EFHW Antenna --- Building The Transformer

Here is how I assembled a 49:1 impedance ratio transformer for my EFHW.
Correction: Torroid part number is 5952003801
Link to torroid www.fair-rite.com/product/tor...
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Newer video • Multiband & EFHW Ante...

[@glevideo]

Thanks for the tutorial on winding the transformer. I built one on two cores for my 100 watt TX and have had it up for a little over two years now with no problems. Originally I put it up because it was fast and simple to get it up and on the air after just moving to this location but it has turned out to be the best performing antenna I have ever had. I'm not taking it down.

[@wm0davis]

Well done presentation of the transformer mounting details. Thanks. Parts on the way. Keep those informative videos coming.

[@w1rcp]

I have built three of these. This video was what spurred my curiosity when a local ham mentioned this channel. I recently had to repair one because the nuts came loose.

[@presidentspilot]

Steve, you make the very best videos!! Your research is so darn thorough!! Your comparison of the inverted 'V' antenna versus the EFHW antenna, was VERY ENLIGHTENING!! ..so I will go with the EFHW antenna, due to the flexibility of the many band capability! I have watched your successive-years progress, in building your many 49-1 baluns, and have recently ordered another 3 X FT240-52 mix toroids, to see if I can improve my SWR on the higher bands over my last build. This build is your latest. I want to thank you for ALL your GREAT VIDEOS!! They are so THOROUGH in providing ALL the needed part numbers and information required for the builds!! Thank you so VERY MUCH, for ALL of your HARD work, to advance Ham Radio, Steve!!

[@barrykery1175]

Very well done video. Very informative. I use a QRP one for portable all of the time. Great little antenna project. Mine is 10 through 40 meters and it fits in my shirt pocket. Barry, KU3X/QRP

[@shawnp6653]

Very nice! Thanks for taking time to share with us - always learning!

[@al7ps317]

absolutely beautiful craftsmanship

[@gsansoucie]

This is excellent Steve. Thanks.

[@BGLENN-dp4tx]

Very nice craftsmanship, explanation, and presentation photography. Thank you very much. 73

[@tglenn3121]

Thanks, Steve, for providing the part number for the box. That helped tremendously!!

[@roncrow3965]

I built this with house wire works great on 20 M using a minimal ground system thanks Steve

[@19134ANDY]

how many feet of wire did you use for 20 meters

[@fontesdeo8582]

Most Lowes stores carries these Carlon boxes under item number 10008. They also have one made by Cantex under the item number.

[@yaesuicomkenwood]

Great Job Steve, thanks for all infos. Regards from Bavaria. Mark

[@fishalcoholic]

5952003801 is the correct toroid part #.....great video!! Thank you.

[@n8nkqrp595]

Thank you. Another excellent source of ferrite and powdered iron magnetics is Amadon Associates. I've bought all of my cores, beads, etc. from them for decades. 73 OM

[@n4lq]

Why Amidon excellent since they are the most expensive? This core cost $15 each from them.

[@n8nkqrp595]

Nobody buys all their parts from one source. Mouser, Newark, DigiKey, etc are fine for an FT37-43 or a T50-2.. but when you're looking for more exotic magnetics, I'm sure Amidon and Fair Rite (sp?) are your only (or easiest) sources. FT240-43 core is $9.75 at Amidon. The coatings on the Amidon cores is in my opinion, far superior, as is the overall quality. When I buy 50 pieces of cores - the Amidon site's ease and convenience mean more to me than cost. I've never bought fro FR but I bet buying from them is just as easy. Just wanted to point out to your subs that there's an excellent source available to them

[@n4lq]

Right and also in addition to the lowest price, Arrow has free shipping via Fedex overnight 1 day service ...Oh and they also take PayPal. Beat that.

[@n8nkqrp595]

Thanks for the info! 73

[@garyscott2741]

Thank you so much for these great videos. I plan on building one like this. Will probably opt for the more expensive torroids.

[@davideisenberger6197]

Excellent video Steve as a PART II to your winding video! 73 David de K8KEM

[@mbutts1139]

great video and parts info!

[@garrykraemer8993]

Great presentation. I took notes and have parts ordered! I can't wait until I get the toroids and wire. Thanks! WD0DUD

[@n4lq]

Great. Be sure to watch this newer version kzbin.info/www/bejne/eKHHoZ6Lerxmb9E

[@hubercats]

Very helpful. Thank you!

