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Discussion Starter · #1 ·
I thought this might be of general interest to Ham Radio operators (and future Ham Radio Operators!)

I built a couple of antennas designed for use on the 2m and 70cm bands, using 300 ohm twin-lead (that old TV antenna stuff) in a j-pole design - and was able to use some pvc and some pvc-fittings to make 'walking-sticks' into which the antenna fit.

Here's the fun part -- the second one I build was CAVERNOUS inside... the 300ohm twin-lead just rattled around inside everywhere I walked... and at first I just put packing peanuts inside around the antenna to keep it still...

But then it occurred to me that you could fill it with other useful things, and make it into a useful carrier of equipment should you be called out as an emergency responder, or simply to "bug out."

I've got the plans to build the antenna, and some photos of the results I got. Both the ones that I built worked really well, and would make great additions to a more extensive "Go Bag." :cool:

If you are interested in either or both, please email me. Also, FYI, the photos are on the Yahoo Group for the Yaesu VX-5, in the photos section.

73 (regards),

Fachento
KD5VEZ
 

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Walking Stick Antenna

Hey I'd be interested in seeing what you made with the PVC pipe. I made one of those antennaes, from the 300 ohm TV cable. Have used it numerous times, when we were RVing, with the top end clothes pinned to the motorhome awning, and the other end to the Yaesu VX5. Works wonders. I don't see your e-mail address. kd5yxw @ arrl.net
 

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Discussion Starter · #3 ·
Parts List / Cost estimate

I thought it might also be helpful to provide a short parts list and a rough cost estimate - assuming you already have the hard-ware to solder.

Parts:
1 chassis-mount BNC connector (Radio Shack)
1 ft. RG-58 Coaxial Cable
5 ft. 300 Ohm Twinlead - to allow for mistakes/practice (Lowes)
5 ft. PVC pipe
2 male-threaded end-caps
2 female-threaded end-caps

$20

[optional]
3 inches of shrink-wrap to cover coax-to-twin lead solder joint
RTV or Silicone-based glue to water-proof BNC connection on inside of end-cap.
$7

I'd be happy to send out photos and plans!

Regards,

Fachento
KD5VEZ
 

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I thought it might also be helpful to provide a short parts list and a rough cost estimate - assuming you already have the hard-ware to solder.

Parts:
1 chassis-mount BNC connector (Radio Shack)
1 ft. RG-58 Coaxial Cable
5 ft. 300 Ohm Twinlead - to allow for mistakes/practice (Lowes)
5 ft. PVC pipe
2 male-threaded end-caps
2 female-threaded end-caps

$20

[optional]
3 inches of shrink-wrap to cover coax-to-twin lead solder joint
RTV or Silicone-based glue to water-proof BNC connection on inside of end-cap.
$7

I'd be happy to send out photos and plans!

Regards,

Fachento
KD5VEZ
I'd like to see the photos and plans!
If you don't know how to post the pictures, post the links and I'll make them show up here for you!
 

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Discussion Starter · #5 ·
Pictures!

I'd like to see the photos and plans!
If you don't know how to post the pictures, post the links and I'll make them show up here for you!
If you want me to email you the plans and photos just send me an email -- fachento @ gmail.com

I'll try and post some of the images here...

Here's the "prototype" -- the experimental one.




Here's of the second try -- the "production model" if you well, after having worked out a few kinks.




I cleaned up the solder joints on the second model, and covered them in shrink-wrap that I got from radio shack, to protect them from getting knocked loose. The second one is pretty big inside -- lots of room for other gear!

Regards,

Fachento
KD5VEZ
 

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What'd you use to tune the antenna? What frequency did you try to target for lowest SWR?

I've been getting into antenna building, playing with j-poles, and picked up an MFJ-249 antenna analyzer on ebay.



Had pretty good luck with my first j-pole I made... some 450ohm ladderline twinlead... hang it off a tree... huge improvement over any duckbill.

I still need to spend time messing around to find the relation between lengths from feedpoints and affect on SWR.

I still haven't found out if there should be dimensional differences between using 450ohm and 300ohm twin-lead.

How do you support your antenna when transmitting?
 

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Discussion Starter · #7 ·
What'd you use to tune the antenna? What frequency did you try to target for lowest SWR?

I've been getting into antenna building, playing with j-poles, and picked up an MFJ-249 antenna analyzer on ebay.

Had pretty good luck with my first j-pole I made... some 450ohm ladderline twinlead... hang it off a tree... huge improvement over any duckbill.

I still need to spend time messing around to find the relation between lengths from feedpoints and affect on SWR.

