AMERITRON AL-80B, Инструкция по эксплуатации

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AL-80B Instruction Manual
18
Tube and Component Life
These guidelines will help prolong tube and component life, and minimize splatter.
1. On SSB or other linear modes, virtually any amount of power will cause splatter if the loading
is too light ("LOAD" control too far counter-clockwise). Always tune for maximum output
with maximum drive power. Reduce the drive power to reduce the output power on SSB, not
the loading control.
2. Lightly loading an amplifier will also result in large voltages building up in the tank circuit.
Under-loading an amplifier is much harder on the tubes and other components than operating a
properly loaded amplifier into a high SWR or with excessive drive power.
3. Never depend on average reading power or current meters to indicate proper operation on SSB
or other linear modes. The best indicator of linearity is either an oscilloscope or the internal
PEP RF output meter. Maximum linearity can be determined by finding the maximum output
power possible and then reducing the
exciter power for a slight reduction in output power.
4. Never exceed 170 mA of grid current on CW carrier during actual operation. The proper grid
current for SSB will range from 0 to 75 mA. The SSB grid current will vary with the operator's
voice, the amount of signal compression or processing, and the tube characteristics.
Tuning
Follow the instructions below in numerical order. Proper tuning will produce excellent output
power, a clean signal, and good tube life. If the various meter readings are different than indicated in
the text, check the external amplifier connections. Consult the manual for the exciter if necessary.
WARNING:
The transformer must be wired correctly for your line voltage. This amplifier is
normally shipped wired for standard 120Vac operation. Refer to the
"Transformer Connection" section on page 12 for details.
Tuning Procedure
Important Note: If you have installed the optional electronic grid protection circuit to prevent
control-grid damage, this amplifier will quit operating if the grid dissipation exceeds a safe pre-set
limit.
The overload circuit responds much faster that the grid current meter. The overload circuit
can respond to excessive grid current before the operator is able to observe excessive current on the
grid meter.
Some exciters generate brief high-level RF pulses when first keyed. These short duration pulses
may greatly exceed the exciter's operating output power setting but may not be indicated on meters.
Unexplained activation of the grid overload circuit may indicate the existence of this exciter
problem. The grid overload circuit can be reset by momentarily placing the "STBY-OPR" switch in
the "STBY" position.