Hello All,
I have not seen a connection like this before. What is this rectified pulse for power supply for? What does it do for the pre-amp ("c" supply?)? Will the radio still function without this connection? Again, I'll find out when I finish the restoration. I think that it will operate on the bench without that hooked up.

Thanks,

Dave

The radio will function without the distrubitor hook-up. This was called "Speed Compensated Volume Control". The purpose is to increase the volume of the radio when the engine speeds up, thereby attempting to overcome road noise when driving.

You can test the function of the circuit with an audio generator hooked to the RCA jack.
Set the audio generator for about 10,000 cycles, at a high output. Vary the output to 0, the radio volume should change.

Better instructions on testing the circuit and what to check if it doesn't work are in the Motorola service manual for the 79MS radio.

Meade

:Hello All,
: I have not seen a connection like this before. What is this rectified pulse for power supply for? What does it do for the pre-amp ("c" supply?)? Will the radio still function without this connection? Again, I'll find out when I finish the restoration. I think that it will operate on the bench without that hooked up.
:
:Thanks,
:
:Dave

Mag,
Does the 10 mf capacitor have to handle 50 volts like the original, or will a lower working voltage capacitor work?

Thanks very much for the information. It makes this radio even more interesting.

Dave
:The radio will function without the distrubitor hook-up. This was called "Speed Compensated Volume Control". The purpose is to increase the volume of the radio when the engine speeds up, thereby attempting to overcome road noise when driving.
:
:You can test the function of the circuit with an audio generator hooked to the RCA jack.
:Set the audio generator for about 10,000 cycles, at a high output. Vary the output to 0, the radio volume should change.
:
:Better instructions on testing the circuit and what to check if it doesn't work are in the Motorola service manual for the 79MS radio.
:
:Meade
:
:
:
:
::Hello All,
:: I have not seen a connection like this before. What is this rectified pulse for power supply for? What does it do for the pre-amp ("c" supply?)? Will the radio still function without this connection? Again, I'll find out when I finish the restoration. I think that it will operate on the bench without that hooked up.
::
::Thanks,
::
::Dave