[time-nuts] Recommendations for a newbie?

[Robert Liesenfeld]

Hello-

My name is Robert Liesenfeld, I discovered this mailing list via the
fascinating website leapsecond.com.  I'm an amateur radio operator (AK6L)
and builder, and my interest in precise timekeeping initially stemmed from
simply wanting a very accurate clock source to which I could reference my
test equipment (counter, spectrum analyzer, etc), but has expanded to a
desire to perform timekeeping experiments.  I have several questions; I
looked for a FAQ but couldn't find one, so I hope it's alright to ask here.

I'm considering the purchase of a GPS receiver to serve as my workbench
10MHz source.  Since learning about precise timekeeping, I've also become
interested in some experiments, such as measuring the stability of the
mains, the effect of the ionosphere on WWV/WWVH signals, and so on.  So far
I've looked at various HP "Z-boxes" (Z3816, Z3815, Z3801, Z3805) and the
Trimble Thunderbolt receiver.  All of these seem to be in the $200-$500
range I'm targeting, but it's not clear what the differences are.  I've
read the Thunderbolt is an older design with fewer channels, but I don't
know if that's really a problem for my intended use.

I've also seen many rubidium devices on eBay, most seem to have been
removed from CDMA cell tower service.  Does anyone here have any experience
with such devices, are the ex-cell-tower units any good?  I have read that
a rubidium standard's short-term stability is not as good as a GPSDO, and
that they're mainly used for holdover - is my understanding correct?  My
thought is to (eventually) use a rubidium device to stabilize a GPSDO
should the receiver lose satellite signal.

Thank you in advance for any advice!

-Robert