4 x 813's Amplifier Deck
This amp project was an exorcise in cheap! The design criteria was to use only components in the "JUNQUE BOX". Turned out I had to purchase a transformer and a half dozen resistors, but everything else was parts on hand. Even the chassis was constructed from salvaged aluminum sheet. The plan was to make it bandswitch 160 through 40, but a problem with the bandswitch has caused it to be fixed tuned on 160 for the time being. If I can find an inexpensive turns counter, I will change the air variable out for a vac variable and solve the switch problem. Note the absence of any form of parasitic suppression devices. The 813's are very well behaved. I doubt that you could make them oscillate above 35 mhz even if you wanted to. I don't believe there is a better choice of tubes for an inexpensive, easy to build, utterly reliable amplifier. No tube matching is required. If I am reading the date codes correctly, one of the tubes is pre-war (WW II) and the other three are scattered through the '40's. This amp project is far from finished, but it is cute enough to warrant it being shown off!