Hamfest find today: HP59309A Clock

[Adam Vaughn]

Not sure that the size of 9V batteries has changed a whole lot since the '70s, but I could be wrong. With something as complicated as this, I'd want to use external batteries anyway, since it probably wouldn't take much battery leakage to mess up the boards. Granted, this was more true in the days of carbon-zinc batteries, but still.

I talked with the seller when I bought the clock, and he said that he wanted to be able to toggle the display on continuously rather than having to press the button every time he wanted to see it. From what I've heard, there's a switch or whatnot somewhere in the unit which indeed sets the display to light continuously, but I'm not sure if he knew about it. In any case, I tend to have the display turned off unless I'm standing near it. It didn't come with a backup supply, so I rather doubt that he used it with one.

Good luck on the frequency standard. I was hoping to be able to use my Heathkit GC-1000 "Most Accurate Clock" to keep the 59309A in-line, but the GC-1000's output is 3.6MHz (why??!?!?!?!), so it'd probably be more difficult than it's worth to convert it to 1, 5, or 10MHz. I also have yet to quantify exactly how much the 59309A's internal oscillator drifts; I have the service manual for it around here somewhere, but I'm not sure if it mentions calibration methods.
-Adam