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==============================================================================
K E N W O O D
>>> A M A T E U R R A D I O S E R V I C E B U L L E T I N <<<
==============================================================================
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
==============================================================================
BULLETIN # 917
MODEL: TS-940S
SUBJECT: VCO CARRIER TO NOISE RATIO IMPROVEMENT
The Carrier to Noise ratio of the TS-940S may be improved by the
following changes. This bulletin supersedes bulletin number 911 dated
September 15. 1986
Parts required:
PLL UNIT (X50-2020-00)
R120,129 3.3K ohm 1/6 watt carbon resistor RD14CB2C332J
R121,124 680 ohm 1/6 watt carbon resistor RD14CB2C681J
C180,181 .01 uF disc ceramic capacitor C91-0117-05
C184,185 .33 uF 35v Tantalum capacitor CS15ElVR33M
RF UNIT (X44-1660-00)
R154,155 3.9K ohm 1/6 watt carbon resistor RD14BB2C332J
C193,194 1 uF 25v Tantalum capacitor CS15ElEOlOM
Procedure:
On the PLL UNIT (X50-2020-00) remove capacitors C176, C180, and C181.
Change resistors R120 and R129 from 470 ohms to 3.3 K ohms.
Change resistors R121 and R124 from 1 K ohm to 680 ohms.
Change capacitors C184 and C185 from .22 uF to .33 uF 35v tantalums
Instal1 C180 and C181 in the positions shown in the accompanying diagrams.
The use of new capacitors is recommended to improve reliability,
don't try to reuse the old capacitors!
Capacitors C181 and C180 should be attached to the foil side of the PLL unit
On the RF Unit (X44-1660-00) install the series RC circuits composed of
R154 and C193, and R155 and C194, as shown in the accompanying diagrams.
As the diagrams illustrate it is easiest to move C132 and C133 to the
foil side of the board and install the series RC circuits on the component
side.
Time required for this modification is 1.5 hour or less.