Rohde & Schwarz ZVB 14, Service Manual

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Instrument Construction and Function Description R&S ZVB
1145.1078.82 3.12 E-4
Receiver
The receiver section has two channels (measurement channel and reference channel) and uses single
conversion. Every channel contains a buffer amplifier, two mixers for each of the frequency ranges 300
kHz to 4 GHz and 4 GHz to 8 GHz (R&S ZVB8 only) with LO amplifiers and an IF amplifier. In the
mixer, the input signal is directly converted to the IF range, approx 15 to 21 MHz. The inputs are
protected by limiter diodes.
Reflectometer Unit R&S ZVB14/20
A reflectometer unit comprising a coupler unit , a generator section (Generator) and a receiver
section (Receiver) are incorporated in every port (Port1 to 4). The Generator and the Receiver are
screwed together to form a compact unit.
Coupler unit
The coupler unit contains a bias-T and two directional couplers. One coupler is used to separate the
signal going to the DUT from the signal coming from the DUT. The reference signal (= measure of the
signal to the DUT) is obtained from the second coupler. The reference signal provides a reference for
relative measurements.
Generator
The generator contains a frequency doubler for the range 8 GHz to 16 GHz, a switchable filter unit, a
second frequency doubler with filter for the range 16 GHz to 20 GHz and a broadband amplifier for the
frequency range 10 MHz to 20 GHz with two adjustable attenuators to keep the output level constant
and to attenuate it electronically.
Range Basic frequency range
from synthesizer
Doubler 1 Frequency Doubler 2 Output frequency
1 10 MHz to 8.0 GHz --- 10 MHz to 8.0 GHz --- 10 MHz to 8.0 GHz
2 4 GHz to 5.05 GHz x 8.0 GHz to 10.1 GHz --- 8.0 GHz to 10.1 GHz
3 5.05 GHz to 6.35 GHz x 10.1 GHz to 12.7 GHz --- 10.1 GHz to 12.7 GHz
4 6.35 GHz to 8.0 GHz x 12.7 GHz to 16.0 GHz --- 12.7 GHz to 16.0 GHz
5 4.0 GHz to 5.0 GHz x 8.0 GHz to 10.0 GHz x 16.0 GHz to 20 GHz
Receiver
The receiver section has two channels (measurement channel and reference channel) and uses single
conversion. The measurement channel contains a buffer amplifier, two mixers for each of the frequency
ranges 10 MHz to 2.5 GHz and 2.5 GHz to 20 GHz, LO amplifiers and an IF amplifier. The reference
channel is equal to the measurement channel without the buffer amplifier. In the mixers, the input signal
is directly converted to the IF range, approx 15 to 21 MHz. The mixers are used as basic wave mixers
in the range 10 MHz to 8 GHz, in the upper range harmonic mixing is used ( IF = 3LO – RF).
Each of the reflectometers contains a voltage controlled fan to perform optimum cooling.