Hi FEI tended to “hang on” to model numbers through many generations of devices. I suspect this made marketing a lot easier. It does not make working out “what do I have here” very easy these many years later.
They never intended any of these devices to be field repairable. Their customers never had any interest in repairing a device in the field. We live in a world of “send it back to the factory” for repairs. This is true of a wide range of items and has been true for decades. Typically the big issue with most Telecom Rb’s ( the FEI’s very much included) is drift of the internal crystal oscillator. You tweak a trimmer and get it in range. The problem unit now works ok. Next up are exploded electrolytic caps. These are often rattling around inside the housing. Fun !!! Bob > On Mar 3, 2022, at 7:17 AM, Clint Jay <cjaysh...@gmail.com> wrote: > > Hi, there's a link to information on the Time Nuts archive: > > https://time-nuts.febo.narkive.com/Bhntgkdy/changing-fe-5650a-frequency > > Schematics might not be included, FE seem to have kept those close to their > chests. > > If the link to the ZIP file fails, archive.org might still have it. > > On Thu, 3 Mar 2022 at 10:55, xtronus--- via time-nuts < > time-nuts@lists.febo.com> wrote: > >> Hello, >> >> Newbie here. >> >> I have a couple of old FEI FE-5650A rubys (one is Opt 3, and the other is >> Opt 3 & Opt 12) both of which I >> literally dug out of a garbage can. One is marked 'bad' and the other has >> no markings. I have not attempted >> to put power on the units as I would prefer to have a look see on the >> schematics first and also, to know what >> the various options provide. Opt 12 is not listed on any literature that I >> have, while Opt 3 = 5 MHz Out. >> >> Looked around the 'Net on/off for several years for info, I've found a few >> tid bits here and there, etc. >> >> Although I have tracked down a marketing flyer and a service manual >> (TM-0107 Dtd Feb 1998), which depicts >> board silk screens, while the document does not actually contain any >> electrical schematics of the PCB boards. >> >> Does anyone know of or can point me to any available schematics for these >> old rubys? >> >> With the can removed I noticed a multi-throw DIP switch, anyone know what >> those settings do? >> >> Also, on sht 12, Fig 4, block diagram, depicts a "serial digital input" >> into a block titled, "Serial Interface", and I did >> track down a FE-5650A RS-232C hack, does anyone know if those signals are >> brought out to the DB-9 connector, >> perhaps via pins 6 & 9 which are marked N.C.? >> >> Thanks in advance, >> >> walt w. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. >> > > > -- > Clint. M0UAW IO83 > > *No trees were harmed in the sending of this mail. However, a large number > of electrons were greatly inconvenienced.* > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.