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The Uniden Bearcat BC245XLT is a scanner that is designed to monitor trunking networks. Yahoo Groups hosts a list devoted to the BC245 trunktracker. The Uniden BC235XLT can be tapped using the same procedure as the BC245XLT.

Of course, this scanner can be equipped with a discriminator output.

The BC245XLT



The opened scanner

The output is made on pin 9 of the MC3361

The discriminator IC, an SMD MC3361, is located at the back of the PCB that becomes visible if you open the scanner. The unfiltered audio can be found at pin 9. One leg of a safety resistor of 10 k is bent so it follows the IC pin. To prevent possible mechanical strain to pin 9, the resistor is fixed to the IC with a drop of glue from a glue gun.

The demodulated baseband signal contains an IF component at 455 kHz. This signal is filtered by mounting a 2.2 nF capacitor between the other pin of the resistor and ground. Together with the resistor of 10 k, a simple lowpass filter is created with a cut-off frequency of about 7 kHz.



Close-up of the discriminator output


The chassis terminal is mounted in the back of the case. The terminal just fits between the housing and the shield of the RF part that is visible in the picture of the opened scanner. The inner contact of the chassis terminal is connected to the joint of the resistor and capacitor. The connector's ground lug is connected to the scanner's ground.

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