W8ji mods, MFJ changed the AL-811 series over the years

W8ji mods, Some were good, some were detrimental, and some were neutral. MFJ changed the AL-811 series over the years. D16 is the metering protection diode, and it fails from tube arcs. The price for both mods is $53 Priority Mail in the USA. ) exciter damage 3. Installing a pair of 200 ohm resistors requires redesign of the input matching network, as W8JI notes. I have them available for $10 including shipping. In addition two gas voltage clamps, GT1 and GT2, are added. Technical resource and information on receiving and transmitting antennas, amplifiers, radios, baluns, for 160 meters 80 meters and other low bands mods and modifications for kenwood TL922 stability and life. The following are known factory improvements as of The W8JI 200 ohm resistor mod increases the drive power from about 40 watts to 45 watts on 80, 40, and 20 meters. Measured airflow is about 1/3 to 1/4 of required safe airflow for four 811 tubes in normal SSB and CW operation. Instructions for fan replacement kit: Fan Mod AL811 AL811H (Rev 1) PDF file Warning: All AL811 and 811H amplifiers using a Cooltron fan have inadequate airflow. net is a Web site dedicated to ham radio (amateur radio). Technical resource and information on receiving and transmitting antennas, amplifiers, radios, baluns, for 160 meters 80 meters and other low bands Instructions for fan replacement kit: Fan Mod AL811 AL811H (Rev 1) PDF file Warning: All AL811 and 811H amplifiers using a Cooltron fan have inadequate airflow. Upgrade Kit AL811 and AL811H amplifier Rev3B 8/5/2025 Information in this modification manual is copyright 2025 by W8JI and CTR Engineering. This mod is also similar to the AL572 mods at this page. This page has information on grid resistors, bypass capacitors, gas voltage clamps, band switch and more. eHam. You can contact me at the following address click this link to View FT-1000 and FT-1000D plug-in modification kit Locate the seven-pin connector J3024 at the middle-front of the AF board. Learn how to improve the reliability and performance of your AL811 amplifier with various modifications, such as removing grid resistors, adding gas clamps, and adjusting neutralization. This mod removes the grid resistors and bypass capacitors, and directly grounds the grids. These are 125-150 volt clamps. The following are known factory improvements as of Neither mod requires soldering! Only a screwdriver is required. ) relay damage 2. Link to AL811 mod. This mod prevents: 1. If the grid and plate meter track and show similar deflection, D16 is often the cause. Find links to parts, service, and repair by the designer of AL811. If the amplifier shows anode current without being keyed but meters are normal, RL1B has welded. ) grid resistor failure Learn how to check and fix the AL-811H amplifier for problems and improve its reliability and performance. designed the AL811 and 811H in 1991.


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