This article contains notes on installation of a Roger Beep inside a Codan 8528 transceiver (or remote head).
Credit to Bruce Boardman for text and pics.
CAVEAT: Any modifications that you make to your transceiver are entirely your own responsibility. Bruce Boardmand and Owen Duffy take no responsibility for the accuracy of this article, or for the outcome of your modifications. Modification of a transceiver may have implications for original warranty.
For this application the resistor R4(Rs) is 1K, and resistor R5 is 4K7. Use the 2N7000 as suggested, and therefore R6 will be a wire link.
The "Roger Beep" pcb needs to be built without a header plug or pins on the board, as this will inhibit the mounting location. Run wires directly from the PCB. The Pin 1 (+DC) wire needs to be 250mm long and all the others 70mm. Pin 2 is not used, so no wire needed here.
This modification is designed to simply plug in, and requires minimal modification to the radio.
The microphone and PTT wiring runs from the circular microphone connector to the 4 pin header on the motherboard P11.
The wiring of this connector is shown below.
Construct a 4 pin plug and socket arrangement, using a female stackable header and ordinary male header pins. The end pin (PTT) does not connect through. This will plug into P11 on the motherboard and the cable from the mic connector will plug onto the male pins. The wiring from the roger beep pcb will parallel onto this also.
The "Roger Beep" pcb is secured to the end of the selcall board using double sided foam tape.
The DC wire (pin1) runs around the radio motherboard and connects to test point A, which is the +12V rail.
The PTT "in" wire comes from pin 1 of the new plug/socket assembly coming from the mic connector, the PTT "out" goes to pin 1 towards the motherboard, the ground connects to pin 2, and the audio to pin 3. Pin 4 has no other connection and goes straight through.
NOTE: Some Codan microphones have a second set of contacts on the PTT switch inside the microphone, this is used to short the mic on receive. This short will need to be removed otherwise it will short the TX audio when the PTT is released, and will prevent the beep tone from being transmitted.
Note: if the radio has a remote head the RB needs to be installed in the remote head, not in the main radio body. In the remote head, the place to pickup 12VDC varies with PCB verions, the A rail can be accessed from the input to the LM317 regulator.
Before closing the transceiver:
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