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Author Topic: Pneumatic Antenna Launcher  (Read 9829 times)

Offline spore

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Pneumatic Antenna Launcher
« on: December 30, 2009, 1830 UTC »
Anyone built or tried one of these???


Seems like a good idea, especially for portable ops. A few minutes time and a full size end fed vertical could be stuck fairly high in one charge/shot.

I built one of those wrist rocket/reel launchers and it does work after a fashon with several attempts and some expletives clouding the air.


Offline Seamus

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Re: Pneumatic Antenna Launcher
« Reply #1 on: December 30, 2009, 2047 UTC »
I haven't built one exactly like that, but my airgun/launcher uses a 1" sprinkler valve to dump up to 180 PSI of air into a barrel behind a 1.25" slug of epoxy and lead fishing weights. 

For years and years, it was the best thing I had for stringing antennas, because I didn't have a bow and arrow available.  It could be used in tighter confines than the bow-and-arrow solution too, due to the lower penetration of the slug, as compared to the arrow with virtually no cross-section area.  The arrow just tends to sail right through everything and into/across the neighbor's yard, making it less than ideal for stringing those covert antenna installations.  The plastic-and-lead slug, on the other hand, will blow through quite a bit of canopy and get plenty of altitude, but eventually loses enough energy to fall back to earth before traveling too far downrange.

Recently, my launcher's performance has fallen off due to dry-rot of the rubber diaphragm in the valve.  In theory, I could just replace the diaphragm (they sell them as replacement parts for the valve), but after fifteen years of use, I have enough design notes accumulated through the launcher's use that I'm more likely to build a new launcher rather than fix the old one.

That, and I now have access to an archery rig for stringing antennas, and I've gotten much better at figuring out when the neighbors are going to be out of town.   :D

Offline spore

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Re: Pneumatic Antenna Launcher
« Reply #2 on: December 30, 2009, 2131 UTC »
Good deal!  ;D

I had been accumulating parts and concepts for a custom small scale sawdust cannon when i ran across that. Was considering making it modular for multi purposes / flexibility, i like your idea of the smaller penetrator slug and the tennis ball idea for softer landings / less damage for over the tree top installs in town (always have friends that need help with antenna work). Thinwall 2.5"  pipe isn't available locally to fit a tennis ball, but standard 3" is and making a patch out of an old wash cloth seems to make the TB fit it well (IIRC they recommend 4oz for optimum performance, twice a TB's weight).






« Last Edit: December 30, 2009, 2141 UTC by spore »

Offline Lex

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Re: Pneumatic Antenna Launcher
« Reply #3 on: December 31, 2009, 0252 UTC »
I tried various pneumatic launchers when I lived in a rural area on a lake front, including a gas propelled spud/tennis ball gun.  Fun, but they all make some noise.  No longer practical now that I live in town.

For expedient launching of receive-only antennas, I use a sling.  Not a slingshot with elastic bands, but the ancient style rope or string type sling.  In urban and semi-urban areas, using anything that resembles a weapon would be inadvisable.  With the sling it takes only a few quiet, discrete whirls and off it goes.

I use heavy duty fishing line, usually the flat ribbon type I use with bass fishing through weeds - it resists tangles and birdnesting.  The weights are improvised, often a small soft plastic pill bottle left over from vitamins or ibuprofen - the white HDPE bottles are durable and soft enough to cause no damage when they hit something.  I fill 'em halfway with coffee grounds, sand, whatever's handy.

This trick is good enough to get a receive-only random wire - usually very thin magnet wire - up a tree or across a roof in a few minutes.  Works great at the local parks too for getting some wire in the air to improve reception with a portable.  The fishing line and plastic bottle for launching reduce the risk of electrical shock if the line happens to cross an unseen power line - occasionally a risk in any urban or semi-urban area, tho' so far I've managed to avoid that risk by scouting carefully beforehand using binoculars.  After the fishing line is satisfactorily high enough, I'll attach the antenna wire to the end and use the fishing line to drag it up the tree.  I hitch the other end of the fishing line, with the pill bottle, around a tree trunk, fence post, whatever's handy.  From 20 yards or so away it's all virtually invisible to casual glances.

Might be adaptable to field expedient transmitting antennas, dunno, haven't tried it.
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Offline olddxer

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Re: Pneumatic Antenna Launcher
« Reply #4 on: January 01, 2010, 1948 UTC »
Very interesting! Thanks for posting.
Drake R8B, Ten-Tec RX340, NRD-515, Perseus SDR, Anan 8000DLE, a bunch of Hammarlunds, Inverted V multiband dipole


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Re: Pneumatic Antenna Launcher
« Reply #5 on: January 01, 2010, 2225 UTC »
This is totally a Mythbuster-esque contraption... I like it :D


Offline W7LPN

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Re: Pneumatic Antenna Launcher
« Reply #6 on: May 27, 2010, 2102 UTC »
I use a wrist rocket sling-shot, 1-2oz fishing weight, a spinning real mounted to the rig. With 10lb or lighter line you can shoot it up quite high and pull a larger twine over the tree. I do this every summer and It's cheap, especially if you already have a wrist rocket and an old broken fishing pole, to take the real from.  8)