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Cross for 2SA49

Discussion in 'Electronic Repair' started by [email protected], May 24, 2006.

  1. Guest

    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
    Pc=150mW
    fT=300Mhz
    hfe=40

    http://www.nteinc.com/specs/100to199/pdf/nte126.pdf
    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?
     
  2. Ralph Mowery

    Ralph Mowery Guest

    The Ic looks low on the replacement you have. It will depend on how the
    device is used as to how important the paremeters are. In non critical
    circuits the Vc, Ic, and having more hfe are important. Ft is important if
    the device is used in high frequency (RF ) applications.

    The negative values are usually put in for PNP devices in the spec sheets to
    denote the collector is usually connected to the negative of the supply
    voltage. It can be leftout by whoever prints the spec sheets. Just as if
    you ask the price of something in the dollars price range and a guy says 25.
    You usually think of dollars in the US and not 25 pennys or 25 dimes or 25
    quarters. but he may say 25 dollars.
     
  3. The 1996 Transistor Substitution manual lists 2SA1015 as a substitute for
    the 2SA49.
     
  4. Franc Zabkar

    Franc Zabkar Guest

    That's the collector-emitter cutoff current (Vce = 15V).
    This is the minimum hfe at collector currents of 10 - 100 milliamps
    (Vce = 0.3 - 1.0 volts).
    My vrt databook lists AF124 ... 127, AF200 as possible replacements.

    - Franc Zabkar
     
  5. Guest

    AF124 (NTE160) looks to be a much better match.
     
  6. Guest

    I found a Sams cross reference manual at the library, and it too was
    showing NTE126 as a sub for 2SA49, but NTE160 certainly looks better.
    By the way, the Ic of 100uA for the NTE126 is incorrect, this
    information is not on the datasheet, that is the value of the C-E
    cutoff current, the Ic is not given in the datasheet, can it be
    calculated? This stuff is all new to me, one would think NTE database
    would cross to the on-the-face-of-it better choice of NTE160.
     
  7. ian field

    ian field Guest

  8. ian field

    ian field Guest


    It might work - but the 1015 looks like a Si type, if the original is part
    of a matched pair or duplicated in another channel it might cause an
    imbalance!
     
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