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Author Topic: Best Installation for 30m End-Fed  (Read 8271 times)
AF7DN
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Posts: 4




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« on: October 17, 2013, 08:21:26 PM »

I have an LNR 40-20-10 that I have been pleased with, so I bought their 30m model to try with my HB1B;  it looks like a nice rig for use in the woods or a park. 

I have a location about a mile West of a 1,000 foot 'hill' in Northern Idaho,  I have no trees, poles, or tower nearby so it won't be up high.  I mostly expect to use it during the daytime there.

My thought currently is installing a 20' pole on my pickup trailer hitch, and sloping the wire down NW to SE to enhance SE low-angle radiation.  I would be interested in any suggestions. 

AF7DN

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W1JKA
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Posts: 1619




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« Reply #1 on: October 18, 2013, 04:48:23 AM »

  FWIW 30m is my favorite band and since my Par is the 40m model I home brewed a 30m end fed and matching unit. With either one my best results were an inverted l at about 20 ft.(bottom feed) or a sloper (same height) but with the matching unit on the high end (longer feed line).Depending on clear space around set up the direction can be easily changed as your strongest signals are not always from the direction you are aiming for depending on current qth and ground conditions. Reading other qrp related post these seem to be the two most popular configurations for the PAR efs.
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K5LXP
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« Reply #2 on: October 18, 2013, 06:27:04 AM »

Another option I would offer, not far off from AF7DN's inverted L is to configure your EFHWA as an inverted vee when you have only one support.  That puts the current node at the apex where most of the radiation happens.

Mark K5LXP
Albuquerque, NM
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WB6BYU
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Posts: 13027




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« Reply #3 on: October 18, 2013, 09:40:19 AM »

Quote from: W1JKA

... or a sloper (same height) but with the matching unit on the high end (longer feed line)...



Shhhhhhh!  If you say that too loudly you're going to upset all those folks who are trying to
claim that there is no current on the feedline with these antennas!  (Obviously, if it makes
a difference which end has the feedpoint, then the effect must be due to radiation from
the coax.)


When the 30m band was opened I found there was a significant difference in antenna performance
compared to 40m, which was my favorite band.  Relatively low dipoles made lots of contacts out
to 1000 miles or more on 40m, but similar antennas worked poorly on 30m.  Vertical polarization
turned out to be better unless I could get the high current portion of the antenna up high enough.
(This is due to the vertical angles of radiation supported by the ionosphere.)  The same is true for
20m and higher frequencies, but there it isn't as hard to get a dipole up close to 1/2 wavelength.

The problem with using a sloper from a 20' mast is that, since a half wave is ~46' on 30m, the
antenna will be more horizontal than vertical, and the average height of the portion with maximum
current (therefore contributing maximum radiation) is only 10' off the ground.  A better approach
would be to run the wire up at a steeper slope so that there is perhaps 30' of wire leading up to
the top of the mast, with the remainder running off from the top as horizontally as possible.  That
will maximize your low angle radiation.  (Or just run a wire up the support and feed it against the
truck body as a ground - with a loading coil or a bit of a top hat you can make it resonant.)

Otherwise, find a longer pole, or take a kite with you to hang it from!
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W1JKA
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Posts: 1619




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« Reply #4 on: October 18, 2013, 12:37:20 PM »

Not only "The Shadow" but the Clamp Meter also knows.
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AF7DN
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« Reply #5 on: October 18, 2013, 05:11:12 PM »

Lots of ideas I never thought of.  Much appreciated.

Does anyone have any feelings about using a Tuner between the radio and the coax?  It isn't weatherproof so it can't live at the coax-wire interface.

AF7DN
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ZENKI
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Posts: 906




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« Reply #6 on: October 18, 2013, 08:19:03 PM »

Add radials!

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W1JKA
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Posts: 1619




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« Reply #7 on: October 19, 2013, 01:41:01 AM »

Re: AF7DN

    For any single band antenna cut and tuned to your most used frequency range a tuner is not necessary and just extra weight and hassle while operating portable. The matching unit on the end of your EFHW and an antenna Tuner are two different animals.
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NO9E
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Posts: 382




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« Reply #8 on: October 23, 2013, 04:35:00 AM »

The end fed antenna has a maximum current and thus radiation in the middle. So it seems that an Inv V with direct feed and the middle of the antenna on top of the pole may work better than with the feedpoint elevated.

I did some experiments with EndFed 40/20/10 and KX3 wit AT. EndFed was almost vertical to a tree. The other antenna was a low dipole. On all bands, including nonresonant bands of EndFed, EndFed matched by AT was better than a low dipole but same when the wire of EndFed was directly attached to KX3 and the other end was a short counterpoise.

So 2 choices for QRP without a tuner. Buy an EndFed and have one or some bands covered. Or buy Elecraft T1 tuner and have all bands covered. EndFed is a simpler choice if one sticks to a single band. 

Ignacy, NO9E
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AF7DN
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Posts: 4




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« Reply #9 on: October 24, 2013, 06:53:59 PM »

Inverted-V would be easy to implement at my location (and I have never had one ...)

Interesting results you mention with the tuner in place.  I don't personally see the harm although the manufacturer suggests NOT using a tuner, they don't really suggest why.

The EF-30 arrived this week so perhaps I'll get a chance to test it shortly.

AF7DN
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WB6BYU
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Posts: 13027




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« Reply #10 on: October 25, 2013, 10:11:38 AM »

Quote from: AF7DN

Interesting results you mention with the tuner in place.  I don't personally see the harm although the manufacturer suggests NOT using a tuner, they don't really suggest why.




The antenna should have a low enough SWR to be used without a tuner.

Typically the weak link in such an antenna is the voltage rating of the capacitor
used in the matching network at the antenna feedpoint.  If the SWR is high enough
that you need to use an external tuner with the antenna, then - depending on the
cause of the high SWR - it is possible that the capacitor will have a higher voltage
across it, which will lower the power rating of the antenna.

Generally, when an antenna is supposed to have a low SWR but  it doesn't, it is
better to find what is wrong with the antenna than to simply slap a tuner on it.
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K6DZ
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Posts: 16




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« Reply #11 on: November 02, 2013, 07:19:06 AM »

Inverted V sounds good to me for 30 meters. A twenty foot high telescope fishing pole holding the center and at 120 slope angle the two 22 foot dipole sides would reach down about 5 feet off the ground. You can reach up and adjust the length a couple inches or so for low SWR, no tuner needed.

Nothing like a tuned antenna.

The yoyo antenna would be easy to adjust a few inches shorter or longer in 10 seconds, they have a model with a 1:1 balun.

http://www.hamradiofun.com/yo-yo-vee.htm

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AF7DN
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« Reply #12 on: November 05, 2013, 04:40:20 AM »

I'd never seen 'the yoyo' before - clever trick.
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W1JKA
Member

Posts: 1619




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« Reply #13 on: November 05, 2013, 04:52:35 AM »

Easy to build your own yo-yo antenna with the plastic camping cloths line spools in camping dept. at Wally World or use the Stanley plastic chalk line holder/spools.
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