SB-902
Service BulletinAmateur Radio Division

Subject: TS-430S - Low/intermittent RXDate: October 18, 1985

Low or intermittent receive on the TS-430S may be caused by a poor contact on one or more of the LPF relays. In most cases the following procedure will correct this problem without having to replace relays. The procedure has two steps; first initial cleaning of the contact by passing a relatively high current through them (about 500 mA), and then installing a contact maintenance circuit that will apply a relatively low current (about 8 mA) whenever a new band is selected.

Procedure:

  1. Initial contact cleaning procedure.
    Parts List: qty 2 - 56 ohm 5W ceramic resistor (R92-0622-05) (or qty 1 - 28 ohm 10W resistor)
    1. Press and hold the "UP" bandswitch of the TS-430S (ensure the 1 MHz switch is ON).
    2. Apply 13.8V DC to the antenna terminal through the 28 ohm, 10W resistance for approximately 1 minute. This will cycle through all the relays and burn any oxidation/contamination from the contacts.


  2. Contact maintenance circuit installation.
    Part List:
    Terminal Strip (E22-0371-05)
    C1, C2 (CK45D2H473M) .047 F 500V
    C3 (C91-0117-05) .01 F 50V
    L1 (L33-0259-05) 470 H
    R1 (RD14CB2E102J) 1 K ohm 1/4 Watt
    Small length of hookup wire, about 6 inches
    1. Disconnect the center lead of the coaxial cable from the antenna terminal.
    2. Install the contact maintenance circuit as shown in the accompanying diagrams. Attach the terminal lug strip with one of the filter unit cover screws.

      (I prefer to add the contact maintenance circuit to the back side of the filter unit rather than add the terminal strip.)
    3. Solder the 8v lead to the "JP" terminal of the Filter Unit.



©1985 Kenwood