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You're right, E is May....F is June...<nt>

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Chris Garrett

(B)

In Reply to: Re: Amperex 6922 variant posted by Sondek on November 07, 2002 at 15:02:49:

nt

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Re: You're right, E is May....F is June...<nt> - Jtn 20:34:12 11/07/02 (4)
Thank you for all your help.
I feel pretty good about my purchase. (considering they cost less than Sovteks)
Out of the batch that I bought, there were some that were made in the U.S. (it has the * etched code (Amperex, NY) right?) But, the tube still said Made in Holland???
One other difference that I noticed between the Dutch (Heerlen plant) and U.S. ones was that the Dutch ones do not have the perfect glass envelope. They have a very slight dent near the middle. But not so much as the pinched waist ones that I've seen pictures of.
Could these be considered pinched waist?
- Re: You're right, E is May....F is June...<nt> - Chris Garrett 20:54:02 11/07/02 (3)
  If you're happy, that's all that matters.
  The '*' is for Hicksville, NY and overrides what is stamped on the tube in ink.
  VR is the code for the 7308 and 7L is code for the 6922. These will appear on the top line with a single digit after them, for the variation number. I guess they fine tuned the tubes and marked the changes.
  You are correct in that the pinched waiste tubes are very pronounced and slight bowing in of the glass on the Dutch tubes do not make them PWs. I have a Dutch PW and a US PW here and you know it when you see it--very deliberate.
  Good luck, Chris
  - Also... - Gerry E. 10:27:22 11/08/02 (2)
    My observations indicate that Amperex/Philips PW 6922s were only made until about 1958 in Holland and 1959 (possibly 1960) in the USA.
    Gerry
    - You're good, touche'..... - Chris Garrett 14:16:56 11/08/02 (1)
      I have a Beckman labeled PW made at Hicksville and the code is 7L4/*9K, even though the ink date is 60-10, for the 10th week of 1960. This tube was actually made in November of 1959. Only one example of two, of this family type that has the Philips 3 character bottom line code. They went to 4 characters in 1960, placing the week on there as you know.
      My second PW is a Mullard labeled Heerlen made 6922 with the code 7L3/A8B where A is the delta A for the Dutch Philips factory. So my comments about the 6922 being introduced around 1960 are wrong. This tube is my oldest and shows that the 6922 was made as early as February of '58, so the 6DJ8 has to be a bit earlier.
      I really hadn't looked at these in quite sometime and had forgotten about them. I still haven't plugged them into circuit yet, because they are different in orign, but they really do look identical right down to the D Getters, mica spacers and internal construction.
      Actually, since the BC preamp splits the L/R triodes for the L/R channels in the gain and buffer stages, so I can mix and match the three variations. Both of these test right at 100%, but I need to listen to see if they're microphonic.
      Thanks, Chris
      - Re: You're good, touche'..... - Sondek 15:56:15 11/08/02 (0)
        
        In Reply to: You're good, touche'..... posted by Chris Garrett on November 08, 2002 at 14:16:56:
        
        Chris,
        I think I read somewhere, or maybe I dreamed it, that the 6DJ8 was introduced in early 1957. The oldest ones I have are Dutch made in early 1958. So, your February 1958 vintage 6922 has got to be a VERY early production tube. It makes sense to me that the "industrial" or premium version of the 6DJ8, the 6922, probably was introduced in fairly short order after the initial introduction of the 6DJ8.

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