[ARC5] 12SB7Y - where found?

Wed Apr 6 22:36:54 EDT 2016

Jim Cross is a member of the Tube Collectors Association. He also owns Vacuum Tubes, Inc. in Orlando, FL and is considered one of the authorities on collectable (rare) vacuum tubes.

By what I was told, Ken-Rad probably intended to introduce the 12v version of the 6SB7 but didn't go into production due to miniature tubes taking over the industry at that point the time. Therefore only the several engineering samples were made.

Timing of introduction of a new product means everything when technology is changing rapidly.

I recently read about the demise of DEC (Digital Equipment Corporation). Their PDP and VAX minicomputers almost made them bigger than the IBM mainframe computer business then in the 1990s microcomputers supplanted minicomputers and they were sold to Compaq who was then sold to HP. The owner, Olsen, thought desktop computers and personal computers were stupid ideas. Wrong!

Big corporations often wait too long to introduce new products because they like to avoid retooling and they like to milk the existing product cash cow for too long. Then they wake up too late to survive. It's the bureaucracies, internal empire building, and overpaid senior executives that cause good companies to eventually flounder...

Phillip W4RTX 

Sent from my iPhone

> On Apr 6, 2016, at 9:24 PM, Richard Knoppow <1oldlens1 at ix.netcom.com> wrote:
> 
>    It might be worth asking on the Tube Collector's Association list. Someone there may know the whole history of this tube and could tell you if it was ever formally registered and, if so, by whom. 
> 
> 
> http://www.tubecollectors.org
>> On 4/6/2016 5:30 PM, J Mcvey wrote:
>> OK, curiosity has gotten the best of me on this thread.
>> 
>> If the 12SB7 was never produced, then what would use one? A prototype radio that was also never put into  production? 
>> 
>> 
>> On Tuesday, April 5, 2016 1:35 PM, Richard Knoppow <1oldlens1 at ix.netcom.com> wrote:
>> 
>> 
>>     Well, Ken-Rad was a division of General Electric. The 6SB7Y never became popular, I think because it came out too close to the time miniature tubes began to supplant octal based ones.  The 6BA7 is a nine pin                       miniature with very similar characteristics.  There is a 12BA7 listed in the RCA handbook so it might be possible to make an octal to 9 pin adaptor and use one in place of the 12SB7.  There is also a 12SA7 but the conversion and oscillator transconductance is much lower than in the later tube.  The SB will work in place of an SA but probably not the other way around. 
>>     You might also ask at the Tube Collector's Association list, they have a vast amount of knowledge and could say if this was a prototype or engineering sample or special production run. 
>> 
>>  http://www.tubecollectors.org
>> 
>> On 4/5/2016 10:03 AM, Phillip Carpenter wrote:
>>> Ken and Others,
>>> 
>>> I found out the story on the 12SB7 from Jim Cross at Vacuum Tubes, Inc.
>>> 
>>> Jim says that only a few engineering samples were ever made and these were only made by Ken-Rad. He has one sample in his collection.
>>> 
>>> Jim said that LEEDS never had those they listed and Lintech's listing of a RCA 12SB7 is phantom stock.
>>> 
>>> So only a few were ever made and none for production.
>>> 
>>> Respectfully,
>>> 
>>> Phillip W4RTX 
>>> 
>>> Sent from my iPhone
>>> 
>>>>> On Apr 4, 2016, at 11:50 AM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
>>>>> 
>>>>> On 3 Apr 2016 at 22:23, Phillip Carpenter wrote:
>>>>> 
>>>>> Does anyone have one or two 12SB7 tubes? These are the same as 6SB7 except for
>>>>> the filament voltage. If so, please reply direct to me.
>>>>> 
>>>>> These were made by RCA for the military (I think it was an Air Force contract).
>>>>> They are still listed in stock by two military parts suppliers (though at
>>>>> extremely inflated prices...you know like the $900 hammer).
>>>> Really?!?!? I must admit to being very surprised since my checking every 
>>>> possible source for data on the 12SB7Y over the past year or two returned  
>>>> absolutely nothing.
>>>> 
>>>> AFAIK, there were never any 12SB7Y tubes built for normal users, but there 
>>>> most certainly could have been some made on special order for the military. 
>>>> 
>>>> Stranger things have happened.
>>>> 
>>>> I am very interested in where you have seen any 12SB7Ys for sale. I have 
>>>> never yet found any.
>>>> 
>>>> The 6SB7Y was specifically designed for use in early broadcast or home 
>>>> entertainment FM tuners and receivers and exhibits about double the 
>>>> conversion transconductance as the 6SA7 which it can directly replace.
>>>> 
>>>> Ken W7EKB
>>> 
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>> 
>> -- 
>> Richard Knoppow
>> 1oldlens1 at ix.netcom.com
>> WB6KBL
>> 
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> 
> -- 
> Richard Knoppow
> 1oldlens1 at ix.netcom.com
> WB6KBL
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