On Tue, 29 Nov 2016 22:48:31 +0100, "Carlos E.R."
wrote:

My clocks (I have 4) do not have a ferrite rod, like those in the
wikipedia. Unless minimal and well hidden.

They have ferrite rods buried inside somewhere. Even the "atomic
wris****ch" has a tiny loopstick coil inside. Look for something like
these, which are a bit large for a wrist watch:
http://www.c-max.com.hk/en/technology/rct/rct_perp
http://www.c-max-time.com/products/showProduct.php?id=20
The key performance factor of a VLF receiver is the Q of the pickup
coil. Higher Q doesn't produce more signal, but does dramatically
reduce the inband noise levels. The higher the Q, the less noise is
picked up, and therefore the better the SNR (signal to noise radio).
Tiny rods are marginal, but do work. Big rods are much better for
reception. Big loops are even better, but without the ferrite core,
they tend to be huge.

Photos of both loops and loopsticks:
https://www.google.com/search?q=wwvb+loop+antenna&tbm=isch

It can easily be done with a Raspberry Pi.
http://www.satsignal.eu/raspberry-pi/DigitalClock.html

Interesting, but complicated.

If it were easy, it would probably not be any fun.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558