Antenna

Started by PuJo, September 05, 2015, 09:10:16 am

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PuJo

Morning guys.
I have posted this question on other forums and getting mixed answers.

I have a KX3 W/ATU, DRF, etc....

I want to operate from the gulf on the oil rig I work.
Antennas always the question.

My options are to get the Super Antenna MP1 and set it on top of the helideck that is a 40'x40' square iron plate, or an end fed wire antenna hanging down the side of the structure.

I do not have a antenna analyzer so getting the MP1 on the spot would be kinda hard, but not impossible.
I wanted the MP1 for super fast deploy and retrieval. Helicopter on a 5 minute final is all the notice I will get to retrieve the antenna.

End fed 9:1 unun or without balun is the other option.
I can let it hang downward toward the water however it will be extremely close to the metal structure.
Using a fishing pole I could get it away from the structure somewhat but its windy out there.

If I use the wire antenna without a balun, I would still have to use coax ran down the fishing pole to the wire.
Should I just use the 9:1 unun balun fed with coax to the end of the pole then start my wire?

Not sure how to setup or what to use. I'm looking for opinions. Now that I am 100% QRP/P I do not want to invest in big antennas, but I do want effectiveness.

Look at the image below, I am on top with my Arrow working SO-50.
Any ideas on how I could try and setup an antenna??

The platform is pyramid shape and I would like to operate from the highest point. Its a long walk from the bottom to the top with your gear.
220 steps to be exact!!

Anyway, what do you all think?


RichardSinFWTX

I would go with the 6m-40m end-fed from KX3Helper.com.  It rolls up nice and small.  Mine fits in a zip-lock sandwich bag and comes with a balun.  I've worked DX contacts as far away as Kyrgyzstan, Russia and Chile.

I like the QSL card you've got there!  Maybe we can work each other sometime!

Good luck!


gil

Hello,

The MP1 like the Buddistick is a compromise antenna.. It works fine, but an end-fed will get you more contacts. Problem with the MP1 is if you're in the bathroom while the helicopter shows up! I would use a fishing rod as you suggest to bring the end-fed away from the metal. You will probably get a weird radiation pattern anyway, but I would try it. Put a fishing weight at the end of the wire.. I would suggest an adjustable tuning box like the ILERTENNA, though a simple UNUN like the EARCHI end-fed: http://www.earchi.org/92011endfedfiles/Endfed6_40.pdf; very easy to make, and they work (I made one).

Gil.

PuJo

What about feed line.

I've seen hams use RG-174 portability and packing.
If I use the fishing pole method, I would need close to 50'.
I haven't seen the specs on RG-174 but guessing that there would be lots of loss.

Recommendations?

Thanks,
-PuJo

RichardSinFWTX

I keep 50' of RG-8X coiled up in a Rubber-Maid container along with a 100' extension cord and other accessories that I use with my HF station in a box.  You can coil RG-8X to less than 12" in diameter...possible 8 or 10" so packing it up shouldn't be a problem.

PuJo

September 06, 2015, 01:26:51 pm #5 Last Edit: September 06, 2015, 01:40:26 pm by PuJo
You are correct packing should not be an issue, however it is for me.
When we go out to the platform it is by helicopter. We are limited to two bags. My regular bag, and I was hoping to use a pelican for the radio and hold everything as well.

Using the RG-8X may be more weight than my telescopic crappie rod can handle....
I have to try and keep the weight down to a minimum if I strap coax to the rod, then hand the antenna at the end.

Would RG-8X be the best choice for this?

Check out this coax, let me know what you think. http://www.picwire.com/pdfs/PIC_Overviews/PIC_50_Ohm_RF_Product_Line.pdf

Thanks,
PuJo

gil

Hello Pujo,

If all you can bring is RG-174 then use that and don't worry about it. You would benefit more from a tunable matching box than using a simple UNUN though. Either will work of course, and even if you radiate only a fraction of your output power, it will be enough. You are surrounded by salt water which is great. I would ground the radio to the metal structure and see if it helps.. Try it in a QSO and see what your contact says.. I bet it will help..

Gil.

cockpitbob

The loss of 50' of RG174 at 10MHz is about 25%.  Considering an S-unit is a 4:1 change, the loss is less than 1/4 of an S-unit.  In other words, the loss is negligible.  Besides, I would think the weight on the fishing pole of anything heavier would be too much.

PuJo

Thanks guys.
I am thinking about purchasing this unit. http://kx3helper.com/endfed-40-6m-antenna
Unless one of you know of a better end fed. If so, please post a link.

Thanks,
-PuJo

NWARadio

If you get on HF on the rig, let me know. I'd like to try and work you. Off topic: Have you returned to Facebook yet?
So long, and thanks for all the fish

gil

http://ea3gcy.blogspot.com.es/2014/04/ilertenna-end-fed-qrp-antenna-tuner.html

With this one, you match the impedence at the wire, not the radio, much less loss in the coax.

Gil.

PuJo

Quote from: NWARadio on September 06, 2015, 09:52:33 pm
If you get on HF on the rig, let me know. I'd like to try and work you. Off topic: Have you returned to Facebook yet?


Hey Deer Whisperer, I will defiantly let you know when I'm set up for HF on the rig.
Lots of stuff to do before I'm ready.  Still need to get everything into the pelican and just get everything the way I want it.
At this point, I am just trying to find the perfect antenna for my needs while I am on the rig.

I still haven't returned to FB, I don't want to subject myself to all the unnecessary drama and selfies  :P ;D

-PuJo

PuJo

Quote from: gil on September 06, 2015, 10:30:12 pm
http://ea3gcy.blogspot.com.es/2014/04/ilertenna-end-fed-qrp-antenna-tuner.html

With this one, you match the impedence at the wire, not the radio, much less loss in the coax.

Gil.


Gil,
I looked up the unit and seems that it will not handle full power of the KX3, unless I misread as I did just glance at it. I think it was 10 watts P.E.P.
I like a little but more room if I need it. Also, I really wanted the 6-40 meters, or 80 meters even. Maybe just a longer wire may get me the bands I am looking for.

While I haven't ruled the unit out, I do like the way it works, as you said matching at the wire, not the antenna, efficiency.

Are there any others you would like to share?

Thanks,
-PuJo

gil

Hello Pujo,

The power rating of all those tuners is pretty underestimated. I have put 12W through them all with my KX3 with no trouble. The fact is that with a "random" wire you will lose more than with a half-wave end-fed, which is resonant. Better use a half-wave wire with the corresponding tuner. And antenna like the LNR precision 10/20/40m end-fed might also serve you well. All you need is a couple bands, one for daytime and one for night time. One of the reasons I sold my KX3 was because I only used a couple bands and CW only, and my K1 could do that just as well. If you want a multi-band antenna, keep in mind that it is a compromise, and it won't work as well as a resonant antenna. Remember, you have 12W.. In CW, no problem is you end-up with only 2W radiated.. In SSB, you're in trouble..

Gil.

PuJo

September 07, 2015, 08:29:35 am #14 Last Edit: September 07, 2015, 08:47:22 am by PuJo
Gil-

Point taken.
The object is to get as much radiated power to the antenna as I can.

So maybe a mono band end-fed should be what I am looking for.

A wire cut to resonance connected directly to the radio could do the trick?

-PuJo