[time-nuts] Symmetricom X72
Heathkid
heathkid at heathkid.com
Sat Jul 24 21:46:28 UTC 2010
Bob, so you're saying the Efratom LPRO is better than the three FE-5680A's I
already have? Sounds like I do need a TBolt anyway.
----- Original Message -----
From: "Bob Camp" <lists at rtty.us>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Saturday, July 24, 2010 5:20 PM
Subject: Re: [time-nuts] Symmetricom X72
> Hi
>
> The only way to be sure of what's going on is to have several (hopefully)
> accurate references. With at least three you can begin to guess how good
> they are.
>
> The TBolt is different from the Rb in a couple of regards:
>
> 1) It's short term stability isn't as good when locked tightly to the GPS.
> 2) It's long term stability is much better than the Rb when it's locked.
> 3) It's easier to tell what's happening with it if you hook up a PC and
> the Lady Heather (free) program.
>
> The Rb will need a couple of things to make it play right:
>
> 1) It's got to have a pretty good heat sink on it. An 8 x 10" piece of
> 1/4" aluminum is a reasonable start
> 2) It's got to be run for a while (possibly 24 hours) before it will be
> stable
> 3) You need to watch the lock, and lamp voltages to be sure it's not doing
> something crazy.
>
> My recommendation based on cost is the Efratom LPRO for a cheap Rb. They
> are in the ~$60 range and seem to work pretty well.
>
> Setup wise, I would get a TBolt in addition to the Rb. You need something
> to calibrate the Rb (and your counter TCXO) against. Both are "secondary"
> standards. They (unlike a Cesium) are adjusted to match a known good
> reference.
>
> Once you have the Rb and the TBolt, next step is up to you. Cesium is
> always an alternative, so's a Hydrogen Maser ....
>
> Bob
>
>
> On Jul 24, 2010, at 3:32 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...
>>
>> 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...
>>
>> ----- Original Message ----- From: "Bob Camp" <lists at rtty.us>
>> To: "Discussion of precise time and frequency measurement"
>> <time-nuts at febo.com>
>> Sent: Saturday, July 24, 2010 9:31 AM
>> Subject: Re: [time-nuts] Symmetricom X72
>>
>>
>>> Hi
>>>
>>> At least looking at the spec sheet it's not really very impressive.
>>>
>>> Bob
>>>
>>>
>>> On Jul 23, 2010, at 11:06 PM, Heathkid wrote:
>>>
>>>> Hello. Does anyone have any experience with the Symmetricom X72?
>>>>
>>>> Thanks...
>>>>
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>
>
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