A collection of Amperex boxes, dates, and tubes.
These are all European made tubes (except the Russian fake). 
In the last years of Amperex the tubes were mostly General Electric.
"North American Philips" is on the later generation boxes beginning in the 1970s.

33audio.com homepage

Philips Vacuum Tube Codes

Datasheet Index

Descriptions are written above the corresponding picture.

The white block is used to keep the tube from rolling while taking a picture.
"(NOKEY)" in the manufacturer code means that the symbol has no key on the keyboard.

1956 code: 8t0 +6K.   + means Philips Sittard,Netherlands.  6 means 1956.
BugleBoy - 4 seams on top - note the 50s logo on the box.
The green on the tip was not put there by Amperex.  It means the tube was tested.

6AQ5/EL90  code: 3N3 (NOKEY-no key on keyboard)8d. 
NOKEY is the symbol for Heerlen,Netherlands.
8 in code means 1958 - (6009) 9th week of 1960 is the date in white marking.
Amperex is still using the old box logo in 1960.  In transitional years they may have
used up the old boxes while simultaneously using boxes with the new globe logo.

ECC88/6DJ8 code:GA4 (NOKEY)0L2  NOKEY manufactured in Heerlen, Netherlands.
date code 1960 - date in white writing is (1 14) 1961. 
4 seams on top.  BugleBoy logo.
Note that in 1961 the globe logo is used on the box.

EF83/6BK8 BugleBoy code:4G1 D5D3.  D is Valvo Hamburg.
code date is 1965. Date in white writing is (6551) 1965.
4 seams on top. 

PQ6689/E83F  PQ (Premium Quality) logo is on other side of tube.
code: VE3 NOKEY6B2  NOKEY is Heerlen,Netherlands.  4 seams on top.
code date is 1966.  No date written in white letters.

6CA4/EZ81  code: ??? B7I2  Blackburn Mullard.  2 seams at top.
(1 06) in orange marking 6th week of 1971. Evidently this tube sat for
4 years before being boxed. Orange globe logo on tube.
Note that this box has North American Philips written on it.

6X4/EZ90.  code: YY5 P8G1.  P is Papesa,Buenos Aires.  4 seams on top.
8 means 1968.  (6851)51st week of 1968 date in orange marking.
Papesa appears to be a misprint in the Philips data. 
Fapesa is a large electronics industrial complex in Argentina. 
Philips Miniwatt has been (was?) a part of this industrial complex for decades.
Fapesa is located in several cities in Argentina.

12AU7/ECC82  code:Gf8 (NOKEY)9C2 - NOKEY is Heerlen, Netherlands
9 is 1969 date. Orange marking on tube (6928) 28th week of 1969.
4 seams on top. Orange globe logo on tube.

6GK6 code: AX1 (NOKEY)9J1 - NOKEY is Heerlen, Netherlands
4 seams on top, 9 means 1969 in code. 
Orange globe on tube.
(7425) in orange writing 25th week of 1974. 

6267/EF86 Russian made labeled Holland.  No manuf. code.
Date code in orange writing is (7441) 1974.  No seams on top.
Box and orange writing appear to be authentic when compared to 6GK6 in picture above.
Note the pointed pins which are characteristic of a Russian made tube.

6227/E80L code: VDA R0H4.  R means Mullard Mitchum.
0 means 1980.  Date in orange writing is (8136) 36th week of 1981.
4 seams on top.  This tube is marked "made in England" in orange lettering. 
Almost all Mullards say "Made in Great Britain."