Rectifier valve - UK Vintage Radio Repair and Restoration Discussion Forum

acorn · 27th Aug 2019, 2:18 pm

Good day all

I have a Rectifier valve with the logo missing on the glass envelope, but there is an etched number on the glass F31 and B8F I would be grateful if any one could indicate were this valve was made, ie it looks like a GZ34.

Cheers Acorn

GrimJosef · 27th Aug 2019, 2:27 pm

I take it the type code is actually f31. f3 is the code for a GZ34 and the 1 is a version number. F3 is the code for a 35L6GT which would look rather different.

B means it was made in the Mullard Blackburn plant. 8 means it was made in a year ending in 8 (likely 1958) and F is the code for June. If there was an extra character, 1 to 5, that would tell you the week within the month.

Cheers,

GJ

acorn · 27th Aug 2019, 2:41 pm

Thanks for the information, you have got it in one , yes its a Mullard GZ34 made in Blackburn, I thought it may be a GZ34 but had no idea where it was made.

Acorn

greg_simons · 27th Aug 2019, 5:48 pm

Looks like you're sorted but sometimes shining the beam from an led torch on the glass can reveal the faint letters and numbers.
Greg.

27th Aug 2019, 2:18 pm	#1
acorn Pentode Join Date: Aug 2006 Location: Dorchester, Dorset, UK. Posts: 114	Rectifier valve Good day all I have a Rectifier valve with the logo missing on the glass envelope, but there is an etched number on the glass F31 and B8F I would be grateful if any one could indicate were this valve was made, ie it looks like a GZ34. Cheers Acorn

27th Aug 2019, 2:27 pm	#2
GrimJosef Dekatron Join Date: Sep 2007 Location: Oxfordshire, UK. Posts: 4,311	Re: Rectifier valve I take it the type code is actually f31. f3 is the code for a GZ34 and the 1 is a version number. F3 is the code for a 35L6GT which would look rather different. B means it was made in the Mullard Blackburn plant. 8 means it was made in a year ending in 8 (likely 1958) and F is the code for June. If there was an extra character, 1 to 5, that would tell you the week within the month. Cheers, GJ __________________ http://www.ampregen.com

27th Aug 2019, 2:41 pm	#3
acorn Pentode Join Date: Aug 2006 Location: Dorchester, Dorset, UK. Posts: 114	Re: Rectifier valve Thanks for the information, you have got it in one , yes its a Mullard GZ34 made in Blackburn, I thought it may be a GZ34 but had no idea where it was made. Acorn

27th Aug 2019, 5:48 pm	#4
greg_simons Octode Join Date: Jul 2004 Location: Evesham, Worcestershire, UK. Posts: 1,422	Re: Rectifier valve Looks like you're sorted but sometimes shining the beam from an led torch on the glass can reveal the faint letters and numbers. Greg. __________________ Picture, sound?, DOOR.