18. Gain Compression
OUTPUT LEVEL RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . -20
Care should be taken to disturb the cable assembly as little as possible,
since flexing may cause a change in the measured power level. The
power sensor should be placed near the spectrum analyzer input to
minimize flexing when the cable is moved.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Connect equipment as shown in Figure 2-32, with output of
synthesizer connected to power sensor. Power is measured at
the end of the cable assembly, not at the synthesizer output
connector. Adjust synthesizer output level for a power meter
indication of -25.00
f0.05
Disconnect cable assembly from power sensor and connect free
end to spectrum analyzer RF INPUT as indicated in Figure 2-32.
Key in analyzer settings as follows:
2
. . .
. . . 30 Hz
. . . 3 MHz
Press the SCALE LIN pushbutton, then press (SHIFT)
to obtain amplitude readouts in
Turn the AMPTD
CAL control fully clockwise.
Press MARKER (NORMAL)
Connect cable to power sensor and adjust synthesizer output level
for a power meter reading of -15.00
Reconnect cable to the spectrum analyzer RF INPUT.
Change spectrum analyzer
[
REFERENCE LEVEL
)
to -5
Record the MKR A amplitude:
This is the IF
gain error in changing the reference level from -15
to -5
with
0
input attenuation.
Set
[
REFERENCE LEVEL
)
to -15
Adjust AMPTD CAL to place
the signal trace approximately 1 division down from the reference
level line.
Press MARKER
Connect cable to power sensor and adjust synthesizer output level
for a power meter indication of -5
f0.02
Reconnect
cable to spectrum analyzer input.
Change
[
REFERENCE LEVEL
)
to -5
Record the MKR A amplitude:
Subtract the value obtained in step 9 from the value recorded
in step 13 to find the gain compression:
The
result should be
(less than 1
compression).
Press
on the spectrum analyzer. Press (SHIFT)
[SHIFT)
0
2-76 Performance Tests
