I got fake 2SA1302's, 2SC3281's. 2SA1265's and 2SA3182's from Andrews
Electronics.

The 1302 and 3281 caused me a VERY expensive re-do. I broke open the failed
transistors and compared them to the original Toshiba product. Obvious
fakes. Poor finish quality, and the semiconductor dies were 1/2 the size,
which I suppose means 1/4 the rating, since in electronics, these things
often vary to the square of voltage of current.

I returned the others, but Andrews would not acknowledge they had a problem.

They were in SK bags, which means Thomson sourced them from Hu-Nos-Hu in
China and sold them to Andrews.

By the way, the 2SA1302 and 2SC3281 have been discontinued for a long time
so any "new" ones you see are probably fakes.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Karl Uppiano" wrote in message
...

"Richard Crowley" wrote in message
...
"Karl Uppiano" wrote ...
If the specs are the same, what makes them fakes?

The specs AREN'T the same. At least not at high power.

What difference would it make?

Cheap devices re-branded with an expensive part number.

Like bleaching $1 bills and printing $100 on them.

That was the answer I was looking for: The specs aren't the same. Thanks.
Who is selling transistors with fraudulent ratings? Let's list them here!

My $0.02 - Years ago I build a series of power modules using MJ15003/4 output
transistors, and although all previous modules were very stable, robust and
forgiving (with Motorola transistors), the new modules all occasionally broke
into oscillation and quickly fried. I eventually found some Motorola
transistors, which fixed the problem. All the other parts on those PCBs were
from the same bins as the previous production, so I'm fairly certain it could
only have been the fake output transistors. The supplier (a large retail / mail
order house) said they only ever had fakes, but they assured me the fakes had
exactly the same specs as the Motorola parts. Clearly they didn't work that way
(at least Ft was probably substantially different). They may not have been
inferior, just very different, although it wouldn't surprise me if the dies had
been smaller too (I didn't check that).

On Sun, 29 Feb 2004 07:10:56 -0600, "Mark D. Zacharias"
wrote:

I got fake 2SA1302's, 2SC3281's. 2SA1265's and 2SA3182's from Andrews
Electronics.

The 1302 and 3281 caused me a VERY expensive re-do. I broke open the failed
transistors and compared them to the original Toshiba product. Obvious
fakes. Poor finish quality, and the semiconductor dies were 1/2 the size,
which I suppose means 1/4 the rating, since in electronics, these things
often vary to the square of voltage of current.

I returned the others, but Andrews would not acknowledge they had a problem.

They were in SK bags, which means Thomson sourced them from Hu-Nos-Hu in
China and sold them to Andrews.

By the way, the 2SA1302 and 2SC3281 have been discontinued for a long time
so any "new" ones you see are probably fakes.

Mark Z.

Tony (remove the "_" to reply by email)

My $0.02 - Years ago I build a series of power modules using MJ15003/4 output
transistors, and although all previous modules were very stable, robust and
forgiving (with Motorola transistors), the new modules all occasionally broke
into oscillation and quickly fried. I eventually found some Motorola
transistors, which fixed the problem. All the other parts on those PCBs were
from the same bins as the previous production, so I'm fairly certain it could
only have been the fake output transistors. The supplier (a large retail / mail
order house) said they only ever had fakes, but they assured me the fakes had
exactly the same specs as the Motorola parts. Clearly they didn't work that way
(at least Ft was probably substantially different). They may not have been
inferior, just very different, although it wouldn't surprise me if the dies had
been smaller too (I didn't check that).

On Sun, 29 Feb 2004 07:10:56 -0600, "Mark D. Zacharias"
wrote:

I got fake 2SA1302's, 2SC3281's. 2SA1265's and 2SA3182's from Andrews
Electronics.

The 1302 and 3281 caused me a VERY expensive re-do. I broke open the failed
transistors and compared them to the original Toshiba product. Obvious
fakes. Poor finish quality, and the semiconductor dies were 1/2 the size,
which I suppose means 1/4 the rating, since in electronics, these things
often vary to the square of voltage of current.

I returned the others, but Andrews would not acknowledge they had a problem.

