"You've tried the solar tube with a dynode of the same alloy as the driver cathodes?" "Uh-huh. Nothing at all. Oh, I'll take that back. I got a scratch. With a pre-meter gain of about four hundred decibels, I read three micro-microamperes. That was detected from a driver tube forty feet across the room, running at full blast. I wondered for a minute whether the opposing driver was doing any cancellation, and so I took a chance and killed it for about a half second, but that wasn't it." "Nuts. Does the stuff attenuate with distance?" "As best as I could measure, it was something to the tune of inversely proportional to the cube of the distance. That's not normal for beams since it shows that the stuff isn't globularly radiated. But the amplifier gain was hanging right on the limit of possible amplification, and the meter was as sensitive as a meter can be made, I think. You couldn't talk from one end of Venus Equilateral to the other with a set like that." "No, I guess you're right. Hey! Look!" The meter took a sudden upswing, danced for a minute, and died once more. "What have you got in there? What did you change?" "Oh, I got foolish and tried a tuned circuit across the output of one of the miniature transmission tubes. It's far enough away from the big beams and stuff at the north end so that none of the leakage can cause trouble. Besides, I'm not getting anything like our beam transmissions." Channing laughed. "Uh-huh, looks to me like you're not getting much of anything at all." Farrell smiled wryly. "Yeah, that's so," he agreed. "But look, Don, Hertz himself didn't collect a transcontinental short-wave broadcast on his first attempt." "If Hertz had been forced to rely upon vacuum tubes, his theories couldn't have been formulated, I think," said Channing. "At least, not by him. The easier frequencies and wave lengths are too long; a five hundred meter dipole can't be set up in a small room for laboratory tinkering. The kind of frequencies that come of dipoles a couple of feet long, such as Hertz used, are pretty hard to work with unless you have special tubes." "Hertz had rotten detectors, too. But he made his experiments with spark-gap generators, which gave sufficient high-peak transients to induce spark-magnitude voltages in his receiving dipole." "I'm not too sure of that tuned-circuit idea of yours, Wes. Go ahead and tinker to your heart's content, but remember that I'm skeptical of the standard resonance idea." "Why?" "Because we've been tinkering with driver tubes for years and years--and we have also been gadgeting up detectors, radio hootnannies, and stuff of the electronic spectrum all the way from direct current to hard X-rays, and we have yet to have anything react to driver radiation. Ergo, I'm skeptical." The call bell rang for Channing, and he answered. It was Walt Franks.