[time-nuts] Heathkid - New time-nut needs help...

Heathkid heathkid at heathkid.com
Tue Jul 27 00:08:13 UTC 2010


Steve,

I changed the subject line because everything that follows has nothing to do 
with the X72.  I hope this doesn't confuse anyone but this subject is 
probably much better related...

Yes, the FEI 5680A's I got are programmable from 1Hz to 20MHz (SMA output / 
currently set to 10MHz) plus has the RS232 for programming and one of those 
pins (besides the Rb lock pin that goes low and I've got a LED on it) has 
the 1pps.  Besides the "C" field potentiometer it also has a 0 to 5V fine 
tune voltage.  The slowest of the three takes only about 4 seconds to 
achieve Rb lock.  Here are the exact units I got (and "flyingbest" is a 
great and honest seller):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180435915714

The Thunderbolt I bought from fluke.l as he seems to be the "TBolt seller of 
choice" around here.  I also got the LCD display option (looks like fun to 
see what it's doing when not connected to a PC).

Okay, so today... I bought a "real" frequency counter.  After a LOT of 
looking and reading... I chose a HP 5335A.  It has option 10 (Oven 
Oscillator) and 030 (C Channel 1.3 GHz ) plus the HPIB plus math and 
statistics functions standard and includes operating and service manuals on 
CD.  It'll also be calibrated just prior to shipping to me (current Date Due 
03/19/11) but it will be re-calibrated just for me so at least I know it'll 
work and if there is a problem, I can return it.  :)

So, now I have the following (when the rest shows up):

(3) FEI 5680A Programmable Rubidium Frequency Standards w/ 1pps
(1) Thunderbolt "Complete Kit" w/ LCD display - from fluke.l
(1) HP 5335A Universal Counter w/ Options 10 (Oven Oscillator) & 030 (C 
Channel 1.3 GHz)

Hopefully, Stanley got my payment for the PICTIC II boards and I got an 
email back from Bob about getting me on the list for the programmed PICs.

That's where I'm at right now.

73 Brice KA8MAV



----- Original Message ----- 
From: "Steve Rooke" <sar10538 at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Monday, July 26, 2010 7:54 AM
Subject: Re: [time-nuts] Symmetricom X72


