Where can I find suitable replacement tubes for reel-to-reel tape recorders with tube technology?

For classic reel-to-reel tape recorders with tube technology, suitable tubes are mainly sought for preservation and restoration. This applies, for example, to the Revox G36, professional Studer machines such as the C37, as well as popular Grundig units such as TK 20 or TK 45 and many models from Philips. In such tape recorders, depending on the model, tubes such as EF86, ECC83, ECL82, EM80, EM84 and EZ80 play an important role. Anyone who wants to make such a machine operational again or preserve it in original condition will find these at BTB Elektronik.