[time-nuts] FE5680 GPS Disciplined Controller
Ernie Peres
ernieperes at aol.com
Wed Jun 18 15:40:03 EDT 2014
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.
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oday's Topics:
1. FE5680 GPS Disciplined Controller (EWKehren at aol.com)
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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
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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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