[@STxFisherman]

Great video, thanks.

[@dheller777]

I have an Mfj half wave 10-80 end fed. I think I paid a little over $80 for it. I use it as an inverted V and the swr is over 3-1 on most bands and it is only rated for 800 watts. Yours looks to be a much better unit and It seems to perform much better than mine. Thanks for sharing.

[@f.allenrisler5303]

kzbin.info/www/bejne/n37Ff5Krecqsi5I

[@TennesseeArborist]

Interesting bit of info - I work for the company that handles the waste from the Carlon plant. I find these boxes in their plastic waste bin ALL the time :) of course i have an extensive collection going W3GST

[@Stingmni]

A treasure. If I was closer I would buy a dozen from you

[@alexalonso2093]

If I may contact you about those boxes I would just buy a few from you so I could build my set up like Steve Ellentins .

[@midimagic7097]

WOW they are over £20 in the UK.

[@acoustic61]

Nice work!

[@pmsecretary52]

STEVE YOU ARE THE MAN!!!

[@allanmacuser]

Thanks for the video its has been a great help best regards Allan G6TMO Stoke on Trent UK

[@floridasaltlife]

Excellent video...

[@janvisser8452]

Steve, it would be interesting to test this on a 2500 ohm rf resistorset. These are small these days and are designed for a heatsink. At 10 watts this should give about 158 V on the load. And from there to look for power saturation and the bandwith. We hope to hear from you.

[@19134ANDY]

Great Video and very informative on the parts you used Thank you

[@mortimersnerd801]

Nice video quality and nice workmanship Steve. Even though not trying to be a 'big gun' and operating with modest equipment (FT 891) I am constantly amazed at how well a 130' EFHW works, it's up 30' at one end and 55' the other. I work almost every DX station I hear if I get a break. Careful attention to workmanship, and winding spacing makes all the difference Steve. Like most I now use a single (no I don't run 1500 watts I'm on a 12 V battery) 43 mix core, but it's efficiency starts to drop above 21mhz and I start to see a wee bit of VSWR creep...Works OK but you can tell. If you primarily operate on the higher bands maybe the 52 mix is the way to go. I use #18 enameled wire now because it allows windings to sit tight against the core and you can shift the windings closer or further apart.. very important. No counterpoise, no common current chokes, don't need em just the coax which is LMR 400....and an earth ground drain for electrostatic build up because the antenna is high Z. Am going to try a 52 core next then stack a 52 and a 43 to see what happens. If the vswr creep disappears I know I will have won some efficiency back.

[@n4lq]

Since 52 mix has lower permeability you will need to have more cores in order to maintain the same inductances. Even if you're not running a KW you still need that inductance. 52 mix will give you more efficiency. Also you say you don't need a choke. Well maybe you don't think so but you will have RF on the coax's shield and it will act as part of the antenna. If you mount the transformer near ground, put the choke near it and connect a ground wire with a ground rod. If you measure the antenna's current with an RF ammeter you will see it increase since all of the current is forced into the antenna and not the shield. That translates to DBs. The coke needs to have high impedance. Use 8 turns of Teflon coax around a 240-31 core then another. Yes, 2 cores in series which doubles the impedance. This will pay off in DX.

[@K6TJO]

Steve!! I need to take you and your wife to dinner. Love this!! Building mine now! K6TJO 73

[@ukiahbikeman1]

Thanx Steve How were u able to get in there to solder the center pin of the SO239?

[@cbjackson4310]

The series capacitors. One end at the external ground and the other at the so239 center post or thr so239 ground? Thanks

[@Guns_N_Gears]

Just curious, have you ever tried 4 or more cores? Unless I have missed something, seems powerhandling goes up with more cores.

[@rossbrawley]

Great video! I would love to see one on the wire! 134ft total or 134 plus tied ends, or 134 with the coil or 134 without coil and then add in coil so maybe 136 and coil making it 134. It's confusing me! Your great Steve. Ross KG4NWE Chester SC

[@k8aik8ai]

Lowes has those enclosures as well

[@fontesdeo8582]

Curt Benjamin, You’re correct. Most Lowes stores carries these Carlon boxes under item number 10008. They also have one made by Cantex under the item number.

