Radio Preppers

General Category => Antennas => Topic started by: K7JLJ on May 13, 2015, 07:56:47 PM

Title: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 13, 2015, 07:56:47 PM
So next month i take my general and i now have an ft-817

I've only made a few 10min antennas with limited RX on 20/10M but want to get a "real" antenna setup for my anticipated upgrade.

Max $$$ is in the $300 range, that includes a tuner, pole, antenna, etc

All that said, here is what I'm wanting and would appreciate any advice.

I'd like the most efficient antenna that has a good match for EMCOMM (low pro SHTF and BUGOUT capable) with the following weighted abilities

The tuner issue is that i don't have one and it adds $80-130 to the cost (MFJ-971)

A collapsible pole ~$70.

Desired Abilities
1. Portable 40/20/10
2. Small footprint and stealthy
3. QRP efficient
4. Tunerless

My choices seem to be:
1. SOTAbeam inverted V ($55)
    PRO: light
    CON: needs roach pole
              taken down to change bands
              needs a tuner for best results?

2. Enfed 40/20/10 ($75)
    PRO: light
             Easier to setup without a roach pole
    CON: not mobile and needs space

3. EzMilitary ($300)
    PRO: easiest to setup
             Auto tune
             Can double as vehicle antenna
             Stealthy
             
    CON: read that its very inefficient with 5W max
              Pricey!!!

4. Buddistick ($200)
    PRO:  easy setup
               Tunerless (tune by ear)
               Small package collapsed
               Vehicle ops capable
               Stealthy
    CON:  little high priced


The big question is also... Will i eventually need a tuner anyway and would having one like the 971 that can tune random wire be a better option?  I figure on 5w that a tuner is just wasted energy?

Also, i googled "alpha match" (ezmilitary antenna) and have no clue what that means?  How do they provide a continuos match across several bands?

Appreciate any advice, if im  missing the bigger picture please draw it for me :)
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: cockpitbob on May 13, 2015, 09:14:57 PM
You've clearly done your homework.  Everything on your list is good stuff.

Since you've got an FT-817 you can work any band.  I would get a tuner.  For a base operation, if you have trees and room, a balanced line fed dipole is hard to beat.  Very cheap and with the tuner you can make it your bitch and force a tune on any band you want to work.

I think it really boils down to do you want a wire antenna or a vertical.  If you go vertical, the BuddiPole's reputation is the best.  If you go wire, I would go with an end-fed for the field since it's much easier to deploy.  I would go with either the LNR 40/20/10 or get a SOTA tuner and some wire.  With my SOTA tuner a 63' length of wire works well on 40/20/15 & 10(sort of).  And you can cut wires for any other band.  The LNR's advantage is that it's weather proof and there's nothing to adjust.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 13, 2015, 09:35:21 PM
Thanks for the response Bob.  I really want a vertical but dont want to loose signal strength compared to the LNR (which is the one i had in mind) but without any real world experience and not being able to  google fu any direct comparisons because they are apples and oranges...  I have no clue how much more inefficient a buddistick is to the LNR in an inverted L which is probably 90% of the time what it would be in.

The ezmilitary looks too good to be true IMO.

The buddistick is a solid performer and well made, but are we talking 50% the efficiency of a tuned dipole?

If its in the 10-20% efficiency loss area, then thats my first choice for sure.

Gil, i saw a post that you had the buddistick and  were impressed with it.  What % loss would you rate it at compared to a tuned Dipole or Enfed?

Also, once i had the LNR tuned (i saw a video from TinkerJohn? That showed it didnt need tuning with his setup)  does environment (trees, etc) really detune antennas that much?
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: cockpitbob on May 13, 2015, 10:12:37 PM
Also, what do you want to do with it?  I'm not a propagation expert, but I believe the vertical antennas have a low take-off angle making them good for Dx but not good for shorter distances (<500 miles).

I use end feds a lot and trees don't seem to bother them.  Not being able to get it up high lowers the resonant frequency a little, but don't be afraid of a little SWR.  Unless you have a really lossy feedline, a 2:1 SWR only reduces your effective transmit power by a small amount (about 10% if I remember).  And since 1 S-unit is a 4:1 change, that 20% loss is nothing.  In Feb I was in a cabin with Boy Scouts for a weekend.  I strung my 63' end-fed out the door and horizontally about 15' up.  Not an ideal set-up.  The SWR indicating LED in the SOTA tuner was kinda bright, but I made lots of contacts.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 13, 2015, 10:39:15 PM
I'd like to use it primarily for DX       as a source of out of state emcomm and on the hobby side, to DX CW. 

Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: gil on May 14, 2015, 01:50:21 AM
Hello,

I would also go with either the LNR 40/20/10 end-fed. That antenna got me 5200 miles with 1.3W! Very easy to set-up if you have a tree nearby, or as you say, a pole long enough. It does not even require radials. You can't beat the price, it's light, works on 15m too (might need a tuner), and is great for DX. Better yet, you'll still have money for a second antenna.

The Buddistick is great down to 30m. I own one. 40m, not so much. It is a compromise antenna. You don't get much radiated power out of it, but it a pinch, it works. Great when you have no trees around for your end-fed.

Try not to use a tuner, but sometimes it is nice to have one. See the tuners on http://qrpkits.com (http://qrpkits.com). Cheap and very easy to assemble. I have the SOTA tuner, it works great. Their BLT+ and SLT+ are great too, and all have an SWR indicator LED. If you want an end-fed tuner, see the ILERTENNA or the one from SOTABEAMS.

You are getting into QRP, stay QRP, don't spend hundreds on antennas. The best antennas are often the cheapest ones. The expensive ones always try to offer more than they can efficiently deliver. Nothing beats a long wire antenna. Wire is cheap.

Gil.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 14, 2015, 01:54:05 AM
I'm QRP only for sure, can't afford anything more.  I think I'm going to pull the trigger on the LNR.  Didn't know the BS was < 40, good information.

Will look into the kits!
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: gil on May 14, 2015, 02:01:05 AM
QuoteDidn't know the BS was < 40, good information.

Well, it does work on 40m, but I never got anyone with it so low! Didn't try too long either. Such a short antenna doesn't do 40m well. I did get good results on 30m though, with a QSO with Ray on 30m, 2W with the BS clamped to my coffee table inside the house! 810 miles, not bad. On 20 and 15m, it works pretty well.

Gil.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 14, 2015, 11:57:09 AM
That SOTA tuner looks great for random wire. 

Question: Would I be able to use the LNR 10/20/40 on 11m without a tuner @ 5w?

Being able to monitor and maybe talk CB without any changes would be a nice feature for SHTF. 

Would the SWR be unacceptable?

Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: cockpitbob on May 14, 2015, 12:17:44 PM
Actually, the SOTA tuner requires the wire to be 1/2 wave long, or some multiple.  A 63'(ish) wire works on 3 bands because it is 1/2 wave long on 40meters, 2 half waves on 20 meters and three half waves on 15meters.  It's about 4 half waves long on 10meters, but that's pushing it for a wire that long.  If I wanted to work a lot of 10M I would use a 31' wire and work 20M and 10M.

For the LNR, you can put whatever wire you want on the coupler to work other bands.  The wire just needs to be 1/2 wave long (or a multiple of halfs).  With a different length wire it will work on 30M or 17M or 12M. 

For a random length end fed wire you need a "real tuner" and a ground or long counterpoise.  Something like qrpkit's SLT or the MFJ-971 you mentioned would work well.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: linkclan on May 23, 2015, 03:49:57 PM
With my whopping 6 months of experience, I'll throw this out there. Resonance is key and just as important is element elevation for the band of interest. I have been thinking about this for our upcoming field day antenna/s(no I do not want to become a con-tester, just learn and experience). It got me thinking about making dedicated band dipoles on the cheap, PVC insulators and #14 building wire from Home Depot and some para-cord. The 500ft roll of wire will build an antenna for all the bands except 160 and your total cost would be about $60. You would get bonus bands as 30 and 15 seem to work on the same wire. The only hard part is getting it up in the air. You could do it with a single support mast, tree etc, and an eyelet at the top to pull your center up. With dipoles, your sweet spot elevation stops are 10m=17ft, 12m=20ft or as you may see the pattern, about 1/2 wavelength for each band. 40 and 80m are hard to get up high enough and most of us will be limited to NVIS on these low bands.

The down side to this is that you have to go outside for 10 or 15 minutes to change bands. The up side is resonance right where you want it. If you wanted to cover the entirety of say 20 and 40m you could double the elements on those and spread them a bit, see "Fat Dipole".

Of course, I'm not saying this best as Gil and others have had great success with random and not-so-random wires. I'm even thinking about throwing one up in the tree today and connect it directly to my KX3 with binding posts. This will be deployed right off the deck with an already +/- 25ft elevation.

