Agilent Technologies E8285A Manual page 30

Introduction
Product Description
RF Analysis
RF signals connected to the front panel RF IN/OUT connector or
ANTENNA IN connector go to the RF I/O module. The signal level and
RF frequency are measured, and the level is adjusted using fixed step
and variable attenuators in the separate downconverter module.
Over-Power Damage
CAUTION
The ANTENNA IN connector is only used for very low level signals
(60 mW or less), and cannot be used for Transmitter (TX) Power
measurements. Exceeding this limit may destroy the RF I/O module.
The RF IN/OUT connector is used to measure direct mobile transmitter
power up to 2.5 Watts continuous.
The downconverter mixes the input signal with a local oscillator signal
from the Receiver Synthesizer assembly to produce a 114.3 MHz, 614.3,
or 385.7 MHz IF signal (depending on the frequency of the received
signal). The signal goes through a bandpass filter and then on to the
Receiver assembly.
If the IF is 614.3 or 385.7 MHz, the Receiver assembly mixes the signal
with a 500 MHz local oscillator (LO) signal from the Reference
assembly to obtain the 114.3 MHz IF. If the IF is 114.3 MHz, the signal
bypasses this downconversion. The 114.3 MHz signal divides into two
paths.
Figure 1-3 Received Signal Downconversion
RF I/O
RF IN/OUT
Power
Detector
ANTENNA
IN
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Downconverter
1200-1700 MHz from
Receiver Synthesizer
Assembly
385.7 MHz
114.3 MHz
486-1026 MHz from
614.3 MHz
Receiver Synthesizer
Assembly
Receiver Assembly
114.3 MHz
AM, FM, SSB
Demodulation
500 MHz from
Reference Assy
114.3 MHz
To LO/IF Demod Assembly