[time-nuts] Power and heat re: Heathkit WWV clock / where are the good oscillators?

[Joe Duarte]

Hi all – I've been reading up on the *Heathkit GC-1000 Most Accurate Clock*
from the 1980s, which syncs with WWV. I've seen numerous reports of the
flawed power supply and regulator, and the intense heat it generates in the
chassis, and I'm stumped. Why does it need so much power that it's getting
hot? There's hardly any computation involved in syncing with WWV, decoding
its BCD bitstream, etc. Can I expect similar issues if I build my own clock
instead of restoring a GC-1000?

Quartz watches can sync with WWVB and run for a couple of years on, what,
≈200 mAh coin cells? I'm amazed that some are able do GPS, which is far
more computationally taxing, but I think most of those are solar with a few
months of battery backup. I don't understand why a WWV clock isn't sipping
milliamps in cool silence like a watch. Is it something to do with the WWV
medium band frequencies (5-15 MHz) compared to WWVB's long wave (60 KHz)?
(Why did Heathkit sync to WWV and not WWVB? I thought the latter has less
propagation delay.)

The oscillator runs faster than a standard 2^15 Hz movement, but so do lots
of high accuracy quartz watches. I've looked for an Omega quartz ship's
chronometer from the early 80s, but they're too rare apparently. It has a
2^22 Hz oscillator and runs for a couple of years on two AA batteries.
(Scroll down to the ship's version:
https://en.wikipedia.org/wiki/Omega_Marine_Chronometer) And the new Citizen
Caliber 0100 movement runs at 2^23 Hz, in a watch... (
https://www.hodinkee.com/articles/citizen-eco-drive-caliber-0100-review)

By the way, why am I not finding any RTCs better than 20 or 15 seconds per
month accuracy? I've looked on Mouser and Digikey. It's like there's been
no progress since the 80s. That Omega was good for maybe 0.4 sec/month
drift, worst case, and the new Citizen is unbelievable at under 0.1
sec/month. What performance can we expect in a disciplined oscillator like
the GC-1000's? I haven't found any specs on its *endogenous* accuracy after
some break-in period with enough disciplining. I'd like to have less than
0.1 sec/day between syncs – syncing isn't possible at all hours, and GPS
won't work for my application. So a 3 sec/month clock on its own. The world
is full of quartz watch movements more accurate than that, without needing
ovens, many dating to the 1970s, so I'm confused by why movements that sit
on a desk and never move are so subpar compared to watch movements. Has
anyone leveraged a watch movement in a desktop chassis? I wonder about the
interfaces, since they're all used in analog watches and I don't know if
they express/output time in a way that can be used by a controller.

Thanks,

Joe