The AL-811H is a grounded grid linear amplifier developed by
Ameritron using low cost 811A power triodes. It operates in
class AB2 for SSB and CW.
1. Fast Warm Up Time: The 811A tubes take approximately
10 seconds to warm-up.
2. Long Tube Life: The 811A tubes are long life, reliable
transmitting tubes. 811A tubes offer rugged, reliable
operation even on RTTY and SSTV.
3. Tuned Input: A Pi-Network tuned input matches the 811A
tubes to 50 ohm exciters.
4. Two Illuminated Panel Meters: The AL-811H has two
illuminated panel meters. The Grid Current meter provides
a continuous reading of the 811A grid current to indicate
proper loading of the amplifier. The other meter switches
between high Voltage (HV) and Plate Current (Ip).
5. Multi-voltage Heavy Duty Transformer: A unique
"buck-boost" winding allows adjustment of primary
voltages to match a wide range of line voltages centered on
110 and 230 volts. This versatile Ameritron feature allows
the user to maintain optimum voltages on the tubes and
other components to obtain maximum performance and life.
6. Vernier Plate and Load Adjustments: Both tuning
controls have vernier 6:1 reduction drives for smooth tuning
logging scales for accurate and rapid tune-up.
7. Safety interlock: AC input power is removed from the
transformer when the cover is removed. Never attempt to
defeat this switch.
8. Operate/Standby Switch: Used to remove the amplifier
from the RF line while filament and plate voltages are
maintained during "barefoot" operation.
9. XMT Indicator LED: Provides a front panel indication of
proper amplifier keying by the exciter.
10. ALC: The drive level is detected to provide a control
voltage for the exciter. ALC prevents over-driving of the
linear and reduces distortion from excessive drive power.
11. Neutralization Circuit: Reduces unwanted feedback to