HISTORY:
This component has been pulled from a very nice (fully functioning) KEPCO BOP 50-8M!
"Pulled" because that is exactly how it is mounted, in a PCB socket on the power output heatsinks, no "de-soldering" no chopping of the legs! (Ouch!)
Why "part out" the KEPCO? I have decided to make this equipment an "organ donor" because I have had it advertised elsewhere as a fully functional unit but no interest, too "high brow" I guess.
Additionally it is VERY HEAVY (this is a FULL rack size unit, approaching 40Kg when it was packed) and I noticed light damage to the steel casing as well (scrape marks due to moving it around over the years).
Originally we acquired this equipment from an international R & D laboratory and used it ourselves for various test and research tasks, although the BOP range of Bi-polar power supplies can undertake many other tasks.
In brief, the KEPCO BOP 50-8M is a Bi-polar power supply providing 0-50V dual supplies at up to 8A current each.
But to be more specific it is much more than a Bi-polar power supply, the unit contains two high speed, high power Op amps and NO capacitors on the output (which can effect the frequency response/speed). The Op amps can operate up to 24Khz (resistive loads) with Ultra low noise, Ultra low ripple and they are MIL spec compliant.
The power Op amps are four quadrant, bi-polar operation with full control of the voltage and current on each channel via the front panel controls OR remote control/programming.
This KEPCO BOP 50-8M is not a "spring chicken", date of manufacture was in the late 1990's - not used very often but when it was called upon, it never missed a beat.
KEPCO designs and manufactures some wonderful professional laboratory and industrial power test equipment, take a look HERE for their latest offerings
The company began around the mid 1940's in Queens, New York along with two other very well known power supply design/manufacturing companies Sorenson and Lambda. Of the three companies, only KEPCO remains in Queens and remains an independent company.
So, that is the background of this component and now let's get down to describe the component or module I have carefully extracted from the equipment, and where feasible/worthwhile, tested to ensure full functionality.
TOSHIBA (Japan) - Power Transistor
Made in Japan
Type: 2N3773
Various batch numbers: 9122, 9048, 9240
Bipolar
NPN
Vce 140V
Ic 16A
Pw 150W
Current gain has been tested on EVERY device offered (and marked on the underside of the case) - see below for specific details
COSMETIC CONDITION:
USED
Clean
Bright, shiny legs on all available transistors BUT ....
Notice that six of the 2N3773's are discoloured "top-side" (pretty easy to spot!) This is light oxidisation of the steel (Yes, rust!)
This is a curious thing with the design of the KEPCO equipment, forced air flows through the heatsink which has 6 transistors on each side of the "channel". One side is absolutely clean but the other has this oxidisation and it appears that during humid conditions the airflow (with a higher water content) accelerated this oxidisation of the heatsink mounted transistors but on just one side.
Top side the six transistors don't look "like new" but the functionality is in no way affected. The underside of ALL transistors is clean and shiny, they have all be less exposed to this airflow and surrounded by silicon grease previously. Don't let the appearance put you off, these are all "fine to go"
Legs have NOT been cut or altered in any way (these were originally inserted into special PCB sockets)
Stored on a special TO-3 foam carrier which has then been sealed in clear plastic, they will be supplied in the same manner
TESTING:
Every device has been tested and the hFE results marked on the underside of the transistor.
In summary, here is an indicator of the gain test results:
12x 2N3773 transistors in total tested
Lowest hFE 42 (1)
Highest hFE 77 (1)
hFE Band Groupings:
hFE 40 ~ 50 (3)
hFE 51 ~ 59 (2)
hFE 60 ~ 69 (2)
hFE 70 ~ 77 (5)
TOSHIBA (USA) datasheets indicate hFE should be a minimum of 15
The compliment of this transistor is the 2N6609 and YES, I have those (MOTOROLA MEXICO) please take a look HERE
