Refurbsiehd Ameritron AL-811H 800W Output Linear Amplifier S/N:18803
Refurbished and checked by Ameritron November 2021 and good to go!!
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.
You also get efficient full-size heavy duty tank coils, computer grade capacitors, heavy duty high silicon core power transformer, slug tuned input coils, operate/standby switch, transmit LED, ALC, dual meters, QSK compatibility with QSK-5 option and much more!
AL-811/H Tips for Operation and Preventative Measures ...
Here are some tips about the AL-811/H type amplifiers regarding operation and potential prevention of breakdown...
1) Never tune the amplifier using AM. Always use a solid carrier mode such as CW, FM, or RTTY for tune-up. Also make sure that if your transceiver has a built in antenna tuner, that it is disabled. If you have an autotuner, be sure the tuner does not start tuning during the same time you are trying to tune the amplifier. This could damage the tubes as well as the tuner itself.
2) Try not to exceed 600mA of plate current. If 600mA is exceeded reduce the drive from the transceiver. This model is made for 600 watts CW or max of 800 watts PEP on SSB. Do not operate the amp at 800 watts CW (keydown) this is overdriving the amp and will result in premature tube failure.
3) If using AM or FT-8 modes, do not drive the amp harder than 10 watts input or about 100 watts output max. If you are using digital modes and find that the tubes are getting hot very quickly and not lasting long, it is okay to install 572B tubes. These tubes are more robust and will handle the heat dissipation better than the 811A. However, since the grid of the tube remains the same the 572B tubes can still only be driven at the same power level and will still only produce the same amount of power output.
4) Try not to leave the amp running for extended periods of time if the amp is not being used. This uses up tube filament life as well as filter capacitor life.
5) If you have trouble tuning, see the tuning instructions in the Instruction Manual or the instructions given here in number 6. Ameritron has YouTube videos explaining proper operation and tune up of this amplifier if the written instructions are confusing. Here are parts 1 and 2 of the video tune up procedure ...
https://www.youtube.com/watch?v=OT1UaCrVvd4 (Part One)
https://www.youtube.com/watch?v=zPcfRfn_No0 (Part two)
6) Here are some additional written tuning instructions ...
ATTENTION: Before operating the amplifier, make sure that the antenna is tuned and has a low SWR (below 1.5:1). Tuning on a 50 ohm dummy load is recommended, but not necessary. If an antenna is not resonant, an external antenna tuner may have to be used. Never operate this amplifier with the internal tuner of the transceiver turned on.
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With about 50 watts of drive (60 watts for the AL-811H) from the transceiver (radio), key the amplifier. If using a footswitch or key paddle, the transceiver should be in CW mode. If not, place the transceiver in FM mode and use the microphone. Never hold the key for more than 5 seconds during this procedure.
It is easier to tune the amplifier using an external wattmeter.
Place the PLATE and Load controls and BAND SWITCH of the amplifier to the specified locations labeled CW PROCEDURE as shown on page 7 of the AL-811 (or page 6 for the AL-811H) Instruction manual.
Key the amplifier and observe the external wattmeter. The needle on the wattmeter should go up and peak as the PLATE control of the amplifier is turned (can be either clockwise or counter-clockwise). Next, take the LOAD control, key the amp again and tune for peak power the same way as with the plate control. Again, it can go counterclockwise or clockwise. Always look for the power to peak on the external wattmeter.
Go back and tweak both plate and load controls. With about 50 watts in, you should see about 500 watts out CW (or 600 watts using 60 watts drive). This means that on SSB, the power would probably be 600-650 watts peak watts out (750 to 800 using 811H). At this point the Plate Current (Ip) should be no more than 600mA and the Grid current (Ig) should be no more than 150ma. These readings or anything below is acceptable.
At this point the amplifier is tuned and ready.
NOTICE: This procedure has to be repeated every time the band is changed. It is always a good idea to re-peak the tuning of the amp before every use, even if the amp is tuned up, turned off, and left overnight. Always tune up before operating.
