View Full Version : Was there ever a dial light in the Zenith K731?; CD markings


Jeffhs
08-27-2004, 04:31 AM
I have a 1959-vintage Zenith K-731 AM/FM radio which plays very well on AM and FM, even out here in the boondocks 45 miles from most Cleveland AM/FM stations. (Zenith didn't call these radios "Long Distance" for nothing--I can hear stations on my '731, especially at night, that my other radios don't get at all. :thmbsp: They don't make them like that anymore.) :(

However, I have a question regarding the dial light (or lack of it) in the K731s. Did these radios ever have a pilot light behind the tuning dial, if only to illuminate the area between the AM and FM tuning scales, where the pointer is located? If not, would it be possible and/or practical to install one in this chassis? My best guess as to why the '731 series (and the plastic-cased cousins of these sets) did not have pilot lights is that these radios use a selenium low-voltage rectifier instead of a tube (most pilot lights in AC/DC radios are connected across the rectifier tube filament; the tube is generally a 35Z5, 35W4, or, in some very old Sylvania sets, 35Z4). Would it still be possible to connect a low-voltage pilot light (say #47) somewhere in the LV power supply (not necessarily across a selenium rectifier, the output of which would blow any low-voltage bulb in the blink of an eye)? :yikes:

Speaking of old Sylvania radios (as I mentioned above), I wonder about the FM coverage of some of their early AM/FM sets. I had a great-aunt who owned a 1950s-vintage Sylvania AM/FM receiver; on one visit to her house in the '70s, I could swear I saw, on the FM side of the dial, the number 109 at the top end of the tuning range of the vertical dial scale. Did these radios actually tune to 109 MHz, which of course is 1 MHz above the top end of the present 88-108 MHz FM broadcast band, or was this a design flaw?

One more question. I have seen Zenith K731 radios with and without the Civil Defense icons on the AM tuning dial scale. The sets made from '63 to '65, after Conelrad was abolished, of course did not have these markings. My own K731, in the Early American walnut cabinet, was made in 1959, but the dial does not have the CD icons--unusual, since Conelrad was still in use in the late '50s and until 1963. The '731s in the modern style cabinet (with legs), which were introduced in the early '60s, IIRC, however--at least the ones made after '63--do not have the CD icons for the foregoing reason.

My question, however, is simply this: If my '731 was manufactured in 1959 (which the date on the tube layout chart on the bottom of the cabinet clearly states), why are there no CD icons on the AM dial on my set, while other late '50s '731s in the same style cabinet do have them (as I have noticed while browsing ebay)?

It makes no difference to me either way, since Conelrad was abolished over four decades ago (and never used except for weekly tests while it was in place), but I'm curious.

One last question about the CD icons on most AM radios of 1953-'63 vintage: Were these required by FCC rules on the AM dials of radios made in this date range? I ask this because, again, I have seen radios of '50s vintage (post-'53, of course, not necessarily Zenith) without the CD symbols on the dials.

About the CD emergency alert system in general: Why was there such a system when it was never used? The CD network was originally designed to disseminate information and warnings pertaining to enemy attacks during the Cold War era, but the only time it was ever activated was during weekly or monthly FCC-mandated tests (not unlike today's Emergency Alert System and all warning systems preceding it). I grew up in a suburb of Cleveland and don't remember Conelrad or EBS ever having been activated except for tests. :dunno: I remember those early Conelrad tests. One that particularly sticks in my mind (and which I may never forget, as it had such an impact on me) was in 1963, when I was seven years old. We had a 21" Crosley Super V TV in the living room at the time. One day I was watching something (don't remember what it was anymore), when the show broke for a commercial (this was back in days when TV and radio stations could only have one minute of commercials every hour). That didn't faze me, but what did was what followed the commercial. The station chose this time to run a Conelrad test. "This is a test," the announcer intoned. While he was speaking, the Conelrad symbol, which was a large black ball with a white triangle, upon which was superimposed the letters "CD", showed on the TV screen, big as life. Man, I ran for the hills (actually, just down the long hall from our living room to the back of the house)--I thought sure the Russians were going to blow all of northeastern Ohio off the map! :eek: :yikes:

Well, it didn't happen (thank goodness), but the memory of that Conelrad test has stuck with me all those years (over four decades). I guess when you've had a scare like that, especially as a little kid, you don't forget it in a hurry.

Chad Hauris
08-27-2004, 06:13 AM
So far as I know Conelrad was to avoid enemies locating the exact point where the radio transmission was coming from. Each AM transmitter had 2 crystals: the normal one for the station's frequency, and the Conelrad crystal which was either 640 or 1240 khz. During an attack, stations would switch to the Conelrad crystal and operate for a short period of time, then switch off, then come on again later. I don't know what the period of on to off was. Since all stations were operating at 640 or 1240, listeners would hear continuous information, even though different stations were providing it over a period of time on the same frequencies.

The Zenith AM/FM sets with selenium rectifier used a neon indicator lamp (just an indicator, did not light up dial) in earlier models, and a 28 volt lamp in the dial with a dropping resistor directly off the powerline in later models.