User`s guide

3-10 Chapter3
Theory of Operation and Troubleshooting
Troubleshooting
If the LEDs are working on Port 1 and Port 3 and the bias voltage
is still incorrect on switch S0, move the S1 bias connector from J6
to J3 (see Figure 3-17) on the test set interface board. Press Seq,
TTL I/O, TTL OUT, TESTSET I/O FWD, 6, x1, I/O REV, 6, x1
. Check the
bias voltage (+0.62 Vdc and + 16.3 Vdc) on S1 (see Figure 3-13).
Toggle the instrument between the REFL: FWD S11 (A/R) and
REFL: REV S22 (B/R) states. If the bias voltage does not change,
replace the test set interface board. If the bias voltage does
change, replace S0.
Symptom 3: RF Source at Test Port 1
No RF Source at Test Ports 2 or 3 or Both
Check the bias connection to switch S1 (see Figure 3-13) and the J6
connection (see Figure 3-17) on the test set interface board. If the bias
connector is loose, reconnect it. If the bias connector is firmly in place in
the J3 connector, check the bias voltages (+0.62 Vdc and +16.3 Vdc) on
switch S1. The center bias pin on S1 should be approximately +22 V.
1. Use the tab on the side of one of the switches (S0, S1, or S2) as the
ground connection point.
2. The red wire is the common drive pin and should measure
approximately +22 V.
3. The blue wire is the solenoid drive for pin number one. The voltage on
this pin measures approximately +16.3 V.
4. The green wire is the solenoid drive for pin number two. The voltage
on this pin measures approximately +0.62 V.
5. Measure the solenoid voltages.
NOTE Voltages may vary depending on the test port state of the instrument.
a. Press Preset, Meas.
b. Press Seq, TTL I/O, TTL OUT, TESTSET I/O FWD, 6, x1.
c. Toggle between REFL: FWD S11 (A/R) and REFL: REV S22 (B/R) while
measuring bias pins 1 and 2 on S1.