I’ve recently jumped head first into the mysterious world of vacuum tubes. When I was a child, tubes were those little jewels my father pulled from the back of the old 1956 Zenith television–black and white, of course. I’d go with him to the dime store (remember those?) and he would test them on the cheap emission tester that was placed atop the steel cabinet that held new stock in their little elongated boxes. He’d put some back in his pocket, and some he would toss into the waste basket that the store owner hoped would be used more often than the tester.
Replacing them in the television and switching it on, there was that glow from the little curlicue on the top of some tubes, the bigger ones seemed to glow from down deep in their bowels. After ten seconds or so warm up, the picture emerged, this time no longer rolling from a faulty vertical-hold or whatever it was that was now fixed. And there was that smell–impossible to fully describe–a perfume mixture of warm phenolic, solder rosin, capacitor wax, coil and transformer dope, air ionized by high voltage, and dust.
Bigger tubes, 6L6’s of one subtype or another, made up the cityscape on the open-chassis monaural phono amp (a Heathkit I think) that was mounted on the wall inside the furnace closet. My grandfather had a similar setup, except his was homebrewed and it was distributed on three chassis inside a living-room cabinet. One chassis was for the power supply with its huge transformer and oil-filled capacitors, another was for the intermediate stages of the amplifier, and the third–the largest–mounted the final stage, its immense output transformer, and the also-huge chokes of the crossover network (he ran separate wires for the bass, mid-range, and tweeter to the speaker across the living room). He built a Heathkit tube preamp that I loved for it gold facade and knobs the size of silver dollars, but even his speaker (singular, since stereo was still rare)–the size of a small refrigerator–was home brewed.
The beginning of the end for vacuum tubes in our family came the day the preamp built into the turntable cabinet failed. I don’t know the specific reason, but I distinctly recall going with my father to a local parts store where he bought a kit for a transistorized preamp. The new whiz-bang. The wave of the future.
I guess it was as a kid, then, that electronics meant tubes to me, and the little TO-5 transistor can just didn’t have the same allure. At least it was metal. Now, plastic is the enclosure-of-choice, an army of TO-92s marching into the future. Not only were they tiny and featureless, but they didn’t glow, and they didn’t have the futuristic entrails that so fascinated me then (and now) with vacuum tubes. And without the heat and high voltage, the smell was gone.
Fast-forward more than half a century, and I’m rediscovering these little crystalline beauties, this time with some knowledge of how they work, and why. But aren’t they obsolete has-beens? Fragile, bulky, and prone to burn out? The twenty-pound power transformers, and filter caps the size of soda cans? Surely these are the dinosaurs of audio, video, and radio technology.
The thing is, they still work as well as they always did, and they have some characteristics that took a while for solid-state devices to emulate. According to electric-guitar players and hyper-sensitized audiophiles, nothing has yet replaced the sound of the vacuum tube, often described as warmer than modern transistorized and integrated audio circuits. They’re still necessary for high-power amplifiers, both radio and audio.
So why not at least keep a hand in the old tech? Why must new technology mean the total abandonment of the old? In some cases, of course, it doesn’t. Paper, pen, or pencil have not been obsoleted by the typewriter and now by the computer. Books have not gone away, and not likely to. Photography and now video did not mean the abandonment of oil or watercolor painting (or even photo-chemical photography), and I predict that 3D printers are not going to obsolete sculpture, either. I think there’s something healthy about maintaining (and passing on) competence in older ways. It means adding to the body of human knowledge rather than dumping some overboard to make room for the new. If the new truly represents progress, then it has to make the capacity for knowledge larger, and not just the same size with newer contents.
Naturally, this applies to modes of radio operation as well. Digital modes are really cool, but the simple straight key (for telegraph or radio) kept the world informed for a century and a half before it faded into a special skill some worry will eventually die. Using the hand and the trained ear to communicate in dits and dahs is pretty cool, too. Animals communicate with a few tones and clicks patterned in a recognizable manner, and they can do so in a way that can carry some distance and that cuts through the background noise. Surely anything a bird can do we can do better, right? Yes, we too can encode meaning in simple patterned sounds–the dit and the dah–and we can send those halfway around the world with no more energy than is given off by a struck match ( a few Watts).
If there are others of you who are hot on vacuum tubes, or CW for that matter, make yourself known. Share your latest exploits. We are fortunate there are still a large number of Hams who spent the better part of their lives with the old technology. We should beg them to teach us.