User's Manual

5.8 Fault Finding
M889-00
02/10/95 Copyright TEL
5.5.2 Power Control
Use RV63 to adjust
output power to 60W.
Adjust RV48 until forward
power LED is just lit.
Power control OK.
N
N
N
Y
Y
Y
Y
Ensure RV69 is fully clockwise.
Check sense voltages from
directional coupler on IC3 pins 1 & 7.
With the 3dB pad connected to
the PA, adjust RV52 until the
high reverse power LED is just lit.
Short R72 to ground with spike, etc.,
while adjusting RV74 until PA
output power is set to 35W.
Does high reverse power alarm
LED light when PA operated into
a mismatch of 3:1 or worse?
To test, connect an unterminated
3dB pad to the PA output,
thereby setting up a 3:1 mismatch.
High Reverse Power Alarm Check
Does the output power reduce to
35W at high operating temperatures?
To test, heat R72 with the tip of a
soldering iron.
Over-Temperature Shutdown Check
Does low forward power alarm
LED light when output power
reduced to 60W using RV63?
Low Forward Power Alarm Check
Does output power adjust over
the range 20-100W using RV63?
RF Power Level Control Check
N