> Yes, it's because of the various types that you need to verify exactly
> what you have. A number of them are made to customer specifications
> with undocumented option numbers but if you have anything like an
> option 8 then you have the 1Hz to 20MHz version. Beware that to
> program the thing you need to provide +5V as well as the +15V to run
> it. Along with the output options, there are a slew of options on such
> things as ageing and temperature stability. If you have one from a
> telecom's cellular tower, it's likely to be of higher spec.
>
> Steve
>
> On 26/07/2010, Bob Camp <lists at rtty.us> wrote:
>> Hi
>>
>> One issue with the FE's is they often show up as conversions. Various
>> sellers take the 1 pps version and hack in a 10 MHz output. There is a 
>> lot
>> of room for error in the conversion process.
>>
>> Bob
>>
>>
>>
>> On Jul 26, 2010, at 7:06 AM, Steve Rooke <sar10538 at gmail.com> wrote:
>>
>>> Brice,
>>>
>>> On 26/07/2010, Heathkid <heathkid at heathkid.com> wrote:
>>>> Last night, as suggested by several people on this list... I ordered a
>>>> Trimble Thunderbolt from Bob Mokia, fluke.l so I should be in pretty 
>>>> good
>>>> shape there to get started once it arrives.
>>>
>>> Sounds like your starting on the long path to time-nuttiness :) Bob
>>> has supplied a lot of stuff to people on this list and he will look
>>> after you if anything is amiss.
>>>
>>>> The counter I mentioned (it's a DFD4 - modified with the tcxo as the 
>>>> "a"
>>> ...
>>>> anyway).  :)  By the way, when I built it, I calibrated it by zero
>>>> beating
>>>> against WWV at 10 and 20 MHz.  That was the best way I had at the time
>>>> and
>>>> if the DFD4 is now 7 Hz off after all these years... it's not doing so
>>>> bad
>>>> (based on it's limitations).
>>>
>>> Not bad considering it's a TCXO.
>>>
>>>> So... that's what that counter is for and not for what I'm doing now.
>>>> I'm
>>>> currently looking for a nice/used HP counter.  Please don't think I'm
>>>> going
>>>> to use the DFD4 for measuring my Rb standards.  It's a wonderful 
>>>> counter
>>>> for
>>>> what it was designed for and that's it.
>>>
>>> Dependant upon what your looking for in a counter, you could broaden
>>> your choices as there are other useful counters out there that may be
>>> more affordable but still as good. Try looking for a Racal-Dana 1992,
>>> preferably with the high stability option timebase (although these
>>> turn up seperately anyway and are a doddle to fit). It makes a nice
>>> footprint 1ns counter and can be referenced to your T'Bolt.
>>>
>>>> I'm not giving up on the FEI's anytime soon.  I understand now that 
>>>> along
>>>> with the Trimble Thunderbolt (and a decent counter) I'll be on my way 
>>>> to
>>>> "getting started".
>>>
>>> You'll have to see if those FEI's are the programmable types which can
>>> be set to produce frequencies up to 20MHz. Do they have jut the D'Sub
>>> connector or have an RF connector as well. There are different
>>> variants of these produced by FEI under the same product code.
>>>
>>> 73 de Steve ZL3TUV & G8KVD
>>>
>>>> 73 Brice KA8MAV
>>>>
>>>>
>>>> ----- Original Message -----
>>>> From: "Steve Rooke" <sar10538 at gmail.com>
>>>> To: "Discussion of precise time and frequency measurement"
>>>> <time-nuts at febo.com>
>>>> Sent: Sunday, July 25, 2010 8:40 AM
>>>> Subject: Re: [time-nuts] Symmetricom X72
>>>>
>>>>
>>>>> Excuse my replying to my own posting please.
>>>>>
>>>>> This post is really about the DFD1 frequency counter.
>>>>>
>>>>> Heathkid: You are comparing a Rb against a frequency counter with a
>>>>> TCXO that you tweaked yourself to calibrate it against no known
>>>>> frequency standard. Try running the three FEI-5660s for 24 hours and
>>>>> then measure the output of each with your frequency counter. Pick the
>>>>> mean of them and adjust your DFD1 to match that. At least you should
>>>>> be in a better position than you are now.
>>>>>
>>>>> As you built the DFD1 yourself, you should have the schematic and may
>>>>> be able to engineer in a connection for an external reference. There
>>>>> is plenty of people here who would be happy to advise you on a
>>>>> suitable interface if you can attach the part of the circuit where the
>>>>> TCXO is located. If you do get a T'Both, you would be able to use it
>>>>> as a reference or, perhaps, build in one of the FEI-5660s as an
>>>>> internal reference. The limiting factor though is how good is the
>>>>> circuit used in the DFD1 which will limit it's stability and accuracy.
>>>>> There are many factors, including input circuit, voltage regulation,
>>>>> counter stage design, level detection, etc. which have a major impact
>>>>> here. What I'm getting at is that to write-off a bunch of FEI-5660s
>>>>> after checking them with such a device as this, is a very poor
>>>>> decision.
>>>>>
>>>>> Maybe you could look at a better counter on fleeBay before you make
>>>>> further assumptions.
>>>>>
>>>>> 73,
>>>>> Steve
>>>>>
>>>>> On 26/07/2010, Steve Rooke <sar10538 at gmail.com> wrote:
>>>>>> Sage advice Bill!
>>>>>>
>>>>>> Heathkid, you don't need another Rb unit when you have 3 perfectly
>>>>>> decent ones! You really need a standard to calibrate your Rb units 
>>>>>> to,
>>>>>> a Trimble Thunderbolt is likely to be the cheapest choice for you. 
>>>>>> Bob
