WB4KDI Engineering Notebook

HELP! I Just Got a TS-660

Building upon the designs of the TS-120, TS-130 and TS-430, the TS-660 Quad Bander adds coverage of 6 Meters at the expense of 80 - 17 meters. There are a frightening number of adjustments but fortunately the TS-660 holds it's adjustments well so very little maintenance is required. One concern is that all of the PC boards, including the Final, are of brown paper phenolic construction (NOTE: needs verification).

Preventive Maintenance

  1. Replace C119 and C120 (1000 F @ 16V) on IF board.
  2. Check to see if any mods and Service Bulletins have been applied.
  3. Carefully apply contact cleaner/lubricant to all switches and pots.


  1. See troubleshooting chart in Instruction Manual and Service Manual.
  2. On the RF board, L4 and L38 have their metal shields grounded with a leaf spring. The springs tend to push L4 and L38 sideways breaking the soldered connections. Remove the existing solder, reposition and resolder. Remember to replace the springs.

Adjustments and Alignment

  1. See ADJUSTMENTS in Service Manual
    1. Carrier point adjustments can be made easier by using Spectrogram or another FFT display.
    2. S-Meter can be adjusted to match standards (S9 == 50v and 6db/S unit) from about S3 through 40 over S9.
      uv0.20.4 160500160050001500050000
      S 1 2 3 4 5 6 7 8 9 10 over 20 over 30 over 40 over 50 over 60 over

Mods and Improvements

  1. Apply SB-856.
  2. Muffled received audio - The TS-660 has a roll-off at about 2800 Hz.
    1. SSB - Change high frequency rolloff for better clarity. Change C40 on the IF board to 0.003μF or 0.0047μF.
    2. FM - On FM-660 change C50, 0.033μF to 0.0033μF or 0.0047μF. Restores high frequencies on received FM signals.

  3. Muffled/mushy transmitted audio - On the Switch Unit, change C6, 0.015μF to 0.001μF.

  4. Selectable fast/slow agc - Remove D53 on the IF unit. Attach where cathode of D53 was through new diode to a switchable source of 9V. 9V on = slow agc, off = fast.
  5. LSB ? - LSB can be added using circuits similar to those in the TS-120, TS-130 and TS-430. An 8.8285 MHz crystal would be required.
  6. Adjustable sidetone pitch - The sidetone circuit is similar to what Kenwood used in other rigs. R129 on the IF board may be adjusted if needed.