Kenwood DM-81 - User Manual

DM-81
DIP METER
INTRODUCTION .............................................................................................................. 1
Inductive coupling (Fig. 1A)........................................................................................... 1
Capacitive coupling (Fig. 1B)......................................................................................... 1
FEATURES ........................................................................................................................ 3
SPECIFICATIONS............................................................................................................. 4
CONTROLS ....................................................................................................................... 5
PRECAUTIONS................................................................................................................. 6
Battery and Oscillation Coil Loading ............................................................................. 6
Obtaining a Dip Point ..................................................................................................... 6
Measuring Transistor Resonant Circuits......................................................................... 6
Caution in Measuring Transmitters ................................................................................ 6
Caution in Motor Pointer Deflection Change................................................................. 7
APPLICATIONS................................................................................................................ 7
Use as a Dip Meter.......................................................................................................... 7
Other Frequency Measurements ..................................................................................... 8
Resonant circuit measurement.................................................................................... 8
Use of the capacitive probe......................................................................................... 8
Antenna resonant frequency measurement............................................................... 10
Use as a Signal Generator......................................................................................... 11
Use as Crystal Checker and Marker Generator......................................................... 11
Use as an Absorption Frequency Meter.................................................................... 12
Use as a Field-Strength Meter................................................................................... 13
Capacitance and Inductance Measurements ............................................................. 14
ADJUSTMENT ................................................................................................................ 17
VR1: 01 Bias adj........................................................................................................... 17
VR2: Meter zero adj...................................................................................................... 17
VR3: Sensitivity adj...................................................................................................... 17
VR4: Battery voltage check adj.................................................................................... 17
PARTS AND SERVICE................................................................................................... 17
Ordering Spare Parts..................................................................................................... 17
Service........................................................................................................................... 17
PARTS LIST..................................................................................................................... 18
PRINTED CIRCUIT BOARDS ....................................................................................... 22
SCHEMATIC DIAGRAM ............................................................................................... 24

Summary

Introduction to the Kenwood DM-81 Dip Meter

Inductive Coupling Measurement

Explains how the dip meter's oscillation frequency is absorbed by the circuit at resonance.

Capacitive Coupling Measurement

Describes using a probe to touch the circuit for measurement, a special feature.

Precautions for Using the Dip Meter

Battery Installation and Coil Loading

Instructions for battery installation, checking, and coil loading procedures.

Obtaining an Accurate Dip Point

Guidance on positioning the dip meter for optimal measurement accuracy.

Transmitter Measurement Safety Precautions

Warning about high RF energy and proximity to circuits to prevent damage.

Motor Pointer Deflection Precautions

Explains false dips and how to avoid them by adjusting meter position.

Applications of the Kenwood DM-81

Using the Kenwood DM-81 Dip Meter

Step-by-step guide for using the device as a primary dip meter.

Resonant Circuit Frequency Check

Basic measurement of resonant (tuned) circuits using inductive coupling.

Capacitive Probe Measurements

Using the probe for measurements in narrow or shielded spaces.

Antenna Resonant Frequency Measurement

Measuring antenna resonance using a one-turn coil and the dip meter.

Signal Generator Application

Using the DM-81 to align receivers by generating a signal.

Crystal Checker and Marker Generator

Using crystals with the DM-81 for checking and calibration purposes.

Absorption Frequency Meter Function

Measuring external RF energy and indicating frequency.

Field-Strength Meter Application

Measuring transmit antenna field strength.

Capacitance and Inductance Calculations

Calculating L and C values using resonant frequency measurements.

Adjustment Procedures

Control Adjustments (VR1-VR4)

Details on adjusting bias, meter zero, sensitivity, and battery check controls.

Parts and Service Information

Parts and Service Support

Information for ordering replacement parts and returning equipment for service.

Kenwood DM-81 Specifications

General

Type	Digital Multimeter
Continuity Test	Yes
Diode Test	Yes
Power Supply	9V battery
Display	LCD
Measurement Functions	DC/AC Voltage, DC/AC Current, Resistance, Continuity, Diode
AC Voltage Range	200V, 750V
DC Current Range	200μA to 10A
Resistance Range	200Ω
DC Voltage Range	200mV to 1000V