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Author Topic: 6 meter QRP antenna suggestion  (Read 3990 times)
N7ZAL
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« on: May 25, 2010, 03:35:50 PM »

I'm looking for a 6 meter antenna I can use for QRP (CW). It will be mounted to the roof rack of a 5th wheel RV and removed when on the road. I was thinking a 5/8th vertical but can't seem to find any out there. Looking for suggestions/ideas

Thanks, Bill
N7ZAL
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Later, Bill N7ZAL (ex. WA2DPB, WB3BOC, N2FWS)
WB6BYU
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« Reply #1 on: May 25, 2010, 04:22:55 PM »

Are you planning to work FM repeaters or CW/SSB?  Vertical polarization is used for the former, but
horizontal will give better results for the latter.

The 5/8 wave isn't common because it is too tall for most mobile installations (about 12 feet tall.)
But you can make your own fairly easily if that is what you want.  In practice you probably won't
notice much difference between that and a quarter wave vertical fed against the metal roof.
Either should work for FM.

For CW/SSB a horizontal dipole on a push-up mast would work - the mast could be attached to
the side of the roof ladder and extended when parked.  The dipole could be left attached to the
mast when it is lowered if it didn't stick out over the side. An omni loop or a Moxon beam would
also work on top of the mast.
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N7ZAL
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« Reply #2 on: May 25, 2010, 04:35:53 PM »

Exclusively CW and maybe SSB once in a blue moon. If there isn't much of a performance difference between the 5/8th and 1/4 then I will change my mind to the 1/4. The roof is a rubber type, and not metal.

I haven't worked six in many, many years and have to re-educate myself on things. Didn't realize the difference in antenna's for CW/SSB and think you are referring to a "rotatable" dipole ? I think there is enough room to do that.....thanks for the idea and I'll also check into the Omni loop and Moxon. My concern is that I have to get the best antenna setup that I can because of the QRP aspect.

Thanks, Bill N7ZAL
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Later, Bill N7ZAL (ex. WA2DPB, WB3BOC, N2FWS)
K0BG
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« Reply #3 on: May 26, 2010, 07:32:44 AM »

Why don't you look at an M-Squared halo. I have one mounted on the back of my Ridgeline, and although it isn't mounted as high as I would like it to be, it works fairly well. Being horizontally polarized also helps. You can stack 2 of them, if you need more gain, and the harnesses are available from M-Squared.

http://www.m2inc.com/index2.html
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N7ZAL
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« Reply #4 on: May 26, 2010, 08:14:44 AM »

I did look at it and read some great reviews here, but I was told by a good authority that it won't have an advantage over a vertical. I'm looking at it but am now trying to figure how much (if any) advantage it will have over a vertical for CW work. The horizontal polarization does appeal to me.
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Later, Bill N7ZAL (ex. WA2DPB, WB3BOC, N2FWS)
WB2WIK
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« Reply #5 on: May 26, 2010, 09:47:45 AM »

I did look at it and read some great reviews here, but I was told by a good authority that it won't have an advantage over a vertical. I'm looking at it but am now trying to figure how much (if any) advantage it will have over a vertical for CW work. The horizontal polarization does appeal to me.

Your "good authority" is wrong.

Of course it makes a difference on all tropo paths, which represent 90%+ of all six meter activity.

The only time polarization doesn't matter is for ionospheric propagation, which makes up the other 10% or so of what we can work on six meters.

VHF signals maintain polarization for hundreds of miles within our troposphere.
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N7ZAL
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« Reply #6 on: May 27, 2010, 04:39:26 PM »

Well, after talking to a lot of folks I have decided to go with a vertical antenna. I should mention I am in very remote locations and will probably only be working band openings. I doubt I could work any local stations. Heck we are 83 miles from the nearest stop light Smiley

Thanks for all the input and I'll post my results after some testing...
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Later, Bill N7ZAL (ex. WA2DPB, WB3BOC, N2FWS)
KE4DRN
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« Reply #7 on: May 27, 2010, 07:10:48 PM »

hi,

I see you like the vertical, here is a link for Moxon for 6m,
similar gain as a two element yagi but takes up less space
and is direct fed with 50 ohm coax.

http://www.moxonantennaproject.com/wa0wox/wa0wox.htm

you can use it horizontal for cw and ssb and vertical for fm.

I build it out of #10 thhn wire and it worked so good I
built another out of  1/2" aluminum tubing.

73 james
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WX7G
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« Reply #8 on: May 27, 2010, 08:31:00 PM »

A 6 meter Hamstick is $31. The MJF-1606T HF Stick is $20. A mag mount (with a GND wire attached to the motor home) and you're on the air.
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K0BG
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« Reply #9 on: May 28, 2010, 05:27:08 AM »

Bill, if you're planning to work just band opening, you need to go back, and reread Steve's comments.

I have both a 1/4 vertical (cut down CB whip), and the M-Squared loop for 6 meters, mounting on my Honda Ridgeline. Not all of the time, but at least 75% of the time, I can't hear stations on the vertical that are easily worked on the loop.

There was a rare north-south opening here (Roswell, NM) yesterday for about 3 hours. I worked about 15 stations, but didn't hear any of them on the vertical.
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N7ZAL
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« Reply #10 on: May 28, 2010, 07:24:07 AM »

Well, I haven't ordered anything yet so will chew on things a while longer  Smiley
Thanks for all the input and most of it goes along the line of what I experienced years ago with 6 meter polarization, and that was horizontal is the best. However some people who should really know, say otherwise. I sure liked the comments on the band opening yesterday....hard to disagree with performance that was experienced.
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Later, Bill N7ZAL (ex. WA2DPB, WB3BOC, N2FWS)
N5XTR
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« Reply #11 on: May 28, 2010, 08:14:25 AM »

If it is going to be removed while in motion, I would try for a small 3 element yagi.  If you went with the square loop, you could just leave it mounted and maybe work some ssb while traveling.  I know a few hams that have 5/8 wave 2m mobile antennas that they use for 6m ssb.  I haven't had much luck with them but others might have.  The Hustler mobile 54" mast is 1/4 wave for 6m but I haven't tried using them either and I own 2 of them. 
I am building/designing a full wave mobile 6m vertical but I need to buy some argon for my TIG welder so it is just a bunch of parts right now.
My advice is to just try a few different antenna designs and see what works for YOU like ease of installation and removal, performance, and storage.   You are going to be operation QRP so performance is the big issue here but it would be difficult to store a 6 element yagi in your RV.  It will take a compromise but almost all antennas are.
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N7ZAL
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« Reply #12 on: May 28, 2010, 08:30:22 AM »

I did consider the 3 element beam, but I think the wind load would be too much, even in a stationary spot. I do have a Hustler vertical mounted on the roof rack for HF work, and take it down while on the road. I can try several approaches but want to narrow the choices down to help the wallet. Wink As you say, everything is a trade off but because of the QRP aspect, I want the best performance I can in the current situation.
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Later, Bill N7ZAL (ex. WA2DPB, WB3BOC, N2FWS)
WB6BYU
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« Reply #13 on: May 28, 2010, 10:41:23 AM »

Quote from: N7ZAL
...I do have a Hustler vertical mounted on the roof rack for HF work, and take it down while on the road...

Then try it on 6m by just taking off the resonator - the 54" mast should make a good quarter wave
vertical that you can compare against other options.

Doesn't cost you anything to try, either.
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N5XTR
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« Reply #14 on: May 28, 2010, 12:26:59 PM »

Hustler even advertises that the mast will work on 6m.
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