[nykobing]

Posted WTB — looking for a power tube for this BHC w/ Speedball.

I’m hoping there’s someone out there with an orphan needing a good home.

I had a BHC awhile ago and I know I have some good singles left that I will never use, let me have a look tomorrow, believe it or not, I think they are hiding in some kitchen cabinet my wife couldn't reach up to.

 

[JTbbb]

Hello there all,

Just what do I have here? Clear top, bottom D Getters and rectangular top mica supports. The rectangular supports I associate with earlier tubes?
I have seen identical tubes like this marked as ‘Chatham Electronics 5998’ ‘Western Electric 5998/421A’ and ‘Western Electric 421A’ and the internals are the same. And now ‘Chatham Electronics 2399’ with the code No 3002399, which I’m thinking should have the date code in it? Then there is also the number 743, which I take as week 43, 1957?

I am guessing we will never fully understand the why’s and wherefore’s of what manufacturer‘s got up to with markings back then. But any ideas on the pedigree of this tube? Thanks

Share

 

[gibosi]

Hello there all,

Just what do I have here? Clear top, bottom D Getters and rectangular top mica supports. The rectangular supports I associate with earlier tubes?
I have seen identical tubes like this marked as ‘Chatham Electronics 5998’ ‘Western Electric 5998/421A’ and ‘Western Electric 421A’ and the internals are the same. And now ‘Chatham Electronics 2399’ with the code No 3002399, which I’m thinking should have the date code in it? Then there is also the number 743, which I take as week 43, 1957?

I am guessing we will never fully understand the why’s and wherefore’s of what manufacturer‘s got up to with markings back then. But any ideas on the pedigree of this tube? Thanks

Share

First, "2399" and "3002399" are IBM inventory parts numbers. IBM purchased so many of these for their early mainframe computers that they were able to ask Chatham to put their inventory numbers on the tubes they bought.

And as you have noticed, quite a few 5998s manufactured around 1957 had bottom getters and clear tops similar to the Western Electric 421A. There is some speculation that they are in fact the same tube, but again that is only speculation.

Enjoy!

 

[maxpudding]

That’s a unicorn tube

 

[JTbbb]

First, "2399" and "3002399" are IBM inventory parts numbers. IBM purchased so many of these for their early mainframe computers that they were able to ask Chatham to put their inventory numbers on the tubes they bought.

And as you have noticed, quite a few 5998s manufactured around 1957 had bottom getters and clear tops similar to the Western Electric 421A. There is some speculation that they are in fact the same tube, but again that is only speculation.

Enjoy!

Thanks for the detailed reply. And of course, being the owner I will go with it being a WE421A . Having said that, I will be sending this tube for testing in the next couple of months. And I am going to ask my tester if the transconductance can be measured (on paper WE 421A has 20,000 uMhos, and 5998 has 14,000 uMhos). My tester has the AVO MK IV Valve Characteristic Tester, and AVO VCM 163. So am hoping it can be measured. Results could answer the speculation! The tube was bought as testing at NOS levels.

 

[SHIMACM]

Thanks for the detailed reply. And of course, being the owner I will go with it being a WE421A . Having said that, I will be sending this tube for testing in the next couple of months. And I am going to ask my tester if the transconductance can be measured (on paper WE 421A has 20,000 uMhos, and 5998 has 14,000 uMhos). My tester has the AVO MK IV Valve Characteristic Tester, and AVO VCM 163. So am hoping it can be measured. Results could answer the speculation! The tube was bought as testing at NOS levels.

I have a valve just like yours only named "Chatham 5998". With internals similar to those of the WE 421a and transparent top with the getter at the bottom.

Looking forward to your test result.

 

[JTbbb]

I have a valve just like yours only named "Chatham 5998". With internals similar to those of the WE 421a and transparent top with the getter at the bottom.

Looking forward to your test result.

I may hasten this to the fella that tests my tubes now! I used to own a pair of “Chatham 5998’s” and I wouldn’t say the internals were similar to early WE 421a’s, they were identical, as is this IBM marked tube. I hope the results I get will be conclusive!

 

[JTbbb]

Thanks for the detailed reply. And of course, being the owner I will go with it being a WE421A . Having said that, I will be sending this tube for testing in the next couple of months. And I am going to ask my tester if the transconductance can be measured (on paper WE 421A has 20,000 uMhos, and 5998 has 14,000 uMhos). My tester has the AVO MK IV Valve Characteristic Tester, and AVO VCM 163. So am hoping it can be measured. Results could answer the speculation! The tube was bought as testing at NOS levels.

