[time-nuts] Symmetricom X72

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jul 24 16:37:39 EDT 2010

On 07/24/2010 09:32 PM, Heathkid wrote:
> Hello Bob,
> What would you recommend? I already have three FE-5680A Rb standards
> (which I'm quickly learning likely aren't worth the powder to blow them
> to (*insert your own word here*). Okay, that was probably my first
> mistake (thoughts?).
> My frequency counter is one I built from a kit from aade.com that has
> the TCXO option (although I had to tweak it myself so I have NO idea how
> close it is to any accuracy or precision). I have access to some really
> nice HP counters at work so that's my next step is to try one of those.
> My DFD4 measured the output of one of my 5680A's to 10.000.007 MHz after
> about a 10 minute warm-up. I don't know which one is off. Reading the
> specs on the 5680A's before I bought them looked like they were pretty
> decent. I'm learning...

It's the TCXO in the DFD4 which may "only" 7E-7 off.

The DFD4 isn't the right tool for measuring rubidiums with. Neat and 
all, it is not as good as needed. You need to get some better counter.

> So, what "reasonably priced" Rb standard would you recommend?
> Should my next step in this process be a Trimble Thunderbolt? Am I
> starting over?
> Thanks...

A Thunderbolt would be a nice addition... but do keep the 5680s. I can 
get them of your hands if you really need to... but that should be a 
hint to you...

Thunderbolt and some better counter is what you need. There are many 
counters which should be a good step in the right direction for you.
I still use my HP5335A despite I have much better gear around.


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