[JKDJedi]

You'll have to PM me....arrows and all. LOLOL!!

Why am I not laughing....

 

[cddc]

Here is a video that shows how tubes were assembled in Mullard Blackburn factory:

Mullard - The Blackburn Vacuum Tubes Factory (Full)

 

[cddc]

Why am I not laughing....

A chicken won't laugh at another chicken...

 

[JKDJedi]

I read it again, and I feel like it is sort of unlikely that the WE supplied "cage" came without cathodes and grids installed. The space between the 5998/421A plates is pretty tight, it would be very difficult to stick in the cathode and grid assembly between plates. I think it would be much easier for the workers to assemble the cathode and grid assembly first and then enclose it with 2 plates. Can the difference in cathode and grid be caused by different proudction years / batches?

It's also the first time that I read that WE supplied components to TS for 5998 / 421A production. I used to read that WE designed the 421A / 5998 tube but Tung Sol actually manufactured all those tubes for WE and itself.

Who knows really...if we could go back 70 years... They sound awesome, let's go with that.

 

[JKDJedi]

Here is a video that shows how tubes were assembled in Mullard Blackburn factory:

Mullard - The Blackburn Vacuum Tubes Factory (Full)

I saw one at one of them Russian plants, kinda cool how they made the glass.

 

[bcowen]

A chicken won't laugh at another chicken...

Why am *I* now not laughing? Damn, I hope this isn't contagious.

 

[JKDJedi]

Why am *I* now not laughing? Damn, I hope this isn't contagious.

.. ok.. so your in the 421a club. Congrats..

 

[bcowen]

Well, the USPS wasn't messing with me. I'm not sure what to think.

It be here, even in an original WE box. Tests OK, but is definitely not NOS. Seller advertised it as used/untested, so no false advertising on his part. No shorts, leakage undetectable. With the bias set at 27 (which is the dual listing for the 421A/5998), raw reading is 700 on the first triode and 725 on the other. 20X multiplier in play, so 14,000 and 14,500. Min. is 425 / 8500, so still a good strong tube, but well short of a 20k mhos reading for NOS. Now if I go to the 37 bias setting, the readings change altogether with a big spread between the triodes: (500/10,000 and 675/13,500). Strange. Would make more sense if they both decreased proportionally. I think I'll go with the 27 bias setting values 'cause I like them better.

Am I reading that date code correctly as the 13th week of 1961?

 

[JKDJedi]

Well, the USPS wasn't messing with me. I'm not sure what to think.

It be here, even in an original WE box. Tests OK, but is definitely not NOS. Seller advertised it as used/untested, so no false advertising on his part. No shorts, leakage undetectable. With the bias set at 27 (which is the dual listing for the 421A/5998), raw reading is 700 on the first triode and 725 on the other. 20X multiplier in play, so 14,000 and 14,500. Min. is 425 / 8500, so still a good strong tube, but well short of a 20k mhos reading for NOS. Now if I go to the 37 bias setting, the readings change altogether with a big spread between the triodes: (500/10,000 and 675/13,500). Strange. Would make more sense if they both decreased proportionally. I think I'll go with the 27 bias setting values 'cause I like them better.

Am I reading that date code correctly as the 13th week of 1961?

I believe that's correct on the date code .. beautiful tube there.

 

[cddc]

Well, the USPS wasn't messing with me. I'm not sure what to think.

It be here, even in an original WE box. Tests OK, but is definitely not NOS. Seller advertised it as used/untested, so no false advertising on his part. No shorts, leakage undetectable. With the bias set at 27 (which is the dual listing for the 421A/5998), raw reading is 700 on the first triode and 725 on the other. 20X multiplier in play, so 14,000 and 14,500. Min. is 425 / 8500, so still a good strong tube, but well short of a 20k mhos reading for NOS. Now if I go to the 37 bias setting, the readings change altogether with a big spread between the triodes: (500/10,000 and 675/13,500). Strange. Would make more sense if they both decreased proportionally. I think I'll go with the 27 bias setting values 'cause I like them better.

Am I reading that date code correctly as the 13th week of 1961?

Wow, you really scored! The 421A looks pretty new, and it even came with the original box. It looks like a new tube or at least lightly used tube to me.

Maybe the tube should be tested around 14,000 uMhos using 5998 settings, which are NOS values.

That's what I said earlier - WE 421A shows 20,000 uMhos only on paper, because that higher transconductance is likely achieved by using higher testing plate voltage and grid voltage. If you test it with the same plate voltage and grid voltage as 5998's, you'll likely get similar measured transconductance for both of them. However, this is yet to be verified until you receive your 5998, let's hope the lost 5998 will someday show up or you can score another 5998 tube.

 

[cddc]

I believe that's correct on the date code .. beautiful tube there.

I think so too, 13th week of 1961.

 

[bcowen]

Wow, you really scored! The 421A looks pretty new, and it even came with the original box. It looks like a new tube or at least lightly used tube to me.

Maybe the tube should be tested around 14,000 uMhos using 5998 settings, which are NOS values.

That's what I said earlier - WE 421A shows 20,000 uMhos only on paper, because that higher transconductance is likely achieved by using higher testing plate voltage and grid voltage. If you test it with the same plate voltage and grid voltage as 5998's, you'll likely get similar measured transconductance for both of them. However, this is yet to be verified until you receive your 5998, let's hope the lost 5998 will someday show up or you can score another 5998 tube.

I'll have to score another 5998...already received my money back for the first one which went missing over 3 months ago. I'll keep my eyes peeled as I'm interested in seeing how these test against each other as well.

 

[cddc]

Well, the USPS wasn't messing with me. I'm not sure what to think.

It be here, even in an original WE box. Tests OK, but is definitely not NOS. Seller advertised it as used/untested, so no false advertising on his part. No shorts, leakage undetectable. With the bias set at 27 (which is the dual listing for the 421A/5998), raw reading is 700 on the first triode and 725 on the other. 20X multiplier in play, so 14,000 and 14,500. Min. is 425 / 8500, so still a good strong tube, but well short of a 20k mhos reading for NOS. Now if I go to the 37 bias setting, the readings change altogether with a big spread between the triodes: (500/10,000 and 675/13,500). Strange. Would make more sense if they both decreased proportionally. I think I'll go with the 27 bias setting values 'cause I like them better.

Am I reading that date code correctly as the 13th week of 1961?

You mentioned earlier that bias = 27 is the newer setting, so I think they updated the bias from 37 (old) to 27 (new) for a reason. Maybe tubes under bias 37 are not stable or it will give wrong results, it would possibly explain for the unevenness.

Anyway, sticking with the updated 27 bias should give you more reliable measured transconductance.

 

[bcowen]

You mentioned earlier that bias = 27 is the newer setting, so I think they updated the bias from 37 (old) to 27 (new) for a reason. Maybe tubes under bias 37 are not stable or it will give wrong results, it would possibly explain for the unevenness.

Anyway, sticking with the updated 27 bias should give you more reliable measured transconductance.

Agree. 27 it is.

 

[JKDJedi]

Agree. 27 it is.