It sounds like a "plain 80" rectifier. 73 Bob WA2UEH >I have an Eveready Raytheon >ER 280 4 pin tube which I am unable to test. >A friend has a TV7 but it won't test it which surprised me as I was >sure that would test every tube in the world!! >Is anyone familiar with this tube or know where/how I can test it?