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

[Tobias Pluess]

Hi Tim
it is this amp which I mean:

http://www.techlib.com/files/lowamp.pdf

Actually I dont care too much about TO92 because I mostly use SMD parts
anyways. Using dead-bug technique, they are even suitable for prototypes
and experiments.

Tobias


On Sat., 4 Apr. 2020, 13:41 Tim Shoppa, <tshoppa at gmail.com> wrote:

> 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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