[Amps] Ameritron AL-800

Paul Decker kg7hf at comcast.net
Wed Dec 10 13:00:21 EST 2025


> > Has anyone created a work around to replace the 3CX800A7 tubes in the
> > AL-800, the AL800H, Alpha, Ten-Tec and other amps that used this tube?

The 3cx400U7 and 3cx800U7 are usually much cheaper alternatives and in many cases can be NOS. The datasheet lists the working B+ as lower, but I suspect that is simply due to the higher frequency rating of the U7

The only issue is changing out the base which seems daunting at first. There is an "RCA like" plug connector that fits the base really well so that only the grid ring needs to be figured out with some simple finger stock and a metal plate. 

Someone with talent could design an adapter board that would work well too! 

Paul
KG7HF



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