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Old 01-05-2012, 06:24 PM
Hart Hart is offline
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Join Date: Jan 2012
Posts: 3
More on Dating GE Tubes

I hope the people who posted the previous information about dating GE tubes are still watching. I have found this information greatly helpful and want to pose some more questions.

I presume that the code 188-5 indicated the Owensboro plant, but I also have some tubes coded 188-21. Do you know what plant that is? In this case, the tubes are GE 8425A/6AU6As. 8 of them are in the same Tektronix plug in, all marked and coded the same, so they are certainly OEM. The code 69-13 appears on them, but then, just above the 188-21 code appear the letters JZ. Could that be a Rosetta Stone? I also have a 6DJ8 with HZ over 188-5, and another one marked HW - both of these are likely OEM tubes. I also have a 6DJ8 which was used as a replacement in a scope and which is coded JL over 188-5. Does this imply that there were two different GE codes, one for OEM tubes and one for open market supply?

The codes ending in Z seem to be inconsistent with the code sequence discussed in earlier posts related to Owensboro tubes. I wondered if anyone can shed any light on this.

When I worked at ARC back in the 50s, we got most of our tubes from GE, and all the ones I still have are open date coded. I have a group of JG 6AU6WA coded 4-48 over 188-5 and 6136 Five Star dated 60-04 over 188-5. I presume that the 4-48 indicates the 48th week of 1954.

These codes are extremely important to dating equipment as you well know, and are fascinating besides. Any comments or further insight would be greatly appreciated.

Paul Hart
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