C3 U79 Stereo Radio

[Jimmy B.]

Is there a way to tell a 68/69 stereo radio from a non stereo upon looking at the faceplate only? Does a 68 still have the round yellow light in the upper rh corner? Does only stereo radios have 2 amps? Thanks in advance.

[Joe L.]

Re: C3 U79 Stereo Radio

Jimmy-----

All U-79 stereo radios in the 68-76 period have the stereo indicator light in the upper right corner of the lens and the lens has the word "stereo" on it. So, those are the best way to differentiate a U-69 from a U-79.

As far as I know, both the U-69 and U-79 radios use a single, external "amplifier" unit. However, the units are different for U-69 and U-79. I think that the U-79 unit incorporates the same external component used with the U-69, but attached to an additional electronic assembly.

[Jack H.]

Re: C3 U79 Stereo Radio

Joe Lucia answered part of your question, here's the balance.

On stereo/U79, there are two considerations: early vs. late and standard vs. A/C equipped car. On early Sharks like the '68-69 period you referenced, the other 'box' under the dash that was cable connected to the radio chassis installed in the center console was called an 'adaptor'. There were two versions of the adaptor, one for non-A/C cars and another for A/C equipped cars with the difference being the length of the interconnect cables from the adaptor to the radio chassis and the geometric silhouette of the adaptor's chassis.

Standard AM/FM car radios of this period (U69) also used another under dash 'box' to make the radio work and it was called a 'convector'. The convector was essentially an aluminum heat sink with a DS501 germanium transistor mounted on it that served the function of being the final audio output stage (convert voltage waveforms into current pulses). Obviously, designers were having trouble squeezing all the needed radio components into the space allocated for the radio in the center console area.

The Stereo 'adaptor' box contained the multiplex signal detector circuitry, adjacent channel separation circuitry, and RH audio output speaker drive components. The adaptor was a LOT more of an electronics package than the monorual convector...

Later in Sharkdom (mid '70 era), solid state component integration allowed more circuitry to be packed inside core radio chassis housed behind the center console. These radios look pretty much the same as from the faceplate level as the early Shark radios, but the 'extra box' behind the dash changed... Then, the adaptor disappeared with its integrated electronics going upstream into the main radio chassis and what was cable connected to the radio was simply an expanded heatsink with two DS501 audio drive transistors (R/L channel) mounted on it.

[J B.]

Re: C3 U79 Stereo Radio

Jimmy,

One other tidbit of info from my 68/69 judging manual. In a 68 AM/FM stereo radio the backlit word STEREO is in script lettering while in 69 and beyond the STEREO is in block lettering.

I don't think the yellow light replaced the word STEREO until 72.

[Jimmy B.]

Re: C3 U79 Stereo Radio

Thanks for the information, this is what I needed.
Jim Blakely

[Reba Whittington]

Re: C3 U79 Stereo Radio

John, you are correct about the yellow stereo light beginning with 1972. Also when looking for a radio, note that 1968s have STEREO in script lettering; 1969 and up is in block letters. The numerals are also green 1968-71 and white 1972-76.