[Transcriber's Note: This etext was produced from
Thrilling Wonder Stories October 1948.
Extensive research did not uncover any evidence that
the U.S. copyright on this publication was renewed.]
Me, I'm just a radio mechanic. No genius, that is. But handy with asoldering iron. If it's genius you want, take my friend Bill Marra.He's a communications engineer—telephone, radio, or what have you.He's invented enough gimmicks so he doesn't have to work any more, justpotters around his basement inventing more gimmicks.
Thinking them up, actually, is all he does. Give him a screwdriver anda pair of pliers and he can wreck anything in five minutes. That'swhere I come in. He thinks 'em up, I build 'em. He busts 'em, I fix'em. And when he gets into a jam, I'm the guy comes to bail him out.Like, for instance, this last gadget of his. Nothing dangerous aboutit, but it could have got him sunk in the river with his feet in ablock of cement. It all started with an amplifier.
I found the diagram in the mail when I came into the shop one morning.Looked like an ordinary audio amplifier at first sight, and I startedlaying out a chassis. Picking out parts, I noticed something; even Billcan make a mistake sometimes. But I don't stick my neck out any more,so I got him on the phone.
"About this amplifier of yours," I started.
"Well, what about it?" he yapped. "Never seen one before?"
"Look, bub. I've built hundreds of 'em. If I hadn't I'd 'a built yourslike you drew it here, and you'd been stuck with it."
"Stuck with what?"
"OK. Look at your coupling condensers. Maybe it's just a misprint,or you wrote mmf where you meant mfd. But if you use condensers thatsmall, it might work but you'd never hear a sound out of it. Lowfrequency cut-off way above the audible limit."
"Gives you an 'A' for effort anyway. Keep punching. And build it theway I drew it. And stop worrying."
Well, now, what do you do with a guy like that? I built it. Had to testit with a scope to find out if anything got through it. Couldn't hear asound. When I delivered it, he just grunted.
"Mind letting me in on the secret?" I asked. "Now you've got an outfitthat will amplify sounds you can't hear, who's going to listen to it?"
He just tossed me a couple of sketches. "That's the output section,"he explained. "We'll connect it to the vertical sweep of a cathode raytube. The rest of the circuit is an automatic time base, so you getstanding wave patterns at any frequency."
"OK with me. But what're you going to feed into it?"
"Uh-uh, almost forgot. Midget condenser mike. Through a high-passfilter, cut-off at 12,000."
Well, I still don't know any more than I did at the beginning, but whatthe devil—I get paid for it even if it doesn't work.
Couple of weeks after I finished the outfit, I was still wondering. SoI dropped in on his basement lab one night. He had the rig set up andworking. The microphone was on the floor. Bill's dog, a nondescriptpooch named Meginnis, was tied up in front of it. Bill was strokinghim, petting him, annoying him. And as far as I could see, nothingwhatever was happening. The amplifier was running, the 'scope tube waslit, showing a nice steady base-line and nothing else.
"Maybe your mike's no good," I said helpfully.
"It's OK," he muttered. "Look."
He picked up a little silver whistle and blew it. No sound came outthat I could hear, but the dog jumped as if he were shot, and a nicepattern of standing waves showed up on the 'scope.