[time-nuts] Buffer amplifier, OP Amp, vs MMIC, vs discrete?

[Tim Shoppa]

Tobias, are you talking about the Wenzel AF Preamp
that uses paralleled JFET's? That uses a 2SK369 JFET which is actually
still in production and distribution and commonly available in TO-92 even.

(Contrast with J310 which was once pure jellybean but today no longer made
new in TO-92!!!)

Tim N3QE

On Fri, Apr 3, 2020 at 7:55 PM Tobias Pluess <tpluess at ieee.org> wrote:

> Hi Taka
>
> what are those discrete amp designs you mention? I have seen some, but not
> those you mention. These which I have seen seem to be quite dated, use
> strange or old parts (selected 2SC... transistors which are not so easy to
> obtain here) or have other issues.
> There is also the Wenzel amp, but building it seems to involve some black
> magic as it works only with some very sophisticated, selected, exotic parts
> and I have never seen a proper explanation about how it really works and
> how the part values are calculated (for example if you want to change the
> gain).
> As I am (mostly) not afraid of discrete circuits it would be interesting to
> which designs you mean.
>
> Best
> Tobias
> HB9FSX
>
>
> On Sat., 4 Apr. 2020, 00:07 Taka Kamiya via time-nuts, <
> time-nuts at lists.febo.com> wrote:
>
> > I'm seeing a fairly obvious trend on this list.  When it comes to buffer
> > amplifiers, many people, in fact, most I've seen recommends fast OP Amp.
> > Discrete Amp, such as ones from K5FX design, NIST design, Clifton amp,
> and
> > others are mentioned only sometimes.  Trends are similar for distribution
> > amps.  Video amps are generally not recommended.
> >
> > But I have never seen a suggestion of MMIC like ones from Mini-circuits.
> > There are few that work from DC, fairly good NF, but often too high of
> > gain.  Other than high gain, are there reason NOT to use MMIC?
> >
> > ---------------------------------------
> > (Mr.) Taka Kamiya
> > KB4EMF / ex JF2DKG
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