Wednesday, September 08, 2010

Antenna line launcher

So here's the deal ..... pictures of the "new" homebrewed W2LJ antenna line launcher.  No new idea, no new technology, no new radical concepts.  Based on the same concept as that well known brand that is seen in all the popular Ham radio publications at a fraction of the price.  THAT is the only advantage!  Plus, if I can do this, YOU can do this.  When it comes to stuff like this, sometimes I am all ten thumbs and all of them left thumbs to boot!


The materials are: 1) Cheapie slingshot acquired from eBay 2) A 99 cent tent peg from Target or Wal-Mart, can't remember exactly which one 3) Fishing reel that used to belong to my father-in-law 4) Two hose clamps 5) Some 1/4 X 3/4" long screws, nuts and star lock washers.

As you can see from the photo, I made about a 3/4" notch into the tent peg.  Directly above the notch, I drilled a 1/4" diameter hole through the plastic.  I also drilled a 1/4" hole in the bottom of the slingshot; and then opened it up and inserted one of the screws and secured it with a star washer.


I reassembled the slingshot and then placed the screw through the hole that I had previously drilled through the tent peg. I secured the slingshot in place with another star washer and a nut.  After tightening the nut with a wrench, it became apparent that the lock washers are really holding everything in place as I can't easily rotate the slingshot on the tent peg platform.  It is there to stay unless I disassemble everything.


The fishing reel is held in place with two hose clamps.  I have attached a 1 ounce fishing sinker to the monofilament line; but I really have to buy some fluorescent paint and do up a bunch of sinkers.  If they are brilliant orange or yellow or even pink, they will be easier to spot in the tree; or in the grass where they would land in the field.

I took this contraption out to my backyard, to the tree which supports the center portion of my G5RV.  With only about 50% tension on the slingshot, I easily (and I mean EASILY) cleared my 40 foot tall maple tree.  I can see where full pull back on the slingshot elastic will allow an easy 50 - 60 foot shot.  Plenty high for one of my doublets or the wire for the Fuchs tuner.  I didn't want to go full throttle in my backyard as I didn't need the fishing weight making a rude entrance through a neighbor's window.

So what was the cost?

Slingshot from eBay - $5.00 (with shipping)
Tent peg - $0.99
Hardware (screws, nuts, lock washers) - $2.00 as I had to buy packets
Hose clamps - $3.00 (for two)
Fishing reel and sinkers - in my case free, as they were my father-in-law's.  I can imagine that you can find a suitable reel, line and sinkers at Wal-Mart or someplace like that without breaking the bank.

I'm sure I will need some practice with this, to get a good feel for it; and to get the hang of placing the line just so.  But I do know this is going to make the job of getting a doublet or end fed wire elevated all that much easier.  It's small enough to fit into my antenna knapsack; and I look forward to having even more outdoor QRP fun in the future.

This weekend, I am definitely going to tackle some of those 60 foot trees in the local park that eluded my antenna line efforts last weekend.

72 de Larry W2LJ
QRP - When you care to send the very least!

4 comments:

Paul M6PCZ said...

Hi Larry, this looks a nice and simple design, just what I've been looking for as I have a lot of trees here, and one in particular I have not been able to swing a line over.

73 Paul.

Jspiker said...

Hello Larry..I use the same kind of launcher too but don't mount it on a tent stake. I just lay the reel on the ground, aim, and let it fly.

A simple way to make the "sinker" more visible, is to wrap a little "survey tape" around the weight and tie it off.

I was out a few days ago with a challenging shot over two very tall trees. I had success with the first one, but when shooting the second, the weight just hung over the far side of the tree about 25 feet off the ground. Just high enough that I couldn't reach it.

I had actually "run out of fishing line" and it came off the reel. Hihi

With a good eye and a little luck, I think a 50 foot tree is a possibility. (if you have at least 100 ft of fishing line on the real).

The sling shot works very well.

Anonymous said...

Thank you amazing blog, do you have twitter, facebook or something similar where i can follow your blog

Sandro Heckler

Anonymous said...

Thank you for the instructions and photos. We used a piece of 2x2 and a cork with the sling shot and reel. Only cost $7 as we had to buy a sling shot. You saved us from having to call in a tree service. Can't thank you enough.