Agilent Technologies 856290216 service manual If Signature, KHz

The assembly contains a reference limiting amplifier. This amplifier provides a known amount of limiting for the automatic IF adjustment routines. (Limiting occurs only during the automatic IF adjustment routines.) The LC34Short switches are open during sweeps. The current in the reference limiter is increased during sweeps to prevent limiting.

Caution	For troubleshooting, it is recommended that you use an active probe, such as
	an HP 85024A, and another spectrum analyzer. If an HP 1120A active probe
	is being used with a spectrum analyzer having dc-coupled inputs, such as the
	HP 8566A/B, HP 8569A/B and the HP 8562A/B, either set the active probe
	for an ac-coupled output or use a dc-blocking capacitor between the active
	probe and the spectrum analyzer input.
Caution	n Do not short control voltages to ground. These voltages are not short-circuit
	protected. DACs damaged by shorting these voltages might not fail until
	several weeks after the shorting takes place.
	w Do not short power-supply voltages to ground. The HP 85623 spectrum
	analyzer power-supply current limiting cannot protect the resistors in series
	with the power supply.
Note	Some transistors have collectors connected to the case. Electrical connection
	of the case to the collector might not be reliable, making collector voltage
	measurements on the transistor case unreliable.

IF Signature

1.Disconnect W27 (coax 3) from A5J5.

2.Connect an SMB tee to A5J5, using a short coaxial cable with SMB connectors.

3.Connect one output of the tee to cable W27 (coax 3).

4.Connect an HP 85024A active probe, with a 1O:l divider installed, to the other output of the tee.

5.Connect the output (type N connector) of the active probe to the input of the HP 8566A/B spectrum analyzer.

6.Connect the probe power cable to the HP 85623 spectrum analyzer front-panel PROBE POWER connector (you may need to use a probe power extension cable, HP 10131B).

7.Set the HP 8566A/B controls as follows:

Reference level	+lO dBm
Center frequency	10.7 MHz
Span	. . . . 0 Hz
Resolution bandwidth . . ..*	300 kHz
Videobandwidth	. 300kHz
Sweep time	. ..5.5s
Trigger	. . Single

8.On the HP 8566A/B, press @K] (trace A blank) to set detector to SAMPLE mode.

9.On the HP 85623 spectrum analyzer, press [m) and set the controls as follows:

9-22 IF Section