Motorola R-20010 Maintenance Manual page 435

Table 18-1. Controls, Switches and LEDs on the Front Panel (Cont)
Control, S witch, or LED
Function
OSCILLOSCOPE Controls
Tri ~
Level/ Position CSil a nd RIO)
S! I
Selects automatic or normal t riggering. In automatic mode. the AUTO/ NOR
TRIG SEL output, which goes to the Scope Amplifier board (A2), is - SV. In
this mode, the scope sweep free- runs when there is no triggering. In normal
mode, the AUTO/ NOR TRIG SEL output is pulled
to
+ SV hy a pull-up resistor
on A2, a nd the scope sweep is blanked in the
a h~e nce
of triggering.
H HI
Adjusts the reference (Trig Level) to which the input signal is compared for
scope triggering. The
triggerin~:
circuit
i~
on the Scope/DVM Control board
IA7J.
Huriz ISIO. H9. Hill
S ill
Selects one of si x horizont.al -sweep speed s or ex ternal horizont.al input. When
one of the SWP SEL or EXT HORIZ SEL outputs is high, the correspond in!(
hurizvntal mode has heen selected. These outpu ts are interfaced to processor
control by circuitry on the Front -Panel lnterface hoard.
I{!)
Provides a continuously variable de voltal(e at the SWP VERNIER VOLT
output, which goes to the Scope Ampl ifier hoard , and thus provides a
continuously variable horizontal-sweep speed. When R9 is fully clockwise, the
horiwnt.al-sweep speed is ca librated.
HI!
In external horizontal mode, adjusts the horizontal-input sensitivity over a
range of 0.1 V/ Div to !OV / Di v.
\'en IH141 and Horiz (Rii;)
H1 4
Adjusts the scope's vertica l pnsitim• hy adjusting the
otf~et
in the vertical pre-
amplifier on the
Front - Pa n ~ llnte rfa ce
hoard.
H i t•
Adjusts the scope's horizontal position by
adju~ting
the offset in the horizontal
amplifier on the Scope Amplifier hnard.
Port: \'ert/ Sinad/ Dist/DVM/Counter In -
Most of the basic measurement functions of the S ystem Analyzer can he
Multipurpose Input
performed on signals connected to this purL . The particular measurement he in!(
performed is indicated by the display LEOs.
Pori: Ext Hnriz (External Horizontal Input)
Controls the scope's horizontal sweep in external -horizontal mode. R8 controls
input sensitivity of 0. 1 V /Div to !OV /Div.
MONITOR Controls
Squekh IH71
Controls the de vnltage at the SQUELC H LEVE L output (which goes
to
the
Receiver), and thus controls the RF level below which the Receiver is squelched.
Volurnt>IH!lJ
Controls the volume of the speaker output.
lrna;re/l)plx !S iil - lmal(e/ Duplex Switch
Selects high-side or low-side mix in!( during normal moniwr operation. and
selects high-side or low-side otfset durin!! Duplex operation. During high-side
mix or high-side ,,tfset, Sli is open and the IMAGE Hl/ LO signal is pulled up to
+5V by a resistor on the Front-Panellmerface hoard. During low-side mix or
low-side otfset, St
i
is closed a nd the IMAGE HI/ LO
~i l(nal
is pulled low. The
IMAGE Hl/LO output is interfaced to procesgor control hy circuitry on the
Front-Panel Interface board.
HW (SJ{)) - Handwidth Switch
Controls the generator's FM sensitivity, the Receiver's demodulation sensitivity,
and audio filters in the Receiver. In wide band mode, SIS is open, and the WB/
NB output is pulled up to + 5V by a resistor on the Front-Panel Interface board.
In narrowband mode, S I S is closed , and the WB/ NB output is pulled low. The
WB/ NB output is interfaced to processor control hy circuitry on the Front -
Panel Interface board.
BF'OtH I!!l Controls the d e voltage at the BFO FREQ CNTL output, and thus controls the
frequency of the varacwr-tuned BFO on the Receiver board.
Port: l>t mod Ou1 In monitor mode, the Receiver's demodulation output comes out of this port. In
FM, the out.put level is 1 vol t-peak per k Hz of peak deviation in narrowband,
and I volt-peak per 10kHz of peak deviation in widehand. In AM , the output
level is a nominal I volt-peak per 10 percent AM .
18-2