Filter
Top Products
Theory of Operation
3-12
2715 Spectrum Analyzer Service Manual
RF Mother Board and Phase Locked 2nd LO
This section contains a detailed description of the RF Mother board and P hase
Locked 2nd Local Oscillator.
The RF Mother board converts the 1st IF frequency to 10 MHz in two frequency
conversions. The first conversion (2nd mixer) mixes the 2.11 GHz 1st IF with
the 2 GHz 2nd LO to create a 110 MHz second IF. The 2 GHz LO is generated
on the board and is phase locked to the 100 MHz crystal reference. The 110 MHz
2nd IF is amplified (with variable gain) and filtered by a 5 MHz bandpass filter.
A portion of the 2nd IF signal is sent to the sweep board for use by the satellite
demodulator. The 3rd conversion mixes the 2nd IF with the 100 MHz reference
to produce the 3rd IF frequency of 10 MHz. This signal is amplified and sent to
the variable resolution module.
This section provides a block diagram description of the RF Mother board as
illustrated in F igure 3--5.
IL
R
100 MHz
2110 MHz IF
10 MHz IF
BPF
PIN
I
L
R
110 MHz
Sample
Figure 3- 5: Block Diagram of RF Mother Board
The RF Mother board converts the 1st IF frequency (2.11 GHz) down to
110 MHz by mixing it with a 2 GHz LO. This LO is created by phase locking a
VCO to the 100MHz reference frequency. This reference is provided by the
Reference Oscillator module.
Overview
RF Mother Board
Block Diagram