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Author Topic: Help me choose an LNR EndFez antenna  (Read 2255 times)
AE7UT
Member

Posts: 72




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« on: February 11, 2013, 01:12:00 PM »

I've been using a ZS6BKW, Yo-Yo dipole and an Alpha DX antenna for portable work.
I'd like to try an end fed antenna - I'm happy with all the others but one can never
have too many antennas.  I'm using an Elecraft KX3, CW & SSB.  Usually 5 watts max.
Most of my time is spend on 80/40 CW.

I am looking at the LNR EndFedz and was hoping to get some feed-back from the Guru's.
The choices I have come down to are:
   - EF-10/20/40MKII, 25 watt, 40 ft
   - EF-40/20 , 100 watt, 66 ft

I'm leaning toward the 66ft/100watts just because more wire seems to get more signal and
I might want to run more power but never have.

Or I could build one using the Balun Designs 9:1 Unun and some wire of my own.
This would get me the 80 mtrs I like to hang out on.
http://www.balundesigns.com/servlet/the-102/QRP-9-cln-1-Unun-1.5/Detail
What wire would you recommend for this? 
Anyone have a favorite length of wire?  It looks like 52.5 or 124 ft. are the sweet spots.
Does anyone use a counterpoise with this and what type?
Do you think it would perform as well as the EndFedz?

Thanks for any help you can be.
73
Stan AE7UT
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N3DF
Member

Posts: 252




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« Reply #1 on: February 11, 2013, 01:34:46 PM »

I like to string a dipole between trees and/or structures when I'm portable.  Works great and costs $0-$20 depending upon what's in the shack junk box. 
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Neil N3DF
AA4PB
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Posts: 12897




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« Reply #2 on: February 11, 2013, 01:57:20 PM »

If you have the built-in tuner with the KX3 then you can just hook the end of a wire to the KX3 and you have an all-band end fed. No need to buy a commercial antenna. I think the Elecraft manual has some suggestions for wire length. Basically you want to stay away from an exact multiple of 1/2 wave on any band because the very high impedance is sometimes difficult to match.
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KB1GMX
Member

Posts: 782




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« Reply #3 on: February 11, 2013, 03:57:59 PM »


Of the two LNR antennas I use the tribander EF10/20/40 as that offers the three
bands likely to be either DX or at least useful for local contacts. Not affiliated
just a very happy user of a few of these.

The 25W limit is well above the portable radio category and that's a continuous
not intermittent limit.  The only band that is shortened is 40M and the difference
is small compared to full size.  Being shorter its easier to hang as a vertical
(one end up) or sloper (in case of short trees).  I've also run it as flat top, inverted V,
and inverted L.  It's small and light fits in a ziplock and 15ft of RG174 will be enough
as a sloper or vertical. Of all the LNR antennas its the only one that can be set up
as 10/20M only (take off the choke and 7ft tail) or replace the wire with any
half wave length between 5 and 30mhz.  With mine I carry a wire cut for 17M and
another for 15M for those times.  (other bands can be 60M, 30M, and 12M).
It's pretty flexible.  Download the manual (its pretty small) and see what possible
things you can do with that one.

The longer ones give you 80 but by day I've found 80 to be high absorption and plagued
with permanent nets.  By night it goes long and can be very noisy.  You do also get 40
but the added length is a installation overhead for not much more gain.

Then there is the is the practical issue of antenna height.  Unless you are running it as
vertical (Vertical, sloper, inverted L) a dipole needs to be high. Optimally a half wave
or more or the signal is mostly going UP. That means getting ropes in high trees and all
assuming they are available. 

If you have a choice higher is better than longer.  If you really want 80M make a plain dipole
and deploy it as a vertical with one radial or if high clear trees exist then go for getting it up.
But remember if you yanking rope for a 40ft high lift of a wire that means you need 100ft of
light cord for each end. and more than 40ft of feed line.  That's a lot of stuff weight and bulk.

Now that balun designs is a nice product but it's not small or light being rated for 300W. 
An untuned wire and a balun like that means your going to lay down at least a few radials
or you heating earth worms(or other ground dwellers).  If you are dragging 124ft of wire thats
an 80M Dipole (skip the balun then) Also to end feed a 80m half wave you need a far higher
ratio balun to be useful.   An untuned wire like 43 or 52 ft may work but it will be inefficient
and near useless without a good counterpoise.

You didn't say what the weight limit is but you can see longer and higher means more wire and ropes.

I also lean to field antennas that are simple LNR EF 10/20/40 plus a 15m wire for it as I carry
the least using that.  Alo I lean toward higher bands as 80/75 has been poor for daytime ops.
If trees are uncertain anything that can be deployed as vertical and a light fiberglass pole
(crappy/breem pole)in the 20+foot size helps. 

My free advice.

Allison
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AE7UT
Member

Posts: 72




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« Reply #4 on: February 12, 2013, 09:43:58 AM »

Thanks for the input guys.

The Yo-Yo IS a dipole that can be "reeled" out to any length you want.
It's perfect for multiband use but is a bit time/space intensive.

I have run a wire from the KX3 but I'm often in a cabin/tent/trailer so
a run of coax is usually preferred.

For hiking/snow-shoeing I'm going to try the wire and an EndFedz

Thanks again.
73
Stan AE7UT
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N3JJT
Member

Posts: 31




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« Reply #5 on: February 12, 2013, 05:07:47 PM »

Stan:  I own the 10/20/40 model.  I actually have 2.  One lives in the camper, and is used with the K2 or K1.  I have had great success with this set up.  Nice thing, no counterpoise.  I also own the 30 Mtr version. I have it sloped off of the back of my tower.  Works FB.  Not sure of the SSB performance, as I do not do phone, but on CW I have had nothing but fun, and many contacts on 40 and 20.  I usually run mine as a sloper from a 33' fiberglass telescoping mast.

GL, and have fun!  de Scott  N3JJT
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WB6BYU
Member

Posts: 13340




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« Reply #6 on: February 13, 2013, 11:23:57 AM »

If you want an end-fed antenna for 80m and 40m, then I'd suggest building a
40m J-pole (using direct feed rather than a shorted matching stub) and seeing
where it is resonant on 80m.  You can then adjust the 80m resonance somewhat
without disturbing the 40m setting by adding a reactance between the matching
stub and the wire, which is a high impedance point on 40m.

Otherwise you can use a half wave wire on both bands, just by changing the
matching network or using a parallel-tuned network that has enough range
to tune both bands.
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W9KDX
Member

Posts: 770




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« Reply #7 on: February 13, 2013, 02:37:21 PM »

I was looking at these EF antennas a while back and the main feedback I got from the people who had used, tested, and compared these to other options was that they were rather noisy.  Other than that, people were pleased.  I never tested anything or did a specific comparison, but the one I tried briefly did seem rather noisy.
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Sam
W9KDX
WB6BYU
Member

Posts: 13340




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« Reply #8 on: February 13, 2013, 02:43:09 PM »

An antenna can't differentiate between desired signals and noise:  it pick up
whatever fields are around it.

However, any end fed antenna of that type is going to have common mode
current on the feedline (it has to, or it won't work), and that means that
the outside of the coax is acting to some extent as an antenna.  If the
feedline runs past electronic noise sources in the house on its way from
the shack to the antenna, it can pick up more noise on the coax than
is picked up by the antenna itself.  This isn't unique to end-fed antennas,
they just happen to be susceptible to it because, by design, they have
common mode currents.
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K0CWO
Member

Posts: 419




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« Reply #9 on: February 14, 2013, 06:16:57 AM »

I have a quiet antenna; it is a dummy load and I use it to tune up my amplifier Wink
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