I still haven't found out if there should be dimensional differences between using 450ohm and 300ohm twin-lead.

How do you support your antenna when transmitting?
I just used the dimensions provided in the design that I found for it -- it seems to work perfectly on both 2m and 70cm - so I guess I can't complain! You can supposedly decrease the tendency to have "lobes" of reception by putting a small iron-ferrite core/bead around the coax, but I haven't tried it yet.

I haven't "tuned" the antenna really... the design seems to make things work out well enough!

If I'm just walking around, I'll hold up the antenna with my hand. If I'm going to be parked for a while, I'll either drive in a T-Post and zip-tie the antenna to it, or hang it from a tree. I bought a BNC adapter for my VX-5, and a small coax line to connect the radio and the antenna, and it works out pretty nicely!

I haven't tried it with 450 ohm ladder-line... not sure what differences in dimensions there would need to be. I only found plans for 300ohm twin-lead... but that is getting harder to find in stores these days.

Fachento
KD5VEZ
 

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One thing to consider... they sort of mention it in the article... is 'velocity factor'.

You can make a j-pole in free air (nothing around it) and tune it to a perfect 1:1 SWR.

Now stick that j-pole into a PVC pipe, and it'll throw off the SWF. The PVC has a specific velocity factor that changes how well the antenna radiates. If you do get the opportunity to tune the antenna, make sure it's done with the wire inside the PVC.

Another example of PVC j-poles..
http://hometown.aol.com/alonestaryank/selfj.html

And his version that collapses down, fits inside a larger PVC pipe, and includes a telescoping pole for more antenna height.
http://hometown.aol.com/alonestaryank/VHFDeploy.html
 

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I'd recommend having a look at the ARRL's big Antenna Book. That thing has an amazing wealth of information about antenna design, proper radiation, etc. If you know a few Hams, ask around and see if you can borrow a copy.
 

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Discussion Starter · #10 ·
Reference Materials / Books that are worthy of note

I'd recommend having a look at the ARRL's big Antenna Book. That thing has an amazing wealth of information about antenna design, proper radiation, etc. If you know a few Hams, ask around and see if you can borrow a copy.
I own a copy of it ... it's being mailed up to me as we speak. It's been pretty useful, and I expect to make better use of it as I'm preparing to upgrade license classes.

I've got the line-up of books from the ARRL - the 2002 editions, and they've been handy references. The Antenna Book, the Handbook, the Operating Manual,

I've got several books that my be of interest to Ham Radio operators in the forum:

Stealth Amateur Radio
Independent Energy Guide
ARRL's Low Power Communication

They've got quite a few projects listed that are downright useful as well! I just wish I had a garage to do projects out of these days. :eek:

-Fachento
KD5VEZ
 

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Field Antenna Handbook

For anyone wanting a crash course on antennas, especially field portable antennas, propagation, selecting an antenna and frequency for the task at hand. I have not seen a better handbook than this one, and I have ARRL Handbooks and reference materials going back to the 1930s.

The ARRL is a treasure trove of radio, antenna, and electronic reference materials. Their manuals and books are the 'Bibles' for those subjects, as far as I'm concerned. The only problem with them is they can be so in depth, that they can be intimidating to people trying to get their feet wet and get their arms around a concept and get a foothold.

The Marine Corps Field Antenna Handbook is a crash course.. a 'just the facts Ma'am' of what works, how it works, how to make it work, when it comes to what comes in and out of that radio, how to get it from the radio to the antenna, and how to do it in the field, under less than ideal conditions.

The Handbook is free, and it's available as a PDF file that you can save.

http://www.armymars.net/ArmyMARS/Antennas/Resources/usmc-antenna-hb.pdf

This is a really good reference to have.

Doug
 

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Discussion Starter · #12 ·
Files / Plans / Photos

I've had a few people contact me in the last few months, asking if I still have plans / photos of what I have been able to do.

The answer is: YES. I still have the plans, and would be happy to send them out.

I've actually thought it might be worthwhile to spruce up the visuals on it for another rendition -- I'll publish the final result, when I get around to it, here.

- Fachento

KD5VEZ
 

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This needs to come back to the top :D
 

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I wonder if this anttenae walking stick couldnt be made a bit stronger by using a cut down fiberglass shovel or other tool handle. makes me think about looking to see what kind of fiberglass heavy wall tubes I can find. PVC doen'st like sunlight and it gets brittle in the cold. Just thinking out loud mostly but it may cause a brain storm. I really got to get those lil radioes back out and play with them some more and maybe even get my test studies done so I can actually tx with em :p I"m a terrible procrastinator lately.
 
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