Radio question
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From: Piedmont Missouri
Radio question
Hi, my 69 Vette did not have an original radio in it when I bought it. It still has the original amp which is small, so I assume it was a mono radio. My question is, is there a difference in receivers between a mono radio and a stereo radio? I want to put the original mono system back in, if that's what the car came with. I can only find a number in my assembly manual for a stereo receiver (7303211). I know that the most common option was the mono system (option u69). How do I know for sure what the car originally had and what receiver do I look for if it was a mono option? Thanks for any help.
Mark
Mark
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From: Redondo Beach, California
In 1969, a stereo radio would have a FM decoder box in addition to the main radio box. Also, a stereo receiver would have an external aluminum finned heat sink with two power transistors. A mono receiver would not have the additional decoder box, and the external aluminum finned heat sink would only have one power transistor.
After 1972, the external FM decoder box disappeared...(am I correct?) ...the FM electronics were installed in the basic receiver box and the little external box disappeared. The external aluminum finned radiator with two power transistors remained.
In 1969, if you had a stereo radio, I think you'd see a little green "stereo" word light up in the upper right hand corner of the radio. In later years you'd see a little yellow/orange light up. ...Best of my memory..
After 1972, the external FM decoder box disappeared...(am I correct?) ...the FM electronics were installed in the basic receiver box and the little external box disappeared. The external aluminum finned radiator with two power transistors remained.
In 1969, if you had a stereo radio, I think you'd see a little green "stereo" word light up in the upper right hand corner of the radio. In later years you'd see a little yellow/orange light up. ...Best of my memory..
Last edited by 68/70Vette; May 14, 2014 at 11:37 PM.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 249
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From: Piedmont Missouri
In 1969, a stereo radio would have a FM decoder box in addition to the main radio box. Also, a stereo receiver would have an external aluminum finned heat sink with two power transistors. A mono receiver would not have the additional decoder box, and the external aluminum finned heat sink would only have one power transistor. After 1972, the external FM decoder box disappeared...(am I correct?) ...the FM electronics were installed in the basic receiver box and the little external box disappeared. The external aluminum finned radiator with two power transistors remained. In 1969, if you had a stereo radio, I think you'd see a little green "stereo" word light up in the upper right hand corner of the radio. In later years you'd see a little yellow/orange light up. ...Best of my memory..
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From: Southbound
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U69 indicates an AM/FM monaural unit. It used an external heat sink with one transistor (GM calls it a convector) as the final uadio output for the radio.
Often here:
U79 is the stereo unit. It uses a different convector (two transistors) for left and right speaker separation.
The options section in the 69 AIM shows each installation (U69 and U79).
The actual stereo equipment could vary between model years.
Often here:
U79 is the stereo unit. It uses a different convector (two transistors) for left and right speaker separation.
The options section in the 69 AIM shows each installation (U69 and U79).
The actual stereo equipment could vary between model years.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 249
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From: Piedmont Missouri
U69 indicates an AM/FM monaural unit. It used an external heat sink with one transistor (GM calls it a convector) as the final uadio output for the radio. Often here: U79 is the stereo unit. It uses a different convector (two transistors) for left and right speaker separation. The options section in the 69 AIM shows each installation (U69 and U79). The actual stereo equipment could vary between model years.
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From: Crossville TN
I don't believe that the radio head units are the same (FM vs. FM-stereo). There is a multiplexer system built into the head unit after 1973 or 74. They were separate units prior to that, but I still think there were significant differences in the head units.
The convector (alum heat sink and power transistor[s]) was either for mono (one transistor) or stereo (two transistors) and the wiring was different for either.
The convector (alum heat sink and power transistor[s]) was either for mono (one transistor) or stereo (two transistors) and the wiring was different for either.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 249
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From: Piedmont Missouri
I don't believe that the radio head units are the same (FM vs. FM-stereo). There is a multiplexer system built into the head unit after 1973 or 74. They were separate units prior to that, but I still think there were significant differences in the head units. The convector (alum heat sink and power transistor[s]) was either for mono (one transistor) or stereo (two transistors) and the wiring was different for either.