[@wadepatton2433]

Thanks for another video Steve. "Long time" subscriber here. I just mentioned you in a thread on the 7300 page, and forgot that you sold me on those as well! Love my transformers, have helped others build theirs and love the 7300 too. Have my keys handy now and working up my copy skills, and just retrained my fist to run cootie as well. Until my ears get faster, I have no business on the bug or paddles. Have you tried sideswipery?

[@n4lq]

Tks! kzbin.info/www/bejne/j16xeXuHmbZrrbs

[@bmmcwhirt]

I have a few questions. I am going to post them with the disclaimer that I have not had a chance to watch the newer video yet and will get to that this evening I hope. Working 5-20W on 40m-10m. 1. What are we gaining by stacking 3 cores as opposed to 1 or 2? 2. I know I can look up some complex math, but at 5-20W is 14AWG sufficient, and is there any benefit to either silicone or pvc jacketed wire? 3. Given the cost at about $30USD and a size of 1.5 inches x 1.5 inches x 3 inches, is it worth the cost, size and weight to use an air variable capacitor if the system is going to be used without an ATU? 4. Will there be any significant gain using multiple ground radials vs a single? Thanks KB9YEN

[@papasplace2]

I have some stupid questions for you... I run a Yeasu FT897D as my base(was a gift from a good friend) And I had been running to a G5RV. I moved several years ago and haven't had the radio hooked up since we moved. My new location is on the down side of a small holler(valley). It is about 300 ft straight line to the top and a 6% grade. I am thinking about changing over to the EFHW in an 80-10 length. I have watched all your videos on the antenna and transformer. I still have some questions. You sent Today at 10:47 AM #1. will a single FT-240-52 Ferrite toroid core be sufficient for running 100 watts on phone?(I don't do CW) #2. Would you recommend grounding the transformer box? #3 how tall should tall inverted L portion be? #4 Would you also recommend using a choke on the feed line(30-40ft long to transformer) and what size? Thank you so much for time and all the information you have shared! 73's

[@DrHWO]

Excellent presentation, Steve. Is there any advantage / disadvantage to using alternative turn numbers but maintaining the 7:1 ratio. For example 3 primary and 21 secondary to give the 1:49 result? 73, 2E0HWO

[@EricBourlet]

I see some plans call for 14 turns on the secondary and some 14 turns when using 3 cores of Mix 52. What is better?

[@clems6989]

Impedance ratio is equaled to the turns ratio squared.

[@outlaw6595]

What size toroid and how many would you recommend for 200 watt maximum output?

[@watsok]

In the past "Felt" I believe was a cotton product. Today I would bet it is plastic based and can not stand as much heat...along with the adhesive on the back having a low melting point??? Would like to hear of any high temp "adjustment" to the design. If you are going to have one vent , why not two to support cooling from air flow? Thanks for the video.

[@ssubaihi]

is the grounding essential for EFHW ? i am asking this because i think EFHW considered as radialless antenna ... and what if i use it for mobile operation in my car and there's no ground but my car body ?

[@eddiecollins459]

Does the vent have a screen to keep out the yellow jackets?

[@205a2]

Sorry for the question, Is the secondary winding wire soldered to the primary turned wire where it is on the toroid? In all the "How to" videos and pics, it only shows the front of the finished product, not the back where the second winding wire is added.

[@jamesstytle5258]

Beautiful workmanship. Who is your oft mentioned, never named, associate?

[@tomjohannesen2223]

With 3 pcs of stacked cores type 240 size, powr capacity will probably be 2kWpep and some margin ...

[@davidsapadin]

Steve: Does anything go into the center of the SO-239 besides one end if the capacitor?

[@tommcconnell9337]

Steve, I notice that the torroid stack does not move while you rotate/move the box around in the video. Wonder how you have it mounted?

[@n4lq]

I use anti garvity transformer bearings. Hard to find but effective.

[@avt3216]

For anyone using aluminum tubing for a vertical EFHW: The impedance at the feedpoint will be a lot lower than for wire, so adjust the number of secondary windings, or.... tap the coil at various points. Experiment! Enjoy having NO RADIALS!

[@WhatsUpWithSix]

Any chance you have links for the parts? Thanks.

[@paullinnell]

What gauge wire on toroid??? What length wire antenna ?? Thanks!!

