[sdiy] Matched Trannies

[Yves USSON]

Hi

When one needs a matched pair of transistors (PNPs or NPNs) for 
designing an expo converter or
for a moog transistor ladder the existing solutions are SSM2220, 
SSM2210, MAT03,
MAT04,2SC1583,THATxxxx... These are quite expensive. A cheap solution for NPN
matched pair is to use CA3046 or CA3086. Recently, I found another 
possible source of
matched transistors these are SMD components labelled BC857S 
(siemens, supposed to
be equivalent to two BC557 PNP) and BC847S (siemens, supposed to be 
equivalent to two BC547 NPN). These are real cheap : 0.18 euros 
(nearly 0.17$).
My question is the following :
Is there a good reason why I should not use these for designing expo 
converters or moog ladders ?
As someone in the list gave them a try ?

Thanks for your input

-- 
----------------------------------------------------------------------------------------------------------------------------
Dr Yves USSON						ph. +33 476 549 410
Equipe RFMQ, TIMC UMR5525 CNRS				fax. +33 476 549 549
Institut Albert Bonniot, Domaine de la Merci
38706 La Tronche cedex, FRANCE
  http://www-timc.imag.fr/rfmq/PAGES/Y-USSON/