[time-nuts] FE-5680A - pinout, serial commands for 217400-30352-1 model
I recently bought a pair of FEI FE-5680A Rubidium Frequency Standard units on ebay (best offer of $150 for 2, free shipping from Hong Kong - seller tortlex2). It was relatively cheap (compared to EFRATOM units 10 years ago), compact and modern (programmable DDS), perhaps even useful to replace internal timebase in some test equipment. The first thing I found out is that it wasn't easy to find *reliable information on them. Many conflicting pinouts, different packaging, connectors all for the same FE-5680A model. One source (a seller on eBay) lists pin 3 as +5V, when in fact that is the lock indication output - I ran the unit like that initially, and it gave 10MHz out for a while (possibly the ACT240 buffer output diodes taking all the current to back feed the power) until the output buffer burned (if you get 100mA on the 5V, this is a good candidate for replacement - it right by the DB-9 connector, accessible by removing 4 bottom screws (the bottom plate only). I replaced it and used pin 4 instead, which is the correct one. Another difficulty was to get the unit to respond to serial commands, which was ultimately solved after finding the Rosetta stone (a technical manual for the unit in my configuration). This particular model, part number 217400-30352-1 doesn't respond to the trimpot on the side (at least not with any change in frequency) and uses the synthesizer for very fine adjustment of frequency around nominal 10MHz. 32-bit value adjusts in 7E-13 increments (way below the noise floor of the unit stability). After my little tribulation in getting to this point, I decided to post my verified findings, clearly identifying the model number of the unit, to help others that already have the unit or decide to spring $75 to join this nuthouse... er... community. 1. Manufacturer: FEI 2. Model FE-5680A, part number 217400-30352-1 3. Connector: DB-9M (male) with signals: pin 1: +15V input (1.7A max when cold starting, 0.6A typ steady state) pin 2: GND (15V return) pin 3: LOCKn (low=locked, high=unlocked) ACT240 output pin 4: +5V input (80mA typ.) pin 5: GND (signal) pin 6: 1pps (about 1us positive pulse each second) pin 7: 10MHz sinewave (~1Vpp on 50 ohm) pin 8: RS-232 RX (receive commands into unit) pin 9: RS-232 TX (unit sends responses to pc) 4. Trimpot with external access doesn't seem to do a thing - reportedly C-field on other models. 5. Instead of wide range DDS, this unit seems to only generate 10MHz, which can be fine tuned by programming a 32-bit value through the serial commands. Make it very fine - my units needed about 14 counts to change 1Hz - that is about 7E-13 relative change per lsb. ' 6. Serial commands: I found a manual for a slightly different unit (Googled FE-5680A manual and got the top link http://www.ham-radio.com/wa6vhs/Test%20equipment/FREQUENCY%20STANDARDS/FE-5 680A/5680%20TECH%20MANUAL.pdf http://www.ham-radio.com/wa6vhs/Test%20equipment/FREQUENCY%20STANDARDS/FE-56 80A/5680%20TECH%20MANUAL.pdf ), which listed three commands. 9600,8,N,1 worked fine. All commands have the general format [cmd] [lenght_lsb] [length_msb] [xorchecksum] [data] [data] ... [data] [data xor checksum] 6.1 READ CURRENT OFFSET: 2D 04 00 29 sample response: 2D 09 00 24 FF FF FE C8 36 This command simply returns the current offset value. In this example it shows offset of FEC8, which is equivalent to -312 (this unit had to be slowed down by 2.1E-10 to match my GPS trained reference). 6.2 SET TEMPORARY OFFSET: 2E 09 00 27 aa bb cc dd cs (aabbccddee is the 32-bit word to write, cs is the xor of aa,bb,cc,dd) no response is given to this command, use 2D command to verify. Value is lost on power cycle. Example command: 2E 09 00 27 FF FF FE C8 36 6.3 SET PERMANENT OFFSET: 2C 09 00 25 aa bb cc dd cs (same as 2E command but also writes to EEPROM so survives a power cycle) One would use the 2C command during a calibration (EEPROM life is 100k cycles), and use the 2E command for uses like a GPS-trained reference. 7. Notes: Operating the unit without any heatsink gets the external case to around 58C (keeps your coffee warm), could lead to premature failure as ICs get even hotter inside. If you just turn it on for a couple hours at a time, it might be OK, but a large heatsink on the bottom (or a small fan - some of the slim hard disk coolers might be appropriate in size). I set the offset to -4096, 0 and 4096, measured a long average of 10s gate readings, then fit a curve to it and calculated where it crossed 10.MHz, then sent the 2C command to burn it. It is easy to go overboard, as the resolution offered is normally way overkill and beyond measurement or stability capabilities of most time nuts (except perhaps for a couple time-nutcases). For
