Hamfest find today: HP59309A Clock

[BobVA]

(08-09-2016 12:23 PM)Paul Berger (Canada) Wrote:  I hope you don't have many power outages, I think setting date and time from the front panel would get old. You can connect a 9V battery internally but I am not sure how long that would last. I had one of mine connected to a pack of 6 C cells for backup power. There is a BNC connector on the back for external backup power. When using the external connector there is a jumper on the base board near the 9V battery connector that needs to be in place.

Paul.

Thanks!

Surprisingly the deal included a copy of the manual, which was interesting reading. It specifies 24 hours of backup from an internal 9v battery. Another section of the manual quotes the current draw as 2 mA at the external power terminal.

There was apparently a complementary backup battery housing (K10-59992 Standby Power Supply), the same size as the 59309A, which used "D" batteries and would allow one year of backup operation - very similar to your backup.
If I did the math correctly a 9v lithium primary battery should be good for a week or so of backup.

It's drifted about five seconds in 36 hours, so I'll check the calibration soon. Hopefully the TCXO will be the longer term fix to that. I had incorrectly assumed the internal oscillator was 10 MHz, but a closer look at the manual shows it's 1 MHz, so the one I ordered will have to go through the external reference port. I'll have to look around for a 1 MHz model.