[@dondeal3658]

Steve, is the core a 5952003801 (i.e. Fair-Rite 60mm mix 52)? In the video you stated 5952003809, but the fair-rite datasheet suggests that the least-significant digit can only be a 1 or 2.

[@n4lq]

Thanks. I posted the correction under the video. 73

[@rufus4779]

Steve is it possible to shorten the length of the radiating wire by using a coil. Say from 134’ to 88’ by adding an inline coil? I’ve got limited yard space. Jim N2OWM

[@n4lq]

Yes but I have not tried this... See this link www.infotechcomms.net/downloads/Multi_band_EFHW.pdf

[@dback4430]

I love this thing . Thanks for sharing all the info you have on this arrangement . I am having a problem with high swr on 80 though . Everything else is great . Any suggestions ?

[@n4lq]

Usually that's caused by the antenna being too low, under 30 feet, too close to metal such as your house's wiring or aluminum siding or by having a sharp bend in the antenna near the middle.

[@dback4430]

@@n4lq I will have to try it in another location . Thanks for the reply . One more thing , have you ever tried a mono band version ? which core etc would you try ?

[@autosyonal]

Hi Steve thank you very much for this nice video .I have a Question for how to put the antenna half wave up high from the ground en put the transformer 2 feet from the ground ??? i whant to put the antenne horizontal as high as posible. May i Run a ground wire from the transformer down to the ground ore how do i connect the ground from the transformer ?

[@n4lq]

Having the antenna all horizontal is fine and that is how mine is now with the transformer is hanging 80 feet in the air. Since the shield of the coax is connected to the ground lug of the transformer internally you can just ground the coax somewhere before it enters the shack. I have a couple of 8' gnd. rods on mine right near the hole in the wall. It works great this way. 73

[@whatspapadoingnow6197]

I built a 1:1 current balun to feed my full wave 40 M loop antenna. It made a world of difference at quieting the background noise on receive. Could the EFHW be feed with the current balun as well?

[@louisseaman8455]

With the 1:1 BalUn, no, your 1:1 has the wrong output impedance and wrong connection type (BaLuN instead of UnUn) for an EFHW; what he is showing here is a 49:1 current UnUn, since an EFHW is an unbalanced antenna with an impedance at its end of ~2450Ω As far as the noise reduction, that is likely due to your antenna now "ending" where you designed it to "end", since a loop is a balanced antenna and without the BalUn, your entire feedline was part of your antenna, and where your coax shield would normally not allow extraneous signals from affecting the signals picked-up by the antenna, without a BalUn it was not acting as a shield until you installed the BalUn. Also, your antenna has an impedance for the band it was designed for, allowing signals from a particular band to efficiently create currents for that band on the antenna wire, and that goes out the window if that impedance match isn't carried through to your receiver because your coax is part of your antenna without a BalUn.

[@jgayala6045]

Very infornative. Why dont you write down the parts list and procedure? Just a suggestion..thanks for sharing... Joe k4jga

[@19134ANDY]

Can you do a video on how you did the windings?

[@BikerBytes]

The bit I don’t get is they way the winding connects the center core and outer core (ground) . Doesn’t that short it?

[@Gabagabe1]

It's a short on DC, not for Rf AC

[@davido273]

Hi Steve, what do you suggest using to physically mount the torrids to the inside of the matchbox?

[@n4lq]

It's in the video David. Did you watch the end?

[@davido273]

@@n4lq Yes sir, i missed it the first time so I hit the rewind. Thanks for the Videos!

[@cbjackson4310]

Steve, I've reviewed all your videos and my take is that the capacitors are from the SO239 center to the twisted ground. Took a while to glean but success. Thanks.

[@bashcoder]

Thanks so much. I’m a bit confused by the turns count, as I count 13. Did you remove one turn from the secondary due to the third core?

[@n4lq]

There are 14 turns.

[@chrispellenz5800]

@@n4lq did you find there was a benefit to go 8 turns then cross and finish with 6 for the total of 14 vs splitting 7 + 7 turns per "side" or it doesn't matter?

[@n4lq]

@@chrispellenz5800 I went 7 turns, crossed (counts as turn #8, then 6 more for a total of 14. So it's 7+ cross + 6 = 14.

