----- Original Message ----- From: "Chris Albertson" <albertson.ch...@gmail.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Thursday, June 19, 2014 8:31 AM Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
> I've been working in the same thing BUT I don't want anyone who builds it > to need a PCB. And I want the firmware to load over USB so there is no > need to ship programmed chips or deal with external programmers. I think > I can get the cost below $20. That said I doubt I'll get 1E-13 > performance out of my Rb. > > My little Arduino based controller has been running now for a couple months > and keeping a crystal in lock. The board has a pins left over for a serial > port that I'll hook up to the Rb. > > The trick to getting the cost down is NOT to do a custom PCB. Take > advantage of one of the uP development boards and then for under $5 you get > the USB interface, D/A and A/D, serial ports, timers and quite a bit of > logic all 1/3rd the size of a credit card. > > > On Thu, Jun 19, 2014 at 12:57 AM, Jan Boutsen <jan.bout...@telenet.be> > wrote: > >> Count me in for an assembled and tested board. Great project. >> Jan >> >> >> >> >> ----- Original Message ----- >> From: <ewkeh...@aol.com> >> To: <time-nuts@febo.com> >> Sent: Wednesday, June 18, 2014 8:49 PM >> Subject: [time-nuts] FE5680 GPS Disciplined Controller >> >> >> >> FE5680 GPS Disciplined Controller >> With all the FE 5680 rubidium oscillators being used as door stops out >> there some of us decided to develop a GPSDO for it. The main question we >> have: >> Is there sufficient interest among time nuts for a discipline controller >> for the FE5680 to make it available? Looking at the postings over the last >> two years I am not so sure. >> The construction and preliminary testing of a Brooks Shera style GPS >> discipline 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 >> would be interested in obtaining an FE5680 discipline controller (if there >> is >> sufficient interest about $45 a kit shipping included, $75 for an >> assembled and tested board, international orders for an additional $5) >> when >> it is >> released. >> We are also looking for three Beta testers that would be willing to >> purchase, assemble, and test our Beta release controller kit with their >> own >> FE5680A and GPS receiver or Tbolt and provide feedback. Please send an >> email to >> _EWKehren@aol.com_ (mailto:ewkeh...@aol.com) Subject Time-Nuts FE 5680A, >> if you would be interested in being one of the three Beta testers. A key >> requirement is the willingness to get to it right away, the board assembly >> takes about 30 minutes. Instrumentation to measure results is also a >> requirement. We obtained impressive results using a cheap ublox 6M >> receiver. >> >> The FE5680 GPS discipline controller is a small (2” x 2”) board using 8 >> DIP’s and 1 SOT23-5 package powered by +5v with 0.1” headers for all >> inputs >> and outputs. Our plan is to have the kit supplier solder in the only SMD >> device on the board. A GPS receiver 1PPS and 10 MHz sine from the FE5680 >> feed the board with two 9600 baud serial ports sending TTL level tuning >> commands 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. >> In the chip count are two opto couplers that allow the use of isolated TTL >> to USB conversion. These USB adapters are readily available and furnish >> the 5 V necessary for the secondary of the opto circuit. An option is to >> not >> use the opto couplers and send the PIC TTL level RX and TX into a TTL to >> RS232 adapter. Another option is to use a TTL to RS232 converter after the >> opto couplers but then an external 5 V source would have to be supplied >> for >> the opto couplers. >> As I mentioned before to get best performance from the FE5680 temperature >> control is a must and after much fan and metal work I realized that a Lap >> Top heat pipe is the easiest lowest cost solution. Comments appreciated. >> As >> an alternative the temperature correction needs to be disabled. Otherwise >> two control loops fight each other. If you look close on page 7 of the >> brochure temperature stability from –10 to +60 C looks good but a closer >> look >> and you see 4 E-11 changes over small temperature changes in the -10 to 60 >> C range. Extensive analysis has been done on the FE 5680 A and maybe some >> one can tackle that problem. Please look at what N5TNL did. It is attached >> and click on his link. The FE 5680A does have a 4 channel MAX 1246 ADC and >> most likely it is used to monitor temperature. >> Also mentioned before the FE 5680 output is not the cleanest, I did >> observe it and some one posted the attached. I apologize but my records do >> not >> show who did, so if you posted the data please come forward. For serious >> applications where you are using it as your main reference a clean up like >> the >> Morion MV89 or HP 10811 should be considered. >> This addition is not required for beta tests but temperature control will >> help. >> I am also enclosing the express PCB layout, be free to use it but it would >> be more economical to do a group buy if there is enough interest and some >> one steps up to kit. >> Bert Kehren >> To not exceed the attachment limit the plot will be a separate posting >> >> >> >> >> >> >> >> >> >> ---------------------------------------------------------------------------- >> ---- >> >> >> > _______________________________________________ >> > time-nuts mailing list -- time-nuts@febo.com >> > To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.