The finger as an Analog Development Tool (was IC capable of driving 30MHz 10 Vp sin into 300pF)

Joseph2k wrote...
>
> I had been thinking along the lines of the old Teledyne Philbrick
> 1443 ultrafast buffer; it would do at least 100 MHz drive over 2A
> and would slew about 2500 V/us.

The 1443 data*** features a page of Hi-Frequency Troubleshooting
Techniques, well worth a re-read. I enjoyed this paragraph on
page 6, under, The finger as an Analog Development Tool.

"In 15V systems, the finger can be a useful investigative tool,
if thoughtfully applied. It can couple signals in and out and
can also be used as a load. A well-laid-out RF opamp circuit
will be only slightly affected by a light touch. Dramatic
changes reveal a sensitive point! Check a circuit by touching
the amplifier case, the supply rails (carefully), ground, control
knobs, chassis parts, etc. If things change markedly when you
touch these areas, parasitics may be the problem."

> The stuff Apex is putting out now make it look like junk.

I dunno, they go to higher voltages, but none of them slew as
fast as the 1443, for example. Sadly, this limits the value
of their higher-voltage capability to below say 5 to 10MHz.
For example, their PA19 only slews to 1000 V/us, which means
its 60Vpp 2A capability is limited to below 4MHz. Sorry!


--
Thanks,
- Win
.

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