[Lowfer] Lowfer Final Transistors-Switching Time

[Steve Dove]

Hi Andy, JB,

In a parallel universe I've had reason to characterize 
transistors such as these admittedly for other uses, but a 
couple of observations may be of interest.

I am old enough to remember when the Motorola databooks for 
discrete semiconductors came in six thick volumes, at least 
two of which were for small-signal transistors!  Over the 
years the choices have - reductio ad absurdum - whittled down 
to "transistor, small-signal, silicon, NPN" and "transistor, 
small-signal, silicon, PNP";  at any rate the choices are far, 
far fewer.  And if truth be told except for unusual desired 
characteristics (bandwidth, noise, voltage etc.) for the large 
majority of applications they are essentially interchangeable 
anyway.

Enter Asia, and that 'absurdity' becomes reality.  The 
distribution market is riddled with generic parts (not just 
transistors) of *anything* made in commodity quantities; 
specifically on this subject the same small-signal parts with 
different brands and numbers printed on them;  there is a good 
chance with bargain parts this printing is the only 
resemblance to the datasheet.

So, only order real devices made by a known manufacturer from 
a respectable distributor.  Digikey springs to mind.  They may 
be a bit more expensive but they DO keep an eye on this issue.

The 2N4403 is quite an extraordinary part.  As well as having 
a handy close-ish NPN complement in the 2N4401 it is fairly 
beefy, decently gainy, reasonably quick, pretty quiet, and has 
an unusually low base spreading resistance which puts it at 
its quietest at lower-than-normal input source impedances.  As 
such it has become a badly-kept secret input device for 
low-impedance microphone amplifiers and other audio 
applications, rivalling salty boutique transistors and FETs 
for pennies.

Assuming you get genuine parts.

Get a bag of 200 pieces each of the '03 and '01 Fairchilds 
from Digikey for pocket-money, and never have to say you're sorry.

         73        Steve        W3EEE/4



Andy - KU4XR wrote:
> --- On Sun, 8/1/10, John Bruce McCreath <weazle at hurontel.on.ca> wrote:
> 
> 
>>What package are the 4401/4403's? 
>>
>>73, J.B., VE3EAR
> 
> 
> Hi J.B :
> 
> The 2N4401/2N4403 pair is in the TO-92 plastic package. They can be
> purchased from 6 cents to around 11 cents each depending on the
> manufacturer. Decent little transistors for lowFER PA's ... 73 ::
> 
> 
> Andy - KU4XR - EM75xr - Friendsville, TN. USA
> LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
> 
> *** Temporarily OFF, while constructing a new antenna ***
> 
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> 
> --- On Sun, 8/1/10, John Bruce McCreath <weazle at hurontel.on.ca> wrote:
> 
> 
>>Hi Andy, Lowfers,
>>
>>That's some useful data that you posted.  I can't find
>>it right now, but I recall from several years back that Bill
>>Ashlock had found a pair of transistors in the TO-220 package 
>>that worked nicely and where readily available.  What package 
>>are the 4401/4403's? 
>>
>>73, J.B., VE3EAR
>>
>>LowFER Beacon "EAR"
>>188.830 kHz. QRSS30
>>EN93dr
>>