A107
GATE GENERATOR
(20201
97)
This assembly performs the following functions.
Reference Oscillator Control
Gate Generation
Band 3 Amplitude Determination
Power Meter Control (Option 02 only)
REFERENCE OSCILLATOR CONTROL
This circuit selects,
as
the time base for the counter, either the internal reference oscillator or an external
10 MHz signal applied to the rear panel. This circuit provides
a
100 kHz TTL level clock signal for the gate
generator,
a
10 MHz TTL level clock signal for the microwave converter and, in the internal oscillator mode,
a
10 MHz signal (1 volt p-p into 50 ohms) to the rear panel.
The 10 MHz internal reference signal
is
applied to
a
switchable "analog to TTL" converter (01, 02, 03).
When the Ref
IntIExt line is high the TTL converter is enabled. One output goes to drive 04, giving
a
square wave (1V p-p into 50 ohms) on the 10 MHz Ref line. A second output goes to NAND gate U1 (also
switchable for signal isolation. The output of
U1 goes to
J3
to be used by the microwave converter. The
output of
U1 also goes to the clock input of U2. U2 is
a
dual decade divider that divides by 100. The
output of U2
is
a
100 kHz TTL clock signal to the gate generator.
When the Reference
IntIExt line
is
set to external (low) the TTL converter (01,.02; 03) and driver (04)
are disabled, TTL converter
(05, 06, 07)
is
enabled, and U1
is
set to select the external input. An external
reference signal applied to the 10 MHz reference line
is
then converted to the input of U2.
Scans by ArtekMedia © 2007
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