HP 8340B Manual page 196

5-15. ALC ADJUSTMENTS (Cont'd)
Equipment
Power Supply
Digital Voltmeter (DVM)
1 Megohin Resistor
0.1 UF Capacitor
Extender Board
Procedure
1. Disconnect AC power cable from the OUT and allow it to cool for at least two hours.
2. Disconnect cables W26 and W27 from A25J2 and A25J1 respectively (Figure 5-46), and remove
the A25 PC board from the instrument.
Ji
"H"
Figure 5-46. ALC Detector A25 Temperature Compensation Adjustments Location
3. Install an Extender Board in place of A25.
4. Set the DVM for Ohms measurement and connect the input between pins 4 and 26 of the extender
board. Note the resistance measured. This value is thermistor resistance, RT, and will be used for
calculations in later steps.
5. Connect the test equipment as shown in Figure 5-45 with cable W27 connector connected to an
SMB-to-BNC adapter.
Connect the
6. DVM
output for 5.00±0.01Vdc. Move the DVM connections back to the SMB-to-BNC adapter as
shown in Figure 5-45.
5-90 Adjustments
J2
"L"
Ri 15 R37
across the output terminals of the Power Supply and
A25
R36 Ri 09
HP 6294A
HP 3456A
HP P/N 0757-0059
HP P/N 0160-0168
HP P/N 08350-60031
R80
EX
—
the power supply
adjust
HP 8340B/41B