Modifications for the Kenwood T-599

Service Notes on T-599A/D

Author: Trio-Kenwood Communication, inc.

Service bulletin no. 7 (2-11-1977)
  1. No ALC - Drive 10 meters: Check for loose contact at oscillator wafer on coil pack.

  2. No TX any band: Check the T1 on generator board (X52-0009-00).

  3. No TX: Bad driver FET Q1 3SK22(GR) on X47-0004-00).

  4. No relay action when TX: Bad Q8 2SA562(Y). When replacing Q8 change resistor R16 to 4.7 ohm.

  5. Rubber belt sliping on drive and load: TKC has Chain Modification Kit.

  6. No drive when shock: Check for loose output terminals af final rotary switch (S10-1002-05).

  7. No output on any band: Check T2 GEN unit (X42-0009-00).

  8. No TX: Check final relay for burned contacts. (S51-4017-15).

  9. Bias current too high and blows fuse: Check for bad 6-7001A and shorted cathode resistors 10 ohm.

  10. Cannot neutralize: Make sure shield is properly installed on driver 12BY7.

  11. No output from generator unit (X52-0009-00): Bad Q4 TA7045.

  12. No 9 Volt out at AVR (X43-0010-00): CHeck Q1 2SA606(L).

  13. Low output power: If American 12BY7 is used in driver circuit, this can cause parasitic oscillation. Please use standard Kenwood replacement tubes.

  14. Blows fuse: Check for shorted electrlytics at power supply (X43-0011-00).

  15. AC hum on SSB transmission: Send for TKC bulletin.

Reducing 120Hz hum in T-599D

Author: Trio-Kenwood Communication, inc.

Service bulletin no. 17 (6-9-1977)

There hace been some cases of 120Hz hum in the T-599D. This may be reduced by removing L-1 (1mH) on the generator unit (X52-0009-00) and replacing it with a 47 ohm resistor. Shown below is the generator unit board with this change.

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