Output valves with no g3 connection? - UK Vintage Radio Repair and Restoration Discussion Forum

Tractorfan · 14th May 2023, 5:46 pm

Hi,
Many moons ago I was given a homebrew amplifier using the Williamson design, so I was told.
I used a couple of EL43s in it instead of beam tetrodes, therefore g3 (pin 1) was not connected to anything.
It still sounded OK, so I'm wondering the effects of an open circuit suppressor grid.
Cheers, Pete.

kalee20 · 15th May 2023, 1:22 am

It might sound OK, but that could be because negative feedback is doing its job and correcting any non-linearities.

Open suppressor grid could allow it to acquire a charge, which would affect the distribution of cathode current between anode and screen-grid. So maximum power might be affected.

14th May 2023, 5:46 pm	#1
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	Output valves with no g3 connection? Hi, Many moons ago I was given a homebrew amplifier using the Williamson design, so I was told. I used a couple of EL43s in it instead of beam tetrodes, therefore g3 (pin 1) was not connected to anything. It still sounded OK, so I'm wondering the effects of an open circuit suppressor grid. Cheers, Pete. __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

15th May 2023, 1:22 am	#2
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,081	Re: Output valves with no g3 connection? It might sound OK, but that could be because negative feedback is doing its job and correcting any non-linearities. Open suppressor grid could allow it to acquire a charge, which would affect the distribution of cathode current between anode and screen-grid. So maximum power might be affected.