[time-nuts] FE-5680A pinout
The confusion is understandable. There are so many different variants of the FE-5680A, and they are not easy to identify. Some of the information you see out there is from folk who measure the voltage on the pins with a meter, not understanding what they are looking at. When I've investigated such devices (I have several FEI units) I start by tracing my way back from the power supply regulators to determine where the power goes in, and what it should be, to avoid mistakes. It's also been a useful technique with things like GPSDOs where nothing is known about the pinouts (Trimble NTGS-50AA for example). Sure is frustrating when you have one that isn't frequency agile! One of my FEI units is an FE-5680B with only 1pps output. The Chinese supplier thought it was faulty, but the 1pps pulse is only 5us wide, and isn't present until the unit has locked. I found a very useful 60MHz reference inside the unit as well. 73, Murray ZL1BPU ___ 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.
Re: [time-nuts] FE-5680A pinout
I know that several list members have bought FE-5680A rubidiums. Of all the various ebay sellers that you have bought this model from, who would you recommend? If I wanted a straight 10MHz unit vs a frequency agile unit, would you recommend a different seller? Joe Gray W5JG On Wed, Apr 20, 2011 at 1:02 PM, Murray Greenman murray.green...@rakon.com wrote: The confusion is understandable. There are so many different variants of the FE-5680A, and they are not easy to identify. Some of the information you see out there is from folk who measure the voltage on the pins with a meter, not understanding what they are looking at. When I've investigated such devices (I have several FEI units) I start by tracing my way back from the power supply regulators to determine where the power goes in, and what it should be, to avoid mistakes. It's also been a useful technique with things like GPSDOs where nothing is known about the pinouts (Trimble NTGS-50AA for example). Sure is frustrating when you have one that isn't frequency agile! One of my FEI units is an FE-5680B with only 1pps output. The Chinese supplier thought it was faulty, but the 1pps pulse is only 5us wide, and isn't present until the unit has locked. I found a very useful 60MHz reference inside the unit as well. 73, Murray ZL1BPU ___ 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.
[time-nuts] FE-5680A pinout
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Stan, Rex and Peter, Thak you very much for all the information about the oscillator. I´ve just received reply from the manufacturer, as you can see below. I´ll try to get information from Motorola, but I think it´s a rather difficult task. Best regards, José, EA1PX ___ Jose, This is a special for Motorola. You have to contact Motorola for their information. John Cuthbertson Director, Sales and Marketing Tel: 516-794-4500 Ext. 5105 Fax: 516-794-4340 [EMAIL PROTECTED] ___ 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.
Re: [time-nuts] FE-5680A pinout
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hello Jose, Try:http://www.freqelec.com/prod_pdf/FEI%205680A%20Rb.pdf Frequency Electronics Inc. = FEI This .PDF may shed some light. Be sure of the options you have. base unit has 15 VDC, other options use a different voltage for power. May have to go inside and solder a coaxial cable, to get the Ref. output outside. If you need more help, send an email to the factory info desk. They were quite helpful to me. Stan, W1LE FN41sr Cape Cod Jose Manuel wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hello all, this is my first participation here, as I´ve just joined this interesting group. I´m trying to test a Rb oscillator FE-5680A, but I don´t have information about the DB-9 connector pinout, because this model doesn´t have any rf out coaxial connector. I hope someone can help about this issue. Thanks in advance, José, EA1PX ___ 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.
Re: [time-nuts] FE-5680A pinout
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Stan W1LE wrote: ); SAEximRunCond expanded to false Errors-To: time-nuts-bounces+rexa Hello Jose, Try:http://www.freqelec.com/prod_pdf/FEI%205680A%20Rb.pdf Frequency Electronics Inc. = FEI This .PDF may shed some light. Be sure of the options you have. base unit has 15 VDC, other options use a different voltage for power. May have to go inside and solder a coaxial cable, to get the Ref. output outside. If you need more help, send an email to the factory info desk. They were quite helpful to me. Stan, W1LE FN41sr Cape Cod Seems there are lots of versions of the FE-5680A. Several of us bought versions a few years ago that did not match other known information (like the link above). Here is a link to a message I posted back then about what I had learned by digging into my unit: http://www.mail-archive.com/time-nuts@febo.com/msg01569.html The ones we bought needed 5V in addition to 15V into the DB9 to operate. The 10 MHz output did come out on one of the pins on that connector. I think that output pin did match the general information. In spite of the fact that tracing circuits on the board showed RS-232 I/O pins on the DB9 and also on an internal header, and with several people searching for information, we never did figure out any way to adjust the frequency of our versions of the FE-5680A. Stan's, post that he actually got a helpful response from FEI seems contrary to our attempts back then. I just did a quick browse of their web pages today and got a bunch of circular links that never produced an email address that looked like it might be worth a try. Maybe I missed something. Stan, care to share any pointers on how you found this 'factory info desk'? I'm not trying to be sarcastic, just wondering, because everyone got blown off, back then, when we were looking for any clues on our units. My impression of FEI is that they, like many other companies, cannot be bothered with talking with anyone who has not, or may not, give them lots of money. That is certainly their right, doesn't mean I like it. Also, it may be possible that if you find the right person, you might actually get good help. I did that with a different company a while back, by finding an engineer who helped a lot, and then later got a delayed reply from someone else telling me they had no time to tell me about old units, but if I would want to buy a few thousand to my specs they would be happy to help. So, for the OP, there seem to be many versions of these units, all labeled FE-5680A. There seems to be no absolute answer on pin-outs. If you are lucky, your unit will match one of the published configurations and be adjustable using RS-232 command sequences. For the ones we found, we only got them operational by reverse-engineering (results in the archive link), and I have never found any way to get mine really exactly enough on 10 MHz even though other units seem to be programmable, using published command sequences, over a wide range of frequencies. -Rex, KK6MK ___ 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.
Re: [time-nuts] FE-5680A pinout
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hello José, I managed to get a Technical Manual Word document for the 5680A Option 2 a little while ago, and have put it (together with some5650A files) in a zip file on my web site: http://www.barney-wol.net/private/5650Afiles.zip Admittedly the model described has an RF coaxial output connector, but hopefully there will be enough in common with your version that you can glean what you need from that document. Regards, Peter Vince (London, England) On Sun Sep 23 1:11 , 'Jose Manuel' [EMAIL PROTECTED] sent: I´m trying to test a Rb oscillator FE-5680A, but I don´t have information about the DB-9 connector pinout, because this model doesn´t have any rf out coaxial connector. I hope someone can help about this issue. Thanks in advance, José, EA1PX ___ 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] FE-5680A pinout
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hello all, this is my first participation here, as I´ve just joined this interesting group. I´m trying to test a Rb oscillator FE-5680A, but I don´t have information about the DB-9 connector pinout, because this model doesn´t have any rf out coaxial connector. I hope someone can help about this issue. Thanks in advance, José, EA1PX ___ 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.
