End Fed antenna question

Hi. Been thinking a lot lately about trying an end fed antenna. Something like the EARCHI end fed with the 9:1 balun. I understand the basic theory behind how the antenna works.

Question I have is about the coax. Most of the material I have read on the net about this type of antenna says the coax is used as the counterpoise but none discuss the coax length. If using coax in this manner, does the coax need to be a tuned length or will any length work?

I am thinking that if a wire counterpoise is used, then coax length shouldnt matter but if no other counterpoise is used, then it seems that the coax length should be a tuned length. Am I wrong in thinking this? I know a tuner is required to use this antenna. If the counterpoise isnt tuned, will it take a sturdier tuner to be able to tune the antenna?

Question 2. If a wire counterpoise is used instead of using the coax, does it need to be elevated or just toss it on the ground?

My plans are to get 100ft of coax and the MFJ949 tuner. I plan on buying the coax with pl259s already attached. will this length be too long and create too much of an imbalance for the 949 to tune it? I'm also going to try to build the 9:1 balun using the plans on the EARCHI website PDF

http://www.earchi.org/92011endfedfiles/Endfed6_40.pdf this one I suppose?
As the PDF describes the length of the wire should be 24 to 60 feet, the PDF also states the coax ( used as counterpoise) should be 16 feet minimum.

I rather not use the coax as counterpoise, for obvious reasons getting RF in the shack and on the equipment that can get some weird results.
On the 1:9 torroid is a ground connection, use an wire or several if you can and just put them on the ground minimum length the same as the coax should be long, or longer.
Then use another torroid or several clamp on ferrites directly on the coax after the torroid so that the coax really now is RF free.
It also prevents the coax from picking up RF noise on the outer shield and feed it into the receiver.

Additionally also use a few ferrite clamps near the transceiver on the coax.
This setup with 1:9 balun works, but the efficiency on some bands/frequencies might suffer, don't put too much power in the torroid and check if the SWR changes or the torroid gets warm.
If you run 100 watts into it, an efficiency of 10% means 10 watt on the wire, just 10dB down, still enabling you to make fine contacts though.
Some bands/frequencies you will have good efficiency others less, depending on your length of wire used and grounding system.
Using the T 130-2 torroid and 3 x 9 windings the XL would be 357 Ohm at 7.1 MHz, 710 Ohm at 14.1 MHz and 1461 Ohm at 29 MHz.
Personally I think it is a bit low, an end fed antenna fed at an voltage point will have 2500 - 3000 Ohms.
That is the reason you need to pick the length of the wire carefully, making sure you won't hit the voltage point on any of the bands you want to use.
Personally I use the FT 240-43, larger torroid and then make a 5 band end fed half wave antenna with a few coils in it, but that is a different antenna set up.


My Inverted L is fed at the base with an legal limit autotuner coax with ferrite running to my transceiver and even there ferrite on the coax.
Used from 160 - 10 meters.

OK thanks. Yes thats the one EARCHI I am thinking about. The thing about RF getting back into the shack by the coax as counterpoise was running around in the back of my mind as well. I wasn't sure if that would have been an issue as the coax i plan on using will be 100ft.

As to using the wires on the ground, if I use 100ft coax, the wires should be 100ft+? I was thinking maybe 33ft as I don't plan on going below 40m.

Also, what type of ferrite should I use? i know they should be clamps but what mix do I use? Never have used ferrites before on coax.

thanks

A type 43 mix works well at HF.

Use one long radial or use more shorter ones.
Several of 33 feet spread out will work just as fine as 100 feet coax, and not give the coax the RF on it, if you use the ferrite on the coax.( mix type 43)
So on the ground connection of the 1:9 come the radials, then directly after the plug on the coax on the 1:9 come the ferrites forcing the RF to the radials and keep the coax free of RF.

To understand how this antenna works:
http://www.w8ji.com/long_wire_antenna.htm

The ground system with radials is specially important where your wire is about 1/4 wave long and fed in current.
Where the antenna is fed as 1/2 wave the ground is much less important, and fed in voltage.
Since you will use an length that will not be resonant it is the best as I wrote before, use several ( shorter) and longer ground radial wires and decouple the coax with clamp on ferites or use a torroid to wind the coax several times through.

An air coil won't have the full range of frequencies you want to use the antenna for to decouple the coax effectively, most air wound coax coils are nice for one or mostly 2 bands close to eachother but not more.
I even used discarded ferrite bars from old AM radio's and wound the coac around these ( RG 58) that will be quite effective as well.
For thicker coax just tape 3 or 4 old AM ferrite bars together to get a larger diameter to wind the thicker coax around.

Just for laughs, a more effective antenna needing a bit more work:
http://pa3hho.nl/wp/?page_id=471

OK got it. So other then mine wont be a true vertical, the radials and radiating element operates like a vertical antenna? 1 radiator and several radials. simple enough. I just may make it into a vertical as I THINK I have room under my tree. My rope system is about 35ft to the bottom of the branch it's strung over. Sounds easy enough to install and take down when I head off to work then. Thanks guys

Quote:

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Originally Posted by AF5TY

OK got it. So other then mine wont be a true vertical, the radials and radiating element operates like a vertical antenna? 1 radiator and several radials. simple enough. I just may make it into a vertical as I THINK I have room under my tree. My rope system is about 35ft to the bottom of the branch it's strung over. Sounds easy enough to install and take down when I head off to work then. Thanks guys

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The branch or the antenna?

The end of the rope and tie off are a few inches below the branch. The branch is at about 35 ft. The rope goes over the branch. In installing my dipole antennas, I just pulled the rope over the branch to pull the dipole up. I know I should use a pulley system of some other support mechanism but I don't have a ladder high enough to go up and install a permanent pulley and the branch is too thin to support anyone who would be crazy enough to climb out where the rope is anyway...

