
Source Low Band Operation
The low band frequency range is 300
to 16 MHz. These frequencies are
generated by locking the source to a reference signal. The reference signal
is synthesized by mixing down the fundamental output of the fractional-N
with a 40 MHz crystal reference signal. Low band operation differs from high
band in these respects: The reference frequency for the All phase lock is not
a
1 MHz signal, but varies with the frequency of the fractional-N
signal. The sampler diodes are biased on to pass the signal through to the mixer.
The IF signal from the sampler is not fixed but is identical to the source
output signal and sweeps with it. The following steps outline the low band
sweep sequence, illustrated in Figure 12-4.
1. A
LO)
is generated by the fractional-N VCO. The
VCO in the
assembly generates a
CW
or swept signal that is 40 MHz
greater than the start frequency. The signal is divided down to 100
and
phase locked in the
assembly, as in high band operation.
2. The fractional-N VCO
is mixed with 40
to produce a
reference
signal. The signal
LO) from the Fractional-N VCO goes to the
reference assembly, where it is mixed with the 40 MHz VCXO (voltage
controlled crystal oscillator). The resulting signal is the reference to the
phase comparator in the All assembly.
3. The
source is pretuned. The source output is fed to the
sampler.
The pretuned DAC in the All phase lock assembly sets the source to a
frequency 1 to 6 MHz above the start frequency. This signal (source output)
goes to the R input sampler/mixer assembly.
4. The
from the source is fed back
IF’) to the phase comparator.
The source output signal passes directly through the sampler in the
assembly, because the sampler is biased on. The signal
is fed back
unaltered to the phase comparator in the All phase lock assembly. The other
input to the phase comparator is the heterodyned reference signal from the
assembly. Any frequency difference between these two signals produces
a proportional error voltage.
5.
A tuning signal
DRIVE)
the source
and
lock is achieved.
The error voltage is used to drive the source YIG oscillator to bring the
YIG closer to the reference frequency. The loop process continues until the
source frequency and the reference frequency are the same, and phase lock
is achieved.
12-16 Theory of Operation
Содержание HP 8753E
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Страница 289: ...Digital Control Group Block Diagram Figure 6 1 Digital Control Group Block Diagram 6 2 Digital Control Troubleshooting ...
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Страница 350: ...START 030 000 MHZ Figure 8 2 Typical Good Trace Receiver Troubleshooting 8 5 ...
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Страница 451: ...L _ I 7 _ IT J sg6107e Pie 12 3 Digital Control Group Simplified Block Diagram Theory of Operation 12 9 ...
Страница 479: ...Major Assemblies hp A10 A8 All A12 A15 A20 A4 sg654e Al3 Al4 Replaceable Parts 13 7 ...
Страница 481: ...Major Assemblies Bottom CPU Fan A24 Ai A23 A21 A9BTl sg6126e Replaceable Parts 13 8 ...
Страница 483: ...Cables lbp w4 w3 w2 w5 W6 w7 W26 WI2 WI1 WI0 w9 W8 sg656e Replaceable Parts 13 11 ...
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Страница 487: ...hbles Front w22 W23 I AIWI RPGIWI sg658e ReplaceableParts 13 15 ...
Страница 489: ...Cables Rear W36 w21 i w35 w30 sg6113e ReplaceableParts 13 17 ...
Страница 491: ...Cables Source A3A4Wl I A3W3 A3W4 BACK FRONT sg662e Replaceable Parts 13 l 9 ...
Страница 493: ...Front Panel Assembly Outside sg663e ReplaceablsParts 13 21 ...
Страница 495: ...Front Panel Assembly Inside 4 P l a c e s 4 P l a c e s 2 P l a c e s WI7 sg6122e Replaceable Partr 13 23 ...
Страница 497: ...Rear Panel Assembly 8 Places 9 15 0 13 es P A R T O F F A N sg665e ReplaceableParts 13 25 ...
Страница 499: ...Rear Panel Assembly Option lD5 sg666e Replawable Parts 13 27 ...
Страница 503: ... L P l a c e s 3 Places 6 2 PLacesI x 5 3 Places 3 P l a c e s sgbb0e Replaceable Parts 13 3 1 ...
Страница 505: ...Hardware Front sg669e I2 P l a c e s Replaceable Parts 1333 ...
Страница 507: ...Hardware l t Set Deck 5 P l a c e s 8 P l a c e s I A 2 P l a c e s sg670e Replaceable Partr 13 35 ...
Страница 509: ...Hardware Disk Drive Support 4 P l a c e s Q G 4 P l a c e s Replaceable Parts 13 37 ...
Страница 511: ...Replaceable Partr 1339 ...
Страница 513: ...Hardware Preregulator Al5 IL sg673e ReplaceableParts 1341 ...
Страница 517: ...Chassis Parts Inside 16 Places sg675e ReplaceableParts 1345 ...
Страница 527: ...Covers sg677e Assambly Replacement and Post Repair Procedures 14 7 ...
Страница 529: ...Front Pctnel Assembly Asssmbly Replacement and Post Repair Procedures 14 9 ...
Страница 531: ...Front Panel Keyboard and Interface Assemblies sg680e Assambly Replasement andPost RepairProcedures 14 l1 ...
Страница 534: ...Display Iamp and hverter Assemblies 3 Places shg6113e 14 14 mmbly Replacement and Post RepairProcedures ...
Страница 537: ...Rear Panel Assembly 14 18 Assembly Replacement and Post Repair Procedures ...
Страница 539: ...Rear Panel Interface Board Assembly 7 2 Opt ID5 only only sg604e Asssmbly Replasement and Post Repair Procedures 14 21 ...
Страница 541: ...W26 w1 W2L A3 Source Assembly A3 AwnMy Replacclment sad Post Repair Procedures 14 23 ...
Страница 549: ...A9 CPU Board w37 w20 sg6112e Assembly Replacement and Post Repair Procedures 14 33 ...
Страница 550: ...A9 CPU Board I VII c A9 sg690e 14 34 Assembly Replasemeat and Post Repair Procedures ...
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Страница 554: ...Al5 Preregulator A8J2 I b 2 3 Places Al5 A17J3 2 Placed sg692e Assembly Replacement and Post Repair Procedures 1448 ...
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Страница 576: ...Bl Fhn Assembly 4 PLACES hg628d Assembly Replacement and Pest Repair Procedures 14 61 ...