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

Bob Camp lists at rtty.us
Tue Sep 17 20:54:23 EDT 2013


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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