Hello Martin and all,
The 2N3553 device was plagued with a low Ft (high at its introduction)
making it mostly a low frequency device with questionable high gain high
frequency use in typical ham preamps. It is no longer available through the
original manufacturers. Also perhaps you are thinking of the BFQ18A and not the
BFQ19A device. The BFQ19 is at end of its life cycle and in addition the 18A is
widely used now in the MATV industry for wideband amplifiers. I have some
experience with the 18A using it in a wideband Norton style amplifier where it
is providing 10+dB of gain with a measured noise figure of 2 dB on 160 meters.
Its typical IMD is at least listed at UHF on the data sheet. My IMD testing
setup is not adequate to test the range of this device but I can say that it
exceeds any other amplifiers I have built to date. I typically use the 2N3866
which unfortunately is pricing itself out of the market now. I suspect the
2N5109 will follow as inventories shrink.. A pair of the 18A devices at ~$1.00
USD each single price in a push pull Norton configuration would in my opinion
make it worth trying as a killer wideband amp.
Just my $.02 USD.
Lee K7TJR OR
-----Original Message-----
From: Topband <topband-bounces@contesting.com> On Behalf Of Martin Kratoska
Sent: Sunday, July 1, 2018 9:51 AM
To: topband@contesting.com
Subject: Topband: Any experience with 2N3553?
The 2N3553 is a brutal 7 watt device in a TO-39 metal package. Chris Trask,
N7ZMY mentioned some unparalleled IM characterics
'... The BFQ19 (made by NXP née Philips) and the NE46134 (made by NEC) are both
highly popular within the CATV industry, and are virtually identical in terms
of linearity. They compare favorably to the 2N5109 in terms of linearity,
though they pale in camparison with the 2N3553 (as do all the others)...'.
See
http://www.home.earthlink.net/~christrask/Bipolar%20Transistor%20Evaluation.pdf
2N3553 is often mentioned in transmitting applications but I was unable to find
some other details like IM, noise and gain characteristics in high DR preamps
for receiving purposes. Any experience?
73,
Martin, OK1RR
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|