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Author Topic: 6 band rotatable dipole vs 60 ft end fed wire  (Read 2228 times)
KD4KO
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Posts: 13




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« on: May 06, 2017, 08:04:50 AM »

My end fed wire is only 12' in air. I am looking at the MFJ-1775 as an inexpensive alternative to the end fed wire.
I have no trees to support the ends of an inverted V antenna.

David
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KH6AQ
Member

Posts: 7718




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« Reply #1 on: May 06, 2017, 09:52:22 AM »

The MFJ-1775 will work but will be less efficient on 40 meters. On the higher bands they will both be efficiency with the MFJ-1775 exhibiting a dipole pattern while the end fed wire will tend to have multiple lobes. Even though the antennas are close to the GND they can exhibit directivity at low take-off-angles.

If vertical mounting suits your situation the MFJ-1796 is an option. I had one of these and it was easy enough to assemble and tune. Using an antenna analyzer tuning required only two spoke trimming operations per band.
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KD4KO
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Posts: 13




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« Reply #2 on: May 06, 2017, 12:47:09 PM »

Thank you for you're reply.
The MFJ-1775 looks like it would be easier to tune the spokes since they are at chest level.
I can't imagine myself standing on a step ladder, in order to trim the upper spokes.
Since I don't have an antenna analyzer  I would have to us an SWR meter. The companion MT1 Tuner has a small SWR meter.
In the old days, I would make my own SWR meter by snaking an enameled insulated wire under the braid of a short piece of coax, feed the ends of the wire in series with a diode, and ma meter.
David
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KB1GMX
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Posts: 1495




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« Reply #3 on: May 07, 2017, 06:10:26 AM »

The problem is your low to the ground for hf and likely VHF as well.

Going to a shorter dipole and low is going to be worse.  Shortening
any antenna makes it less efficient.

Going vertical as high as possible with say a 26 or 43 ft
with a few radials on the ground would likely be better.

RIght now I can say for certain that my Butternut HF2v with
4 radials on the ground will work better than any horizontal
antenna at 12ft.  I've played much with antennas.

Higher or taller is improved.

Allison
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KB1GMX
Member

Posts: 1495




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« Reply #4 on: May 07, 2017, 06:22:06 AM »

One other thing you can try is to take that 60ft end fed
and make it an inverted L with the vertical portion as
tall as possible and the rest horizontal.

Use a good ground, spike in the earth and radials as
 many as you can but 4 will be a good start.  Length is
not as critical but at least 25-30ft as a start.  More is better.
Feed it at the ground point and go up as far as possible.

A simple way to get the vertical portion high in the air
is a rope over a limb to hold it up.

See it that works better.  Its an old school antenna but
generally effective.


Allison
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KD8IIC
Member

Posts: 648




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« Reply #5 on: May 13, 2017, 09:34:05 PM »

 I work plenty of guys under 100 watts using CW with low antennas. Had a regular 40m CW sked with guy in Atlanta GA, I'm in Columbus, OH, this past winter and his dipole was @ about 12-15 ft. So don't give up. Use what you have and improve upon it.
During daylight hrs the low wire will do you just fine on 40m.
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KB1GMX
Member

Posts: 1495




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« Reply #6 on: May 13, 2017, 09:47:14 PM »

Yes that's true.

For low antennas a portable I use is 130ft of wire off-center fed matching transformer
laying on the ground.  On 40M its worked a few countries.   Look up the K3MT Grasswire.
I get better reports if it was 12ft up and  still better if its 35ft up.

I've used low dipoles, they work on the lower bands (40 and down) because of the ionosphere
if its working that day as then everything going up comes down again.... If not well ISS might
hear it if they had HF.  That would make a good radio experiment.

I've made plenty of contacts off antennas with radiation efficiencies of less than 1%
that doesn't make them great though they were small.   It just proves propagation
is an amazing thing.   Also depending on the antenna the feedline does the work
and the antenna is just a way to excite the shield.  In the end first you have to radiate
and then it has to propagate.


Allison
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