Crossing NTE transistors to industry numbers - sci.electronics.repair

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From: Tim Schwartz <tim...@verizon.net>
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Subject: Re: Crossing NTE transistors to industry numbers
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Date: Wed, 13 Sep 2006 12:37:43 GMT
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captainvideo462...@yahoo.com wrote:
> Is there any way possible to determine which industry numbers will
> cross to a particular NTE number? I need to replace a fairly large
> number of 2N6254 audio output transistors and I have access to many
> 2SC, 2SD and some 2N numbers etc. The 2N6254 crosses to an NTE181.
> Without going through and trying to look up every single one can the
> NTE database be run backwards? Or perhaps is there any other way to
> extrapolate this information? Thanks very much. Lenny Stein, Barlen
> Electronics.
> 
Len,

	The 2N6254 is a 100V, 15A, 150 watt transistor.  MCM Electronics 
(www.mcmelectronics.com) has them in stock.

	Reverse cross referencing is tricky, as usually the 'universal subs' 
choose one transistor to replace many. So, comparing the 2N6254 to the 
NTE 181: original here:

They are both rated for 100V

The NTE is rated for 30 amps instead of 15A

The NTE is rated for 200 watts instead of 150 watts.

	Unfortunately, by doing a "reverse look up" you don't know if the other 
device is good enough, for example, it might be rated only 12 amps.  So, 
you have to carefully compare the device you are replacing (2N6254) with 
the device that you want to replace it with.

	While in general, higher break down voltage, higher current and higher 
dissipation ratings are OK, they also DON'T tell you about the gain of 
the transistor, or the frequency response.  If you have a bunch of 
output transistors in parallel, they should all be of the same type, and 
in a perfect world, gain matched as well, as you want the load spread 
evenly across the bank.

	The frequency response can also be a problem.  If it is too high then 
the amp may have problems with oscillations.

	When using transistors that I can't curve trace, I try to use the same 
lot number in the bank.  Sometimes this requires buying a few extra 
transistors.

Regards,
Tim Schwartz
Bristol Electronics