Was going thru my tube stash and found a couple of 5675's that I had gotten several years ago for my (now late) HP 608 sig gen. I'm in need of 17.000 mhz and 200 khz crystals for the R-390A. Even if you don't need the tubes, holler back if you have the correct crystals for the 390A oven. tnx Tom NU4G