Quozl's Uniden UH-040XR

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The Uniden UH-040XR sold for $AUD99 per unit from Dick Smith in Australia in 2001. It is a 0.5W 40 channel UHF CB transceiver.

MIC and EAR connections

Task: determine how to connect a TNC to the transceiver.

Solution: connect TNC to MIC input via 4.7uF polyester capacitor, connect PTT to MIC input such that a 1k-10k resistance to ground is in effect when the TNC wants to transmit. From a workshop supervisor, care of Peter Illmayer, 4th March 2002.


In July 2001, Uniden declined to provide a schematic of the optional headset with PTT switch.

Relevant aspects of the design:

Conclusion: transmitter is keyed by connecting a microphone through a PTT switch to the MIC input socket.

The following picture shows the connections, the capacitors, and the reverse polarity protection diode.

Figure 4, Close-Up of MIC and EAR connections


You will need a static protected workplace, and a Philips Head #1 (PH1) screwdriver. A PH1 electric screwdriver bit is probably not long enough to reach down to two of the screws.

Note: there are case clips at top right and top left of the unit. See the following pictures.

Figure 1, Location of Case Clips

Figure 2, Right Case Clip Close-Up

Figure 3, Left Case Clip Close-Up


Figure 5, Main Board, Rear Face

Figure 6, RF Board, Rear Face


How to drive the unit from Quozl's pump controller, or other microcontroller based system.

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