Mac's Radio Service Shop: Remote Control and Colored Snow |
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As is often the case with these decades old stories, you learn a little about the conditions of the era along with the main storyline. In this case Mac mentions installing the Regency remote control for the benefit of a friend's child who has contracted rheumatic fever and will be in bed for a few months. That was before better treatment, including superior antibiotics, were available. We've come a long way, baby, in all areas of science. Not everything about 'the good old days' was very wonderful. Note: Regency RT-700 Remote Tuner photos are from the RadiolaGuy.com website. I reproduced them here because they are for sale and could disappear from the RadiolaGuy.com website someday. Mac's Radio Service Shop: Remote Control and Colored Snow By John T. Frye
When he opened the door of the service department, he saw his hunch had been right. A chassis on the trial-run bench was displaying a steady, crystal-clear picture. As Barney watched, another channel was switched on and then another and another until five different pictures were revealed. When the program carried by each channel came into view, the fine tuning was adjusted and the volume was cut down to zero and then brought back up. Yet the only other person in the room was Mac, and he was sitting on a stool clear across the room from the set. "Hey!" Barney exclaimed, "what's going on here? How are you doing that?" "Now calm down, Buster, or you'll flip your lid," Mac admonished. "It's being done with this new Regency remote TV tuner," he explained as he tapped a small mahogany cabinet resting in his lap. Watching closely, Barney saw the picture and sound were being manipulated by two large dual-dials on the face of this cabinet; and he also noticed the unit was connected to the set by a cable about the size of a pencil. "How does it work?" Barney asked. "Inside the cabinet is a complete cascode tuner with its own power supply. These concentric dials on the right select the channel and adjust the fine tuning in the usual manner. The output of the tuner feeds through that small coaxial line to the input of the set's i.f. system. Another connection is made to the receiver's audio system so that this outside dial on the left can adjust the volume. Finally, the remote control unit generates a d.c. voltage, either positive- or negative-going, the amplitude of which is controlled by the inside dial on the left; and this voltage is fed to the set for varying the contrast of the picture. A 'local-distance' switch on the back of the unit permits placing proper bias on the tuner for extremes of signal strength." "Now let me get this straight," Barney interrupted. "If I understand you correctly, that same little concentric cable is carrying an i.f. signal from the remote control unit to the set, an audio signal from the set to the unit, and a d.c. voltage from the unit back to the set. Why that little old chunk of coax must be busier than a party line the night the banker's wife left town with the traveling salesman! How do all those signals keep from getting into each other's hair?" "A good question," Mac said with a chuckle. "It is all done with an arrangement of chokes, blocking condensers, and filters inside a small potted unit mounted inside the set chassis. The coax line goes to this potted unit, and then leads go from it to the various sections of the receiver controlled. Here," he said as he tossed a yellow-covered instruction book across to the boy. "Take that home with you tonight and see if you can figure how it is done by looking at the diagram." "Can you hook that outfit on to any receiver?" Barney wanted to know. "Just about any. It comes in two models: one for sets with an i.f. around 21 megacycles and another for sets with an i.f. near 41 megacycles. A set with an odd i.f. too far removed from these standard frequencies could not use the remote tuner. Neither could the remote control be applied to an old set using manual gain control without a.g.c. But outside of such rare cases, the device will work on any set. It functions equally well with split i.f. and intercarrier systems. When you want to use it for u.h.f. reception, you simply install u.h.f. strips in the remote control tuner. If you want to employ a booster in conjunction with the remote control tuner, there is an a.c. outlet on the rear of the cabinet into which the booster can be plugged." "How about using the unit in a weak-signal area? Can you get as good reception with the remote unit as you do with the set's own tuner?" "If you hook it on to a set employing a less-efficient type of tuner, you will actually get better reception when the modern cascode circuit of the remote unit is in use. In general, you should be able to use this remote control unit in any area in which the set alone will receive a watchable picture." "Whose set is this you are using?" "The wife and I were visiting friends at Big City over the weekend: They have a little boy with rheumatic fever who must spend the next few months in bed. Television is the best thing they have found to keep him entertained; but, like most kids, he likes to do a lot of channel hopping. That means his mother has to dash in from the kitchen, laundry, or upstairs dozens of times a day to adjust the set. I was telling them about this remote control gadget, and they insisted I bring their set home and install the unit. We are going to take it back to them tonight." "That will certainly be a fine thing for him and his mother, and I can see where it could be used to great advantage in a public place where the set must be up high so everyone can see it but yet you want to control it from a convenient location. Also, I can understand how elderly people will like not having to jump up and down every time they want to change programs, touch up the tuning, or adjust the volume; but I wonder if many other people - young and able-bodied people, I mean-will buy them." "I am sure they will," Mac said emphatically. "I remember that when automatic gear shifts were first introduced a lot of people thought that they would only be used by women and 'other' inept drivers. As soon as drivers in general found out how convenient