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

Bazz4CQJ · 17th Jun 2020, 2:59 pm

Sometime ago I built a little unit to do DC characterisation of ECC81's, which is my preferred valve for use as a standard for my AVO163. It soon became apparent with the MkI version that it would sometimes spring in to oscillation, but it settled down with maybe 6 or 10 beads and maybe some decoupling caps, all built in to a diecast box. I think I may have used some feedthro caps on some of the feeds from the external PSU and external meters. It seemed to me that valves with a Gm of more than 4 or 5 were particularly prone to oscillate, as might be expected.

B

17th Jun 2020, 2:59 pm	#28
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Yes, yet another home made valve tester. Sometime ago I built a little unit to do DC characterisation of ECC81's, which is my preferred valve for use as a standard for my AVO163. It soon became apparent with the MkI version that it would sometimes spring in to oscillation, but it settled down with maybe 6 or 10 beads and maybe some decoupling caps, all built in to a diecast box. I think I may have used some feedthro caps on some of the feeds from the external PSU and external meters. It seemed to me that valves with a Gm of more than 4 or 5 were particularly prone to oscillate, as might be expected. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.