Bandit54

I have a 69 Stereo Radio without the multiplex unit. All I need is the multiplex unit, I'm not sure what years would work with the 69 radio. Any information in regards price or where I might purchase the unit would be appreciated.

Rescue Rogers

What is it? What does it look like?

Bandit54

I don't have a picture, I'll see if I can find one. Maybe if another forum member has a picture they could post it I would appreciate the help.

indallas1978

I believe this is it, 'ill have to look in the 68 I just picked up to see if I have one even in there.

restoman1

There are two other parts required if you already have the stereo radio. The first is the mono "convector" that comes with the standard mono radio (It's already in the car, bolted to the firewall on the passenger side - see 1st picture).

The second part is the one that's hard to find! It's the stereo "multiplex" adapter that splits the signal for the stereo radio. (See the 2nd picture below)

The 3rd picture below shows the entire setup for mid 1969 through 1975 or 1976 (Not sure of the cutoff date, but this particular picture is of a 1972 system.).

However, 1968 and early 1969 used a different stereo "multiplex" adapter than the one used mid 1969-197x. It's the one that looks like the very bottom picture.

Ed

Bandit54

That's looks like the unit I need. I don't know what the difference is between different years I will just have to see what comes available.
indallas1978 thanks for posting the picture.

restoman1

Also note that there are differences between the 68 stereo radio, the 69-71 stereo radio and the 72-7x stereo radio.

The 68 has STEREO in script lettering that lights up when you get a stereo signal. The 69-71 also says STEREO, but it's in block lettering. The 72-7x just uses a red light.

Ed

Alan 71

Hi B,
Perhaps you might contact some of the radio "restorers". They may have parts to sell and the one you need.
Try D&M Restorations in South Carolina.
Good Luck!
Regards,
Alan

Tom Larsen

I may have what you need. The two units came out of my '72. If you want pics and part numbers let me know.

Bandit54

PM sent

Rescue Rogers

My original radio is missing but I have some of those parts. I will be taking my dash apart in the coming weeks. When I can see whats behind there I'll let you know

tyrant

Is this it?

Bandit54

No that's for a later model

Rescue Rogers

Is this it. I have an early 68

Bandit54

That's one of the two units I need. The part you have pictured is the convector (to me is a heat sink) it is used on both the standard and stereo radio. The other part is used on the stereo only and is quite a bit larger.

Rescue Rogers

Do you want the heat sink?

Bandit54

Not at this time I want to get both items from the same radio to give me the best shot at it working with my radio.

Rescue Rogers

Okay let me know.

68/70Vette

The 69 Stereo light is a different color than the 70 light, best I remember. I think the 69 is green, and the 70 is red.

The 69 AM/FM stereo has the separate box to achieve stereo. The 70 was self contained.

The AM/FM stereo radios were very expensive. They were also known for being of not good quality...lot of cold solder joints.

These radios use a speaker impedance that is not standard today. You need an OEM speaker to play with an OEM radio. The speaker impedance was an important circuit to provide proper bias for the output transistors. If think if you get one of these old radios restored, they bias the output transistors to be compatible with today's standard speakers. (4 ohms I think)

restoman1

Correct for 1968 and 1969 with one caveat. Starting in late 1969 (exact date unknown, but it was after the model year changeover would have normally occurred if not for the strike), the 1970 AM/FM stereo was installed in some late 1969 Corvettes. So a 1969 Corvette built after August, 1969 "could" have the 1970 radio, and therefore the 1970 red STEREO lens. (My late October, 1969 AM/FM STEREO lens is green, but I've also seen red. Heck, I've even seen BLUE!! - see below)

Close. The 1968-1972 AM/FM Stereo radios used three assemblies - The AM/FM Radio itself, The Stereo decoder (Multiplex) and the single transistor Convector that came on the AM/FM Mono radio. Also note that the transistor date codes on the Convector and the Multiplex weren't always the same week, or even the same year! In my particular case, the Multiplex transistor is dated the 13th week of 1968 and the Convector transistor is dated the 40th week of 1969!

Boy, you got that right! Jerry (Rudbeck) once told me that 80 to 90 percent of these things failed within the first year!!

Ed