they were, though, everybody wanted them. "Remote control of TV sets is not a brand-new idea, for we have had some novel electrical-mechanical systems in the past that worked pretty well. This unit here, however, is representative of several new all-electronic remote controls that are being placed on the market by various manufacturers at this time; and these new units have several things to recommend them. In the first place, they can be installed easily and quickly and do not interfere with the normal operation of the receiver. It is a well-known fact that you can do a better job of adjusting a picture from the viewing position. That is proved by the wide use of that earliest form of remote control: a wife in her easy chair instructing her husband at the set exactly how to set the volume and contrast controls. Unless you are a contortionist, it is practically impossible to set the controls on the set without blocking the view of some of the watchers. Finally, a remote control unit fits in beautifully with the radio-phonograph-TV custom installations that are becoming so popular these days. "I have been thinking these control units would be a good item for small shops such as ours to stock and sell," Mac said musingly. "They are small and take up very little room. Every owner of a set we repair is a potential customer. We have the jump on an ordinary store because only a service technician is in a position to install them. "A technician friend of mine reports a kind of sneaky but effective way he has of selling them. When he has to remove a tuner and send it in for repair, he temporarily installs one of these units so the set can be used while the tuner is away. He says not a single set owner so far has let him remove the remote control when the repaired tuner is returned." "Say, I think I know another use for that remote control unit," Barney exclaimed. "Suppose I run the output of that coax line through a blocking condenser into the antenna connections on my communications receiver tuned to twenty-one megacycles. Then a short piece of twin-lead, run through a high-pass filter to the tuner's antenna terminals ought to make dandy probe for detecting TVI-causing harmonics leaking out of any transmitter. The receiver's S-meter would show instantly any change in strength of those harmonics." "It would probably work," Mac said with a grin; "but you remind me of a guy who can't watch a steam shovel at work without thinking about how he could use it to dig his garden potatoes." Barney wandered across to the bench and picked up a large red-backed book lying by Mac's elbow. "What's this?" he asked. "Handle that with care," Mac warned. "I had a heck of a time borrowing that copy. It contains the information RCA presented to the FCC when they were seeking approval of their color television system." "What kind of information?" "Just about any sort you can think of, from detailed engineering description of the apparatus used in transmitters and receivers to purely personal opinions of the observers." "I've read a lot about color television," Barney remarked, "but I have never seen anything about how color receivers are going to compare with black and white sets in fringe areas. How will color reception be affected by things like adjacent channel interference and noise?" Mac took the book from Barney and flipped the pages to a section near the center. "Ah, here we are," he said. "Color and monochrome sets are about equally susceptible to co-channel interference and to lower adjacent channel interference. Color sets, though, are a little more disturbed by upper adjacent channel interference. Color reception, too, is a little more susceptible than monochrome to random noise. However when the noise is of the impulse type, such as is produced by an electric razor, one type of reception is not bothered any more than the other. And for good measure, I might add that observers decided multi-path reception - 'ghosts' to you - interfered a trifle more with the enjoyment of color reception. The important thing is, however, that in every comparison of the effect of interference on color and black and white receivers, the difference was slight." "That must be a pretty complete report," Barney conceded, "but let's give it one more acid test. See if it can answer the same disturbing question everyone pops at me when I try to talk about color television: What color is the snow?" A slow grin spread across Mac's wrinkled face. "I know the answer," he said, "but I must confess I did not find it in the book. I thought I knew what color it would be, but I was not sure; so when everyone out here in the fringe area kept asking the same question, I wrote to RCA and asked them. They came right back with a telegram, which made me feel that I was getting serious consideration of a rather silly question; but now we have an authoritative answer right from the horse's mouth. "As we might have suspected, snow on color television can be, and is, any color through the whole spectrum. Since it is a manifestation of random noise, it affects the color circuits as well as the others; and this results in the snow's appearing as multi-hued sparkles of light." Barney heaved a big sigh of relief. "It may be a silly question, but I'm surely glad they answered it. You can't imagine the awful thing it was doing to my ego to have to say, 'I don't know,' every time someone asked about the color of the snow. Now I'll just snap, 'It's technicolored, of course!' " Mac's Radio Service Shop Episodes on RF Cafe This series of instructive technodrama™ stories was the brainchild of none other than John T. Frye, creator of the Carl and Jerry series that ran in Popular Electronics for many years. "Mac's Radio Service Shop" began life in April 1948 in Radio News magazine (which later became Radio & Television News, then Electronics World), and changed its name to simply "Mac's Service Shop" until the final episode was published in a 1977 Popular Electronics magazine. "Mac" is electronics repair shop owner Mac McGregor, and Barney Jameson his his eager, if not somewhat naive, technician assistant. "Lessons" are taught in story format with dialogs between Mac and Barney.
Posted March 11, 2016 |
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