They were in SK bags, which means Thomson sourced them from Hu-Nos-Hu in
China and sold them to Andrews.

By the way, the 2SA1302 and 2SC3281 have been discontinued for a long time
so any "new" ones you see are probably fakes.

Mark Z.

Tony (remove the "_" to reply by email)

My $0.02 - Years ago I build a series of power modules using MJ15003/4 output
transistors, and although all previous modules were very stable, robust and
forgiving (with Motorola transistors), the new modules all occasionally broke
into oscillation and quickly fried. I eventually found some Motorola
transistors, which fixed the problem. All the other parts on those PCBs were
from the same bins as the previous production, so I'm fairly certain it could
only have been the fake output transistors. The supplier (a large retail / mail
order house) said they only ever had fakes, but they assured me the fakes had
exactly the same specs as the Motorola parts. Clearly they didn't work that way
(at least Ft was probably substantially different). They may not have been
inferior, just very different, although it wouldn't surprise me if the dies had
been smaller too (I didn't check that).

On Sun, 29 Feb 2004 07:10:56 -0600, "Mark D. Zacharias"
wrote:

I got fake 2SA1302's, 2SC3281's. 2SA1265's and 2SA3182's from Andrews
Electronics.

The 1302 and 3281 caused me a VERY expensive re-do. I broke open the failed
transistors and compared them to the original Toshiba product. Obvious
fakes. Poor finish quality, and the semiconductor dies were 1/2 the size,
which I suppose means 1/4 the rating, since in electronics, these things
often vary to the square of voltage of current.

I returned the others, but Andrews would not acknowledge they had a problem.

They were in SK bags, which means Thomson sourced them from Hu-Nos-Hu in
China and sold them to Andrews.

By the way, the 2SA1302 and 2SC3281 have been discontinued for a long time
so any "new" ones you see are probably fakes.

Mark Z.

Tony (remove the "_" to reply by email)

My $0.02 - Years ago I build a series of power modules using MJ15003/4 output
transistors, and although all previous modules were very stable, robust and
forgiving (with Motorola transistors), the new modules all occasionally broke
into oscillation and quickly fried. I eventually found some Motorola
transistors, which fixed the problem. All the other parts on those PCBs were
from the same bins as the previous production, so I'm fairly certain it could
only have been the fake output transistors. The supplier (a large retail / mail
order house) said they only ever had fakes, but they assured me the fakes had
exactly the same specs as the Motorola parts. Clearly they didn't work that way
(at least Ft was probably substantially different). They may not have been
inferior, just very different, although it wouldn't surprise me if the dies had
been smaller too (I didn't check that).

On Sun, 29 Feb 2004 07:10:56 -0600, "Mark D. Zacharias"
wrote:

I got fake 2SA1302's, 2SC3281's. 2SA1265's and 2SA3182's from Andrews
Electronics.

The 1302 and 3281 caused me a VERY expensive re-do. I broke open the failed
transistors and compared them to the original Toshiba product. Obvious
fakes. Poor finish quality, and the semiconductor dies were 1/2 the size,
which I suppose means 1/4 the rating, since in electronics, these things
often vary to the square of voltage of current.

I returned the others, but Andrews would not acknowledge they had a problem.

They were in SK bags, which means Thomson sourced them from Hu-Nos-Hu in
China and sold them to Andrews.

By the way, the 2SA1302 and 2SC3281 have been discontinued for a long time
so any "new" ones you see are probably fakes.

Mark Z.

Tony (remove the "_" to reply by email)

"Tony" wrote in message
...
My $0.02 - Years ago I build a series of power modules using MJ15003/4
output
transistors, and although all previous modules were very stable, robust
and
forgiving (with Motorola transistors), the new modules all occasionally
broke
into oscillation and quickly fried.snip

Thought you might all like to have a look at this link for some details on
counterfeit transistors

http://sound.westhost.com/counterfeit.htm

"Tony" wrote in message
...
My $0.02 - Years ago I build a series of power modules using MJ15003/4
output
transistors, and although all previous modules were very stable, robust
and
forgiving (with Motorola transistors), the new modules all occasionally
broke
into oscillation and quickly fried.snip

