2SC2785 E49F and 2SC2785 K4XF transistor type?

[HG5AZR]

Hi!

What does it mean on second row on booth transistor?Exact type of booth transistor?

C2785
E49F

C2785
K4XF

Thanks
                Zoli

[KE3WD]

The second row indicates things like manufacturing facility, or date of manufacture, or the particular die used in manufacture, or all three. 

These are typically propietary coded numbers that reference data known to the manufacturer and of no real use to the repair technician. 

Letters listed immediately after the actual part number, however, can be important to us. 

For example, if you were to encounter a part number such as "2SC2785A" or any other letter immediately following the part number on the same line, it indicates a newer design that may not be replaceable by a transistor that does not have the suffix letter.  It is generally fine to replace a transistor with a LOWER suffix letter with one with a higher suffix, though.  For example, a transistor found that may have the A suffix can replace one that has no suffix, or perhaps one that has a C suffix can replace a transistor that has no suffix or A or B suffix.  The C suffix, though should not be used to replace one with D or higher. 


73

[W9GB]

I always start by obtaining the manufacturer's Datasheet for the transistor.

NEC 2SC2785 Datasheet : NPN Silicon Epitaxial Planar Transistor for Switching and AF amplifier applications.
http://www.classiccmp.org/rtellason/...ta/2sc2785.pdf

Based on the NEC Datasheet, their are 6 different ^hFE₂ -- DC Current Gain ranges.

Bluecolour.net (China)
The transistor is subdivided into four groups, O, Y, G and L, according to its DC current gain.
http://www.bluecolour.net/script/pro...1240426773.pdf