Use the Googles, Luke.
As Jim Nabors / Gomer Pyle might say, "SHAZAM! What's that I see at the bottom of page two??"
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As Jim Nabors / Gomer Pyle might say, "SHAZAM! What's that I see at the bottom of page two??"
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The 2N4250 appears to be a low noise PNP with relatively high gain.
Do you have a favorite for that duty?
I have looked at the datasheet for BC550C and BC560C. They are low noise and relatively high gain. The quasi-sat behavior may not be to my liking. I will have to acquire some and make some curve traces that are more useful than the one in the datasheet. The datasheet curves are at currents well beyond where they would be used in this application.
Do you have a favorite for that duty?
I have looked at the datasheet for BC550C and BC560C. They are low noise and relatively high gain. The quasi-sat behavior may not be to my liking. I will have to acquire some and make some curve traces that are more useful than the one in the datasheet. The datasheet curves are at currents well beyond where they would be used in this application.
Yes, that's mine.
Thanks, Doctor!
This looks like a nice project. Whether or not it is held 100% true to the original (impossible!), I can see some nice amps coming out of it.
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Thanks for your earlier suggestions. They were helpful.
I did quite a bit of searching and did not find anything similar to the 2N4250.
The KSA992 I have some of but I do not like the quasi sat behavior.
I will run some BC560C through the curve tracer to see how they behave.
I have a nice stash of Toshiba 2SA970BL but that will not help anyone who wants to build one of these from modern Mouser/Digikey availability.
As of now, I have not found a low noise, high gain, PNP that is in production that has a very low saturation voltage. Still searching.
In the meantime, I purchased some NOS 2N4250 parts that I will run through the curve tracer. We shall see.
Central Semiconductor. Mouser. 3731 pieces in stock. $0.45 at qty=1.
Check those search hits one more time.
Check those search hits one more time.
Even with your hint, it took a while to find.
Central Semi PN4250A
I also found, via Arrow unsolicited suggestion
On Semi PN200A This one is end of life
MPSA42 is suggested in a DIY thread as a substitute for the obsolete MPSL01
The only remaining parts in the schematic not discussed are the casode parts which I think can be just about any of the usual VAS/video parts. I will have a try with KSC2690AY/KSA1220AY.
Mouser and Digikey are both sources for these compenents.
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