Check The Vco (A14) Range With Oscilloscope; Substituting Tuning Voltages To Check The Vco - Agilent Technologies 8719ET Service Manual

Source Troubleshooting
Broadband Phase Lock Problems

Check the VCO (A14) Range with Oscilloscope

1. Connect an oscilloscope to A14TP1 (labeled VCO/2, yellow tabs- rear multi pin
connector).
2. Press the following:
PRESET: FACTORY
Preset
SERVICE MENU
System
3. Vary the fractional-N VCO frequency with the front panel knob.
4. If the waveforms do not resemble
(The amplitude of the waveforms will vary from 3V to 10V p-p.)
Figure 7-3 VCO/2 Waveforms at A14TP1

Substituting Tuning Voltages to Check the VCO

The tuning voltage range of the VCO is approximately +1 to +14 volts. This procedure
substitutes power supplies for the normal voltages from A13 to check the frequency range
of the A14 VCO.
1. Turn off the analyzer.
2. Remove the A13 assembly (orange tabs).
3. Put the A14 assembly on an extender board. It is not necessary to connect the cables
while the A14 is on the extender board.
7-16
Preset
SERVICE MODES
Figure 7-3 at the frequencies indicated, replace A14.
RF Network Analyzers
FRACN TUNE ON
8719ET/20ET/22ET
8719ES/20ES/22ES
Service Guide