[ARC5] Equivalent tube types

[Scott Johnson]

Tubes processed for computer service (subject to extended period in cut-off)
had cathodes that were not subject to "cathode interface", a phenomenon
where the conducting and electron emitting layer became isolated from the
cathode sleeve due to formation of an insulating oxide
between the nickel cathode sleeve and the barium oxide emitting layer.  This
was also a problem for Tektronix in their distributed amplifiers in the
older tube-type scopes.

Scott W7SVJ

-----Original Message-----
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of J. Forster
Sent: Sunday, July 15, 2012 4:08 PM
To: Roy Morgan
Cc: ARC-5 List
Subject: Re: [ARC5] Equivalent tube types

The tubes for 'computer service' may not be the best for analog service.

In computers a tube can be either saturated or cutoff for long times,
leading to cathode emission issues as I remember. The industrial versions
have modified cathode composition or design.

I know the IBM CE came in most days and changed out a bucket or two of tubes
in the 907.

-John

==========


>
> On Jul 15, 2012, at 6:21 PM, Bob Macklin wrote:
>
>> There is a 57?? that is an alternate for the 12AU7.
>
> 12AU7 military/commercial equivalent is 5814  Used in the R-39x series.
>
>> It was made for computer service.
>
>  From my tubes notes file:
>
>> From: Dennis Monticelli <dennis.monticelli at gmail.com>
>> Date: April 2, 2011 1:34:39 PM EDT
>> To: Bob Macklin <macklinbob at msn.com>
>> Cc: ARC-5 List <arc5 at mailman.qth.net>
>> Subject: Re: [ARC5] Interesting occurrence...
>>
>> Right you are, Bob.  The 5814A (not the plain 5814) is a "computer 
>> rated"
>> 12AU7.
> (This is wrong, I think.  the 5814 is industrial/military rated.)
>
>>  The 5963 is a quieter computer-rated 12AU7.  Dual triodes were 
>> commonly used in logic circuits.
> (not sure on the "quieter" part, though computer rated is right.  The 
> 12AY7, is a quiet and microphonics-, hiss-, and hum-reduced medium mu
> double triode intended for low level audio amplification.   (Current
> AES price is $25 each.)  It has differing-ratings equivalents of 6072, 
> and 6072A.  (Current AES price is $25 each.)
>
>> Other computer rated tubes were: 5844, 5915A, 5965, 6211, 6463, 5963, 
>> 5964, 5965, 6197, 6350, and 6887.  Manufactureres were predominately 
>> GE and RCA.
>> These tube types often show up in boxes of misc tubes FS and 
>> frequently as NIB.  Because people aren't familiar with them they 
>> usually go begging for a home.  This is sad because many are just 
>> improved versions of commonly known tubes.  For example the 5844 is a 
>> 6J6.  The 5915 is a 6BE6.  The
>> 5965 is a
>> 12AV7.  The 6197 is a 6CL6.  etc.  Something to think about the next 
>> time you rummage through an old box.
>
> No savvy hamfest tube user should be without a carefully prepared 
> tubes-wanted list.
>
> Use the following link to find equivalents and near equivalents for 
> any tube you can think of:
>
> http://tdsl.duncanamps.com/tubesearch.php
>
> Roy
>
>
> Roy Morgan
> k1lky at earthlink.net
> K1LKY Since 1958 - Keep 'em Glowing!
>
>
>
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