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antenna has to be adjusted for lower SWR. As an alternative, an antenna tuner
may be inserted.
7-4
Turn the POWER switch on. Turn the BAND switch to a desired operating
frequency band. Turn the STAND-BY switch to OPER (operate) position and the
amplifier is ready to go. If you key the transceiver with the carrier level set
relatively low (such as 20-30W), you will achieve an amplified output signal of a
few hundred watts. Monitor this output with the multimeter (at the Pf position)
or with an external power meter. Increase drive level to roughly 50W and see if
the antenna SWR stays constant. (As higher RF currents flow, some antennas
may show a changed SWR value due to heated connector junctions and trap
coils.)
7-5
You can now increase the drive level to nearly 80-90W to achieve maximum
carrier output power of 550W (CW) from the amplifier. If you change to SSB
mode, average voice power of a few hundred watts will be observed on the panel
meter, Pf scale, while peak voice power reaching a little over 550W. For high duty
cycle transmissions like RTTY mode, it is recommended that you reduce the drive
power by some 30%.
7-6
With a high power transceiver in SSB mode, you can overdrive the amplifier
resulting in a distorted output signal. This can occur if you speak too loud or if
you set the microphone gain too high. Speak into the microphone properly to
reduce the possibilities of splattering into the neighborhood. The ALC is effective
in preventing the output signal from being distorted or to limit the carrier level to
within rated output levels. It is strongly recommended to make ALC connection,
especially when 200W out high power radio is used to drive.
7-7
Protection circuits may work during operation depending on the conditions. If the
protection circuit has shut down the amplifier, check the antenna SWR, Vd, AC
line voltage, or try to reduce the drive level. To reset, turn off the POWER switch
once, then back on again. The power transformer has an overheat protection in
the coil layer. If this temperature switch activates, the amplifier will put you in
receive mode with the cooling fan operating until the transformer has cooled off.
It may take ten to fifteen minutes to cool, depending upon room temperature. For
more details on this protection circuit, see Section 9. PROTECTION CIRCUITS.
11
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