HP 8340B Manual page 181

Figure
D-3. A46 7.0 GHz
Low Pass Filter Assembly
Drawing
A47 Sense Resistor Assembly Theory of Operation
The A47 sense
resistor
assembly contains the high power
portions of both the ASS YO driver and the
A28 SYTM
driver. The A28 assembly
is discussed
in
the RF Section.
Many components
on
the A47 sense resistor assembly are part of
the
A55 YO
driver voltage-to-
current converter. These components are mounted
on
the A47 assembly (which
is
a
heat
sink) for
proper heat dissipation.
A48 YO Loop Sampler Theory of Operation
The A48 YO
Loop Sampler mixes the output of the
A44 YIG
oscillator (via the
A45
directional coupler,
AT2
15 dB attenuator and A46
7 GHZ low pass filter) with the Nth harmonic
of the output of the
M/N
Loop.
The sampler
IF
output
is
a
20 to 30
MHz
difference signal that is
output to
the A49 YO loop
phase detector.
A49 YO Loop Phase Detector Theory of Operation
Sampler
IF
signal (from the A48
YO loop sampler) and the 20-30 MHz signal (from the A36 PLL1 VCO)
are
inputs to
the A49 YO loop phase detector assembly. These signals
are
phase-compared and the
result
is
integrated to produce the following
signals:
•
YOTUNE
•
FM
Coil
Drive
•
High Unlock YO (HULY)
HP 8340B/41B
Sweep Generator
-
YO
Loop Theory of Operation D-ll