Hi Bert, I would definitely be interested in a kit.
regards, Paul G8GJA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 18 June 2014 19:49 To: [email protected] 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 [email protected]_ (mailto:[email protected]) 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 -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
