[time-nuts] high rev isolation amps

Tim Shoppa tshoppa at gmail.com
Wed Mar 30 11:18:19 EDT 2016


I usually call those "CATV transistors" :-). 2N5109 etc. They also have
very reasonable power dissipations and despite being "UHF transistors" they
are most commonly used today in low-frequency work where high IP3 is
crucial.

That said, it is possible that going to multiple consecutive common-base
stages with jellybean transistors, is good enough, that layout and
packaging become more important than using specialized transistors.

There's a real beauty to many of the NIST designs - using topology and
jellybean parts to achieve the performance, rather than selected devices.

Tim N3QE

On Wed, Mar 30, 2016 at 2:28 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> --------
> In message <FD679D47-7F70-4055-AB68-A6AEA6E95D9A at n1k.org>, Bob Camp
> writes:
>
> >There were (and maybe still are) SOT-89 versions of the 2N3804 and
> >3906. They will handle more power than most of the other versions.
> >That gives you better Vce on the string. They also have less
>
> Stupid question:  I would have expected them to use capacitance
> optimized transistors, also known as UHF transistors ?
>
> Something like BFQ19 maybe ?
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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