- Posted by Thermionic27609 (A) on July 01, 2009 at 14:05:58
In Reply to: RE: Mystery 12AU7 = RFT posted by CV4109 on June 30, 2009 at 21:52:04
Yes, there's no mistaking the RFT tubes for anything else. The construction is very distinctive: folded plates more like some 12AT7s with three holes and a very heavy-duty getter support. Tube envelopes are large in diameter with unusually flat tops.
I find it difficult to get a good tube photo with my digital camera, but here's a link with one with the exact construction. The labeling is the only difference.
With the date codes, I would think they would be 1960s or maybe 1970s. Was RFT still making these in the 1970s? That might explain why they're Amperex labeled with their East German origin disguised. Or would Hewlett Packard have been making anything with tubes in the late 1970s?
