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Zenith 12s568 early FM? - Printable Version

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Zenith 12s568 early FM? - 37silverstreak - 08-31-2012

I noticed while cleaning the shutter dial on my Zenith 12S568 that one of the bands says "Frequency Modulation". Was this set able to recieve the early FM band or was it just a fancy word for something else? There is also a switch on the back for "television".
When did the first FM sets start coming out? I don't deal much with FM era radio's as I like pre-war set's the best.
Kevin

RE: Zenith 12s568 early FM? - TA Forbes - 08-31-2012

The 12S568s I have seen had two shortwave bands and broadcast band.

What is the frequency range for the frequency modulation labeled band on your set?

RE: Zenith 12s568 early FM? - Dave - 08-31-2012

There was an early FM band (42-49MHz, often refered to as "police band") that was around in the early 40s, but was phase out in favor of the current band that we all know and loathe. The modern band started to appear in consumer radios in the mid to late 40s.
Dave

RE: Zenith 12s568 early FM? - rocketeer - 09-04-2012

The old police band was AM, not FM. What numbers are on the FM band? Pre-war FM was 42-49Mhz or sometimes defined as channels 21-99.

According to the schematic the tuning ranges are:

540-1600Kc (BCB)
1500-5200Kc (Police band and SW)
5700-18300Kc (SW)

No FM. Can you post a pic of the dial(s)?

Larry

RE: Zenith 12s568 early FM? - Dave - 09-04-2012

The term "Police band" was used for both the early FM and AM. They are not to be confused with one another. The police band that came on many prewar radios is in fact AM. Motorola began production of VHF radios during the early 40s that used the 40 MHz FM band, in the two-way radio world we now call this "low band."
Dave

RE: Zenith 12s568 early FM? - rocketeer - 09-04-2012

http://www.motorolasolutions.com/US-EN/About/Company+Overview/History/Explore+Motorola+Heritage/Calling+All+Cars

Larry

RE: Zenith 12s568 early FM? - 37silverstreak - 09-04-2012

Hey everyone.
after cleaning and reassembling the shutter dial and seeing how it works, I think I figured it out. There are only the three faces, standard broadcast, shortwave and police. There is also on the bottom of the faceplate a small window for an indicator plate that mounts on the lever that actuates the shutters. On this indicator are the following, from left to right--- Frequency Modulation- Automatic- Standard Broadcast- Shortwave- Police. When it's all put together right you have "Standard Broadcast" showing in the window. When you rotate the control counterclockwise it activates the shutters to fall away and show "Shortwave" and the corresponding faceplate. The same thing for the police band. If you start on "Standard Broadcast and rotate the control clockwise you will see "Automatic" pop up in the window, but no change in the shutter dials. Automatic is the setting for using the pre-tuned station buttons, I believe. As for "Frequency Modulation" the control shaft cannot be rotated any further clockwise for it to appear. So, I believe that it is not used on this set, it's just labeled on the indicator. Maybe this indicator plate was used on another model Zenith that had that capability, I don't know.
The really good news is that the set is up and running and it sounds really nice too!! It was a big job. I replaced all the caps and resistors as well as all that wonderful rubber coated wire!! Always a big thrill bringing up a set on the variac for the first time after a rebuild! I feel just like Doctor Frankenstein!!!!! In the process now of trying to align it, slowly figuring it out.
Kevin