Another alternate is in the format following: 188-5 69 32 188 is General Electric.
5 is the plant code (in this case, Owensboro, Kentucky). And another is like this: 322 6104-1 322 is Tungsol, 6104 is 1961, 4th week, 1 is the shift code (1 would probably be the day shift) After about 1960, many tube manufacturers went to encrypted alphabetical date codes., such as: KE 188-5 The reason was purportedly to allow factories to track the dates of manufacture of defective tubes (especially important in the case of OEM customers that might send back entire batches of tubes), but avoid possible consumer complaints about "stale" tubes.
I have seen several different builds of the Sears 5XL amp on e Bay and elsewhere on the web.
As many of you may have already figured out through the name of this website, the info on this site will pertain mostly to vintage Shure microphones, mainly, the Shure 520, otherwise known as the “Green Bullet”.
I will also give some info on the early Shure crystal mics, and touch briefly on a couple of the Aststic Corp. I was born and raised in Upstate, NY where I still reside.
They generally follow the following format: (example) 322 5904 where 322 is the manufacturer code (in this case Tungsol), 59 is the year (1959), and 04 is the week.
One alternate scheme is: 274 940 274 is the EIA code (RCA) 9 is the last digit of the year (in this case 1949).
Code formats were not completely standardized, but a little deciphering will generally yield the info of interest.
Note that many makers also stamped OEM (Original Eqipment Manufacturer) part numbers above or below the EIA code, in some cases parts makers or the customer elected not to include the EIA codes, so not all parts have them.
mics, and, a few mics from other companies as well. I consider myself lucky to reside in a city that has such a great number of blues fans, and a wealth of local blues bands that consist of musicians whom are without a doubt, talented enough to be on the national blues scene on their own.
A few local musicians have made it to be part of nationally known blues artist’s bands such as Carey Bell, Savoy Brown, The Nighthawks, William Clarke, and others.
These are codes often seen stamped on components found in US made vintage tube equipment.