EWBrown wrote:Those vintage Telefunken OPTs are pretty good, I've used them in 12B4A and 6S4A SET designs.
They are, indeed. But you have to be careful. Today, I've received two Telefunken SE OTs (7k-4R). FR was just awful:
It's a nuisance that german sellers always say "tested" and "fully working". No, they don't test at all! They grab an old tube radio and switch it on. "We hear anything? OK, it's working! Let`s get everything out of it and sell it on Ebay!"
Even the "tested tubes" seller claims that he measured 4R and 12K resistances using his multimeter. That's simply impossible with DC measurements. I bought from him recently and will post the results. So, be careful and be lucky that you can buy from Edcor.