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Author Topic: Joint for mobile whip  (Read 998 times)
G7HGT
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Posts: 1




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« on: November 27, 2004, 03:31:47 PM »

Hi,

I am a business tarveller and I'm trying to build a suitcase shack. I have just bought an FT-857D and my dealer has said he would recommend the ATAS-120 antenna. My problem is that the maximum length item I can fit into my case is 24 inches and the ATAS whip is much longer than that.

My idea would be to cut the whip in half and then use some sort of joint block to join the halves back together. I'd like something that looks nice. I guess I'm looking for something resembling a short coil from the centre of a dual band antenna (but obviously straight through instead of having a coil in it) or some kind of metal bullet with a couple of hex bolts in it.

I've googled and not found anything suitable. Do such things exist and if so do they have a name? Do you knwo anywhere that might sell them?

Many thanks,
Paul.
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KC2MMI
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« Reply #1 on: November 27, 2004, 06:28:47 PM »

Retract the whip as far in as it goes. Then go to a local machine shop. Ask them to cut them whip 23" up from the very bottom of the ATAS-120 and then again once more so it all fits.

Ask them to *thread* each section that they have cut, and to provide you with a double tapped (threaded) sleeve that can be used to join each section. Two cuts, four threadings, two tapped connecting sleeves...probably cost you $50-100, less if you find an old machine shop in a small town.

Basic machine shop work, no big deal. Unfortunately, the airlines have varying security policies and you still may be required to send that as checked baggage--not carry-on. Anything that can be used as a whip or cudgel can be excluded from the cabin, at the discretion of the airline. It might be aasier to get a drafting tube or other hard tubular case (golf case for two clubs?) and just send it as checked baggage. Since electronic equipment is *not* insured in checked baggage, you'll need to insure it in any case.

Not an ideal solution, sorry.
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K5LXP
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« Reply #2 on: November 27, 2004, 10:24:02 PM »

I think a much more reasonable route than $50 to $100 at a machine shop to make custom parts would be a piece of brass stock and some set screws.  Even if you had to make it yourself it would be a simple job.  Cut the whip to convenient lengths and make one coupler per joint.  

Mark K5LXP
Albuquerque, NM
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K0BG
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« Reply #3 on: November 28, 2004, 06:22:15 AM »

MFJ has two extendable whips. One 108" long, the other 72" long. Both collapse to less than 23". They are US $29.95 and US $19.95 respectfully.

The biggest problem you're going to have is a groundplane for the antenna, no matter what you use. I suspect you could use the collapsible whips for that too.

Alan, KØBG
www.k0bg.com
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KC2MMI
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« Reply #4 on: November 28, 2004, 01:38:27 PM »

Mark-
 <set screws> Nice idea, but have you ever dropped one in a foot of snow in the winter, or tried to set them with bare fingers?<G> I hate set screws!

 Guess you don't get much winter wx down that way.<G>
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AA4PB
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« Reply #5 on: November 28, 2004, 02:36:08 PM »

Personally, I question the advise to use an ATAS-120 for a portable antenna. Take a look at the following sites for possible better solutions:

http://www.superantennas.com/

http://www.buddipole.com/buddipole.html
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Bob  AA4PB
Garrisonville, VA
K5LXP
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« Reply #6 on: November 28, 2004, 08:43:17 PM »

I really like the idea of a telescoping whip, it's compact and you can adjust it to suit your needs.  Having seen both the MP-1 and Buddipoles in action, and owning an ATAS, I would say that performance wise you will do just as well with any of them.  The ATAS won't win any antenna shootouts, especially below 20M but neither will the MP-1 or the Buddipole.  Your ground/counterpoise will have the most impact on performance.  The advantage of the ATAS is remote tuneability, the advantage of the MP-1 is portability but needs manual adjustment.  The Buddipole offers no advantages over either of the verticals- it's more expensive, has lots of tiny parts to lose and isn't that compact or light.  If I was backpacking the MP-1 would make sense, for portable operation I'd stick to the ATAS.  I have a bulkhead connector with wire counterpoise attached I take with me when operating my ATAS portable.  It deploys quickly, tunes 40-10 and works well for a compromise antenna.

Mark K5LXP
Albuquerque, NM
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N8IWK
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Posts: 80




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« Reply #7 on: December 11, 2004, 05:53:48 PM »

Here's a simple inexpensive solution, only should cost you a couple dollars.  Radio Shack and other electronics supply places sell barrier/wire connection blocks, otherwise known as barrier strips, or ty point terminal strips, where you use a screwdriver to splice wire connectons to this block of conections.  These work well to splice wires and should work equally as well to splice two sectons of antenna. All you would need is one of the sections of the block, each section is basically a brass block with a hole drilled through it and two set screws that secure a wire into each end of the block.
They come in various sizes, find one of the appropriate size for the whip, cut the whip to length, place one piece in each end and tighten the set screws to "splice" them together. These blocks usually come with 10, 12 such connections, so you'd have plenty spares if you should loose a set screw.

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N8IWK
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« Reply #8 on: December 11, 2004, 05:58:50 PM »

Follow this link to an image of a barrier strip.

http://users2.ev1.net/~on30/Pics/IM001264.JPG
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