==============================================================================
                             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 # 942
MODEL: ALL
SUBJECT: SERVICE MANUAL TX LEVEL DIAGRAMS						  10/30/88


INTRODUCTION

Kenwood service manual transmit level diagrams provide typical RF levels 
found in working transceivers. This information provides a fast method 
of locating a faulty circuit in a transmitter chain. To use the level 
diagrams, an AF VTVM, RF VTVM, and 50 ohm resistive load are required. 
In addition, since many units are tested with the drive output terminated 
into the load, a coax cable must be fabricated. A sample cable is shown 
below.

HOW THE TX LEVEL DIAGRAM IS DEVELOPED

The transmit level diagrams are developed in a similar manner as the 
receive diagrams. Basically, a working transceiver is tuned for a specified 
output power at center frequency. The mic audio circuit is measured with 
an AF VTVM and the RF circuit is measured with an RF VTVM. The results 
are listed on the diagram as typical levels for a working transceiver. 
The exact setup used to make a diagram varies with the model. The setup 
details are listed in footnotes on the diagram. No matter what procedure 
is used, the end result is a list of typical levels for a working 
transceiver.

For the most part, variations in setup include what mode is used, if audio 
is applied to the mic input, and what reference is used for power output. 
Additionally, many units have the drive signal connected directly to a 
50 ohm load. This requires a fabricated coax cable that can be inserted 
into the drive socket and attached to a load. A coax cable with a terminal 
that fits the drive socket is available in the Kenwood Parts Department. 
SB-905 lists the part numbers of coax cables that are available in 
several lengths and style. Once a cable is obtained, a connector that 
matches your 50 ohm load can be soldered to the cable.

USING THE TX LEVEL DIAGRAMS

As mentioned above, certain units are terminated at the drive output. 
This procedure can be used in troubleshooting to determine if normal 
drive power is available. Simply connect the fabricated coax cable to 
the drive terminal and the 50 ohm load. If the load receives full drive 
power as indicated on the level diagram, the trouble spot is in the Final 
or LPF unit. In this case, reconnect the Final unit and continue 
checking towards the antenna terminal. If low drive is measured, continue 
measuring towards the mic input until a faulty circuit is found.

NOTE

Once a faulty circuit is isolated, DC measurements must be made to 
determine if normal supply voltage is present.