I'm browsing eBay and I find a guy selling
two six HP 3455A references , but he thinks they are crystal oscillators (I guess they look the same to him )
These are HP part numbers 11177B.
- The HP3455A was a 6 digit DVM introduced around 1977/78 I think.
- The reference is a 10 volt reference, well aged by now, and thus will be stable as hell, probably down to 1 ppm per year.
- The core of the reference is a heated zener in a can, HP part 1902-0926, that is very similar to the LM399 (maybe even the same part? Vincent, do you know? )
- The 3455A is described here in the HP Journal: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1977-02.pdf
The reference board also contains about 4 or 5 0.01% 1 ppm divider resistors in hermetic cans. Those alone are worth $30 - $50 each if you try to buy them new.
He's asking $49.00 + shipping, but he's also taking best offers, so if you're looking to build a 10V bench reference then you might be able to get a stable, 10V, heated reference for much less than the $129.00 + shipping that the 3458A references are going for (of course the 3458A refs are also LTZ1000's, I know). It's certainly going to be better than the many plastic chip references that are available from $49 - $100+, that aren't going to be nearly as stable as these HP3455A references will be.
Here is the links:
http://www.ebay.com/itm/HP-11177B-00252-CRYSTAL-OSCILLATOR/161612819510http://www.ebay.com/itm/HP-11177B-01723-CRYSTAL-OSCILLATOR/151599716338http://www.ebay.com/itm/HP-11177A-12883-CRYSTAL-OSCILLATOR/151599739448http://www.ebay.com/itm/HP-11177A-11236-CRYSTAL-OSCILLATOR/151599699094http://www.ebay.com/itm/HP-11177A-12933-CRYSTAL-OSCILLATOR/151599686056http://www.ebay.com/itm/HP-11177A-304-11177-69501-CRYSTAL-OSCILLATOR/151599695954Note that there is some A and B models here.. the picture below is the B model. According to the schematic, the A model has a zener in a can with a heater, and the B model has a temperature compensated zener in a can with a heater,
AND the heater current is in a feedback loop with the diode output voltage. The A models, while still good, are not going to be as stable as the B models.
Why am I posting here, instead of buying these up myself?? Because I'm quite literally broke, and looking for work. I need to save all I can, and as much as I'd love to have this for myself, I don't need it. But I would love to see some EEVblog forum user do something worthwhile with it at a bargain price.
(PS: I am not the seller, the seller is in Texas but will ship worldwide. I am in Canada. Still, you buy at your own risk, since there is no indication that these even work still !)
Here's some pics of the same reference from a random blogger:
http://www.simonsdialogs.com/?p=1209