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RF Deck Con
-
figurations
All 682XXB/683XXB RF deck assemblies contain a 2
to 20 GHz YIG-tuned oscillator, a switched filter as
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sembly, and a directional coupler. Beyond that, the
configuration of the RF deck assembly varies accord
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ing to the particular instrument model. Block dia
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grams of the various RF deck configurations are
shown in the following figures:
Figure 2-4, page 2-21, is a block diagram of the
RF deck assembly for all £40 GHz models ex
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cept for 682X5B/683X5B models.
Figure 2-5, page 2-22, is a block diagram of the
RF deck assembly for all >40 GHz models ex
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cept for 682X5B/683X5B models.
Figure 2-6, page 2-27, is a block diagram of the
RF deck assembly for all £40 GHz 682X5B/
683X5B models.
Figure 2-7, page 2-28, is a block diagram of the
RF deck assembly for all >40 GHz 682X5B/
683X5B models.
The block diagram of the RF deck shown in Figure
2-4 (page 2-21) includes all of the common RF com-
ponents found in the 682XXB/683XXB RF deck as-
semblies. Refer to this block diagram during the
descriptions of RF deck operation presented in the
following paragraphs.
YIG-tuned
Oscillator
The 2 to 20 GHz YIG-tuned oscillator actually con
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tains two oscillators—one covering the frequency
range of 2 to 8.4 GHz and one covering the fre
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quency range of 8.4 to 20 GHz. Both oscillators use
a common internal amplifier.
The YIG-tuned oscillator generates RF output sig
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nals that have low broadband noise and low spuri
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ous content. It is driven by the Main tuning coil
current and bias voltages from the A13 YIG Driver
PCB and the FM tuning coil current from the A11
FM PCB. During CW mode, the main tuning coil
current tunes the oscillator to within a few mega
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hertz of the final output frequency. The phase-lock
circuitry of the YIG loop then fine adjusts the oscil
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lator’s FM tuning coil current to make the output
frequency exact. Frequency modulation of the RF
output is also accomplished by summing the modu
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lating signal into the oscillator’s FM tuning coil con
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trol path.
2-20 682XXB/683XXB MM
FUNCTIONAL RF DECK
DESCRIPTION ASSEMBLIES