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Author Topic: Some recent end-fed play  (Read 6332 times)

KC9TNH

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Some recent end-fed play
« on: July 25, 2013, 11:45:20 PM »
I like to play with end-fed antennas mostly I suppose because they're so darn portable & easy to put up in the air in all kinds of environments.  I've played with a variety of them and a couple of recent efforts are related here.  Both of these were done at home, so that I could validate or rule-out the portable version (very small UNUN and much lighter gauge wire, insulators, etc.)

I had a couple of things I wanted to do specifically.  I used the free version of EZNEC that came with my ARRL antenna book awhile back.  I'm not a huge theory guy.  (Hand me a Smith chart and I'll try to spin it to figure out density altitude or true airspeed.)  But the EZNEC let me learn by failing and allowed performing some theoretical what-if's, since actually getting the dang thing in the tree is the hardest mechanical part.  The best benefit of doing some modeling first was to see results in terms of things like "based on the orientation of the wire, where is the lobe with the biggest gain?" (1)

The first thing I wanted was something that screams dead west and 20? either side of that - just because.  My E-W running OCF dipole - especially with the long leg headed E - wasn't making it by any stretch.  After investigating the way the higher bands perform I realized I had my N-S 36' EF oriented incorrectly.  The plume from a short EF at anything higher than a band that would be NVIS (based on height above ground) is more of looking down on a 4-leaf clover with the 2 ends at the end of the wire having higher gain than those going back & behind the feedpoint.

Once this wire was simply re-oriented pointing due NW, the left side high-gain lobe was headed due west.  While you can completely slope an EF antenna from your tent-floor, they do MUCH better if you can get that feedpoint off the ground, and I found that good things really start to happen at about 6-8' above ground.  This particular wire starts in a tall spruce at 18' and slopes up to about 27', pointing NW.  There is a counter-poise coming off the other side of the 9:1 UNUN that is 8'.  The wire was never intended to do anything but 20m and higher, so 14 was my lowest freq for figuring a 1/8th-wave counterpoise.(2) Confession: I don't remember where I stumbled upon this length as there are all kinds of so-called rules for counterpoises, but I have found this works and the modeling, but more important the results, bear out this small sample. The counterpoise is at a right-angle to the wire off to the right, pointing NE.  20m gives pretty good performance W and WSW - 17m and 15m just scream dead west which was the goal.

The second thing I wanted to do actually was fill-in a delta in things headed ESE and SSE.  So I did a 52.5' wire pointed due East.  This was a fun project with the grand-daughter that I've written a bit about to Ray & mentioned in a QSO to Chris.  An old TV-style tripod with 15' of pole was found languishing at a local hardware store (everybody's got CATV or a dish these days).  I bought it pretty cheap and put up on the back deck; the UNUN starts the feed at 20' above ground.  It slopes up to a big maple in the back corner of the lot about 30'.  It plays wonderfully into Europe, as well as being able to throw a decent 30m or 20m lobe to Ray & Gil's direction which was the prime goal.  This antenna has a 14' counterpoise, at right-angles to the wire, sloping down North.  It also is easy to load up on 40m - well, with the KX3's tuner it's like cheating but, hey, whatever.

Chris got to compare the OCF dipole - part of whose problem is that the short leg approaches the front yard and the 'verdammte' overhead utility lines on the street - with the 52.5' EF on 40m.  I know it hears better and Chris' signal to me went from I think a 449 to a 569.  Admittedly part of this nirvanic state was achieved by having all the antenna and its feedpoint located away from such abominations as commercial AC power.

I wanted to test these in short order so I proceeded to seek out some ladies & gents on mountains running field antennas and low-power as well, aka SOTA.  I don't play that game either, but they are generally very nice folks and give HONEST signal reports and unless trying to work a pileup are open to chatting a bit.  (There are several MTR boxes out there as well as Ten-Tecs, a huge bundle of FT-817's and a freighter-load of stuff that says Elecraft on it. Fun to do alot of QRP to QRP, especially when one of the wires is up at 7-10,000 feet.)

All in all, pretty satisfied and that means those particular wires are good enough to consider for the bag, as in Ziploc.  So... go throw some wire in a tree & play.

