[time-nuts] A couple of Tbolt questions

[Tom Van Baak]

> Unfortunately I can't help with the phase noise measurements either right  
> now but it does seem like an area worthy of further investigation.
> 
> regards
> 
> Nigel
> GM8PZR

Since I have fancy phase noise systems and references here
I ran both ADEV and phase noise measurements on *every*
TBolt to make sure the ones that went to TAPR were all good.
(Now you know why months go by between TAPR group buys).

Typical TAPR Thunderbolt phase noise is about -100 dBc/Hz
at 1 Hz, falling to about -150 at 100 Hz, with a floor just above
-160 beyond 10 kHz. Variations on this, and spurs, seem to be
a function mostly of power supply. For example, see:
http://www.leapsecond.com/pages/tbolt/noise.htm

I would be very surprised if *any* TAPR TBolts showed much
worse or much better PN performance that what you see at:
http://www.leapsecond.com/pages/tbolt/spec-hp.gif

I can't make any claim about the untested TBolts that you see
on the global surplus market. A number of them have problems
and they go on my discard pile.

If you have a pair of OCXO that you'd like me to measure here
in my lab, contact me offline. I take equal delight in unusually
good as well as unusually bad examples. Arnold, I'd be happy
to independently test your two samples. Perhaps this would
shed light on what that little "phase noise" label means.

/tvb
http://www.LeapSecond.com