[time-nuts] My FE-5680A Came In Today

Bob Stewart bob at evoria.net
Tue Sep 17 21:56:35 EDT 2013


OK, I guess I have to get my GPIB adapter working before I can do that test.





>________________________________
> From: Bob Stewart <bob at evoria.net>
>To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>Sent: Tuesday, September 17, 2013 8:07 PM
>Subject: Re: [time-nuts] My FE-5680A Came In Today
> 
>
>D'oh!  But is there a way I can run for let's say 200 pulses on the B channel and see the count on the A channel?
>
>
>
>
>
>>________________________________
>> From: Bob Camp <lists at rtty.us>
>>To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>>Sent: Tuesday, September 17, 2013 7:54 PM
>>Subject: Re: [time-nuts] My FE-5680A Came In Today
>> 
>>
>>Hi
>>
>>For checking things like GPSDO's the pps is actually much more useful than the 10 MHz. Just do the count one to the other trick and you have a very good way to test what's going on. In it's normal configuration it should tune to within about 1 ppt of the proper frequency. That would be 10,000,000 Hz / 1,000,000,000,000  or 1 ns every thousand seconds on the pps. 
>>
>>Bob
>>
>>On Sep 17, 2013, at 8:37 PM, Bob Stewart <bob at evoria.net> wrote:
>>
>>> Hi,
>>> 
>>> I'm just looking for an accurate standard for my GSPDO PLL coding.  As it is, I've been depending on others who have these to tell me the code works.  I understand that when these are retuned to 10MHz, they're .005Hz off due to the DDS.  I'm good with that.  =)
>>> 
>>> Bob
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> ________________________________
>>>> From: Bob Camp <lists at rtty.us>
>>>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>>>> Sent: Tuesday, September 17, 2013 7:30 PM
>>>> Subject: Re: [time-nuts] My FE-5680A Came In Today
>>>> 
>>>> 
>>>> Hi
>>>> 
>>>> Keep in mind that these things make a pretty awful 10 MHz standard. They are spur monsters in a big way. They won't drive your counter nuts, but for anything that wants signal purity - watch out.
>>>> 
>>>> Bob
>>>> 
>>>> On Sep 17, 2013, at 8:14 PM, Bob Stewart <bob at evoria.net> wrote:
>>>> 
>>>>> Hi Bob,
>>>>> 
>>>>> Yeah, I figured that retuning it would lose the 1PPS.  No biggie.  There are a number of those little connectors in this device, and the two that have cables connected use a flat 90 degree connector with a coax that's a bit smaller than RG-174.  I just want to snap a pigtail on it and lead it out through a notch in the cover where the DB-9 connector is.  There are several examples on the web where people solder wires to the connector and to the RS-232 header.  I'd just as soon avoid soldering wires if I can.
>>>>> 
>>>>> Bob
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>>> ________________________________
>>>>>> From: Bob Camp <lists at rtty.us>
>>>>>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>>>>>> Sent: Tuesday, September 17, 2013 7:06 PM
>>>>>> Subject: Re: [time-nuts] My FE-5680A Came In Today
>>>>>> 
>>>>>> 
>>>>>> Hi
>>>>>> 
>>>>>> If you retune it, you probably will throw off the pps. The pps drive strength is a bit weak, so you need to be careful looking for it. On some units there is a software command to enable / disable it (as in pps only when warmed up and locked - like a gps). The can / cover on the unit is mu metal (Rb's are mag sensitive). If you drill a hole in it, you are likely to impact it's mag shielding properties. 
>>>>>> 
>>>>>> Bob
>>>>>> 
>>>>>> 
>>>>>> On Sep 17, 2013, at 6:21 PM, Bob Stewart <bob at evoria.net> wrote:
>>>>>> 
>>>>>>> My FE-5680A Rb standard came in today.  After the usual inspections etc, I fired it up and I have the purple haze.  The native output is 8.38860798/9 (last digit jitter) as read on my 5335A using my GPSDO as an external standard.  I've got a ways to go before it's all setup, but this is looking good.  Does it warmup and change frequency at all, or can I retune it to 10MHz and use it as a reference without any further ado?
>>>>>>> 
>>>>>>> Can someone tell me what type of socket that is where you tap off the RF?  It looks sort of like a uFL connector, but a bit bigger.  I'd rather avoid hacking and soldering on this if I can.  
>>>>>>> 
>>>>>>> Bob - AE6RV
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>>>>>> 
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