RADIOMETER AFM 3, Manual

Page: 16 / 107

D4
Fig. D2. Front plate of the Modulation Meter, type AFM3.
peak can be measured. The AF detector
has two time constants, thereby furnish­
ing two meter responses.
The AF detector is followed by an im­
pedance-matching network providing for
low output impedance to the meter.
CONTROLS, METER AND TERMINALS
General
As can be seen in Figs.D2 and D4, the
Modu lotion Meter, type AFM3, is pro­
vided with the following controls, meter,
and terminals:
Controls, Meter, and Front Plate Ter­
minals (see Fig. D2)
Power Lamp and ON switch (1)
The power switch ON is a toggle switch
monitored by the lamp POWER.
RANGE Selector and Drum Scale (2)
The selector RANGE is an eight-posi­
tion rotary switch. In the first six po­
sitions, the RANG_E selector provides
for selection of the frequency ranges
according to the table printed on the
front plate of the instrument. (Note
that the ranges E and F each cover two
frequency bands.} The next position is
a rest position. In the last position, the
plug-in Crystal Oscillator Unit (if any}
is connected. The selector RANGE is
monitored by the drum scale immediate­
ly above.
TUNING Knob (3)
The knob TUNING provides for adjust•
ment of the local esci II a tor frequency
at
1
MHz from the signal frequency. It
is monitored by a cursor on the drum
scale.
LEVEL Potentiometer (4) and MAN.­
AUTO. Switch
(5)
The potentiometer LEVEL has two func­
tions according to the position of the
switch MAN.-AUTO.
When the switch MAN.-AUTO.
IS In
position MAN., the LEVEL potentiom­
eter is used to vary the sensitivity of
the instrument manually within a range
of min. 40 dB.
When the switch MAN.-AUTO. is in
position AUTO., the LEVEL potentiom­
eter is used for fine-adjustment of the
automatically adjusted sensitivity of the
instrument.