BC245XLT, BC235XLT
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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.
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The BC245XLT
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The opened scanner
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The output is made on pin 9 of the MC3361
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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.
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Close-up of the discriminator output
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Overview
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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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