On Sun, 18 Sep 2005 15:52:03 -0500, James Meek <[EMAIL PROTECTED]> wrote:
>I've just found the time-nuts mail list, and the threads >concerning the programming of the FEI FE-5680A rubidium >frequency sources that some have bought on ebay and been >unable to program. > >I, too, bought one of these from an internet source last year >(a different source from the one mentioned in the thread I found), >and was unable to get anything out of it by simply powering it >up and connecting to it through its 10-pin interface using the >pinouts for a standard FE-5680A. > >However, mine did not come naked or on a cut-off section of PC board >like those I've seen advertised on ebay since then. Rather, it >came attached to a large board containing several voltage regulators, >a serial interface buffer, a serial EPROM chip, and some other logic. >Although I have not yet found the time to fully analyze the >circuitry, it appears to have been set up so as to program the >FE-5680A from the serial EPROM. I have no idea whether it needs >to receive a command from an external source to initiate that >programming, or whether it happens at power-on (perhaps with the >clocking of the serial EPROM by the FE-5680A itself?). > >I read that Rex and Brian Kirby have figured out that the unit needs >a +5V supply (or perhaps just a logic input) in addition to >the 15V supply in order to get any output. If someone could >provide me with specifics on that and anything else they've discovered >about this part, I'd have a lot more incentive to try to figure >out what the EPROM does -- and of course would share my findings >with all here. > >JM Here's what I worked out for the pins on the DB-9 on my5680A... 1 +15V near 2A initially, dropping to about .8A warm 2 gnd 3 lock high = unlock 4 +5V about 160 mA 5 gnd 6 1 pps out 7 10 MHz out 8 RS-232 Rx (into rubidium) 9 RS-232 Tx (from rubidium) The initial impression from the seller was that only 15V was needed. The info on the FEI pages don't mention needing 5V in any option. A lot of the pin functions are different from any description I have seen. I think I have the same full board you have. I looked at it back around the beginning of the year. If I remember right, the RS-232 pins of the rubidium get fed from off-board signals. I did power it up using this board once. There is a dual color led at the edge of the board that indicates lock state, if I remember right. Does your board have a sticker on it somewhere that says: SGLA4000B High Stability Osc Assembly? After lots if web searching, I figured that this seems to be part of older Motorola Cell equipment. I found a site that says they repair them. I tried sending an email asking if they have any documentation, but got no reply. Maybe later I can find time to scan the board. What I remember from the hacking I did, was that there didn't seem to be anything intelligent going on on the board. I don't remember any details though, maybe I missed something. Oh, on the side of the rubidium there is an adjustment screw. I thought for sure this would adjust the C-field and hence the freq, but I don't see any result by turning this. No idea what it is for. I tried all sorts of things sent to the serial port but never saw any effect or reply. I tried this at various baud rates. I also scoped the other side of the MAX3232 chip inside, so I know the data was getting in there. The other port of the MAX3232 is connected too. It goes to what must be a maintenance header inside. Nothing interesting came from trying that port too. So, if you feed it both 5V and 15V, I'd bet your unit will come up and give you 1 pps and 10 MHz. If, like mine, the frequency is a little bit off, it sure would be nice to know how to adjust it. -Rex, KK6MK _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts