Operating instructions

Maintenance DMH Series VHF Radio
Page 5-6 BK RADIO
5.4.3 CORE ASSEMBLY
5.4.3.1 VCO AND RX/TX BOARDS
1. Remove the sheet metal shield from the RX/TX board by prying it up with a flat-blade
screwdriver.
2. Remove the 4 screws from the VCO cover and lift off the VCO cover.
3. Carefully remove the VCO by lifting it from the center or prying it up evenly around the
sides.
4. Remove the 7 screws from the RX/TX board, pull both coax leads (one at a time) through
the ferrite bead, and carefully lift out the RX/TX board.
5.4.3.2 VCO AND RX/TX REASSEMBLY
1. Insert the RX/TX board into the housing, pulling the two coax cables through the hole in
the housing. Pull the coaxes snug and make certain they clear the 12-pin connector
between the RX/TX board and the System board. Thread each coax through the ferrite
bead.
NOTE: Check that connectors are properly aligned with the System board before seating
them firmly.
2. Insert the VCO, using care to not bend the pins.
3. Attach the VCO cover and snug down the screws.
4. Fasten the RX/TX board to the housing with the seven screws.
5. Insert the flex cables.
5.4.3.3 SYSTEM BOARD
1. Remove the 4 screws and lift off the synthesizer cover.
2. Remove the 3 screws from the System board.
3. Disconnect the front flex cable.
4. Lift out the System board by lifting the front of the board first, then pulling the back flex
through the casting.
5.4.3.4 SYSTEM BOARD REASSEMBLY
1. Insert the System board in the housing, carefully threading the back flex through the
casting.
2. Attach the Synthesizer cover with the 4 screws. Insure that the rubber tubing is in the
cavity above the large rectangular capacitor C119.
NOTE: When reassembling the Synthesizer and VCO, snug down the screws on the
covers or malfunctions may occur.
3. Attach the System board with the 3 screws.
4. Insert the other flex cable.