A7
Pulse Generator
A step recovery diode in the pulse generator produces a comb of harmonic
multiples of the VCO output. These harmonics provide the high band LO (local
oscillator) input to the samplers. In low band and super low band the operation
the pulse generator is turned off.
All Phase Lock
This assembly compares the
f&t
IF (derived from the source output in the
A4 sampler) to a stable reference, and generates an error voltage that is
integrated into the drive for the A3 source assembly.
A3 Source
This assembly includes a 3.0 to 6.8
GHz
YIG oscillator and a 3.8
GHz
cavity
oscillator. The outputs of these oscillators are mixed to produce the RF output
signal. In Option 006 (30
kHz
to 6
GHz)
the frequencies 3.0 to 6.0
GHz
are no
longer a mixed product, but are the direct output of the YIG Oscillator. The
signal tracks the stable output of the synthesizer. The ALC (automatic leveling
control) circuitry is also in the
A3
assembly.
Source Super Low Band Operation
The Super Low Band Frequency Range is 10
kHz
to 300
kHz.
These frequencies
are generated by the
Al2
Reference Board. They are the
amplified
output of
the fractional-N synthesizer. This output is not phase locked and is not subject
to ALC control. Refer to
‘lhble
12-1.
‘able
12-1. Super Low Band
Subsweep
Frequencies
I
4o.oto43.3
~0.010to
0.300
~0.010to
0.300
I
Theory of Operation
12-15
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