Description

Almost all Ameritron 811 and AL811H amplifiers have far too little airflow even for normal SSB operation. The Cooltron fan, appearing since at least 2009, is a terrible air mover. It flows roughly 20-30% of the necessary airflow on 60Hz mains. In countries with 50Hz mains, the Cooltron fan only flows <5 cfm. The tubes run too hot even just on filament alone. This kit contains a fused prewired fan assembly with a high/low switch, all necessary hardware, and two 5-watt Zener diodes on a printed circuit board. Amplifiers will use none, one, or two Zener diodes depending on tubes and age. This kit requires simple mechanical work and between one and four solder connections. Please read the instructions carefully and be sure you are comfortable with this kit! The manual and current pictures are at this link https://www.ctrengineeringinc.com/shared-files/990/PCB-Fan-Kit.pdf YOU MUST BUY THE CORRECT Kit. This kit is the internal fan kit used only in the AL811H four-tube amplifier. The fans are modified differently and not easily interchangeable between the three-tube and four-tube amplifiers. THIS IS A FOUR-TUBE AL811H Kit with the internal fan!