Figure 17. Intermodulation distortion products.

TB 9-6625-1914-35

(6) Carefully adjust amplitudes of function generator and signal generator so that

both signal peaks are 3 dB below LOG REF graticule on display screen. The signals at

140 kHz (2f1) and 180 kHz (2f2) (fig. 17) are second order harmonics. Any second order

intermodulation product (due to analyzer) will occur at 160 kHz (f1 + f2). Any third

order intermodulation products will occur at 50 kHz (2f1-f2) and at 110 kHz (2f2-f1). The

intermodulation products should be below -70 dB graticule line.

(7) Repeat technique of (4) through (6) above with function generator at a frequency

of 1.7 kHz and signal generator at a frequency of 2 kHz.

(8) Position SCAN WIDTH PER DIVISION switch to 500 Hz and BANDWIDTH

switch to 30 Hz for model 8552B or 50 Hz for model 8552A. Set SCAN WIDTH to 0-

10f.

NOTE

It may be necessary to tune ZERO ADJ control until local

oscillator feed-through is centered at far left graticule line.

(9) Adjust function generator and signal generator controls to set both signal peaks

3 dB below LOG REF graticule on display screen. The signals at 3.4 kHz (2f1) and 4.0

kHz (2f2) are second order harmonics (fig. 17). Any second order intermodulation

product (due to analyzer) will occur at 3.7 kHz (2f1-f2). Any third order intermodulation

product will occur at 1.4 kHz (2f1-f2) and at 2.3 kHz (2f2-f1). All intermodulation

products should be below -60 dB graticule line.

b. Adjustments. No adjustments can be made.

Figure 17. Intermodulation distortion products.