2m 400 Watt linear using two 4CX250B

2m 400Wlinear inside the 400W linear

I am showing this for interest only. As you can see, this is the classic push-pull 2m linear amplifier featured in the various RSGB handbooks. The case/chassis is made from scrap Westminster lids and the perforated lid is an old aluminum ceiling tile. Strips of aluminum angle are used to hold the various case walls to the chassis. Originaly, the horseshoe shaped anode circuit was not silver plated and was oxidised, having had it silver plated no difference in performance was found. From experimentation, the output coupling loop is now the optimum shape/dimension.I use this amplifier for SSB service, for 3 Watts drive it produces just over 500 Watts of linear pep. It is crucial that an adequate air supply is maintained at all times for the valves, providing this is done the amplifier should give trouble free service. The amplifier has been in use for just over ten years now and has proved to be completely reliable, no valve replacements have taken place. 2m 400Wlinear inside the 400W linear

Barry Zarucki M0DGQ