>>>>>> Mokia, fluke.l, on fleeBay sells them separately or as a starter kit
>>>>>> with everything there to get you going. Once you have this up and
>>>>>> running for quite some time and see that things are looking stable in
>>>>>> the Lady Heather application, then you can start to think about
>>>>>> calibrating the FEI-5680's but only after you have run them in well. 
>>>>>> I
>>>>>> don't know your counter but does it have an input for an external
>>>>>> reference source? If so you will be able to use the T'Bolt as an
>>>>>> external reference for it, providing the required reference is 10MHz.
>>>>>> If it's not, you can divide down the T'Bolt's output to match. If 
>>>>>> your
>>>>>> frequency counter has no reference input (apart from throwing it in
>>>>>> the bin) you should be able to engineer it into the instrument,
>>>>>> depending on your skill set.
>>>>>>
>>>>>> So, first get yourself a frequency standard to work with, IE. a 
>>>>>> T'Bolt
>>>>>> or the like.
>>>>>>
>>>>>> My 2c worth,
>>>>>> Steve
>>>>>>
>>>>>> On 25/07/2010, WB6BNQ <wb6bnq at cox.net> wrote:
>>>>>>> To Bob and Stan (W1LE),
>>>>>>> [p.s. But not just to you two alone]
>>>>>>>
>>>>>>>
>>>>>>> Why complicate the answers to Heathkid (now Brice KA8MAV) with a 
>>>>>>> bunch
>>>>>>> of
>>>>>>> different directions that should only be decided after one gains
>>>>>>> enough
>>>>>>> knowledge and understanding (they are not the same) to properly 
>>>>>>> grasp
>>>>>>> the
>>>>>>> subject matter ? ? ? ?
>>>>>>>
>>>>>>> Clearly Heathkid needs some guidance.  The form should be to start 
>>>>>>> out
>>>>>>> with
>>>>>>> the very basics and get his feet on the ground.  He already has 
>>>>>>> three
>>>>>>> (3)
>>>>>>> Rb
>>>>>>> sources that should keep him busy for quite some time.  However, his
>>>>>>> counter
>>>>>>> is really junk from a lab point of view.  Nonetheless, even it can 
>>>>>>> be
>>>>>>> useful
>>>>>>> if it is understood how to apply it after understanding its
>>>>>>> limitations.
>>>>>>>
>>>>>>> What Heathkid needs to understand is it is not about equipment.  It 
>>>>>>> is
>>>>>>> all
>>>>>>> about how to measure and account for errors and unknowns.  Actually,
>>>>>>> quite
>>>>>>> a
>>>>>>> daunting task depending upon the level of achievement.
>>>>>>>
>>>>>>> I agree he needs some kind of external reference and I agree the
>>>>>>> Trimble
>>>>>>> Thunderbolt (Tbolt) would be the right item for his true reference.
>>>>>>> Even
>>>>>>> the Tbolt has its issues that need to be understood.
>>>>>>>
>>>>>>> He will also need a method of comparison.   The oscilloscope is a 
>>>>>>> good
>>>>>>> start
>>>>>>> but very tedious.  Here Burt's project would help him a lot when 
>>>>>>> Burt
>>>>>>> gets
>>>>>>> it done.  I guess he is close.  I guess, also, the PICTIC II would 
>>>>>>> fit
>>>>>>> the
>>>>>>> bill after he understands what it is.
>>>>>>>
>>>>>>> Still he needs to understand how to apply and use this stuff.
>>>>>>> Confusing
>>>>>>> him
>>>>>>> with suggesting all of the different Rb sources available is only
>>>>>>> making
>>>>>>> him
>>>>>>> think a better one { relative statement } would be the answer which 
>>>>>>> is
>>>>>>> not
>>>>>>> true.  His FEI-5680's are so much better for his particular level, 
>>>>>>> it
>>>>>>> is
>>>>>>> not
>>>>>>> even funny.
>>>>>>>
>>>>>>> What has not been asked of him is what are his goals and intentions.
>>>>>>> If
>>>>>>> it
>>>>>>> is to just say you have an atomic frequency reference, then sit the
>>>>>>> FEI-5680
>>>>>>> on the coffee table; job done.  One cannot be properly guided if the
>>>>>>> goals
>>>>>>> are unknown.
>>>>>>>
>>>>>>> Bill....WB6BNQ
>>>>>>>
>>>>>>>
>>>>>>> Bob Camp wrote:
>>>>>>>
>>>>>>>> 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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>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
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>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
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>>>>>>>>
>>>>>>>> _______________________________________________
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>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
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>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Steve Rooke - ZL3TUV & G8KVD
>>>>>> The only reason for time is so that everything doesn't happen at 
>>>>>> once.
>>>>>> - Einstein
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Steve Rooke - ZL3TUV & G8KVD
>>>>> The only reason for time is so that everything doesn't happen at once.
>>>>> - Einstein
>>>>>
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts at febo.com
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>>>>
>>>>
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>>>
>>>
>>> --
>>> Steve Rooke - ZL3TUV & G8KVD
>>> The only reason for time is so that everything doesn't happen at once.
>>> - Einstein
>>>
>>> _______________________________________________
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>>
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>
>
> -- 
> Steve Rooke - ZL3TUV & G8KVD
> The only reason for time is so that everything doesn't happen at once.
> - Einstein
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
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