Service BulletinAmateur Radio Division

Subject: TS-450S - Calibration Cable ChangeDate: May 11, 1992

The TS-450/690 may not calibrate properly against WWV (JJY) when using the calibration cable that is supplied with early versions of these sets, (Serial numbers below 311XXXX) and when an antenna that is shorted for DC is used. A dipole with a balun is a prime example of DC shorted antenna. This failure is antenna specific; i.e. multiband beams and other similar antennas do not cause this failure.

A new calibration cable is available that provides proper DC isolation. Failure to use the new style cable will result in a PLL unlock condition when calibration is attempted. A temporary countermeasure that can be used until the new cable is obtained is to use a two conductor shielded wire. A minor circuit modification that adds a 100 pf isolation capacitor should also be performed. Please refer to the diagrams below for modification notes.

Parts Required:
E37-0280-05Calibration Cable Assembly1 Ea.
CK73FCH1H101J100 pF Capacitor1 Ea.

Cut the foil pattern between TP1 and PIN 7 of IC-2 on the PLL Unit (X50-3150-XX) and insert the 100 pf cap.
Time required for this modification is 30 minutes.

©1992 Kenwood