@kevingary7018 Looks like strong wire......copper clad steel wire.
i use a screen door spring . its about 3 foot long. works great
Yeah a simple rubber grommet would have reduced abrasion. Plus I prefer a 2.5lb weight to hold tension rather than hard connection or spring.
Problem with bungee cords is they eventually stretch out and will not spring back.
Why not suggest TH W N from Home Depot? The “w” in the nomenclature indicates weather resistance.
I’ve got mine set with small carbon fiber sailboat blocks (pulleys) at the beginning, middle and distant end and then rope and a plastic jug with water close to the ground. I’ve had branches fall on the wire and drag everything down but never break anything.
A simple countersink cutter would take off those sharp edges, before you push the wire through.
A little slack in the wire and a pulley on each end works great
No, don't use a drill... Use a soldering Iron bit... Lovely smooth edge..
DX Engineering carries a premium antenna wire which might fit somewhere between My Antenna's wire and big box store wire as far as cost vs quality. DXE-ANTW-300
thanks for nice information. Will there be less strain if we attach antenna wire to a pulley up to the tree with a counterweight? So that the strain will remain constant?
He could have skipped the hype and bought the Chameleon EFHW and not have had to deal with that loading coil. Still he could pass on that and just run straight wire at the correct length for his unun. I think you can build a better antenna from Palomar Engineering. They are very knowledgeable and helpful. I have some 100 foot pines on my land and those trees get to swaying a good ten feet or more at the top in a storm. Some sort of strain relief is required weights on pulleys, bungees or possibly springs in some cases.
Great videos! How do you attach the bungee cord to the antenna? Thank you.
when i put up a wire like that . I used old ceramic telephone I put a brick on each end of the antenna so if the tree swayed the rope would let the antenna to move. .
COUNTER SINK ! o,r a DE-BURRING tool from Shaviv or Vahrgus, or a heat source to melt a little radius on the sharp edge.
You could use a drill bit thats roughly 2X the size of the hole and bevel it.
Insert a split rubber or neoprene grommet.
A drill with bit rock left to right once in the hole
Excellent advice as usual, Dave. Many thanks! I think it would be very helpful if you presented a model, photograph, or clearly drawn diagram of the tree end of your antenna installations, especially for new amateurs.
For example, how is the bungee end to be designed, exactly? What does the completed configuration look like?
Specificity for the unknowing is the trick. And who better than “Doctor Dave” to tell A N D shows the best way.
Thanks again!
Bill
Chicago
KD9JYS
0
Another fine video Dave. Is the extra screw point for counterpoise or ground? Thank you. (granted they are "related")
How about a countersunk hole?
what is that coil used for David?
What diameter bungee cord do you recommend? I can buy it by the foot, but I’d need to specify the diameter.
I'd suggest a piece of heat shrink on the wire and then through a countersink hole. Brad. KC6NNV
Why not just insert a bushing in the hole and flange the ends?
How far above a metal roof should I place efhw
Why any one pays that price for that antenna is beyond me. So easy to build and very hard to spend 100.00 on it
Actually, you can't get all the parts in EFHW-8010-1K+ for $100 and we sell it for $209.99
@@danielhorvat4340 Sure you can. I built mine for about $50 wire and all. That's a rediculous price.
@@danielhorvat4340 I guess it depends on what grade of coax and how much comes with it.
@@TheRetiredtech Coax?? What is that have to do with the price of the antenna?
I would try shooting some Silicone sealer inside and around that Hole .ALSO install a strain relief at bottom like a spring or pulley with little weight or water Jug . 73 W5heh AJ
How about a rubber grommet
End feds are great and use a 9:1 myself...BUT it seems like they will some more time to get it tuning and some times more work for physically mounting. Get past that stuff and you are JAMMING! LOL
73 de N2NLQ
It IS a design defect..no question. Best practice... You're joking.
That's most probably a mishandled installation of the antenna.
Also, this video has misinformation about the price of EFHW-8010-1K+, it is not $289.00, It is $209.99
Thanks Daniel! I have your EFHW-8010-1K and your EFHW-8010-2K put up in different directions as slopers and I am extremely pleased with both of them. I have also told other hams about your antennas and how well they work. Thanks again! Bill N3EDO.
Do we even need the loading coil? I have end feds that don’t have that but work on 10m fine. Anyone?
The Un-Un in the MyAntenna's EFHW is a tuned transformer with a specific graphite toroid and a capacitor. The loading coil moves the resonant frequency on 80 meters. There is a fair bit of engineering in the specifics to get that antenna to match well in the ham bands to work well with minimal tuning at the radio. There is a channel on YT where the presenter explains it in detail and shows how to build one for a small fraction of the brand name cost.
@@BryanTorok that’s odd bc I have Efhw antennas that are the same length 135’ that don’t need it for 80m
More a transformer than a balun or unun.
It is a UNUN transformer, it does not produce the same magnitude on both ends of the secondary winding. There is also a BALUN transformer too, even for such high ratio of 49:1, we tested it for full-wave doublet.
rubber grummet.
This sounds like a smear campaign
There are a few problems with the complaint from this man. The 1st is that (according to his wild accusation against My Antenna dot Com) he had the antenna installed in two very large pine trees about 100' up with no stress relief at all. The 2nd is that the owner of the mfg offered him a refund on the antenna after it failed about 1+ years after installation. No matter what you have done at the hole location the wire would have failed. I would suggest that had he taken the time to measure the wire he would have found it had stretched over two feet prior to failing. This was an installation error that nothing mechanical on the part of the mfg could have prevented... A good operator would never install an antenna in such a location with no allowance for the movement of trees...
Yes, and he told me that he will start a campaign against us on the internet after we denied sending him another "same badly designed" wire for free. He also does not want to get money back even it is against our return policy, but we do not care much about money but more about the electrical design. Anyway, it seems it does not work for him since we get more sales every time someone tries to tarnish our reputation online. 73 Danny E73M aka N4EXA
@@danielhorvat4340: My comments on the Facebook post under the name:
Alphonso Moscowvitch, (ex-wife problems) and quite frankly he was letting his experience as a lawyer override his lack of knowledge on how to install an antenna... I had no problem paying for a new wire when mine stretched from an event not under your control and did not even ask you to replace it for free, as the problem was not yours, but mine! If this old man that survives on a limited income can find a way to pay for a new wire, it would seem a highly paid attorney should be able to do so as well... Great antenna, and If I had the money I would buy another one, but that will not happen for a while... K5KBK PS: The world now has two fewer Buzzards!