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Uniden Bearcat BC145XL / UBC145XL


The Uniden Bearcat 145XL is a vintage 16 channel scanner. There is ample space to equip it with a discriminator output.

The receiver IC is an MC3359. The unfiltered audio can be found on pin 10. It's quite strong, which could damage a computer's soundcard. Therefore, an attenuation of about 50% is created by a two resistor voltage divider.

Pin 10
discriminator output
Pin 10 of the MC3359 contains the unfiltered audio
The components at pin 10
Chassisdeel in achterwand
Follow the next steps to make the discriminator output:
  • Install a 3.5 mm mono socket in the scanner's back
  • Solder a 10 k resistor to pin 10 of the receiver IC
  • Connect another 10 k resistor to the other lead of the resistor connected to pin 10
  • Solder the other lead of the second resistor to the metal shield of the IF coil.
  • Connect the junction of both resistors with the signal solder lug of the chassis socket (red wire)
  • Connect the chassis socket's ground lug with the metal shield of the IF coil (black wire)
Chassis socket in the scanner's back

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