UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Neil Purling · 13th Jul 2006, 7:42 am

Well, that's quite a significant difference in gain.
While valve data sheets will quote the gain of the 6J5 or each section of the 6SN7GT as having a gain of 20, as a RC coupled class A1 amplifier it manages only 15 on average. I have looked at a resource of valve data sheets and I agree about the value of cathode resistor. It still needs changing, I wonder what sort of difference would be observable?

It justifies the usage of the 6SN7GT, with the combined gain of 30. Perhaps a twin gang volume control working on both grid circuits would be a good idea, if one could get such a thing.

13th Jul 2006, 7:42 am	#16
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	Re: Regarding home made TRF Well, that's quite a significant difference in gain. While valve data sheets will quote the gain of the 6J5 or each section of the 6SN7GT as having a gain of 20, as a RC coupled class A1 amplifier it manages only 15 on average. I have looked at a resource of valve data sheets and I agree about the value of cathode resistor. It still needs changing, I wonder what sort of difference would be observable? It justifies the usage of the 6SN7GT, with the combined gain of 30. Perhaps a twin gang volume control working on both grid circuits would be a good idea, if one could get such a thing.