some UK based seller via ebay offers matched 3503/1381 pairs F suffix. But alas...no brand. I think these are fake . From Reichelt i got D and E the hfe difference at 30 mA 10 volts is quite high
Having worked for a semiconductor maker myself i doubt that someone would produce CRT drivers as there is no demand. The problem is the substrate, the initial doping of the wafers.
The cdil transistors are clearly marked as cdil. They are not fakes.
The real test will be how closely they get to the published datasheet performance/specification.
The real test will be how closely they get to the published datasheet performance/specification.
I don't think CDIL's website is well maintained/updated, so I wouldn't jump to conclusions on that basis. And it doesn't make sense to me, that a fake Sanyo (or Fairchild) transistor would be labelled CDIL... Even so, it would be nice with some confirmation of the origin and the performance of these devices..
>Edit: I will email the supplier (Reichelt.de) and ask them.
>Edit: I will email the supplier (Reichelt.de) and ask them.
On Reichelt the 2SC3503 is apparently Sanyo brand, the 2SA1381 can be also the KSA1381.
This provider usually provides the datasheet based on the brands it sells and if it was CDIL the datasheet would be for CDIL.
This provider usually provides the datasheet based on the brands it sells and if it was CDIL the datasheet would be for CDIL.
Well they are for sure not Sanyo devices, and in my experience, Reichelt often has datasheet from one manufacturer listed, even though the actual transistors are from another. I order from them on a regular basis, and have seen this a few times. But I have just sent them an email, and will post here when I get a reply..
On AmpsLab you can find 2SA1380 / 2SC3502 of Sanyo origin that will fit perfectly but in batch of 20 pieces and quite expensive.
2SC3502 2SA1380 SANYO - Buy Online @ AmpsLab
2SC3502 2SA1380 SANYO - Buy Online @ AmpsLab
I can be certain that no semiconductor maker will produce CRT drivers as there is no profit.
Demand is far too low. I tested alternatives based on schematics by Harman Revox and some others these are cascodes of "normal" audio Bjts also folded cascodes.All these require low driving impedance. The simplest is a folded cascode used in an old AVM CFA topology. But given that the Spice models of 1380/3503 are correct these come out as the best VAS. The disadvantage is that these are best for audio at rather low collector currents which is quite obvious from the respective data sheets. But one has to cope with that alternatives for 2SA1380 / 2SC3502 must be found and be well designed.
Demand is far too low. I tested alternatives based on schematics by Harman Revox and some others these are cascodes of "normal" audio Bjts also folded cascodes.All these require low driving impedance. The simplest is a folded cascode used in an old AVM CFA topology. But given that the Spice models of 1380/3503 are correct these come out as the best VAS. The disadvantage is that these are best for audio at rather low collector currents which is quite obvious from the respective data sheets. But one has to cope with that alternatives for 2SA1380 / 2SC3502 must be found and be well designed.
Yes CDIL = Continental Device India Ltd, who makes a range of transistors (since 1964 they write!), no doubt about that.
But the question at hand here, is whether they in fact make these SA1381 and SC3503, that are now available from Reichelt.de, or if these "new" SA1381 and SC3503 are fake, perhaps re-marked inferior transistors of some other make.
hahfran believes them to be fake, and I am starting to think he might be right, as the "CDIL" TO-126 case is the thin version, as opposed to the Sanyo and Fairchild, that come in a "fatter" TO-126 package :/
But the question at hand here, is whether they in fact make these SA1381 and SC3503, that are now available from Reichelt.de, or if these "new" SA1381 and SC3503 are fake, perhaps re-marked inferior transistors of some other make.
hahfran believes them to be fake, and I am starting to think he might be right, as the "CDIL" TO-126 case is the thin version, as opposed to the Sanyo and Fairchild, that come in a "fatter" TO-126 package :/
No is not!
See here http://www.diyaudio.com/forums/solid-state/237512-2sc3503-2sa1381-source.html#post3523743
and my post above.
BR, Toni
P.S.: measurements far away from 2SC3503 and KSC3503. I throw mine into bin.
Yes Toni,you are on the right way!
I believe that these 2SA1381-3503 from Reichelt are fake!
Long time ago a friend from Germany had donate me 2 pre assembled Slewmaster boards.
Guessing that he had troubles with them i looked what is the fault.
Looking at the predriver stage i saw those unknown, non insulated, 2SA1381-2SC3503 .
Replacing them immedeately with the KSA1281-KSC3503 i ended up with a well working amplifier.
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KSC3503/KSA1381 are not on CDIL product list nor on Sanyo's thus the only maker is onsemi but no distributor offers both with same suffix / hfe class
Reichelt does not even specify a brand any longer ... and theirs are so cheap ..suspicious
Reichelt does not even specify a brand any longer ... and theirs are so cheap ..suspicious
Reichelt says CDIL CSC3503 are genuine
Well the plot thickens, as they say 🙂
I have received a reply from Reichelt.de, and is a quote of the main point:
"We get the SC 3503 from our distributor and only authenticity goods."
They also included CDIL datasheets, which are now also available on the Reichelt product webpage. I have attached them here.
But still:
It does still seem a bit odd though, that the CDIL device is with the uninsulated TO126 package, while the Sanyo and the Fairchild KSC3503, are both in the thicker fully insulated TO126. See attached picture, where the CDIL from Reichelt.de is shown next to a KSC3503 I have from Mouser.
Also, a simple capacitance measurement at 1Khz from Collector to Base, gives very different results:
Fairchild: 135 pF.
CDIL: 1430 pF.
So I don't know, but would like to..
And perhaps this is getting too far off-topic, and further discussion should be moved to a dedicated SC3503 thread, such as the one linked to above somewhere:
2SC3503+2SA1381 E or F source?
Well the plot thickens, as they say 🙂
I have received a reply from Reichelt.de, and is a quote of the main point:
"We get the SC 3503 from our distributor and only authenticity goods."
They also included CDIL datasheets, which are now also available on the Reichelt product webpage. I have attached them here.
But still:
It does still seem a bit odd though, that the CDIL device is with the uninsulated TO126 package, while the Sanyo and the Fairchild KSC3503, are both in the thicker fully insulated TO126. See attached picture, where the CDIL from Reichelt.de is shown next to a KSC3503 I have from Mouser.
Also, a simple capacitance measurement at 1Khz from Collector to Base, gives very different results:
Fairchild: 135 pF.
CDIL: 1430 pF.
So I don't know, but would like to..
And perhaps this is getting too far off-topic, and further discussion should be moved to a dedicated SC3503 thread, such as the one linked to above somewhere:
2SC3503+2SA1381 E or F source?
Attachments
The updated CDIL product site all transistors has no CSA1381 no CSC3503 ....something fishy going on....if one has no alternative circuit he must buy the onsemi/Fairchild from Mouser however with non matching gain