| Jeffhs |
06-29-2009 11:30 AM |
The "signal seeker" was a function on some high-end car radios that literally sought out local signals on the radio dial in a given listening area, starting at the low end of the band; they weren't too common on home radios of the '30s except deluxe Philcos, Zeniths, et al. Many car radios made for Cadillacs in the '50s had this feature as well, as it allowed the driver to tap one button or bar (or depress a foot switch) and have the radio scan for stations without having to take his or her eyes off the road, not unlike the mechanical pushbutton presets on later car radios from the '50s until now; the latter operated by manually setting the pushbuttons for up to five favorite stations. Each time a button was pressed it would move the tuner to the station for which the button was set.
Note, however, that electronic car radio pushbutton tuning systems from about the '80s to now are preset by means of a "set" button, usually located at the far left of the radio looking at the front. The function of the buttons is the same as the mechanical presets used in older radios; most if not all electronic-tuning car radios today have scan and seek tuning that works the same as the older Cadillac signal-seeker radios, except today's signal-seekers are all electronic with no moving parts. The old signal-seeking car and home radios had complicated mechanical linkages, gears, motors, etc. and depended on tube-operated circuitry for their operation, not to mention being a repairman's nightmare to service.
Note as well that almost all the early electronic car radio tuning systems had a sensitivity control that could be set for different signal areas, causing the radio to scan for stations of varying signal strengths. Cadillac car radios had this, with the sensitivity switch located in the center of the scan bar. The switch had three positions, for distant, local and (I think) manual tuning. There was a legend engraved on the signal-seeker bar above the sensitivity switch with arrows pointing to the "distant" position; the legend itself read "more stations" and denoted in which position the sensitivity switch was to be set for maximum scanning sensitivity. This position was ordinarily used in areas with few or no local radio stations; the tuner would scan the dial, stopping at literally the first station it found, which was almost always the strongest station in the area (in many small towns and rural areas the "strongest" station would be a dinky little 250-watt daytimer, with few other local signals to be found, but it was entirely possible that the scanner went wild, picking up one station after another, after local sundown when the AM radio dial opened up to the world; this was in the days of the big 50kW "clear channel" stations, which could reach coast-to-coast after local sunset as they were the only stations on the frequency at that time). The "local" position of the sensitivity selector was, of course, for city and suburban areas; it caused the radio to seek out the area's local stations, and in most areas like Cleveland, Chicago, Philadelphia, et al. it found plenty, as these cities all had (and still have to this day) many 50kW stations. The "manual" position disabled the signal-seeker and permitted the use of the manual presets or the radio's own tuning knob for station selection.
The signal-seeker in home radios (again, only deluxe Philcos and Zeniths, as a rule) worked the same way, also with a control to regulate the scanning sensitivity.
These radios' scanners also likely went wild when the AM radio dial opened up--even more than car radios, as most AM radios of the '30s and '40s had to be used with outdoor wire antennas and could receive quite a few more stations than even car radios. The latter used nothing more complicated than a telescoping whip antenna on a fender, but since automotive radios are built to be extremely sensitive, if you were motoring around between towns or literally "in the middle of nowhere", with few or no local stations to be found, what your car radio would pick up would be literally anyone's guess.
The remotes likely had a couple of buttons, marked with up and down arrows or similar legends, to activate the scanner as well, not unlike the channel up-down buttons on TV remotes. Most bookshelf stereo systems made since the mid-'80s have scan/seek tuning of the AM/FM tuner as well, again with manual up/down scan buttons on both the local unit and the remote, and large numbers of memory presets, some (like my Aiwa CX-NA888 bookshelf system) having as many as 32 presets for both AM and FM stations (the presets can be used for AM or FM). These presets, like almost every other function of the system, may be accessed via the remote as well as via buttons on the unit itself.
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