[time-nuts] FE5680 GPS Disciplined Controller

paul swed paulswedb at gmail.com
Wed Jun 18 22:47:03 EDT 2014

Gmail has been sending lots of emails to spam. "Because it appears like
something else". So if I appear unresponsive I now know why. Crazy!

On Wed, Jun 18, 2014 at 3:40 PM, Ernie Peres <ernieperes at aol.com> wrote:

> Hi,
>  I am interested a complete KIT  ready made and tested. Also if this
> version is not available then just the simple KIT including PCB...parts and
> so on. PIC programmed.
> Rgds  Ernie.
>  -----Original Message-----
> From: time-nuts-request <time-nuts-request at febo.com>
> To: time-nuts <time-nuts at febo.com>
> Sent: Wed, Jun 18, 2014 8:56 pm
> Subject: time-nuts Digest, Vol 119, Issue 25
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> oday's Topics:
>    1. FE5680 GPS Disciplined Controller (EWKehren at aol.com)
> ---------------------------------------------------------------------
> Message: 1
> ate: Wed, 18 Jun 2014 14:49:02 -0400 (EDT)
> rom: EWKehren at aol.com
> o: time-nuts at febo.com
> ubject: [time-nuts] FE5680 GPS Disciplined Controller
> essage-ID: <59d7b.5d95a57a.40d3391d at aol.com>
> ontent-Type: text/plain; charset="utf-8"
> E5680 GPS Disciplined  Controller
> ith all the FE  5680 rubidium oscillators being used as door stops out
> here some of us decided  to develop a GPSDO for it. The main question we
> have:
> s there sufficient  interest among time nuts for a discipline controller
> or the FE5680 to make it  available? Looking at the postings over the last
> wo years I am not so  sure.
> he  construction and preliminary testing of a Brooks Shera style GPS
> iscipline  controller for the later version (6.81e-13 resolution) of the
> FE5680
> has been  completed. We are trying to determine the number of people that
> ould be  interested in obtaining an FE5680 discipline controller (if there
> is
> ufficient  interest about $45 a kit shipping included, $75 for an
> ssembled and tested  board, international orders for an additional $5)
> when it
> s
> eleased.
> e are also looking for three Beta  testers that would be willing to
> urchase, assemble, and test our Beta release  controller kit with their own
> E5680A and GPS receiver or Tbolt and provide  feedback. Please send an
> email to
> _EWKehren at aol.com_ (mailto:EWKehren at aol.com)   Subject Time-Nuts FE 5680A,
> f you would be interested in being one of the three  Beta testers. A key
> equirement is the willingness to get to it right away, the  board assembly
> akes about 30 minutes. Instrumentation to measure results is  also a
> equirement. We obtained impressive results using a cheap ublox 6M
>  receiver.
> The  FE5680 GPS discipline controller is a small (2? x 2?) board using 8
> IP?s and 1  SOT23-5 package powered by +5v with 0.1? headers for all inputs
> nd outputs. Our  plan is to have the kit supplier solder in the only SMD
> evice on the board. A  GPS receiver 1PPS and 10 MHz sine from the FE5680
> eed the board with two 9600  baud serial ports sending TTL level tuning
> ommands to the FE5680 and receiving  commands from and sending status data
> to a
> PC for data logging and system  control via a simple terminal program.
> n the chip count are  two opto couplers that allow the use of isolated TTL
> o USB conversion. These  USB adapters are readily available and furnish
> he 5 V necessary for the  secondary of the opto circuit. An option is to
> not
> se the opto couplers and  send the PIC TTL level RX and TX into a TTL to
> S232 adapter. Another option is  to use a TTL to RS232 converter after the
> pto couplers but then an external 5 V  source would have to be supplied for
> he opto couplers.
> s I  mentioned before to get best performance from the FE5680 temperature
> ontrol is  a must and after much fan and metal work I realized that a Lap
> op heat pipe is  the easiest lowest cost solution. Comments appreciated. As
> n alternative the  temperature correction needs to be disabled.  Otherwise
> wo control loops fight each  other.  If you look close on page 7  of the
> rochure temperature stability from ?10 to +60 C looks good but a closer
>  look
> nd you see 4 E-11 changes over small temperature changes in the -10 to 60
>  range. Extensive analysis has been done on the FE 5680 A and maybe some
> ne  can tackle that problem. Please look at what N5TNL did. It is attached
> nd click  on his link. The FE 5680A does have a 4 channel MAX 1246 ADC and
> ost likely it  is used to monitor temperature.
> lso  mentioned before the FE 5680 output is not the cleanest, I did
> bserve it and  some one posted the attached. I apologize but my records do
> not
> how who did, so  if you posted the data please come forward. For serious
> pplications where you  are using it as your main reference a clean up like
> the
> orion MV89 or HP 10811  should be considered.
> his  addition is not required for beta tests but temperature control will
> elp.
>  am also  enclosing the express PCB layout, be free to use it but it would
> e more  economical to do a group buy if there is enough interest and some
> ne steps up  to kit.
> ert  Kehren
> o  not exceed the attachment limit the plot will be a separate  posting
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