I did a little more digging in that lab today. I have a 475A late serial number on the bench and the 151-0367-00 transistors were not tarnished on the legs. I dug up a data sheet and found that the transistor is a MPSH05 This is speced to have the following:
C->E breakdown voltage 80 Vdc
C->B breakdown voltage 80 Vdc
E->B breakdown voltage of 4 Vdc
E->C Breakdown voltage Not specified
80Mhz switching frequancy
Transistor measured with a DCA pro shows the reverse diode currently assumed bad.
Moved to a Keithley DMM6500
C->E open circuit as expected
E->C 0.754 Volts or 750mV with a test current of 1mA out of the DMM 6500
Just some more thoughts and testing on this matter but this proves that the DCA pro might be getting confused but it IS showing relevant data as confirmed by other instruments of a more refined pedigree. I am interested in doing additional testing if anyone has ideas on what kind of testing could solve this questions definitively once and for all. I can't do SMU mapping of 3 pole devices as I am short the Keithly 2470 but it is on the list. So I am limited to only a Tek 576 and 577 for curve tracing devices over 12.5 as the DCA Pro can only do a collector voltage up to about 12.5 VDC
Zen
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-----Original Message-----
From:
[email protected] <
[email protected]> On Behalf Of John Sykes via groups.io
Sent: Saturday, September 16, 2023 3:42 AM
To:
[email protected]Subject: Re: [TekScopes] Is it possible that the 151-0367-00 transistor story is horribly wrong?
Two thoughts:
- High-ft transistors in (Chinese?) testers: good chance they oscillate at some v high frequency? Might be worth an experiement with a ferrite bead or two on the base.
- In my experience, when Tek selected devices from a hi-frequency part, the selection parameter was generally related to an HF/switching characteristic (ft, Ccb etc) John
