Agilent Technologies 856290216 service manual Assemblies Adjusted, Related Performance Tests

Front End Cal (YIG-Tuned Filter/Mixer (RYTHM) and Frequency Response Adjustment)

Assemblies Adjusted

Al4 Frequency Control Assembly

Al5 RF Assembly

A10 RYTHM

Related Performance Tests

Displayed Average Noise Level

Frequency Response

Image, Multiple, and Out-of-Band Responses

Second Harmonic Distortion

Description

Front End Cal is an automated adjustment that performs the equivalent of two manual adjustment procedures, Frequency Response Adjustment, and YIG-Tuned Filter/Mixer

( R Y T H M )a dusj tment. The RYTHM adjustment is performed first, followed by the frequency response adjustment.

The RYTHM adjustment optimizes the settings of the offset and slope DACs on the Al4 Frequency Control assembly for maximum amplitude response. The offset DAC value is optimized at a low frequency and the slope DAC value is optimized at a high frequency.

The frequency response adjustment consists of applying a signal of known amplitude at several different frequencies to the specturm analyzer. At each frequency, the RF GAIN DAC co&rolling the flatness compensation amplifiers is adjusted to place the displayed signal at the same place on screen. When tuned to a frequency in a preselected band, the preselector is centered before adjusting the RF GAIN DAC.

After both adjustments are done, the preselector slope and offset DAC values, the RF GAIN DAC values, and the preselector peak DAC values are stored in EEROM.

Note	Front End Cal refers to the HP 8481A or 8485A power sensor as the “Channel
	B Power Sensor,” even if a single-channel power meter (such as an HP 436A or
	8902A) is being used.
	If	an HP	8485A Power Sensor is used, it must have a calibration factor at
	10	MHz.	Standard HP 8485As have calibration factors down to only 50 MHz.

3-14 Frequency Response Adjustment Software