A little OT but interesting: Speaking of atomic clocks - reading through the 'uncurated' CA thread on the W4S Recovery - this link was posted -

http://audiotechnologies.gr/index_files/Page311.htm
This company Audio Technology makes some neat gear- like a tubed DAC that can be ordered with a OXCO clock or a Rubidum atom clock. The

USBP-11

USB player

It's a USB only DAC - comes std with the generic TXCO JYEC clocks for 870 Euros, but for another 700 Euros can be ordered with OXCO clocks of their making.

And for ANOTHER 2500 Euros with an ATOMIC clock. A very nice Rubidium one! This really has my interest. To bad it's limited in inputs to only USB.

But they do sell the Rubidum clock separately for 3650 Euros called the RCG-10:

So here is the interesting part - they quote the phase noise numbers for all three clocks: the TXCO, OXCO, and the Atomic - so to compare to the NDKSD and the CCHD- 575:

Numbers in this order: Atomic Rubidum clock, OXCO, CCHD-575, NDK SD, TXCO JYEC (this is the 1st time I have seen accurate measurements for OEM JYEC TXCO clocks at 10Hz - these are often relabled 'Gustard', 'Melodious', 'Vanguard', etc...):

10 Hz: -120dB, -110dB, -100dB, -112dB, -90dB

10KHz: -150dB, -140dB, -163dB, -156dB, -120dB

Soooo the at 10Hz the Atomic and OXCO are clearly far superior to the TXCO's even the NDK and CCHD - BUT!...

At 10KHz the Crystek CCHD-575 crushes! With the best reading by far -23dB better then the OXCO and -13dB better then the $4000 Rubidum clock. The NDK SD is also excellent. closer at 10Hz to the much more expensive alternatives - and not too far behind the CCHD at the high end.

Reminder the X-1 uses the NDK SD's and the F-1 the CCHD-575's - the el cheapo JYEC TXCO are not in the same league with either. Yet these are the clocks that the Gustard, Breeze, Melodious use.

One note the Rubidum and OXCO clocks do have greater stability then the TXCO's: in decending order (all plus or minus) .000007ppm, 0.1ppm, 20ppm, 20ppm, 1ppm

So these more expensive clocks have orders of magnitude greater stability. And over time TXCO's have greater drift - Crystek quotes 3ppm the 1st yr, <1ppm after.

Click to expand...