Vertical will give good DX low angle radiation.
For more "local" qso's you might opt for a nvis low hanging dipole with tuner.

Side question: Is a 40m inverted V fed with coax easily used on 30-10m with a tuner? I could put up a 40 inv V but the ends would be a bit low to the ground. Cant put up a horizontal dipole as I only have my 1 tree I can use.

Yes you can.
A wonderful first antenna is a coax-fed 40 meter inverted vee. If you were to feel really adventurous, you could feed the 40 meter inverted vee with ladder line .

Yes you can.
A wonderful first antenna is a coax-fed 40 meter inverted vee. If you were to feel really adventurous, you could feed the 40 meter inverted vee with ladder line and, using a tuner, use it on 40-10 meters.
If fed by coax use a current balun though, better is feeding it with ladder line and tuner.
This antenna will also work FB (“fine business”) on 15 meters as a 3/2 wave dipole. and have gain.

Just make sure that the enclosed angle of your inverted vee is at least 90 degrees. And, although plenty of purists might disagree with me, when you adjust the length of your new inverted vee for minimum SWR, anything less than 2.0:1 is fine at HF. Don’t sweat the small stuff.
The basic inverted V is about as efficient an antenna as you can get. Feed them with coax of the appropriate size and length and work the world.
If you want to get on the bands without tuner and losses use the "cat whisker" version, for every band hang the appropriate lenth dipole 10 inches parallel to the longest dipole fed at the same feedpoint.
That will ( with some pruning) give you very effective resonant dipoles fed with one feedpoint, if you have the 40 meter dipole in forget the 15 meter dipole the 40 meter dipole works as 3/2 dipole anyway.

( Added some stuff I forgot in the former post)

Quote:

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Originally Posted by AF5TY

Side question: Is a 40m inverted V fed with coax easily used on 30-10m with a tuner?

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Simple answer; no. It should load on 40 & 15 without much trouble, but everything else will have an astronomical SWR. With enough coax, you might be able to get the tuner to load the setup, but the losses from the mismatch would mean you'd lose all your power (or most of it) in the coax. Very little would actually get to the antenna and radiate.

Running EZNEC 5, I get the following SWR on the other bands:

30m: 60:1
20m: 97:1
17m: 67:1
12m: 48:1
10m: >100:1

As Cor suggests, running a 40m dipole fed with ladder line (straight to the tuner, if possible) is a much better choice.

OK just ordered this:
http://www.gigaparts.com/Product-Lin...FJ-18H050.html
http://www.dxengineering.com/parts/dxe-213udx050
http://www.dxengineering.com/parts/mfj-4600.

Still need to get a tuner and split bead ferrites for the coax. When I get some more $$$, I was thinking the MFJ 969. I was looking at other tuners and this one seems to be the best for the buck. Not sure after reading the eham reviews though. Not sure if the low reviews are genuine or just LETS HATE ON MFJ type of entries. I was also thinking an autotuner but I don't see any that have balanced line ports on them so I don't see that as being an option

Ordered both ladder and coax because I also plan on putting up a 2/440 antenna at some point.

Also bought some ceramic dog bones so I can stop using those plastic tie straps

Quote:

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Originally Posted by AF5TY

When I get some more $$$, I was thinking the MFJ 969. I was looking at other tuners and this one seems to be the best for the buck. Not sure after reading the eham reviews though. Not sure if the low reviews are genuine or just LETS HATE ON MFJ type of entries.

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Most of the low reviews of MFJ tuners (and other products they make) has more to do with the quality of construction, more than anything else. The design of their tuners are fine. Where they "fall down" has more to do with a solder connection not done correctly (sometimes not done at all), or hardware not tightened sufficiently.

A few of the low reviews also have to do with trying to make an MFJ tuner do what it wasn't designed to do in the first place. This is not a problem specific to MFJ. You have morons who insist on trying to load their 80m dipole on 160m (or 40m dipole on 80m, etc), then wonder why a 200-watt tuner starts arcing when they pass 100 watts through it. Hint: most tuners rated for 200-300 watts won't tolerate that either, not just MFJ.

Quote:

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I was also thinking an autotuner but I don't see any that have balanced line ports on them so I don't see that as being an option.

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Two options: A) Buy an LDG tuner and get one of their remote baluns (RBA 1:1. or RBA 4:1). B) If the radio is an Icom, look at the AH-4. If a Yaesu, look at the FC-40. Both of these tuners can work with ladder line.

With a good 1:1 current balun, it really doesn't matter what kind of autotuner you use. The trick is getting a good one, because voltages can get scary high (especially if you're running QRO).

Cebik's article on backyard wire antennas is worth the read - http://www.pc5e.nl/downloads/antenne...0antennaes.pdf

Make sure you make the connections on the ladderline watertight outside since the ordered ladderline is steel core with copper on it.
The thin copper layer will wear off fast and steel rusts like h*ll.
I use the MFJ 993-B and the legal limit MFJ 998 autotuners.
Both gobble up what I throw at them and do what they need to do tune and forget.
Even accidentally put 600 watts through the already tuned MFJ 993-B ( 300 watts) and it didn't smoke.
Both were opened on receiving them and checked for loose contacs forgotten solderings etc, nothing found.
Both had the same problem though it took 2 weeks for the small lamp lighting the analog meters to pop.
Replaced them and added resistor on the 998 bringing down the voltage to 7 volts on a 12 volt lamp, still works after 24./7 on for 3 years.
The 993-B I replaced the lamp bu 2 white LED's shining through a yellow paper which gives almost incandescent colour on the meters.

The MFJ 993-B has a balanced port internally ( just a balun) and can feed coax or ladderline as you chose.