These are original E283CC Siemens&Halske, made in Munich plant, early production in old original boxes. E283CC is electricly identical with the E83CC ECC803S ECC83 12AX7, but they have another pin out. For using them as E83CC, ECC803S, ECC83 you need an adapter or to rewire socket. It’s frame grid tube like famous ECC803S Telefunken Ulm West Germany!
This original Siemens&Halske E283CC is identifyed by E88CC type plates, triple mica, dual getter arm (two support rods) and ring getter, frame grid construction
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