[time-nuts] FE5680A Calibration

Bob Camp lists at rtty.us
Wed Mar 14 21:50:28 UTC 2012


Hi

At least the "don't mess to much with it" part has sunk in. That puts you ahead of most people at this point.

A usable counter should be a sub $100 sort of thing either at auction or surplus. With some careful shopping it can be a sub $40 item.

Bob



On Mar 14, 2012, at 4:25 PM, "Chris Stake" <stake at btinternet.com> wrote:

> Hi Bob,
> Thanks for pointing-out the noisy output of the FE5680A. I'll probably try
> to lock a crystal oscillator to it.
> Unfortunately I don't have a suitable counter.
> I was hoping I could use some sort of higher frequency standard but I
> confess I had not really grasped the fact that the unit may well be within
> millihertz of the nominal frequency: too delicate to twiddle with anything
> other than precision equipment and long timebases.
> Kind regards
> Chris
> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Bob Camp
>> Sent: 14 March 2012 16:57
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] FE5680A Calibration
>> 
>> Hi
>> 
>> Do you have a dual channel counter that you can put the GPS into on the
>> "start" and the FE into as the "stop"? The HP 5334, 5335, and 5345 are all
>> examples of this sort of counter.
>> 
>> Bob
>> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Chris Stake
>> Sent: Wednesday, March 14, 2012 12:49 PM
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] FE5680A Calibration
>> 
>> Nice idea,
>> But I haven't got a DSO and the persistence of my scope isn't good enough
>> to
>> view 10Mhz sampled at 1pps.
>> Chris
>> 
>>> -----Original Message-----
>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>> Behalf Of EB4APL
>>> Sent: 14 March 2012 15:46
>>> To: time-nuts at febo.com
>>> Subject: Re: [time-nuts] FE5680A Calibration
>>> 
>>> My fast approach would be to trigger a scope with the 1 PPS from the GPS
>>> receiver and observe the how the 10 MHz output of your Rb drifts.  1
>>> full cycle per second is 1 e-7 so you'll need to use an stopwatch to
>>> time long periods when you are fine adjusting .
>>> Building (or buying) a GPSDO allows yo to make the comparison between
>>> both 10 MHz outputs without the jitter in the GPS receiver 1 PPS.
>>> Probably others in this list can suggest more elaborated and convenient
>>> approaches to this.
>>> 
>>> On 14/03/2012 16:17, Chris Stake wrote:
>>>> Hello all,
>>>> 
>>>> I purchased a FE5680A from a Chinese  Ebay vendor. I have connected it
>>> to a
>>>> 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to
>>> drive
>>>> a LED for the "locked" signal. I can communicate with it using the
>>> excellent
>>>> Fe5680Calibrator software. As received the frequency offset is set to
>>> Zero
>>>> and the unit seems to work well.
>>>> 
>>>> I plan to put it into service as a workshop frequency reference and so
>>> would
>>>> like to set it close to 10.0Mhz. I have various oscillator modules,
>>> signal
>>>> generators, SDR receivers, GPS receivers, a scanner, some uncalibrated
>>>> test-gear. I live in a river valley in North Devon UK so radio
>> reception
>>> is
>>>> a bit restricted but I receive digital television via a masthead
>>> amplifier
>>>> and long downlead.
>>>> 
>>>> Could someone please suggest a way of going about this?
>>>> 
>>>> 
>>>> 
>>>> Regards
>>>> 
>>>> Chris Stake
>>>> 
>>>> 
>>>> 
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>>> 
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