OneRoomStudios

FT: Vintage clear-potted JH 990
« on: February 20, 2019, 03:03:30 PM »
I have a cool old clear-potted John Hardy 990. Unfortunately for me, it's a 24V version, and most of what I'm building lately is in 500 series format, so it does me no good. Anyone want to trade a 990C or maybe a pair of something like gar2520's or gar1731's for it? It's a cool piece of history, looks cool, and functions exactly like a 990C (but only at +/- 24V).
« Last Edit: February 26, 2019, 12:52:28 PM by OneRoomStudios »


Phrazemaster

Re: Cool clear-potted JH 990 for trade
« Reply #1 on: February 20, 2019, 05:00:08 PM »
Are your sure about this?

I bought some 990's directly from JH years ago, and while they do work fine at +/-24V, they also worked down to at least 16V if memory serves.

You might try calling him directly - he's super friendly and can tell you one way or the other.

Mike
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OneRoomStudios

Re: Cool clear-potted JH 990 for trade
« Reply #2 on: February 20, 2019, 06:06:14 PM »
Are your sure about this?

I bought some 990's directly from JH years ago, and while they do work fine at +/-24V, they also worked down to at least 16V if memory serves.

You might try calling him directly - he's super friendly and can tell you one way or the other.

Mike

Thanks Mike. I already talked to John about this one. It's not the 990C version that works at multiple voltages, it's the earlier 990 version (no "C"), that only works at the specified voltage. This one happens to be a 24V version.

To quote John:

"The clear 990 is not a "C" version. If it was a "C" version, it would say "990C" (or, "990C+" for the latest variation  -- see the 990 data package for details). The clear 990 is the "original" version, so it is designed to work at specific power supply voltages. On the bottom of the clear 990 it will show the power supply voltages it is intended to work at, either "12V", or "15V", or "18V", or "24V", meaning +/-12VDC, +/-15VDC, etc. The "C" version has additional circuitry so that it can operate over a wide range of power supply voltages, anywhere from +/-12VDC to +/-24VDC.

The clear 990 and the 990C should work identically, assuming you run the clear 990 at the proper power supply voltages.

They were manufactured from 1979 until about 1988 when I decided to use an aluminum potting shell for each 990. The two large output transistors of the clear 990 are plainly visible. For the "C" version those two transistors were moved to the edge of the circuit board so they could be in direct contact with the wall of the potting shell for maximum heat-sinking. It is not as fun to look at as the clear 990s, but it is a better package thermally."

Phrazemaster

Re: Cool clear-potted JH 990 for trade
« Reply #3 on: February 20, 2019, 09:00:57 PM »
Thanks Mike. I already talked to John about this one. It's not the 990C version that works at multiple voltages, it's the earlier 990 version (no "C"), that only works at the specified voltage. This one happens to be a 24V version.

To quote John:

"The clear 990 is not a "C" version. If it was a "C" version, it would say "990C" (or, "990C+" for the latest variation  -- see the 990 data package for details). The clear 990 is the "original" version, so it is designed to work at specific power supply voltages. On the bottom of the clear 990 it will show the power supply voltages it is intended to work at, either "12V", or "15V", or "18V", or "24V", meaning +/-12VDC, +/-15VDC, etc. The "C" version has additional circuitry so that it can operate over a wide range of power supply voltages, anywhere from +/-12VDC to +/-24VDC.

The clear 990 and the 990C should work identically, assuming you run the clear 990 at the proper power supply voltages.

They were manufactured from 1979 until about 1988 when I decided to use an aluminum potting shell for each 990. The two large output transistors of the clear 990 are plainly visible. For the "C" version those two transistors were moved to the edge of the circuit board so they could be in direct contact with the wall of the potting shell for maximum heat-sinking. It is not as fun to look at as the clear 990s, but it is a better package thermally."
I  stand corrected. Thx for the informative response.
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***************
************
********
*****
** * Kablooie!

OneRoomStudios

Re: Cool clear-potted JH 990 for trade
« Reply #4 on: February 21, 2019, 03:30:34 PM »

OneRoomStudios

Re: FT: Vintage clear-potted JH 990
« Reply #5 on: February 26, 2019, 12:52:37 PM »
bump

Re: FT: Vintage clear-potted JH 990
« Reply #6 on: February 28, 2019, 02:09:19 AM »
Pm'd
F-in' hook some Sh*t up and see if it catches on fire; try to have a good idea about what might and might not catch on fire in the first place. -emrr

OneRoomStudios

Re: FT: Vintage clear-potted JH 990
« Reply #7 on: March 10, 2019, 06:43:19 PM »
bump

OneRoomStudios

Re: FT: Vintage clear-potted JH 990
« Reply #8 on: March 18, 2019, 10:44:53 AM »
Another bump. Someone's got to want this piece of history.

Re: FT: Vintage clear-potted JH 990
« Reply #9 on: April 04, 2019, 11:57:02 AM »
I would be happy to trade a working gar2520 for this. I would really like to have two, if you happen to know where another one can be found!


OneRoomStudios

Re: FT: Vintage clear-potted JH 990
« Reply #10 on: April 10, 2019, 12:06:31 PM »
Unfortunately I only have the one. I was hoping to get more than just one gar opamp for this one since it is rare and all. If there's no interest in that, I'll probably just hold on to it.

OneRoomStudios

Re: FT: Vintage clear-potted JH 990
« Reply #11 on: April 22, 2019, 03:16:04 PM »
Bump.

I'm open to other stuff for trade. Have cool transformers? Other opamps? Some other cool thing?


 

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