UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Mullard 5-20 high DC Voltages

PJL · 9th May 2020, 6:15 pm

The CB design starts with the premise of 'improving' on the 5-20 by re-wiring the EF86 pentode as a triode and putting in fixed bias eliminating the benefits of self correcting auto-bias and reduction in dissipation when driven into class B. Elektor was an electronic hobbyist publication whilst the 5-20 was designed by Mullard and has formed the basis of many professional valve amplifiers.

This may also leave you a problem with advice from the forum members as many will have experience with the 5-20 design but not the CB design.

9th May 2020, 6:15 pm	#112
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Mullard 5-20 high DC Voltages The CB design starts with the premise of 'improving' on the 5-20 by re-wiring the EF86 pentode as a triode and putting in fixed bias eliminating the benefits of self correcting auto-bias and reduction in dissipation when driven into class B. Elektor was an electronic hobbyist publication whilst the 5-20 was designed by Mullard and has formed the basis of many professional valve amplifiers. This may also leave you a problem with advice from the forum members as many will have experience with the 5-20 design but not the CB design.