Pre Amp Valve Identification

[Pow_22]

Anyone help identify this valve i found in a box in out loft (not my uncles loft!). From what i can tell on Google its a blackburn coded mullard? Its a Cv491 with the codes 'Gf2' and 'B4F4' on the bottom. I have no means of testing other than whacking it in one of the Hartkes and seeing if it works.

Can post pics later if it helps

[bertbass]

Here you go. http://www.r-type.org/exhib/aaa0348.htm

[BILL POSTERS]

CV is an old miltary prefix. its similar to ECC82 according to my old wireless world data book

or if you want to decipher it, theres always this; [url="http://www.tubecollector.org/cv/1963/"]http://www.tubecollector.org/cv/1963/[/url]