UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - REVOX A700 Transport Control and Capstanboard: Underdesigned transistors?

paulsherwin · 12th Oct 2017, 10:17 pm

The BC107 is exactly the same as the BC108 except for the higher working voltage so can be substituted everywhere. The BC109 is a low noise BC108, and again a BC107 can be substituted where the noise performance isn't critical.

The modern version of the BC107 is the BC547. This is a cheap and easily available transistor.

The BC337 is a different transistor but will probably also be OK. It has a higher collector current capacity than a BC547.

The BC639 has even higher voltage and current ratings than the BC337. It will probably be OK as well, but I have no personal experience with it. The BC639 has a bce leadout, unlike the cbe leadout of the other types mentioned here.

12th Oct 2017, 10:17 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,957	Re: REVOX A700 Transport Control and Capstanboard: Underdesigned transistors? The BC107 is exactly the same as the BC108 except for the higher working voltage so can be substituted everywhere. The BC109 is a low noise BC108, and again a BC107 can be substituted where the noise performance isn't critical. The modern version of the BC107 is the BC547. This is a cheap and easily available transistor. The BC337 is a different transistor but will probably also be OK. It has a higher collector current capacity than a BC547. The BC639 has even higher voltage and current ratings than the BC337. It will probably be OK as well, but I have no personal experience with it. The BC639 has a bce leadout, unlike the cbe leadout of the other types mentioned here.