Parts List

Enhanced AM/FM Synthesizer Instruction Manual OS(R/T)-3(A/H) 29 - 470 MHz 3-3
3.5.3 Synthesizer Removal and Installation
The synthesizer module is secured to the main board (MT-3 Receiver IF/Audio Board or MT-3
Transmitter Main board) with a single counter sunk Phillips machine screw accessible from the top
cover . Remove this screw to remove the synthesizer module. Using a plastic coated lifting tool,
such as a small screwdriver with the tip covered in heat shrink material, gently lift the synthesizer
module from the main circuit board by applying pressure in a rotating fashion about the four
corners of the synthesizer module. It is important to gently remove the synthesizer module
"straight out" in order to prevent damage to the connector pins. Installation of the synthesizer is
performed in a reverse fashion. It is important to ensure complete connector pin alignment prior to
any application of reinsertion force. Four corner locating pins on the synthesizer housing assist in
connector pin alignment during installation and removal.
Note: Complete synthesizer alignment can be performed without removing the synthesizer.
The alignment procedure starting in section 3.5.5 may now be performed.
3.5.4 Circuit Board Removal
Note: Circuit board removal is not required for tuning purposes.
Using a vacuum de-soldering station, de-solder connections P1, P2 and P3. Remove SMB
connectors J1 and J2 by de-soldering the center pins and removing four M2.0 machine screws.
These connection points are shown in the "OS(R/T)-3(A/H) XXX - XXX MHz Analog Board
Component Layout (Top)" diagrams. Remove seven M2.0 machine screws and carefully remove
the analog circuit board. Removal of the analog circuit board will expose three inter-board wire
connections . Carefully remove three ferrite beads and six Teflon washers from the inter-board
connection wires. Attempt to maintain the position of the three inter-board wires in order to
simplify re-assembly. The digital board may now be extracted by removing four M2.0 machine
screws. Follow a reverse procedure to re-assemble.
3.5.5 Frequency Adjustment and Channel Selection
Connect a radio communications test set through a short section of low loss 50 Ω coaxial cable to
the synthesizer module SMB RF output jack (J2). Select the desired channel number via the BCD
frequency selection switches on the MT-3 Transmitter Main board or the MT-3 Receiver IF/Audio
board (or through .the Frequency Programming Module). Turn the power off and back on and
wait a few minutes for the oscillator to completely stabilize . It should be noted that the internal
synthesizer TCXO, if installed, operates continuously (regardless of the TX PTT state) when
installed in a transmitter .