AMERITRON AL-80B, Инструкция по эксплуатации

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AL-80B Instruction Manual
23
QSK Operation
The antenna transfer relay in the AL-80B takes approximately 15 milliseconds to change states.
This precludes using the standard internal relay for QSK CW operation. Commonly available
vacuum relays are specified at 5 to 7 milliseconds of switching time. Even expensive vacuum relays
are less than ideal for high speed QSK operation. At 60 WPM, less than 50% of the receive-time is
available with vacuum relays.
On PACKET, AMTOR, and other modes, delay can be added to the transmit and receive
changeover to use either vacuum or our standard relay effectively. Ameritron offers two high-speed
PIN diode options that permit operation on modes requiring high speed receive-transmit switching.
Both systems offer noiseless switching times of under one millisecond. Since PIN diode systems
are several times faster than vacuum relay systems, they allow over 90% of the available receive
time to be used at 60 WPM.
Ameritron highly recommends using the external QSK-5 switch. This stand alone PIN diode switch
can be used with almost all types of amplifiers and transmitters. Modifications are not required in
amplifiers used with the QSK-5 unit. The QSK-5 operates directly from 120 Vac power lines.
Ameritron also offers an internal QSK board as a space-saver for the AL-80B. This internal board
is slightly less expensive. However, it provides less flexibility and serviceability than the external
QSK-5 unit. Factory installation of the QSK-5PC is highly recommended. Contact Ameritron for
details on the QSK-5 and the QSK-5PC.
Periodic Maintenance
The high voltage present on various parts of the amplifier will attract dust and dirt. The high
voltage areas at the bottom of the plate choke and the plates and insulators of the air variable
capacitors should be kept dust free. These areas should be inspected periodically, especially if the
amplifier is operated in a dusty environment. These areas may be inspected by unplugging the line
cord and waiting a few minutes for the power supply capacitors to discharge. The high voltage
should then be checked with the internal multimeter by placing the meter switch in the HV position.
WARNING
: High voltages can kill!!! Accidental contact with the voltages in this amplifier
can be lethal!