Transistor identification?

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Previous post problem !

444 is 2N444

NPN Germanium  TO5 15V 25mA 150mW 400 KHz  : equivalent AC176 or 2N2430

Re: Transistor identification?
On 09/06/2015 1:53 AM, Look165 wrote:
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Germanium? That is quite ancient - any designs from the 1970s on would  
be silicon.

If the OP can check the rest of the device to get an idea of the age  
that would help determine if it is possibly germanium.

John :-#)#

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Re: Transistor identification?
On 06/09/2015 17:57, John Robertson wrote:
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I don't recall ever seeing a germanium device in a modern plastic  
package like that.

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Brian Gregory (in the UK).
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Re: Transistor identification?
On Wed, 9 Sep 2015 03:38:00 +0100, Brian Gregory

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Only one or two germanium parts in TO92 - AF306 and AF339, but don't
forget plastic RF types in SOT37/TO119 'T' packaging.

If ever there was an electonic industry version of trivial persuit,
this would be a likely question.

RL

Re: Transistor identification?

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The only plastic cased germanium transistors I've ever seen were UHF types  
in TV tuners, AF139 or something like that.

They were pretty fragile - they weren't potted encapsulation, but 2 plastic  
cups glues together to enclose the die header. A few fell apart as I tried  
to unsolder them.  


Re: Transistor identification?
On Thu, 17 Sep 2015 20:22:17 +0100, "Ian Field"

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That's the SOT37/TO119 package intended for stripline UHF. I can
assure you that reputable vendor parts (like AF279 AF280 -
siemens/valvo/telefunken) were encapsulated in solid molded bodies.
I can send you some 'decap' images if you'd like.  

This may have required a two-stage process, initially, but the
construction that you describe, with no die or lead support, in a
plastic shell, would not have survived common manual soldering and
assembly methods.

Even parts assembled inside TO18/TO72 cans (as AF139), or TO1 glass
envelopes, relied on an internal fill/coating, for die and bonding
surface integrity. Even then, niether were expected to survive severe
lead-out mis-manipulation that could occur in careless lead forming or
point-to-point wiring assembly methods.......

Earliest pro-electron germanium parts in SOT37 were AF2xx or higher.
In TO92, only the two numbers listed previously. All low power
VHF/UHF.

RL

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