than is available from the coarse loop alone. For ap-
plications requiring a resolution finer than 1 kHz,
an optional tuning resolution of 0.1 Hz is available.
The Coarse Loop and Fine Loop outputs are derived
from high-stability 10 MHz and 100 MHz signals
generated by the Reference Loop. For applications
requiring even greater stability, the 100 MHz refer-
ence oscillator can be phase locked to an optional
10 MHz reference (internal or external).
RF Outputs
0.00001 to
65 GHz
Refer to the block diagram of the RF Deck shown in
Figure 2-1 (page 2-7) for the following description.
The 690XXB/691XXB uses one YIG-tuned oscillator.
All other frequencies output by the instrument, ex-
cept for 0.01 to 10 MHz, are derived from the funda-
mental frequencies generated by this YIG-tuned
oscillator.
0.01 to 2 GHz
RF output frequencies of 0.01 to 2 GHz are devel-
oped by down converting the fundamental frequen-
cies of 6.51 to 8.5 GHz. This is achieved using a
6.5 GHz local oscillator signal that is phase locked
to the 500 MHz output of the Reference Loop. Pre-
cise control of the 0.01 to 2 GHz frequencies to
1 kHz (0.1 Hz with Option 11) resolution is accom-
plished by phase-lock control of the 6.51 to 8.5 GHz
fundamental frequencies prior to down conversion.
20 to 40 GHz
RF output frequencies of 20 to 40 GHz are produced
by doubling the 10 to 20 GHz fundamental frequen-
cies. Phase-lock control of the 10 to 20 GHz funda-
mental frequencies, accomplished prior to doubling,
ensures precise control of the 20 to 40 GHz frequen-
cies to 1 kHz (0.1 Hz with Option 11) resolution.
40 to 65 GHz
RF output frequencies of 40 to 65 GHz are devel-
oped by quadrupling of the 10 to 16.25 GHz funda-
mental frequencies (refer to Figure 2-7, page 2-24).
Precise control of the 40 to 65 GHz to 1 kHz (0.1 Hz
with Option 11) resolution is accomplished by
phase-lock control of the 10 to 16.25 GHz fundamen-
tal frequencies prior to quadrupling.
0.01 to 2.2 GHz (Option 21A)
RF output frequencies of 0.01 to 2.2 GHz are devel-
oped by down converting the fundamental frequen-
690XXB/691XXB MM
2-13
FUNCTIONAL
FREQUENCY
DESCRIPTION
SYNTHESIS
Summary of Contents for 680 C Series
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