Bottom line here is there are many options "on the cheap" and the really important part is to simply to get on the air! Better to spend good money on quality feed-line than wire elements anyways.

I hope this helps and I don't get kicked in the shin.

Paul-K6PLE
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: gil on May 23, 2015, 04:24:05 PM
QuoteWould I be able to use the LNR 10/20/40 on 11m without a tuner @ 5w?

It might work. I should go get my CB out of storage and give it a try... If you use the LNR on 10m at the bottom of the band, then you're really close to the top of 11m. If you trimmed it to use higher in the band, it would be less likely to work.

Gil.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: KK0G on May 23, 2015, 10:22:51 PM
Not that there's anything wrong with resonant antennas, but resonance is way over rated. Some of the most efficient antennas are non-resonant.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 28, 2015, 07:27:24 PM
OK, after a little more homework and finding a review of the ezMil against the LNR at eHam forums (LNR was better every time he tested ) I'm set on the LNR trail 40/20/10 and getting a 31ft fiber pole

Question:
Inverted L
Sloper
Or straight elevated

How much efficiency of any do you loose between them?

The sloper is obviously the easiest to setup but am I loosing a lot compared to an inverted L?

Also will putting the feed point at the bottom of the pole and running the antenna up then sloped down give worse result?


- Jim
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: cockpitbob on May 28, 2015, 09:36:34 PM
Jim, good choice and good questions.  I wish I had answers.  I do know that end-fed antennas are hard to accurately model so you might not get good answers searching the interwebs.  I'm pretty sure a vertical or inverted-V will work best for Dx due to lower takeoff angles.  Yes, end-feds work fine as an inverted-V.

If you are operating portable you'll probably find the location dictates how you hang the antenna.  I wouldn't over-think the mounting of the antenna much.  I have 2 end-feds at home, one vertical and one sloping 45 degrees.  They both make contacts.  I've also gotten good results (in good band conditions) with a 63' long wire strung out the door of a cabin and horizontal 10' - 15' above the ground.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: gil on May 28, 2015, 10:00:50 PM
QuoteQuestion:
Inverted L
Sloper
Or straight elevated

The issue would not be of efficiency, but radiation pattern. I would go for the sloper with the lower end toward the receiving station, fed at the bottom of course. Don't forget to get a slingshot and fishing line/weight(1oz). I have never needed a pole, most often found a tree tall enough to go full vertical. I do use the LNR 40/20/10 trail wire/trap with a couple different end-fed tuners. Sometimes I still end up with a sloper, and never noticed a performance difference.

Gil.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: K7JLJ on May 28, 2015, 11:10:00 PM
Thanks guys... A vertical? I thought that was a bad thing? 

In my country I can probably always find a tree to use for a sloper or vertical? But not always to setup an elevated horiz so I thought a pole might be a good idea but would rather not have it.

Maybe I could stop asking R so many questions (thanks for being Patient with the newb) if I had a good antenna book.

I thought about getting the ARRL one.  Is there a really good one out there that explains theory and application better?


- Jim
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: gil on May 29, 2015, 12:10:56 AM
QuoteA vertical? I thought that was a bad thing?

Nooooo :o  ;)

People complain about verticals because they use quarter-waves, and they require a good ground, often meaning lots of radials, which they don't bother doing properly, so results suffer... There are ground losses too...

However... We are talking half-wave here, not quarter-wave ;D Your antenna is complete as it is!

Half-wave verticals radiate at a low angle, which is very good for DX. They also radiate equally in all directions, which in our case is great, since we don't quite know who we're going to be talking to...

Now if you want to talk regionally on 40m during the day, you would install your EFHW horizontally, not too high, to use NVIS... It's like spitting up in the air, it comes back down nearby...

Antenna radiation for a half-wave is perpendicular to the wire, with the most radiation in the middle (high current in the middle, high voltages on the ends). So, theoretically, your half-wave vertical should be radiating at zero degrees to the horizon... Because of the proximity of the ground the angle is more like 10 to 30 degrees, depending on ground conductivity and height, ideal for hitting the ionosphere far away while avoiding obstacles near the ground, like, say, trees, cows, hills and such..

Gil.
Title: Re: Help me decide please: Only 1 QRP antenna setup
Post by: Lamewolf on December 09, 2015, 09:46:17 AM
Have you ever considered an Off Center Fed Dipole ?