Motorola R-20010 Maintenance Manual page 35

2.1 1.2 VERTICAL INPUT
One of four possi ble signals can be switched to the
vertical amplifier's input by a select switch on the
Scope/DVM Control board. The 700-kHz IF and SPEC
ANA VERT signals from the Receiver hoard provide
the displays for IF envelope and spectrum analyzer,
respectively. T he vertical character-sweep ge nerator
provides the vertical sweep for the raster -scan char-
acter display. The remaining input (VERT FROM
RNG SW) is connected either to the front panel's
external vertical input or to the modulation-scope
input (INT SCOPE TO RNG SW).
A vertical pre-amplifier on the Front-P anel Inter-
face board gives a vertical sensitivity of 10m V /Div and
provides positioning and vernier-gain capability for its
input. This amplifier provides the VERT FROM RNG
SEL output to the A 7 board.
It
is preceded by a four-
decade range attenuator which is controlled from the
front panel's vertical switch through the processor. The
attenuator provides external vertical-input sensitivi-
ties from 0.01 to 1.0 V /Div and modulation-scope sen-
sitivities from 0.25 to 25 kHz/Div.
A select switch ahead of the attenuator chooses
between the external ve rtical input or the modula-
tion -scope inputs. Further switching selects ac or de
coupling for the external input. The modulation-scope
signal path is switched to one of three possible sources
on the Scope/DVM Control board. Demodulation sig-
nals from the Receiver are selected via the DEMOD
CAL AUDIO path. FM signals are selected via the
MOD CAL AUDIO signal pat h; AM signals a re
selected via the CARRIE R + MOD LVL signal paths.
The Audio Synthesizer board provides the MOD CAL
AUDIO signal, while t he RF Input module provides the
CARRIER + MOD LVLsignal.
A Z-Axis select circuit on the Scope/DVM Control
board gates either the CHARACTER GEN signal for
character displays or the retrace blanki ng signal from
the time base generator fo r scope displays to the Z-Axis
modulator on the Scope Amplifier board.
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