ua208a

[bitrex]

Is there a suitable modern replacement for the ua208a TO-99 can-type
op amp as used in e.g. the HP oven oscillators, that's available and
doesn't cost an arm and a leg?

<https://datasheetspdf.com/pdf/1305470/Fairchild/UA208A/1>

Probably less expensive to just buy another module, maybe

[Peter W.]

Have you tried Fairchild directly? They may have attic stock somewhere.

https://www.semiconductor-technology.com/contractors/component/fairchildco/

Peter Wieck
Melrose Park, PA

[bitrex]

I haven't. Rochester has some possibly appropriate subs but there's
relatively large minimum quantities:

<https://www.digikey.com/en/products/detail/rochester-electronics-llc/PM1008AJ/12120663>

I'd tend to guess anyone with "attic stock" doesn't want to deal in
onsies and twosies, either.

This site lets you add onsies and twosies to the cart of Rochester items
but seems a bit sus:

<https://www.sinlinelec.com/>

And there's always fleabay mystery meat:

<https://tinyurl.com/ms38bfxd>

Finding a sub among other things means it's specced to the mil
temperature range, -55 to 125 C. A cool thing about the CA3140 is most
variants in DIP have that spec which I believe is a little unusual,
unfortunately since it's a FET input even the boutique grade of it has
offset voltage too high.

[Peter W.]

> I'd tend to guess anyone with "attic stock" doesn't want to deal in
> onsies and twosies, either.

My experience has been exactly the opposite. Worth a shot in any case.

[bitrex]

Oh nice, OK good to know thank you

[jf03...@gmail.com]

I think this is just the Fairchild equivalent of the National LM108/2008/308 series, with the LM108 being the high-spec version and the LM208 and LM308 being cheaper versions. The LM part numbers are readily available on the bay and probably from your favorite surplus electronics dealer (especially if the LM308 is good enough for you).

[bitrex]

It's pretty close, though the 208 has tighter V offset max, 0.5 mV vs 2.

Under the circumstances (of it not being the year 1980, say) the 108
might be the best compromise

[Dave Platt]

In article <e4791536-d5a1-4b2c...@googlegroups.com>,

There are also plenty of more modern high-spec single op amps in small
SOIC-8 and DIP-8 packages. Brown Dog makes an adapter (020601A) which
accepts a DIP-8 IC, and converts to a TO-99 circular pinout pattern;
you can buy it either with or without pins installed for the TO-99, and with
or without a socket.

The ua208a has provisions for a compensation capacitor; you might find
that modern unity-gain-stable op amps are fast enough and stable
enough that you could simply ignore this (leave the TO-99 pins
unconnected).

[bitrex]

On 8/25/2022 8:24 PM, Dave Platt wrote:
> In article <e4791536-d5a1-4b2c...@googlegroups.com>,
> jf...@my-deja.com <jf03...@gmail.com> wrote:
>> On Thursday, August 25, 2022 at 8:26:24 AM UTC-7, bitrex wrote:
>>> Is there a suitable modern replacement for the ua208a TO-99 can-type
>>> op amp as used in e.g. the HP oven oscillators, that's available and
>>> doesn't cost an arm and a leg?
>>>
>>> <https://datasheetspdf.com/pdf/1305470/Fairchild/UA208A/1>
>>>
>>> Probably less expensive to just buy another module, maybe
>> I think this is just the Fairchild equivalent of the National LM108/2008/308 series, with the LM108 being the
>> high-spec version and the LM208 and LM308 being cheaper versions. The LM part numbers are readily available on
>> the bay and probably from your favorite surplus electronics dealer (especially if the LM308 is good enough for
>> you).
>
> There are also plenty of more modern high-spec single op amps in small
> SOIC-8 and DIP-8 packages. Brown Dog makes an adapter (020601A) which
> accepts a DIP-8 IC, and converts to a TO-99 circular pinout pattern;
> you can buy it either with or without pins installed for the TO-99, and with
> or without a socket.

That'd be a helpful tool

> The ua208a has provisions for a compensation capacitor; you might find
> that modern unity-gain-stable op amps are fast enough and stable
> enough that you could simply ignore this (leave the TO-99 pins
> unconnected).

OPA228PA is a nice precision OA with the mil spec temperature range:

<https://www.mouser.com/ProductDetail/Texas-Instruments/OPA228PA?qs=7nS3%252BbEUL6ulkTCjUT78yA%3D%3D>