3
6
7
4.
With the external power meter reading the correct output power, place the meter switch to
FWD and check the TUA100FA Amplifier front panel % Power Meter for a 100% indication.
If this reading is not obtained, adjust potentiometer R9 of the Metering Detector (A3) for a
100% indication. The Metering Detector is mounted on the right-hand side wall near the front
of the amplifier drawer and is accessible through the holes in the side wall. The % Power
Meter on the TU20F Driver will read less than 100% which is an appropriate indication.
3.6b
Reflected Power (
OPTIONAL
):
5.
On the right side wall of the 100W Power Amplifier drawer, adjust potentiometer R30 of the
Metering Detector fully clockwise to disable the VSWR overload detection circuit and place
the meter switch to REFL.
6.
Place the Transmitter/Driver OPERATE/STANDBY switch to STANDBY and the OPERATE/
ALIGN switch to ALIGN. In the amplifier drawer remove and reverse the forward power (J3)
and reflected power (J4) coupling port cables on the Metering Coupler (DC1). J1 and J3 of
the Metering Detector (A3) should now be connected to J4 and J3 of the Metering Coupler
(DC1), respectively. This simulates an open circuit at the amplifier’s RF OUTput (J2)
delivering maximum returned power to the REFL port of the Metering Detector. Insert a step
attenuator between the Receiver’s IF OUTPUT and the Transmitter’s IF INPUT and set the
step attenuator for 10dB attenuation.
7.
Place the Transmitter’s OPERATE/STANDBY switch to OPERATE. Remove attenuation
from the stepper for an external power meter reading of 69.5W [44W]. Check the amplifier
drawer's front panel meter for a 100% [70%] reading and, if necessary, adjust potentiometer
R27 of the Amplifier’s Metering Detector for the proper reading. R27 is accessible through
the right-hand side wall of the drawer.
8.
Decrease the translator's power to 50% by increasing the step attenuator 3dB for an external
power meter reading of 34.75W [22W]. This power level is used for setting the trip point of
the VSWR overload detection circuit. Adjust R30 of the Amplifier’s Metering Detector slowly
counterclockwise until the front panel VSWR OVLD indicator illuminates red and the
Translator/Driver drops into standby.
9.
Check the VSWR OVLD trip point by increasing the step attenuator an additional 1dB. Press
the momentary VSWR RESET switch to reactivate the Translator and remove the additional
1dB of attenuation from the attenuator. The VSWR OVLD circuit should again trip. If it does
not, repeat this section beginning at step #5.
10.
Place the OPERATE/STANDBY switch to STANDBY. Return the Amplifier Metering Coupler
cables to their original ports, J3 and J4. Reinstall the top cover, slide the drawer back into
the cabinet and secure it properly. Properly load the Translator and place both the
OPERATE/ALIGN and the OPERATE/STANDBY switches to OPERATE.
