TS-950SD Early protection with TL-922A
Author: Trio-Kenwood Communication, inc.
Service Bulletin no. 962 (17-1-1990)
The TS-950SD RX to TX switching time in semi break-in is approximately 10 mS. At the key down, the transceiver momentarily sees an open circuit because the linear's keying relay has not engaged. As a result, the transceiver's protection circuit turns on, causing the output power to be reduced. The following modification will make the RX to RX switching time, in semi-break-in, approximately 30 mS. This modification does not affect full break-in switching. Increasing the switching time to 30 mS may restrict certain long distance high speed communications.
Digital transistor (QTY 2) (DTC124ES)
100 Kohm, ¼ resistor (RD14BB2E104J)
2.2 µF, 50 V electrolytic capacitor (CE04EW1H2R2M)
- Disconnect the power cord and antenna.
- Remove the top and bottom covers (18 screws).
- Remove the top screw from each side of the front panel assembly.
- Loosen the bottom screw on each side of the front panel assembly.
- Pull the front panel assembly forward to expose the Digital and Control boards.
- Remove the two screws that secure Control board B/3 to the top of the chassis and swing the board out of the way.
- Remove the 4 screws from Control board A/3 and rotate the board down. Disconnect the right hand plugs as necessary to expose the foil side of the Control board.
- Install the circuit shown in figure 1 on the foil side of Control board A/3.
- Assemble the transceiver by reversing steps 1 - 7.
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