Commtel COM225 / GRE PSR-225 / Albrecht AE100T
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The Commtel 225, GRE PSR-225 and Albrecht AE100T are base scanners that cover 25 - 1300 MHz.The narrowband FM receiver IC is a 31136,
a TA31136 clone, with the baseband audio at pin 9. |
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Commtel COM225
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A 10 k resistor is soldered the solder pad (indicated with an arrow) that is connected to pin 9 of the 31136 by a short PCB trace. This resistor can be mounted vertically. The inner conductor of a strand of shielded wire is connected to the
resistor's other lead. The braid can be soldered to the metal shield of a nearby coil, which is grounded.
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Pin 9 of the 31136 is the discriminator
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Resistor and shielded wire
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The other side of the shielded wire is connected to a 3.5 mm mono chassis terminal, which is mounted in the back of the scanner.
The inner conductor is connected to the solder lug that connects to the tip of an inserted 3.5 mm jack. The shielding braid is soldered to the other lug.
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The discriminator output, left of the antenna connector
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