Antenna Launching in the 21st Century
Getting lines over trees for wire antennas has been the most frustrating part of ham radio for me for many years. I've tried a number of methods, with varying degrees of failure. I'll describe the evolution of antenna line launching below:
PRIMITIVE MAN'S METHOD--ROCK & STRING
The simplest technique is to tie the line to a rock and hurl it. This is fine for some guys, but Sandy Koufax I ain't. I'm not sure I could clear a 25 foot limb. Plus, after two or three attempts my arm would hurt for a week.
HUNTER/GATHERER PHASE--BOW & ARROW
Things picked up after our sons got bow and arrow sets one Christmas. I made a nice arrow out of a fat dowel stick with some heavy solder wrapped around the tip. Even had some feathers glued on for guidance. I'd tie the line from the Zebco 33 to the arrow and launch away. The biggest problem was that these bows were almost, but not quite grown-up sized. About 50 feet was the most I could do and it might take several tries to get there.
20TH CENTURY MODERN MAN--THE SLINGSHOT
Decided to upgrade to something better. I'd been reading a lot about using slingshots, the kind with two strong pieces of rubber tubing attached to a leather pad and a forked handle. Using plans found on the web, I bent a flat steel bar and mated a fishing reel to the weapon. I took this device to my mountain place for QRP to the Field. My neighbor came over to assist. The problem with this thing was that the line kept snagging and the projectile would come right back at us at high velocity. I think it may be because I use an open-faced reel and the line tends to spill out and catch on something at just the wrong time. We detoured into the Old Testament version when my neighbor claimed to have been good at the 'David & Goliath' style slingshot as a kid. That's where you tie on a rock and spin it in a four-foot circle at high speed, then release. The effect could be impressive, but the projectile was subject to going just about any direction 360 degrees from the launcher. I hid behind the trailer while my neighbor tried to regain his youthful skill. He eventually got the rock over a tree, although it wasn't the one he was aiming at. My QRPTTF antenna was a pathetic 25 feet high.
I decided to give the slingshot method one more try when I needed to erect a 6 meter dipole at home. I pulled the leather back a mile and launched the rock. It went out about ten feet, came straight back and cracked me on the second joint of my middle finger. It still hurts today. I decided I'm too old to be hitting myself with rocks and set out to find something better.
FUTURE MAN 2001--THE SPUD GUN
I'd been reading about them on QRP-L. I printed out an article from the Flying Pigs’ October, 2000 issue by K8YS on the subject. Hey, a spud gun is so simple even a mechanically challenged guy like me can build one. I immediately noticed that there’s one area where you have a lot of flexibility and can show your creativity, and that's how you make the spark. Well, my son had been bringing home some disposable cameras from the 1-hour photo shop where he works. That flash circuit thing oughta be able to make a nice spark.
There are easier ways to produce a spark, but it seemed in keeping with the ham radio theme to use something electronic to do it. The flash gizmo turned out to be a little more complicated than I'd imagined. Took some head scratching to figure it out. Turns out there are three electrodes. Two from the 300 volt capacitor go to the electrodes of the krypton bulb, and the third goes to a piece of foil partially wrapped around the tube. The firing circuit generates some seriously high voltage to this third electrode which ionizes the gas (the 300 volts alone won't do it). Then the capacitor can dump its energy into the ionized tube. So I had to put three electrodes in the spud gun too. The HV ionizes the air gap and then the cap dumps all its charge across the ionized path. ka-POW!
Naturally, while experimenting with the thing I managed to get across the 300 volt capacitor at least once. I hit the deck; heard departed relatives calling; smelled St. Peter's after-shave; saw the smoky red light ...
Anyway, the firing circuit was impressive, much better than those wimpy BBQ grill igniters. It made one heck of a loud pop and blue flash, even with no hairspray. The next hard part was getting up the nerve to shoot the gun. All the articles I read had lots of cautions and disclaimers about how they won't be held responsible if you blow your head off. The fact that the 4 inch PVC pipe was stenciled "not for pressure use" was a little disturbing. I wrapped the whole thing in a towel to catch the shrapnel in case it blew up. The first time I fired it, I just leaned it against a support and stayed a foot or two away as allowed by the wire length from my firing circuit. I wasn't prepared for the cherry-bomb loudness of it. The recoil sent the gun flying backward, tearing the electrode wires off. I fell backwards as well, from the startle reflex. Then I ran into the house and hid, ears ringing, thinking all the neighbors on the block were busy dialing 911.
I kinda stayed away from the thing for about a week, then took it to the mountain to give my neighbor the honor of breaking it in. Hey, when you need to test something scary ... that's what kids and friends are for, right? It worked great but I didn't have the fishing reel mounted on it yet, so no antenna launching was done. My son found out that it was good for shooting at squirrels raiding our bird feeders. To keep from knocking neighbor's houses down, he just fired dish towels at them. As we got comfortable with it, I could see myself establishing hegemony over Southwest Russellville, AR. Kind of a spud-gun Matt Dillon.
OK--the denouement: Yesterday the big VHF test started. Time to go back to the mountain and put up a 6-meter dipole. Words fail to describe it. It's like comparing a J-38 to a Brown Bros. paddle and smooth keyer. Point and shoot. There's no more of this, "Should I shoot for that limb? Or do I dare go for that higher one?" kind of hesitation. Just shoot over the whole cotton pickin' tree. One shot, one line. Wow. In the old days I could have spent all afternoon putting up one line, inventing new cuss words, rocks and arrows hanging from limbs everywhere. Now I can't wait for Field Day. I've got the spud gun antenna line launching system. Go ahead. Make my potato salad.