Service BulletinAmateur Radio Division

Subject: TS-120S - Ant Input Transformer ReplacementDate: August 12, 1980

Supercedes SB-040; see also SB-832.

TS-120S transceivers subject to strong static fields, high RF or other similar high current atmospheric discharges may suddenly exhibit low RX sensitivity on all bands. Tx will not be affected. Suspect T1 on the RF unit X44-1260-01.

When replacing T1, L34-0696-35, check that the value of C20 is 33pf. Early units may have a l5pf for C20, and may have T1 as L34-0696-05. In either case, replace the transformer with a L34-0929-15. If C20 is 15pf, replace it with a 33pf capacitor. Since T1 is a broadband transformer, no adjustment is necessary.

Replacement Parts
Old Part No.
New Part No.
T1L34-0696-05/L34-0696-35L34-0929-15Antenna coil
C2015pfCC45RH1H330J (33pf)Capacitor

In addition, add two 1S1587 diodes after the transformer as shown to further protect the receiver.

Changes are circled in green.

©1980 Kenwood