I have been in touch with the chap who tests my tubes regarding the above, and have been enlightened by his response, or should I say, has proved my ignorance . His response is below. As it turns out I have been getting these results anyway (expressed differently) on previous 5998/421a tubes I have sent for testing. I have included a pic of a 421a I had tested a long time ago, obviously low testing, but doing great service in my Bottlehead Crack. 3rd tube down.

So, for those following this little saga! I will be sending the early 1957 “Chatham Electronics/IBM 2399 clear top, rectangular Mica supports, bottom D getters,” which is identical to early WE421A’s, for testing. 1st tube down.

It just so happens that I have another, this one 1958, “Chatham Electronics/IBM 2399, but chrome top, with the more conventional oval mica supports,” which is identical to Tungsol 5998 which will also be sent for testing. 2nd tube down.

I bought these tubes as being tested at 62/64 and 63/64 where 40/40 was minimum good. So this little escapade might prove conclusively that the early clear top rectangular mica 2399 is indeed the same as a 421A. But then again, it could end up proving nothing, which may well be the outcome! But still fun to see!

“regarding the transconductance measurement of the 5998 and 421As it is the same as the TC measurement I give you, but expressed in different units so uMhos (ohms spelt backwards), is the old imperial way of measurement and found in a lot of old valve data sheets, the SI unit is Siemens. A very simple way of converting is just knocking off the decimal points so 14,000 uMhos is TC 14.0 and 20,000 is TC 20.0 etc.”

 

[jbua5150]

I received my shipment of tubes today.
The 5998 do appear to have the top and bottom getters.
They all tested over 100% on an Amplitrex AT1000.
I’m a happy guy

 

[leftside]

I received my shipment of tubes today.
The 5998 do appear to have the top and bottom getters.
They all tested over 100% on an Amplitrex AT1000.
I’m a happy guy

Very nice. Happy to see someone else on here with an Amplitrex. That thing has saved me thousands of dollars in refunds and returning tubes that tested nowhere near close to "advertised". This was the latest message I received after receiving tubes that were supposedly "NOS" but tested below 50% emissions and GM. I have thankfully also received plenty of tubes that test as advertised and even a few that test stronger than advertised.

 

[therremans]

Mullard 6080 for a decent price, if anyone needs one.

https://www.ebay.com/itm/1449037423...roZ8AOWRMO&var=&widget_ver=artemis&media=COPY

 

[AudioDuck]

I received my shipment of tubes today.
The 5998 do appear to have the top and bottom getters.
They all tested over 100% on an Amplitrex AT1000.
I’m a happy guy

You… have… FOUR?!
[drools]

(Seriously though, congratulations! If I run into some spare cash I’ve found a couple of pairs that I can pick from- I just need the extra funds to justify the purchase)

 

[jbua5150]

Very nice. Happy to see someone else on here with an Amplitrex. That thing has saved me thousands of dollars in refunds and returning tubes that tested nowhere near close to "advertised". This was the latest message I received after receiving tubes that were supposedly "NOS" but tested below 50% emissions and GM. I have thankfully also received plenty of tubes that test as advertised and even a few that test stronger than advertised.

I am very fortunate to have a shop 5 minutes away from my house that lets me rent time with the Amplitrex.
It does come in extremely useful for my obsession with buying tubes from eBay. Many sellers list NOS, and sell tubes that are very low. Even if you run the Amplitrex in “Auto Bias”, well used tubes may auto bias to look much better than with the fixed bias setting.
Just today I tested some Tung Sol 6AS7G that were listed as “NOS”, fixed bias showed very low, but auto bias looks pretty good. I’ve never had a seller argue with me when I send the the test results.
I also scored 4 MELZ, a Mullard metal GZ34, and a pair of Tung Sol 6C8G that all tested new today. Low scores on pairs of Mullard 6080, and TS6AS7, but the 5998’s more than make up for it.

 

[jbua5150]

You… have… FOUR?!
[drools]

(Seriously though, congratulations! If I run into some spare cash I’ve found a couple of pairs that I can pick from- I just need the extra funds to justify the purchase)

I have been fortunate to be in the right place at the right time…..more than once

 

[CAJames]

Very nice. Happy to see someone else on here with an Amplitrex. That thing has saved me thousands of dollars in refunds and returning tubes that tested nowhere near close to "advertised". This was the latest message I received after receiving tubes that were supposedly "NOS" but tested below 50% emissions and GM. I have thankfully also received plenty of tubes that test as advertised and even a few that test stronger than advertised.

That's pretty funny. I have a TV-7 myself, and have had pretty limited luck returning tubes that didn't test as advertised. But then I usually buy cheap tubes
.