Section VII
TM 11-6625-2781-14&P-2
PERFORMANCE TESTS (cont'd)
7-10. Spurious Responses
SPECIFICATION: Spurious Responses: For -30 dBm signal level to the input mixer* : image responses, out-of-band
mixing responses, harmonics and intermodulation distortion products, and IF feedthrough responses all more than 70 dB
below the input signal level (2 MHz to 110 MHz); 60 dB, 1 kHz to 2 MHz.
Third Order Intermodulation Products: For -30 dBm signal level at input mixer*, more than 70 dB down for input signals
of 100 kHz to 110 MHz.
*Signal level at input mixer = Signal level at RF INPUT (INPUT ATTENUATION + 10 dB)
DESCRIPTION: The outputs of two signal generators tuned within 50 kHz of one another are applied to the spectrum
analyzer RF input. Their levels are adjusted (-33 dBm each) to -30 dBm total power at the analyzer input mixer. No
responses other than the signals from the signal generators and the spectrum analyzer's 1st LO feedthrough (at zero
frequency) should be present on the CRT within 70 dB of these signal levels. This corresponds to a level of -100 dBm.
Figure 7-2. Intermodulation Distortion Test.
EQUIPMENT:
Signal Generator......................................................................................................................................... HP 606B
Signal Generator......................................................................................................................................... HP 608F
Cable Assembly (2) ................................................................................................................................. HP 10503A
BNC Tee................................................................................................................................................. UG-274B/U
1. Connect the test setup shown in Figure 7-2 and make the following control settings:
Analyzer:
RANGE- MHz ................................................................................................................................................ 0 - 110
BANDWIDTH ................................................................................................................................................... 1 kHz
SCAN WIDTH ...........................................................................................................................................20 kHz/div
FREQUENCY ................................................................................................................................... (see procedure)
INPUT ATTENUATION ...................................................................................................................................... dBm
SCAN TIME PER DIVISION........................................................................................................ 2 MILLISECONDS
LOG REF LEVEL......................................................................................................................................... -30 dBm
TUNING STABILIZER.......................................................................................................................................... ON
VIDEO FILTER .................................................................................................................................................. OFF
SCAN MODE.......................................................................................................................................................INT
SCAN TRIGGER ............................................................................................................................................ AUTO
7-3
