[time-nuts] FE-5680A

Jose Camara camaraq1 at quantacorp.com
Thu Nov 10 18:05:52 EST 2011


On a couple that I bought there was no response to pots, the only frequency
adjust was through the DDS chip.  I wanted to beat it to 1E-30 (kidding) but
had to be content with the DDS granularity close to 1E-13. Good enough,
considering all other sensitivities that will degrade beyond that (turn it
upside down and watch a 4E-11 change).

Some other variants reportedly respond to the trimpot, others have real wide
range DDS, allow 3MHz if you set it so. Although output filter might need
tweaking if you are way off the intended range.



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Peter Bell
Sent: Thursday, November 10, 2011 2:38 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-5680A

As far as I can see, the trimpot has no effect at all - the only frequency
trim on the unit is via the RS232 interface on pins 8 and 9 of the
connector I suspect this is adjusting the c field, but have not actually
verified this. It does definately change the output frequency, though.
On Nov 11, 2011 6:17 AM, <EWKehren at aol.com> wrote:
>
> Thank you Peter
> With Jose's and your input I will power it up in the morning. Mine has the
> same part # and a date code 0330. Does yours respond to the trim pot, I
> plan to  bring out the tuning voltage to a modified Shera controller.
> Bert
>
>
> In a message dated 11/10/2011 5:03:07 P.M. Eastern Standard Time,
> bell.peter at gmail.com writes:
>
> Assuming  it's the same as the units I have (two labels, with "FEI  P/N
> 217400-30352-1" on the upper label and two barcodes on the  lower
> label) then the +5V supply runs all the logic in the unit. There  are
> no special power sequencing requirements, but you need both  supplies
> for the unit to operate. The current drain on the 5V line is  fairly
> low - about 90mA - the 15V will pull about 2A when the unit is  cold
> and then drops to 500-600mA once everything is warmed up.  Pin 3  is
> the lock indicator - driven low when locked.  The output (10MHz  sine)
> is present on pin 6, and appears immediately after power up -  although
> the frequency is not accurate until the lock pin is  asserted.
>
> The 4 digit prefix on the lower barcode is a date code - so  "S/N
> 0416-77234" would indicate a unit made in week 16 of  2004.
>
> Regards,
>
> Pete Bell
>
> On Fri, Nov 11, 2011 at 12:30  AM,  <EWKehren at aol.com> wrote:
> > I did purchase one of the  "New"  FE-5680A Rb's. Looking at packaging
 and
> > the housing  it does look new. I have not powered it up because of +5
> Volt on
> >  pin 4. Does any one know its purpose and is there a power up  sequence.
> Any
> > help will be appreciated.
> > Bert Kehren  Miami
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