-=> Roy J. Tellason said to Greg Mayman
 -=> about "BAG OF CHIPS" on 01-22-04  04:07.....

 RJT> Yeah,  I remember seeing them and thinking "Now I don't have to bother
 RJT> with _THAT_ any more...!"

Yup. Me too!

 RJT> In those days I was a little fuzzy about what slew rate implied.  :-)

So was I. I knew it had something to do with increasing distortion
at high frequencies, but I didn't really start to understand it
until I actually saw it on a CRO.

 RJT> They were still useful,  though.  And really,  how often do you need
 RJT> that wide a voltage swing in most stuff?  I can remember running into
 RJT> it fairly seldom, the one big exception being in early analog synths
 RJT> where a 10 volt p-p waveform wasn't all that uncommon.  Most audio
 RJT> stuff is at a lot lower level, until you get into power amp stages.  I
 RJT> guess this is of more concern with other uses...

We designed a lot of broadcast studio gear using 741s and the
twin version 747. They were running at a nominal 100mV RMS, and
at the peak rating of the equipment, the level was only about 3v
peak to peak on those stages.

The level had to be kept low as we were using FET switches, and
when the signal got too high it would turn them on and break
through on peaks. That was back in 1970 and was our first effort
at using integrated stuff.

The low level stages used Fairchild 739(?) low noise op amps that
had a single-ended output. IIRC we had to follow them with a 741
to get low enough output impedance to drive the 10k faders.

We used the same op-amps in the high level stages as that single
ended output was ideal for driving a complimentary output pair of
transistors.

 RJT> So it'd be good for picking up a weak and distant station that was
 RJT> close in the band to a stronger and more local one?  Interesting stuff!

Yup. Although you have to watch out that the adjacent channel
doesn't cause overload and intermod distortion in the IF strip if
it's much stronger than the signal you're trying to pick out.

I have an article about the advantages of sync detectors in HF
communication receivers in a "World Radio & TV Handbook" from a
few years ago, but it is 2 1/2 pages of fine print so I won't
attempt to type it up here.

From Greg Mayman, in beautiful Adelaide, South Australia
   "Queen City of The South"    34:55 S  138:36 E

... Don't EVER spend your gross salary.
___ Blue Wave/386 v2.30

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