[time-nuts] FE-5680A performance - 1 PPS output issue

[Robert Benward]

You've had more progress than I did, I don't get anything out of pin 6.  I 
did see the levels toggle, but that was about it.  On various websites I 
read to get exactly 1pps, you need a programmable 5680 because it needs to 
be set to something like 8.388MHz (2^23) to divide down properly.  I suspect 
you may not be able to get both; 10MHz and 1pps.

Bob



----- Original Message ----- 
From: "beale" <beale at bealecorner.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, January 05, 2012 12:46 PM
Subject: Re: [time-nuts]FE-5680A performance - 1 PPS output issue


>I think there is something funny about the 1 PPS output on pin 6 from the 
>currently available cheap FE-5680A units. I have three of these units. On 
>one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 
>1 microsecond wide.  But after a power cycle it never came back, although 
>the unit indicates a locked condition, and is apparently working. The other 
>two units also seem to work (10 MHz output OK, lock OK) but I have never 
>seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of 
>triggering on and displaying a 1 usec pulse.  Is it possible the pulse 
>appears only after a RS-232 command, or after some other special condition?
>
>
>>  -------Original Message-------
>>  From: David <davidwhess at gmail.com>
>>  To: Discussion of precise time and frequency measurement 
>> <time-nuts at febo.com>
>>  Subject: Re: [time-nuts] FE-5680A performance
>>  Sent: 05 Jan '12 07:49
>>
>>  On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray
>>  <hmurray at megapathdsl.net> wrote:
>>
>>  >albertson.chris at gmail.com said:
>>  >>
>>  >> Have an older Tek 465 scope that is in only "fair" shape and I see 
>> nothing
>>  >> on that pin but milivolt level sine wave of about 60MHz. I can't set 
>> the
>>  >> scope to show any hint of a PPS ...
>>  >
>>  >I do have a 465. You should be able to see a 1 uSec PPS.
>>
>>  60MHz is about a 6nS rise time and is easily fast enough to see it.
>>
>>  >Now turn up the Intensity until you can see the pulse. It might help to 
>> turn
>>  >down the room lights.
>>
>>  This is the problem. With a 1 second repetition rate, the brightness
>>  is going to be very low.
>>
>>  The old ways of viewing such a low repetition rate signal include
>>  using a hood or dark room, special CRT phosphors, photographic film,
>>  MCP (micro channel plate) intensified CRTs, and of course analog
>>  storage and later digital storage.
>>
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>
>
>