So here's a good reason to start your own thread to ask a question. I'll be able to find it using the forum's 'search' feature.
Somebody asked about the TRC-446 at the end of another thread. Looked at my shop's archives and found a bench file dated 2003.
Just can't find the thread where this question got asked. Oops.
For the record, this radio uses the center pin of the power socket to feed "keep alive" power to a memory chip in the channel selector circuit. Allows it to remember what channel was selected when you switched the radio off. In a vehicle, this pin connects to a 1-Amp fuse leading to the vehicle's unswitched battery power.
The modulation limiter is RV201.
Mike pinout: Has an electret cartridge.
Pin 1 is audio
2 is receive
3 is transmit
4 is channel down
5 is ground.
Never did take the mike apart to see how you step the channel up.
Final transistor is 2SC2078, driver is an incredibly-tiny 2SC1906.
Does lead me to wonder how it compares to the TRC-447 model. The full service manual and schematic are available for that one.
Makes me wish I had noted the circuit-board number in this file.
73
Somebody asked about the TRC-446 at the end of another thread. Looked at my shop's archives and found a bench file dated 2003.
Just can't find the thread where this question got asked. Oops.
For the record, this radio uses the center pin of the power socket to feed "keep alive" power to a memory chip in the channel selector circuit. Allows it to remember what channel was selected when you switched the radio off. In a vehicle, this pin connects to a 1-Amp fuse leading to the vehicle's unswitched battery power.
The modulation limiter is RV201.
Mike pinout: Has an electret cartridge.
Pin 1 is audio
2 is receive
3 is transmit
4 is channel down
5 is ground.
Never did take the mike apart to see how you step the channel up.
Final transistor is 2SC2078, driver is an incredibly-tiny 2SC1906.
Does lead me to wonder how it compares to the TRC-447 model. The full service manual and schematic are available for that one.
Makes me wish I had noted the circuit-board number in this file.
73