Endnotes:
(1) Judicious use of this means one could theoretically get a lobe (without using a beam) to a friend and just possibly put a dead-null right on someone they didn't want having easy copy.
(2) I have noticed on the higher bands, such as 17m & 15m, that the SIDE the counterpoise comes off away from the radiator can influence a bit the way the main lobe swings and the lobe will tend to the direction AWAY from where the counterpoise is pointing - so there is that to cheat with a bit.

cockpitbob

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Re: Some recent end-fed play
« Reply #1 on: July 26, 2013, 12:54:55 PM »
Great write-up Wes.  I'm also a hughe  fan of end-feds.  Especially my 63' 1/2 wave one that don't need a tuner for 40, 20, 15 & 10(sort of). 

Keep up the good work.

gil

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Re: Some recent end-fed play
« Reply #2 on: July 26, 2013, 01:54:32 PM »
I am a big fan of end-feds as well. Easy to put up a tree using a slingshot, fishing weight and line. I've gotten pretty good at it now, and often succeed on the first try..

Gil.

KK0G

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Re: Some recent end-fed play
« Reply #3 on: July 26, 2013, 03:11:34 PM »
EFHW antenna is all I use for portable QRP operating in the field for the exact reason Gil stated. In addition there's no feedline to lug along, plus it's extremely light weight and compact, the fact they work so well is just icing on the cake. My recent QSO with Wes using his end fed and this article have me itching to try a permanent one at home.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

raybiker73

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Re: Some recent end-fed play
« Reply #4 on: July 28, 2013, 11:49:12 PM »
Everyone always sings the praises of end fed antennas, so I'm going to give one a try. I ordered a Par EndFedz 40-20-10 Trail Friendly to try out with my FT-817. I've had pretty good luck with verticals and longwires using the Emtech ZM-2 tuner that I built, so I'm anxious to see how the end fed antenna compares. Any tips from those familiar with these antennas?

gil

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Re: Some recent end-fed play
« Reply #5 on: July 29, 2013, 12:16:16 AM »
Quote
I ordered a Par EndFedz 40-20-10 Trail Friendly

You'll like it Ray, great little antenna. I use it, except that my matchbox is the betterqrp.com  EFHW tuner, instead of the LNR Precision box. Just because the tuner does have an SWR LED which tells me if it is safe to use with my MTR. Of course your FT-817 has an SWR meter, so no problem there. What I also like with the tuner is that you can use different wires for 15 and 30m, though my MTR does not have those bands. I use the PAR (LNR Precision) regular end-fed 40/20/10 at home as a semi-permanent solution. I use a Weber "Tenna Dipper" to check SWR. I only have two antennas at home, my PAR and my magnetic loop for 30m and 40m (the PAR is higher/better on 40m). While camping the trail friendly wire and betterqrp tuner combination performed flawlessly. I do suggest using masking tape on the ends of the RF choke to avoid getting it caught on some branch 40ft up...

Gil.

KC9TNH

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Re: Some recent end-fed play
« Reply #6 on: July 29, 2013, 08:10:44 AM »
Everyone always sings the praises of end fed antennas, so I'm going to give one a try. I ordered a Par EndFedz 40-20-10 Trail Friendly to try out with my FT-817. I've had pretty good luck with verticals and longwires using the Emtech ZM-2 tuner that I built, so I'm anxious to see how the end fed antenna compares. Any tips from those familiar with these antennas?
To be clear (since I've sung a few praises in my time) EF's excel for several things due to their portability and that they're often used in locations that are NOT subject to many of the RFI sources found at the home shack. (Although Gil is clearly an exception and has made that work at his home location.)

They are not inherently less noisy than a balanced antenna and don't typically adhere to the "1/2-wave for this band, make it this long" dicta of a dipole. Done long enough, they can become a "long-wire" for several of the higher bands in terms of being over a wavelength long for that band.  As a field-antenna they're not going to approach the gain of a standard dipole - but let's face it, most of us don't toss up wires at anything approaching 1/2-wavelength in height for the band.

I wrote the original post using these for a couple of reasons.  Testing at home of something I want to pack portable, scaled down in components.  Also, I'm lot-limited and putting up a wire one direction with a counterpoise at right angles to it gets me more efficient use of space overall.

A tuner or some kind of matching unit is essential to enjoy multi-band capability on one, as there are some serious electrical properties present on an end-fed that need to be dealt with & mitigated before presenting that to the typical radio's antenna input, where if greater than a 3:1 they do a Suzy Cream-cheese freak-out and refuse to tune at all. A counterpoise (or radial if you like that term) coming off the matching device or tuner's ground lug mitigates some of this as well and also helps the RF back to your radio situation. That wire can be relatively short, although I've found 1/8th wavelength of the lowest band to be used a worthy rule of thumb.