[@chrispellenz5800]

@@n4lq OK, I see now. It seems that I went 6 + cross + 7. Do you think that is a problem? I could of course re-wind it but thats kinda difficult. lol

[@JimN5QL]

Hi Steve, just gathering the last few parts to finish building an EFHW. My back yard is small and I was wondering what effect two 90° turns in the antenna wire would have on the operation of this antenna. Any guidance will be much appreciated. Thanks and 73, Jim Clark, N5QL

[@n4lq]

It will affect the swr depending upon where the bends are located and what band you are using. There are just too many variables to guess at it. Give it a try. I'm sure you will end up needing to use your tuner on some bands.

[@JimN5QL]

@@n4lq thanks for your input Steve. I will let you know how things turn out! Thanks

[@whatspapadoingnow6197]

Steve. I just ordered my three 240-52 cores from Mouser. I have some 14 GA wire on hand. Most of the time I operate 100 Watts on SSB. On occasion I use my Ameritron amplifier that uses one 3-500Z output tube. Will 14 GA wire on three 240-52 cores hold up to 600 to 700 Watts SSB?

[@moondog13gmail]

Did you ever experiment with this? I’m getting a similar Ameritron amp and am wanting to redo my 49:1

[@jgwimmer]

Arrow doesn't carry that stock number any longer, there is one by number 5943003801that looks similar, but the specs are not clear. My understanding is that the SWR is a bit better across the band if you use the 64:1 rather than the 49:1....16 turns to 2 turns vs 14 turns to 2 turns....may have to do both of them and compare. 73 Jeff W5JGW

[@chrispellenz5800]

When I measure the impedance with a VNA at the so-239 on the bench, what should i expect?

[@louisseaman8455]

Unless it's hooked up to an antenna, it will be in the 1000s of ohms, and dependent on what is around the terminals transformer's that the VNAs pulses can couple to.

[@donniemckinley9048]

Does it make sense to use hot glue to secure the torrid inside the box?

[@n4lq]

No... Hot glue will melt quickly. You really don't need anything since the wires will hold it. Also if you want it to be tight in the box, go to Lowe's or Homedepot and buy a pack of felt furniture sliders. They are like little strips about 3/8" thick and will stick to the inside of the lid. When you fasten the lid they will push down on the core and keep it snug. Don't worry about them melting or burning.

[@mumi009]

how did you affix the toroid in the box? Wire gauge used?

[@n4lq]

See the fuzzy pad in video

[@iamhe999]

Steve, I hope this question is not out of line here. Has anyone built this transformer with the DPDT relay circuit inside the same box. Would the relay coil throw the thing out of wack, and would it matter if the relay coil operated DC or AC?

[@janvisser8452]

With 10 cm distance they don't see each other. AC will hum terrible and dc not. Are you a ham operator ?

[@sincerelyyours7538]

Thanks Steve, that's just what I needed to build my first ham antenna. How long is your long wire, can I ask, and for which band is it optimized?

[@urbanbushcraft3018]

EFHW stands for End Fed Half Wave....so if you want it for 80m you will need about 40m of wire. (About 120'). Great looking job Steve.

[@sammyboyde6489]

If you were building a unit with a single 240 size torrid, for lower power, say 5 to 50 watts, would you use the same number of turns? Thank You Steve.

[@n4lq]

Just one toroid is inefficient. You will suffer unnecessary power loss and that is exactly what you don't need with low power however if you insist on only one core then it will work ok if you don't mind the loss.

[@paulkazjack]

@@n4lq How much loss then?

[@Guns_N_Gears]

I'm gonna try making 1 myself, great video! I'm curious, would 4 magnets at 52 mix dissipate more heat, or would it not electrically work correct?

[@wjess3569]

Hi Steve.. I have a question.. I have an MyAntennas 80-10 EFHW. I don't have room for the full 80m. I'm pretty sure I can cut it to a 40-10.. but, can I simply fold it back to make it 40-10? If so.. a simple fold back or wrapped back on itself. I'd appreciate your thoughts.

[@n4lq]

Maybe but I haven't tried this. I think it will work however your harmonic related bands may not fall within the proper range. It's easy to try though.

[@wjess3569]

@@n4lq Thank you..

[@PatAutrey]

If I were only interested in reso rating on the phone portions of the various bands 80-10, how would change the size and placement of the coil, wire lengths, and capacitor midway?

[@n4lq]

I would make the entire antenna about one foot shorter then put the 75 meter capacitor in the middle using about 250pf.

