Hi, I have an HP 5370b that uses 10V ref from an LH0070-1h. The LH0070 failed and the box won't turn on. 5370b references all voltages to that 10V. If I apply 10V, the box comes up. I have parts coming but they can take a while. I've tested a couple of refs I have, and the issue is the 16.2v regulated that is on that board, cant take much current draw as the 16.2v zener is fed by 315ohm resistor. I don't want to do much surgery on the board. The LH0070-1h is a .02% device. I can live with .1% for now. I can use a couple of 9v batteries to get ~18V but would need milliamp current draw again.
Here's what I have on-hand:
1) Qty 5 LM399H.
2) a reference module from an HP 3455 volt meter. This is the A11 board and I think that is an LM399 on it. It uses 29.5V. I've tested it and it's stable but I don't have 29.5V handy in the 5370. Just +/-15, 5.4 and 5v.
3) I have some opamps around but not an lt1001 as in the LM399 reference design I've seen. I have handy: LT1007, LMH6703, lt1677, AD706, op176(?), op(27), TL5532, TL5534, TL082, and probably others. there is an lm725H on the hp 3455 reference board.
I have lots of precision resistors, etc. If I had to drop the power, I have 3045 regulators handy.
So can I put something together with that above or do I wait?
Thanks
Jerry