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                             K E N W O O D
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                        Kenwood Service Centers

   Kenwood Service Corporation             Kenwood Service Center, East
   2201 East Dominguez Street              829 Lynnhaven Parkway, Suite 130
   Long Beach, California 90801            Virginia Beach, Virginia 23452
   Telephone 1-310-639-5300                Telephone 1-804-340-1702

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BULLETIN # 995
MODEL: TS-450S/TS-690S
SUBJECT: Calibration Cable Change

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:
E37-0280-05	Calibration Cable Assembly	1 Ea.
CK73FCHlHlOlJ	100 pF Capacitor	        1 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.