Section VII
TM 11-6625-2781-14&P-2
PERFORMANCE TESTS (cont'd)
7-10. Spurious Responses (cont'd)
Signal Generators
Signal Generator No 1 (606B) FREQUENCY ........................................................................................... 9 950 MHz
Signal Generator No 2 (608F) FREQUENCY ................................................................................................10 MHz
AMPLITUDE ................................................................................................................................................-30 dBm
2. Adjust the signal generator output attenuators and verniers so the signal amplitude reaches 3 dB below the top
graticule line. Use as much attenuation as possible to reduce intermodulation distortion caused by signal
generator interaction prior to application to the mixer.
3. Combine the signals as shown in Figure 4-12 and apply them to the analyzer.
4. Tune the analyzer to 50 kHz and check' for a second-order intermodulation product. Another second-order
product will appear at 19.950 MHz.
50 kHz
-100 dBm
19.950 MHz
-100 dBm
5. Tune the analyzer to 10.050 MHz and check for third-order IM. Third-order products also occur at the following
frequencies: 9.900 MHz, 29.950 MHz, 29.900 MHz.
10.050 MHz
-100 dBm
NOTE
Signal generators exhibit harmonic distortion, typically about 35 dB below fundamental level.
Harmonic distortion will occur at multiples of 9.950 and 10 MHz. Care must be taken not to
confuse harmonic distortion produced by the source with intermodulation distortion produced
by the input mixer.
7-11. Residual Responses
SPECIFICATION: (Referred to signal level at input mixer*)
200 kHz to 110 MHz: <-100 dBm
20 kHz to 200 kHz: < --85 dBm
*Signal level at input mixer = Signal level at RF INPUT - (INPUT ATTENUATION +10 dB).
DESCRIPTION:
Signals present on the display with no input are called residual responses. To measure residual responses, select a
reference so that -100 dBm is easily determined. Carefully search the display for residual responses under the various
test conditions called out.
1. Set the analyzer controls as follows:
RANGE MHz ................................................................................................................................................... 0-110
FREQUENCY ............................................................................................................................................... 60 MHz
FINE TUNE.................................................................................................................................................Centered
BANDWIDTH ................................................................................................................................................... 1 kHz
INPUT ATTENUATION ........................................................................................................................................... 0
SCAN WIDTH ....................................................................................................................................PER DIVISION
7-4
