Equipment information
Kenwood DM-81 Other
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Model:
DM-81
Date:
Category:
Group:
Description:
Dip Meter
Information
A dip meter is used for adjustment of radio equipment and
antennas. The DM-81 is a
self-excited Oscillator designed for external coupling to
the equipment being tested. It
features both inductive and capacitive coupling for
measuring enclosed coils and toroidal
coils (patent pending). This is not possible with
conventional testing instruments.
The DM-81 has the following two functions:
Inductive coupling
As shown (Figure 1A), place the coil unit of the dip meter
in close proximity to
the circuit being measured.
Adjust the dial. When the dip meter oscillation frequency
coincides with the
resonant frequency (tuned circuit), oscillating energy is
absorbed by the circuit,
thus decreasing the oscillation strength.
This strength is indicated on the meter. The pointer swings
back momentarily at
the resonant point. Since the meter pointer dips at a tuned
point, this instrument is
called a dip meter.
Capacitive coupling
This is a special feature of the DM-81 which is not found in
any other dip meter.
The resonant frequency can be checked simply by touching the
capacitance probe
to the hot side of the resonant circuit under test, instead
of coupling the DM-81's
coil and measuring inductively. The frequency is read
directly on the dial. See
Figure 1B.
Radio equipment is miniaturized and most coils are enclosed
in metal shields.
Also, toroidal coils are used in many types of radio
equipment, and these coils do
not couple to conventional dip meters. The DM-81 has solved
this problem.
Manual Type:
Service and User Manual
Pages:
26
Size:
1.12 Mbytes (1179488 Bytes)
Language:
english
Revision:
Manual-ID:
Date:
Quality:
Scanned document, all readable.
Upload date:
2015 05 14
MD5:
63ad82b037592cbdbe756b74ac8055a4
Downloads:
756
Information
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