If one already has a matching device of some type, they can me made for next to nothing in parts - really. I've mentioned Craig's Dollar-Store antenna several times here with its quickly changeable counterpoise and it works.  I use a 9:1 UNUN and have some specific wire lengths that work well with that given to me by the maker (short to very long) that keep one from encountering unworkable "multiples" of a given wave-length.  Others have matching devices that work as well.

Finally, even though they're usually done as a sloper, getting the feed-point end of the antenna off the ground even 6 feet (just suspend it from that nice branch providing you shade) helps the antenna help you.  The main portion of the RF comes off the end; generally at 30m and lower it's an NVIS proposition, which is OK.  The higher bands will have a definite pattern to them so you might "point" it 45? left or right of target if you have a specific direction you want to emphasize.  In fact if you are set up in a clearing you can get the end of the wire in a tree and literally shift your operating position around the wire to go one direction or another (to a certain extent).

Good luck.  :)

KC9TNH

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ERRATA
« Reply #7 on: August 01, 2013, 08:16:18 AM »
During a recent chat with KK0G on 40m I decided to use the shortie 36' EF and got another of the benefits of having a sked with someone. While the wire was able to be matched (both by the KX3 ATU and the Palstar anchor that holds down the house) the efficiency is clearly degraded - completely expected but good to have that verified by a human on the other end. Chris had a notable diff on his end in terms of consistent loudness and the signal being subject to QSB. There are no magic pills for antennas; when you get down around a 1/4 wave & especially at QRP power levels every lazy electron you can make jump off that wire helps.  So use the longest wire you can reasonably use based on its height above ground and your other constraints.

For real multi-band purposes, the 52.5' EF with the 9:1 UNUN is the thing that would go in the back as it also does well on 30 & 40m.
Happy trails.

raybiker73

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Re: Some recent end-fed play
« Reply #8 on: September 02, 2013, 01:14:24 AM »
Just a follow-up on an old thread: I've been using my EndFedz 40/20/10 TF for about a month now, and it's great. I REALLY like this antenna. It's a perfect packer for with the FT-817. Money well spent.

gil

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Re: Some recent end-fed play
« Reply #9 on: September 02, 2013, 01:56:46 AM »
I love mine, though I don't use the LNR matchbox, but the betterqrp.com tuner. It gives me an SWR indicator LED and the possibility to use other length wires, though the LNR matchbox allows that too. I highly suggest taping (masking tape) the ends of the choke before shooting it up a tree, or it might get stuck on some branch..

My PAR 40/20/10 has served me well at home for a whole year. The trail friendly wire I only use for camping. I can't wait for the cool weather this winter! That will also give me the opportunity to try my homebrew 80m end-fed, which I have not been able to stretch and test properly for lack of space.

Definitely my favorite antenna by far!

Gil.

cockpitbob

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Re: Some recent end-fed play
« Reply #10 on: September 02, 2013, 11:25:04 AM »
I love end feds, especially multi-band ones like the LNR.  Super easy setup with a short feed line and no fussing with a tuner to change bands.
 
I just got back from a week in a lake-side cabin in Maine with no internet or tv (or dishwasher!!! :P ) I brought my FT-857 and a home brew 100W 40/20/15/10 endfed.  I was pleased when my first try with the slingshot and 1oz fishing weight went right where I wanted.  I had the whole QTH set up in 10 minutes!  Either the band conditions were better than average or that location is better than my home QTH which is essentially at the bottom of a 50' well.  I heard some asian contries that I have never hear before.  I couldn't work them but at least I heard them :) .
 
My home brew is basically a broadband step-up transformer.  No LC resonances and nothing to adjust.  I use a ~64' piece of wire which is 1/2 wave at 40m, 1 wave at 20m, 1.5 waves at 15m and 2 waves at 10m.   SWR is marginal on much the 10m band so I turn the rig's power down to 50% to make sure I don't overheat the finals.  I love an antenna that fits in a 1 gallon ziplock bag 8) .
« Last Edit: September 02, 2013, 11:27:47 AM by cockpitbob »

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Re: Some recent end-fed play
« Reply #10 on: September 02, 2013, 11:25:04 AM »