You are right Alison indeed. In one old fujitsu monitor video stages,
I found 3 1,2ghz hitachi wide band transistors 2sc4308, 4pf
capacitance. There is also several wats output video amplifier
transistors 2s3953 by sanyo ft 400mhz 2,7 pf capacitance 8w.
Also driver for them is 2sc2705 by toshiba pct based technology, 1,8pf
ft 200mhz, 0,8w. Comonly used universal transistor in most of the
stages is 2sc458, hitachi, 3,5pf ft around 200 mhz. In my opinion
2sc945 has the most linear characteristics upon current change. So
this is good guideline for salvaged parts. cs9018 and cs9016 from old
disfunct radio receivers of taiwaniese origina are excellent and have
love noise figure.
73 de
Max 4N1ZM
--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
--- In BITX20@..., "Max" <m_orwell@y...> wrote:
I dont agree. PCT process is newer than used for 2n2222. As far
as I
remeber of some article from 1982. This gave lower capacitance
and
noise than usuall transistor technology.
Yes it did yeild both lower noise and better gain. That still does
not make the 2sc1815 a good transistor at more than 1/10th it's Ft
in other than common base circuits. However there were other
transistors developed with that process that were good to much
higher
frequencies.
As to the 1982 process for the 2n2222. That was then. There is
such a thing as the 2n2222A and the process is epitaxial planar
which over time evoled and also produces very good devices good
to GhZ range. The problem is that current (last 10 years)
manufacture devices are likely to be far better than earlier
do to process changes that must be implmented to keep the
manufacturer profitable.
Also most metal can transistors often ehhibit higher capacitances
as a side effect of the much higher power dissapation capability.
However:
The 2n2222 is a 300mhz Ft with a 500mw power dissipation and can
switch 800ma. Noise figure is 4db at audio.
The 2n3904 is a 350mhz Ft with 500mw power dissipation and can
switch 300ma. Noise figure is 5db at audio.
The 2sc1815 is a 80mhz Ft (at 1ma) and increses to 500 at 150ma.
It has a 400mw dissipation and can switch 150ma. Noise is 1DB at
audio with a maximum of 10db. Looking at the curves the device
is also optimized for 6V applications. The gain curves and Ft
curves indicate this device as optimal for amplifiers which use
negative AGC (gain reduction with reduced bias).
While the 2n2222 maybe a rough call due to origins (not all are
good quality) the 2sc1815 is not suitable for the bidirectional
amplifiers without paying close attention to applied bias and
collector load impedence. Myself I'd not use it in a feedback
amplifier those as a oscillator I'd expect excellent results.
Allison
--- In BITX20@..., "Arv Evans K7HKL" <arvevans@e...>
wrote:
Hi
The 2SC1815 is the 2N2222 of transistors in Japan. It is even
more
plentiful and readily available there than the ubiquitous
2N2222 is
in
other countries. While they are usually of quite high quality,
I
suspect
the main reason that Sunamura JF1OZL uses so many of them is
that
they are
plentiful and relatively inexpensive.
Arv
_._
On Thu, 25 Aug 2005 19:06:45 -0600, Max <m_orwell@y...> wrote:
2SC1815
--
Life is too short to be serious. 8-)
