Over Temperature Protection; Alignment Procedure - RF Technology PA 150 Operation And Maintenance Manual

RV1 is normally set so that the RFO LED comes ON at 1-3 db below the normal
power output.
2.7

Over Temperature Protection

Thermistor RT1 is mounted to the case of output transistor Q4. If the transistor
case temperature rises above 90 degrees C the resistance of RT1 increases and Q2
is turned ON.
This causes the TEMP LED to come on and also reduces the dc reference voltage
to the output power error amplifier U2d. The input power will then be reduced by
the transmitter ALC circuits and the output transistors are kept within safe
operating limits.
3

Alignment Procedure

The following procedures may be used to align the amplifier for optimum
performance.
Standard Test Conditions
RF Input Source
T150 Series transmitter
25 watts maximum
Set RFO Level
Step
1
2
3
RF Technology PA150
Power Supply
13.8 Vdc at 15 A
Input
None
Centre channel
frequency from the
T150, 25W max
threshold
As above
3 ALIGNMENT PROCEDURE
50O 150 watts
VSWR < 1.2:1
Measure
Set RV1 and R2
RF output power at
J2
RFO LED
Load
Adjust
Fully counter
clockwise
Key transmitter
adjust RV2 for
desired output
Key transmitter
adjust RV1 to
where the RFO
LED just goes OFF
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