The Puxing PX-888 is a cheap Chinese portable transceiver. Different versions exist: VHF-, UHF- and dual band. The microphone socket can be modified to carry the unfiltered demodulated signal
The receiver IC is a TA31136, with the unfiltered audio on pin 9.
To open the transceiver, the two knobs need to be removed. After that, the three washers can be loosened using a pair of fine tip pliers.
Next, the back part of the transceiver can be taken apart from the front half, starting at the bottom. To make the two halves easier to handle, also the flatcable connecting the two halves can be loosened.
Schematic microphone socket
Connection of the discriminator tap
Schematic receiver IC
The microphone socket is reused, so no drilling is required.Follow the next steps to add a discriminator tap:
Using a 3.5 mm (1/8") mono or stereo plug, the unfiltered audio is available on the tip and ground.
This modification does not affect the operation of the radio. Both an external speaker/microphone and the USB programming cable still work correctly.