Thought you might all like to have a look at this link for some details on
counterfeit transistors

http://sound.westhost.com/counterfeit.htm

"Tony" wrote in message
...
My $0.02 - Years ago I build a series of power modules using MJ15003/4
output
transistors, and although all previous modules were very stable, robust
and
forgiving (with Motorola transistors), the new modules all occasionally
broke
into oscillation and quickly fried.snip

Thought you might all like to have a look at this link for some details on
counterfeit transistors

http://sound.westhost.com/counterfeit.htm

"Tony" wrote in message
...
My $0.02 - Years ago I build a series of power modules using MJ15003/4
output
transistors, and although all previous modules were very stable, robust
and
forgiving (with Motorola transistors), the new modules all occasionally
broke
into oscillation and quickly fried.snip

Thought you might all like to have a look at this link for some details on
counterfeit transistors

http://sound.westhost.com/counterfeit.htm

I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?

Thanks

I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?

Thanks

I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?

Thanks

I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?

Thanks

"Analogdesigner" wrote in message


I would think that if the Ft of the counterfeit output transistors
are much less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the
high gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Since the counterfeit chips are almost always appreciably smaller, they very
likely also be appreciably faster than the good originals. This can also
cause oscillation.

"Analogdesigner" wrote in message


I would think that if the Ft of the counterfeit output transistors
are much less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the
high gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Since the counterfeit chips are almost always appreciably smaller, they very
likely also be appreciably faster than the good originals. This can also
cause oscillation.

"Analogdesigner" wrote in message


I would think that if the Ft of the counterfeit output transistors
are much less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the
high gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Since the counterfeit chips are almost always appreciably smaller, they very
likely also be appreciably faster than the good originals. This can also
cause oscillation.

"Analogdesigner" wrote in message


I would think that if the Ft of the counterfeit output transistors
are much less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the
high gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Since the counterfeit chips are almost always appreciably smaller, they very
likely also be appreciably faster than the good originals. This can also
cause oscillation.

Analogdesigner wrote:
I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Actually an amp is more likely to oscillate if the Ft is higher. The
reason is that for an oscillation to occur and to be sustainable, there
needs to be enough gain around the loop at the oscillation frequency. A
lower ft device would have lower gain at the frequencies where
oscillations may occur. Although in general, you need to analyze the
circuits, take into account all the parasitics, especially the power
supply coupling paths and the various loading on the amp, to see if the
circuit is stable or not.


Thanks

Analogdesigner wrote:
I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Actually an amp is more likely to oscillate if the Ft is higher. The
reason is that for an oscillation to occur and to be sustainable, there
needs to be enough gain around the loop at the oscillation frequency. A
lower ft device would have lower gain at the frequencies where
oscillations may occur. Although in general, you need to analyze the
circuits, take into account all the parasitics, especially the power
supply coupling paths and the various loading on the amp, to see if the
circuit is stable or not.


Thanks

Analogdesigner wrote:
I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Actually an amp is more likely to oscillate if the Ft is higher. The
reason is that for an oscillation to occur and to be sustainable, there
needs to be enough gain around the loop at the oscillation frequency. A
lower ft device would have lower gain at the frequencies where
oscillations may occur. Although in general, you need to analyze the
circuits, take into account all the parasitics, especially the power
supply coupling paths and the various loading on the amp, to see if the
circuit is stable or not.


Thanks

Analogdesigner wrote:
I would think that if the Ft of the counterfeit output transistors are much
less than the original part then oscillation will result.
The phase shift will occur at the output stage and feed back to the high
gain input stage resulting in oscillation.

Anyone well versed in control theory to verify this?


Actually an amp is more likely to oscillate if the Ft is higher. The
reason is that for an oscillation to occur and to be sustainable, there
needs to be enough gain around the loop at the oscillation frequency. A
lower ft device would have lower gain at the frequencies where
oscillations may occur. Although in general, you need to analyze the
circuits, take into account all the parasitics, especially the power
supply coupling paths and the various loading on the amp, to see if the
circuit is stable or not.


Thanks