[@PatAutrey]

@@n4lq Would you still include the loading coil on a phone only antenna

[@MichaelLloyd]

RadioPrepper's videos led me here and FB. Is there any benefit to building a 64:1 (3T primary, 24T total), 52 mix version (oops, you answered this mix question) of this vs 49:1? I'm a fan of 6m (when I can be :o) ) and one of his recent videos talked about using FT-240-61 mix, 2T primary, 14 turn total for 6m.Thoughts? I'll have to go back to the video and check the length of the antenna (for 6m). QRO for me is not more than 100W (CW, SSB, and Digital) so I should be good with 240 cores. Great video. 73 NE5U

[@n4lq]

I have some 61 mix 240 cores and all I have tried is to use them on HF. They don't work. Possibly they would do fine on 6m. I hope you give it a try and let me know what happens. 6m is so short that a J pole seems like an easier way to go. With a J pole you get the 1/2 wavelength end fed and don't need to mess with a transformer. 73

[@MichaelLloyd]

@@n4lq I agree with you about the J-pole. I suppose a window line version would work for a field antenna, sftarc.org/index.php/newsletter/tech-blog-main-menu/display-tech-blog-articles-menu/217-home-built-6m-j-pole-antenna-2 but a single wire might be more portable. Something to play with. For some reason, probably a project I thought I needed to build and didn't get to, I have quite a few T-140-61 cores that should work for QRP experimentation. 73

[@warrenposey5998]

What type wire .gauge and length do you use for the antenna

[@n4lq]

Length is 134 feet. Wire can be whatever you want. 14 awg insulated wire is fine.

[@whatspapadoingnow6197]

Do you still recommend using 12 AWG wire and three 240-52 mix toroids for high power 40M through 10 M operation?

[@n4lq]

yes indeed!

[@whatspapadoingnow6197]

Thanks Steve.

[@JD144-]

Great video! Gonna build one myself, but why the 3 toroids instead of just 1 like others? Thanks.

[@n4lq]

What others? All the legitimate manufactures use multiple cores to handle high power. Sure you can use just one core for 100 watts however the transformer's efficiency actually improves with more cores.

[@JD144-]

@@n4lq I guess the lesser power videos are what I’m referring to. Wasn’t sure why. Thank you for the info, just looked and my local Home Depot has 7 boxes in stock. Headed that way!

[@user-sw7oh9oy6f]

Hi Bloke Can you throw light on why my 49:1 box resonates on 40 M with 12ft more wire than calculated 468/7 = 67ft Half Wave ~ but actually needed 79ft !! vswr 1:1@7Mhz with 2 radials off of floor 8ft & 6.5ft

[@louisseaman8455]

Sounds like you have excess capacitive reactance and you're having to balance that out by adding inductance (with your added wire length) You may be loading up to the earth, is the wire horizontal or vertical? Or something metallic is nearby. You may also need to change the value of the capacitor in the balun. Get your hands on a VNA and see what the values are and you should then have a better idea what to do about the issue. At 79', it's not a resonant antenna, but that's almost a 5/8 antenna on 40M, and may be very good for you if you're vertically polarized.

[@19134ANDY]

Hey what value Cap you have there?

[@fasnuf]

he said in the video..

[@gilbertnelson9565]

Steve. Is there a parts list with numbers for this project ?

[@n4lq]

Yes. Check towards the end of this video. kzbin.info/www/bejne/eKHHoZ6Lerxmb9E&ab_channel=SteveEllington

[@davephelps9126]

Did you end up using 12awg or 14awg for the windings?

[@n4lq]

I'm using 12 ga now

[@Lugnuut1]

@@n4lq I have 14ga.. how much would that limit my power handling capabilities? I have a 600w amp that a run closer to 500... Thanks!

[@n4lq]

@@Lugnuut1 It won't matter at all. Go ahead with 14 ga. I just though my SWR was better with 12ga but it's up to you.

[@techiefan1986]

Why three cores? What if only one core is used?

[@jay-rus4437]

Counterpoise?

[@paulkazjack]

Sorry did i miss the build part of the video?

[@fasnuf]

what keeps bees or other bugs from nesting in the box due to the vent? Thanks

[@n4lq]

My pet aardvark

[@daveycrockett9447]

Juts cut some plastic screen mesh and find a way to cover the vent opening- that is if you don’t have access to a pet aardvark

[@chucksw1]

Should I use 12G or 14G wire for the Transformer windings?

