JOTRON electronics a.s.
December, 99
Page 25
measured directly on a power meter, the measured level will not be the same as the output
when connected to the 10W power amplifier in the TR-6101. Because of this, it is
recommended to have both the driver unit and the 10W amplifier connected together when
any adjustments are made, measuring the power and modulation on the N-connector output of
the TR-6101.
Also, it is important to notice that the modulation level and the output power are dependent
on each other. If the power is decreased the modulation level will increase and if it is
increased the mod.level will decrease. Therefore it is necessary to adjust both the power and
the modulation level if any of them are changed.
To do the adjustments, at least the following instruments should be at hand:
Power meter.
Modulation meter.
Distortion meter.
Audio generator.
Never attempt to adjust the output power to more than 10W, although it is possible to do such
adjustment, the result will be an distorted output signal because the transceiver could not
handle the peak power that will result when it is modulated. Remember that the peak power
will be 4 times higher than the carrier power with 100% modulation.
•
Open the top-cover of the transceiver, TR-6101, by turning the 2 screws in the cover a half
turn counter clockwise.
•
Connect the power, modulation and distortion meter to the output of the TR-6101
transceiver.
•
Key the transmitter by connecting pin 3 and 4 of the microphone socket together.
•
Measure the output power and adjust R33 to the correct level.
Turning the pot.meter clockwise will decrease the output power and opposite.
•
Apply 10 mV, 1kHz modulation signal to pin 1 of the microphone socket and check the
modulation. The modulation should be adjusted to app. 80-85% with this input signal.
•
Check that the distortion of the output signal is below 5%.
•
Alternatively, the modulation could be checked with an RF oscilloscope.
•
Replace the top-cover of the transceiver.