On 24 May 2006 06:24:10 -0700, put finger to
keyboard and composed:

I have a suspect transistor in the MPX circuit of an HK330A receiver
that is not decoding stereo. The one in question, 2SA49, crosses on
the NTE site to an NTE126. I provide the specs for the 2SA49 and the
NTE126. Is this a good substitution? Might there be a less espensive
option (NTE126 is $4.86 or so).

2SA49 (PNP Ge)
Vcbo=-18V
Vebo=-12V
Vceo(sat)=?
Ic=-5mA
Pc=60mW
fT=?
hfe=30-200

(From the Japanese Transistor Manual
http://www.datasheetarchive.com/search.php?q=2SA49)

NTE126 (PNP Ge)
Vcbo=15V
Vebo=2.5V
Vceo=15V
Ic=100uA

That's the collector-emitter cutoff current (Vce = 15V).

Pc=150mW
fT=300Mhz
hfe=40

This is the minimum hfe at collector currents of 10 - 100 milliamps
(Vce = 0.3 - 1.0 volts).

http://www.nteinc.com/specs/100to199/pdf/nte126.pdf

From what I have learned so far, the important parameters for this
application are Ic, fT, Vceo. Do I have enough information to select a
sub? Also, what is the significance of the negative values indicated on
the 2SA49 spec sheet, does this impact how I would install the
replacement?

My vrt databook lists AF124 ... 127, AF200 as possible replacements.

- Franc Zabkar
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