Instruction Manual
DE
DANIELS
ELECTRONICS
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 fastened 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 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
fashion reverse to the above procedure. It is important to emphasize the importance of connector
pin alignment prior to any application of reinsertion force. Four corner locating pins assist in
connector pin alignment during installation and removal.
Note: Complete synthesizer alignment can be made 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 desoldering station, desolder connections P1, P2, and P3. Remove SMB
connectors J1 and J2 by desoldering 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 interboard 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 interboard 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 through 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 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. This continuous operation results in approximately 10 mA of additional
standby current.
The measured RF output signal should be within ± 1.0 ppm of the specified oscillator frequency at
an output level of +5 dBm. Note that unlocked synthesizer operation will be indicated by an