[@n4lq]

12 ga

[@chucksw1]

Steve Ellington Thanks , my parts are on order, and need to go to Lowe’s this week:)

[@PatAutrey]

Good morning Steve I hope you’re doing well thanks for all that you do! I was curious is it possible to create an EFHW that would work on VHF / UHF and The HF bands?

[@n4lq]

Probably not. The transformer looses efficiency at VHF and higher. It's best just to use a separate antenna for that.

[@PatAutrey]

@@n4lq Yeah I kind of figured but I just wanna double check thank you

[@PatAutrey]

@@n4lq Good morning I was wondering if you could chime in on a question that has been plaguing me I'm wanting to put up a long wire antenna for field day somewhere between 200 and 250 ft long and I plan to use it on 20 m and my question is what transformer should I use in this situation, 9:1? 49:1?, Any idea of what the impedance would be and what kind of gain would be generated if it was mounted 5 m in the air

[@n4lq]

@@PatAutrey First. Ask yourself why you would want to do this. Every band will have a vastly different impedance, none of which are consistent. Therefore there is no one transformer that makes any sense. It's a random wire. People use 9:1 ununs but they suffer lots of power loss since due to the terrible mismatch there are lots of ground currents and without a good radial system you loose lots of power so why bother? Just put up an 80m half wave, feed it with a 49:1 and you get all the nice field day bands with one antenna. IT's 134 feet long. Fell the extra gap with rope. Just being longer actually makes things worse.

[@PatAutrey]

@@n4lq The goal is to create a high gain multi-wavelength antenna to be used either on 20 m or 40 m so it could be six seven or eight wavelengths long on 20 m That's what I'm trying to accomplish and I understand this is a very high gain antenna, so with that additional explanation can you offer any additional insights

[@JD144-]

What gauge magnet wire did you use? Thanks!

[@n4lq]

12ga. 14 works too

[@JD144-]

Thanks again!

[@PatAutrey]

If I choose to use a 64:1 Will that make any difference on how far the compensation coil is or the size of the capacitors?

[@n4lq]

No on the compensation coil. The capacitor is unknown but I doubt if it matters much. 64:1 will do better on 80m only. The upper bands will end up with higher SWR. That's why it's not recommended.

[@PatAutrey]

@@n4lq for NVIS purposes on 80m, 60m, and 40m do you still recommend 49:1 over 64:1?

[@n4lq]

@@PatAutrey Depends on what you mean by NVIS. The average ham thinks it means a really low antenna at some ridiculous height like 7 feet. If that's the case on 80m your impedance will be way higher than even a 64:1 can handle. The fact is; the best height for an NVIS antenna is 1/4 wavelength. This yields the most gain at 90 degrees, straight up. That's 65 feet for 80m and 34 feet for 40 meters. Those are actually pretty common heights. For multiband, multi-height installations, any ratio is going to be a compromise.

[@PatAutrey]

@@n4lq thanks again for your help sir, I’ll strive to get as much height as possible

[@steve0321]

would 2 240-43 torriods, 14 AWG wire, 3/21 winding handle 600 watts SSB on 160 meters?

[@n4lq]

For 160m you need 3 cores minimum and 3/21 ratio. 240 will probably handle it but please splurge and get 290 cores. 14 awg is fine.

[@steve0321]

@@n4lq Two 290's? or three?

[@n4lq]

@@steve0321 3

[@das1252]

How do you know when you need this?

[@n4lq]

If you must ask, you dont.

[@budnocera1834]

Steve, is it possible to build a 49:1 transformer for a 40 m half wave end fed that will withstand a full strap AM duty cycle?

[@n4lq]

Sure. Just use this same design. I use 12 awg wire for the transformer nowadays. 40m is much more forgiving than 80m and AM has a shorter duty cycle than CW as long as you keep talking :*)

[@k2icc]

Wire size and gauge? 73

[@beekeeper8474]

How many cores do I need for 500 watts?

[@n4lq]

3

[@beekeeper8474]

Used 3 52 and can't get it to work.

[@19134ANDY]

Can't seem to find the toroid everyone is out of them

[@n4lq]

One word. China

[@k2icc]

Wire size?

[@n4lq]

12 awg

[@k2icc]

@@n4lq Thanks a lot.