Digital Monitoring XR6 Manual do Utilizador descarregar pdf (Página 7)

XR3/XR6 Frequency Change Procedure Page 5 of 7

IS07012 Issue 1.0

Figure 5: RF Power Module Tuning

(TP14 and TP15)

(f) Follow the procedure in the XR3/XR6

Troubleshooting Manual to remove

the RF power module from the test

cable. Remove the tuning assembly’s

cover and tighten the locking nut. Re-

install the tuning units cover and the

modules both side covers.

(g) Install the RF power module in the

transmitter.

(h) Repeat steps (b) through (g) for the

second (if applicable) RF power

module.

(i) On the transmitter’s GUI screen press

the Status soft key. From the Status

screen press the Reset soft key. The

alarms on the RF power modules

should clear as well as any alarm

LEDs on the control panel. All red

LEDs should now be off.

2.4 Transmitter Fine Tuning/Test

2.4.1 VERIFY FREQUENCY

(a) Turn on the ac power.

(b) Monitor TP7 on the RF synthesizer

PWB with a frequency counter and

oscilloscope. The oscilloscope should

display a 15 V (approx.) square wave

at the frequency set in 2.1.1.

(c) Monitor J5 on the RF drive buffer

PWB with an oscilloscope. Adjust the

RF synthesizer PWB’s SYMMETRY

potentiometer (R32) for a 50% duty

cycle on the oscilloscope.

(d) Select exciter B (see XR3/XR6

Operations and Maintenance Manual)

and repeat steps (b) and (c).

(e) Turn off the ac power.

2.4.2 MONITOR PA VOLTAGE, RF

VOLTAGE AND RF CURRENT

Monitor PA voltage on the front panel GUI

and use an oscilloscope to monitor the RF

voltage and RF current at the back of an

RF power module.

Figure 6: Monitoring PA Voltage and RF

Current

(a) Install the RF current probe and

connect the RMS voltage meter as

shown in Figure 6. NOTE that current

will flow from the plug to the inductor.

Reinstall the transmitter’s rear cover,

taking care not to damage the probe

or voltage meter leads.

(b) Apply ac power to the transmitter and

press RF ON. Increase the power until

the PA voltage (measured on the GUI)

is 40 V. The RF output current should

be 3.45 ± 1 A. If the RF current

exceeds 4.45 A recheck filter tuning

and verify that there are no shorts in

the filter.

place the voltage

probe on this

point

place the current

probe on this

twisted wire pair

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