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TS-950SD Early protection with TL-922A | Radioaficion Ham Radio

TS-950SD Early protection with TL-922A


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.

Required parts:

Digital transistor (QTY 2)                     (DTC124ES)
100 Kohm, ¼ resistor (RD14BB2E104J)
2.2 µF, 50 V electrolytic capacitor (CE04EW1H2R2M)
  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Remove the top screw from each side of the front panel assembly.

  4. Loosen the bottom screw on each side of the front panel assembly.

  5. Pull the front panel assembly forward to expose the Digital and Control boards.

  6. Remove the two screws that secure Control board B/3 to the top of the chassis and swing the board out of the way.

  7. 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.

  8. Install the circuit shown in figure 1 on the foil side of Control board A/3.

  9. Assemble the transceiver by reversing steps 1 - 7.

TS-950SD Early protection with TL-922A

Kenwood Amateur Radio Dealers & Service

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