Three tough 811A transmitting tubes, extra heavy duty power supply, all HF band coverage, pressurized ventilation, tuned input, dual illuminated meters, adjustable ALC & more. The first 600 watts make the difference The Al-811 gives you 600 watts PEP output -- thats nearly 2 full S-units over your barefoot rig.

Four 811A Tubes: Uses four rugged, fully neutralized low cost 811A PA tubes. Vertical Tube Mounting: Prevents shorting of tube filament/grid, prolongs tube life. Fully Neutralized: Improves stability and performance on higher bands. Input Tune Circuit: Adjustable rear panel slug tuned input circuit. ALC Control: Built-in adjustable ALC control.

This instruction manual and the 811 kits are the result of direct feedback from servicing several dozens of amplifiers. Read these instructions thoroughly before you start working on your amp.

There are tons of suggested mods for the AL-811, including a number of kits and suggestions from W8JI. 1. Grid-overload protection using an auxiliary board. MFJ sells one, but I purchased the W8JI "tune on the fly" mod, which provides a useful indicator LED. 2. Soft start module. The AL-811 made a "clunk" noise whenever I powered up.

200-ohm 25-watt non-inductive TO-220 case load resistor kit with hardware and grease (reduce gain and add stability in 3 tube 811 models). This also can make the AL811H more compatible with 100W radios, reducing power overshoot in rigs like the ICOM 7300. I designed the AL811 series many years ago.

The AL-811 is rated at 600-watts PEP voice, or just over 400-watts carrier in normal CW modes. These ratings are ICAS with a reasonable conversational duty cycle. The difference in power supply voltages on voice and carrier modes is the major contributor to differences in peak power between voice and carrier modes.

Only the AMERITRON AL-811H gives you four fully neutralized 811A transmitting tubes. You get absolute stability and superb performance on higher bands that can't be matched by un-neutralized tubes. AMERITRON mounts the 811A tubes vertically, not horizontally, to prevent hot tube elements from sagging and shorting out.

These kits include all the parts to bring your Ameritron AL811 and AL811H amplifier up to date. We also sell quality 572B, 811A, and 3-500 tubes and almost any other RF parts you might need. The following is a list of critical production problems: Proper airflow results in a noticeable air movement a foot or so away from the vent holes by the tube.