http://myantennas.com/wp/product/efhw-16040-1k/

Is it just a 9:1 and 257ft of wire?

I ask, because I have the wire, and I have the stuff to build a balun, so naturally I'd rather spend $time instead of $200.

9:1 balun is the correct answer.

Similar to the 'QSO King' sold on e-bay.
Check his add, he has the length info for various bands.
Of course, with a tuner.....
Still, don't want a 'wrong' length.

A compromise?  

I'm building one of these for my brother-in-law. I'd rather have an OCFD 80-10 and a 160m dipole.

So far I've got the core wound, box drilled, and wire length decided. I need to stop by TSC tomorrow and pick up the stainless steel bolts, washers,wing-nuts, eye-bolts, and a pulley.

We're gonna put it on the side of his house, and run it about 256ft almost directly north (he doesn't have a choice with his lot) to give him 160, 80, and 40 meters. He's got a MFJ Mag-loop that gives him everything else.

Should be a fun install.

There was much hubub on qrz re this antenna and the designer/seller.

While the designer/seller was a bit evasive or perhaps deceptive, the box likely contains a 9:1 turns ratio transformer (81:1 impedance ratio), or somethng close.  It also has a loading inductor that centers up the upper bands.

Like all end feds, it needs/has a counterpoise, whether that is an actual few ft of wire, or just the coax.  Also like all end-feds, it suffers from coax shield radiation and possibly RF in the shack unless a healthy choke is used at/near the feedpoint.

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Yeah, but if it works, who cares. the 160-40 doesn't have an inductor, the 80-10 is the ones that does.





I need to get a better label maker.

Ah yes, quite right about the loading inductor - thanks for the correction.
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However, the 9:1 impedance ratio unun shown above (3:1 turns ratio) is probably not the unit that's in the commercial end-fed box.

The commercial unit likely contains a 64:1 or 81:1 impedance ratio transformer or unun (8:1 or 9:1 turns ratio). A 64:1 or 81:1 impedance ratio, or thereabouts, turns out to be a decent transformation ratio for hi-Z end fed operation.  

There's always endless confusion and hilarity when talking about transformer ratios - half of us are talking turns ratio, the other half of us are talking impedance ratio !#%&!*%#!!!!

Both are popular - the 9:1 impedance ratio is GREAT for wideband use with a tuner (and is part of the BMU (Base Matching Unit) recommended for verts and L's and EARCHI types), but likely the end-fed unit is used WITHOUT a tuner and is more like these 64:1 or 81:1 impedance ratio transformer units:



.... and transform impedance to be a fairly close match to the impedance seen at the end of a half-wave and it's harmonics - like this:



The 9:1 turns (81:1 impedance) ratio unit is good, the 8:1 turns (64:1 impedance) ratio unit is probably a bit better.

The graph also shows that the system is pretty INsensitive to counterpoise length, which is kinda cool.

I'm not quite sure why anyone would want to put up a 250 ft antenna to get 160M coverage, when 1/2 that, or 1/3 that would likely be a better DX antenna in a base-fed vertical, slopper, or inv-L configuration.... (assuming one can install some sort of ground radial or counterpoise system).  And, if DX work is your goal, hanging this half-wave antenna any lower that around 180 ft is going to be pretty disappointing - 160M is not an easy band!!!  DX work is almost exclusively done with vertical polarization.

However, if NVIS is your goal, then you'll be just fine.

So,  if end-fed is your cup of tea, remember that as stated above, a very good feedline choke should be used to knock down the common mode current on the coax shield.  RF in the shack is one potential problem, but the other SNEAKY problem that coax shield current causes is noise pickup from the coax, which often runs right next to every noise producing item in your house.

My BIL is pretty lazy when it comes to antennas, and paranoid about "things getting caught" on the wire.

He wants one antenna to fill in the gaps from his 30-10mhz loop, and to use as little coax as possible to feed it.

ETA:
Yep, you're absolutely right. I just ran it through NEC, and it's not gonna work the way I have it wound. Guess I get to bust my fingers again tonight, lol.

I am interested in that antenna so this is basically an OST.

I have used Par End Fedz antennas for years, portable.
They are really nice to use portable because you only really need one high support. I was mostly using these in the desert where there were no (zero) trees. So I had to provide the one support and then I ran the antenna out usually as a sloper to a piece of sage brush or to a fence post.

I really liked how handy they were and they seemed to work pretty good. I worked a lot of DX on them, however I should point out that I was at elevations of like 9k or more, so anything would have probably worked.

I have thought of using and end fed antenna here at home, mainly to give me more antennas and since they are easy to install.....................
The problem is that all of the ones I have seen in the past will not handle much power.

I finished up the UnUn for my Brother-in-law. Finally got around to hitting up Tractor Supply for stainless steel hardware.




I only had a 240 ohm resistor, so it comes out around 30 ohms. It's good to about 10MHz, and great under 5MHz. Number 43 mix, so, yeah. Expected.



I've only got about $25 into this build, including all of the parts I had already laying around the house. We'll be putting it up tomorrow.

There is an article in this month'so QST about this antenna.

I am buying one.

The mfr/seller Danny is over on eHam showing that he doesn't understand how his own antenna works, or why EFHW tends to be noisy and inefficient in many cases.

There's some pretty good tech there on how EFHW actually works (although not much of it comes from the seller...)

http://www.eham.net/ehamforum/smf/index.php/topic,108127.msg910695.html#msg910695