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One thing I learned about tube date codes when working at a distributor in the 1980's - there are different schemes for OEM tubes (installed at the factory) and distibutor tubes (sold at a parts distributor) codes. GE was famous for this - the TV/Radios had a block of letter codes and the distributor tubes had their own as well. RCA used three-letter codes for distibutor stock at one time, then later made all tube codes "numbered" (yr-wk). Some audiophiles will argue that an "RTN" date code sounds better than an "RSN" tube. A-yep, I sold many sleeves of 12AU7 tubes only after the audiophile went through them, cherry-picking date codes.
The reason was simple - distributors were not to honor OEM warranty, nor was the OEM warranty program to honor distributor tube warranties.
GE distributor stock often had both date code schemes (two letter distributor codes) and the yr-wk OEM code. The reason? Simple - the Owensboro tube plant had one line, and put the OEM date code on for the Utica/Syracuse and Portsmouth plants, and any overruns went to distributor stock after adding the distriubutor date code. 67-14 = OEM code. 'EH' = distributor code
I only wish I still had the "gouge" sheet we used to decipher the codes for GE tubes.
BTW, my GE portacolor has all the originial tubes, based on the OEM codes.
Cheers,
__________________
Brian
USN RET 22YRS (Avionics/Cal)
CET-Consumer Repair and Avionics ('88)
"Capacitor Cosmetologist since '79"
When fuses go to work, they quit!
Last edited by Findm-Keepm; 10-23-2008 at 09:39 PM.
Reason: grammar - thanks Ms Eley!
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