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Uniden PC 122, PRO 640 & PRO 810 Clarifier Mod. These radios use a lower cost chassis and you can just squeak 5 KHz down from them using a 5.6 µh chock in series with the varactor diode D23. The following instructions will open and increase the clarifier range: 1. Remove D25 2. Jump D24 3. Lift the ground side of D23 and install a 5.6µh choke from the open lead of the diode to ground. 4. With a volt meter find +8 volts on the clarifier control and cut that trace. Make sure nothing else is connected to this potentiometer contact. 5. Connect the open terminal of the clarifier control to + 8 volts constant (IC4 pin 1). 6. Jumper the other side of the clarifier control to ground. 7. Set the clarifier to the 3 O'clock position. 8. Connect a frequency counter to TP3. 9. In AM adjust L16 to 16.4900 MHz. 10. In USB adjust L17 to 16.4925 MHz. 11. In LSB adjust L18 to 16.4875 MHz. The President AR144 and Cobra 146GTL have similar circuits and the above instructions are adaptable to them. © CBWI

AUGUST VOLUME 1 ISSUE 5