My CTC51K, all the OEM tubes are Japanese, but the 3A3. There was three tubes changed by the original owner. Two 6GH8's and a 11HM7.
Naturally, the 6GH8's were in the color circuit and were GE. The 11HM7, video output was a Sylvania.
After I bought it, I had to repair the vertical circuit. It's a set, I referred to in an earlier thread.
