Gerry Sweeney Inspired FE5680A Frequency Standard - Page 1
Forum section: electronics / projects

author: Cones
author_rank: Regular Contributor
timestamp: October 03, 2013, 11:45:41 am
content: Hi,Thanks to the excellent series of videos from Gerry Sweeney and the various teardowns by both Dave and Mike I decided to build a 10MHz standard based around the FE5680A module.But I have run into a few problems with actually getting a working FE5680A.The first FE5860A is a revision B unit. This powered up O.K. but refused to lock. Pin 3 was always in the high state. No 1 PPS output and the DDS board also appears to be faulty as the LED is not lit or flashing.The replacement FE5860A appears to be an earlier model with a different internal PCB design. But not the same as the one Dave took apart. This one does lock O.K. but I don't get a 1 PPS or a frequency output. But I am not sure what the unit is actually supposed to give out?There seems to be may variations on the same unit and only greater detail on certain models is available from 3rd parties.I have tried to communicate over the RS232 connection on both modules, but cannot get any response.I am wondering if anyone has the same FE5680A as my second one shown below and knows anything more about it?This is the build album for the whole project :-http://s699.photobucket.com/user/cones_stuff/library/FE5680A%20Frequency%20StandardThis is the second FE5680A module :-I'll post some project build photos and notes below, but wanted to ask my main questions before I got into the rest of the project.Many ThanksMark

author: Cones
author_rank: Regular Contributor
timestamp: October 03, 2013, 12:43:29 pm
content: The case was as recommended by Gerry from an Ebay seller. Originally made by Extron as a video distribution unit.The main PCB needed to be modified to change the system to 50 Ohm impedance. I've never worked on any SMD devices before so it was interesting learning how to solder the new 51 Ohm resistors into place.

author: Cones
author_rank: Regular Contributor
timestamp: October 03, 2013, 12:51:02 pm
content: The plan was to put the fan in the same spot as Gerry on the base of the unit.So I drilled a series of holes.... using a hand drill... but I found this easier to control than my powered multitool which tends to wonder all over the place.Once the holes were drilled, I changed my mind about the fan placement!I thought I could place the 15V Power supply flat in the case and then mount the fan on the lid of the case.

author: Cones
author_rank: Regular Contributor
timestamp: October 03, 2013, 12:57:12 pm
content: But the mounting studs were in the way of the fan.No problem just chop them down with the multitool and a small cutting disk.I gridded and marked all the holes with a punch. Then had another thought that the middle part is covered by the fan hub. So why drill all the holes?Just drill what was needed to clear the fan opening.

author: Cones
author_rank: Regular Contributor
timestamp: October 03, 2013, 01:06:34 pm
content: To fix the PSU down I took it apart so that I could mark the hole positions exactly.I also checked the cap screws to make sure they were not hitting the underside of the PCB.I thought I could use the existing PCB supports for my new vero board based circuit.Scored both sides with a knife. Very easy to get a nice clean edge.Plenty of clearance for the underside.Again following Gerry's example to use the cheap buck converters for the supplies. I originally intended to mount them flat. But then again changed my mind and stood them on end with some 90 degree pin headers.

author: Cones
author_rank: Regular Contributor
timestamp: October 03, 2013, 01:15:49 pm
content: A quick assemble to see if everything is going to fit.Wire everything up.This is also the first time I have used a PIC device or the programmer. Using Gerry's code it worked first time with no problems. I would like to learn more in the future so it was a good excuse to buy the PIC demo kit from Farnell. This was cheaper than just the PICKIT3 on it own!The mains cables will be shortened once the rest of the project is finished.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: October 03, 2013, 01:24:10 pm
content: Another project on my list of things to do .Then you had to remind meThanks

author: grego
author_rank: Frequent Contributor
timestamp: October 04, 2013, 03:07:45 pm
content: It's funny because I've been working on the same. My FE-5680A arrived a few days ago and my Extron just got delivered yesterday afternoon. I went and looked in my part bin and don't have any 50 or 100 ohm SMDs so I'm ordering some (going Gerry's route with the stacked 100s because 50 ohm from digikey surface mount were stupid expensive).Great work by the way. I'm very impressed.

author: Cones
author_rank: Regular Contributor
timestamp: October 12, 2013, 12:59:04 pm
content: Hi,I've done a lot more work on this now.My 3rd FE5680A unit arrived and it does at least work unlike the first two. But it is a different design internally and I cannot connect to the RS232 on the DDS board with Hyperterminal to change the settings. So I am stuck with a 8.3886235 MHz frequency output for now. So I need further information to be able to adjust it. Or alternatively I will have to buy a unit where the 10 MHz output is already available. But these seems to be a premium price at the moment.I have stripped the paint finish from all of the aluminium case components. Using the new Nitromors formula, which was terrible. It take almost 5 times longer than the old formula, which I think was banned for being too unsafe for the general public to use!I sanded the heatsink flat to get a better surface for heat transfer.All other surfaces were finished with 1200 grit wet and dry paper.It's not perfect but still more than acceptable than the chipped paint.

author: Cones
author_rank: Regular Contributor
timestamp: October 12, 2013, 01:05:34 pm
content: Time to drill the heatsink 2.5mm holes to be tapped for 3mm countersunk screws.Screw threadsMark through the drilled heatsink onto the flat front plate. Then drill and countersink the holes so the screws can sit flush.Bolted on.Space for the FE5680A unit.

author: Cones
author_rank: Regular Contributor
timestamp: October 12, 2013, 01:14:18 pm
content: Flat mounting area.Does it fit?JustRoom for a switch if I want to add one later.More holes to drill.Just enough clearance for the bolt heads.A bit scuffed as it rotated on the wood block, but I will sand it out later.I acquired an old scrap laptop and used the WiFi cables as the coax is nice and thin.This is the pickup for the 8.38862 MHz signal.I drilled a small exit hole in the case shell.Ready for assembly.I am quite pleased with the way it looks.Any help with the DDS frequency change would be very much appreciated.ThanksMark

author: SeanB
author_rank: Super Contributor
timestamp: October 12, 2013, 01:20:15 pm
content: Nice looking there, though the fan holes could be a lot bigger as otherwise they impede airflow a lot. You really need them to be separated from each other by about 2x the panel thickness.

author: bingo600
author_rank: Super Contributor
timestamp: October 12, 2013, 04:08:13 pm
content: I was trying to buy 2 of those dist-amps, but the UK seller refused to ship them to DKWould also have used the one for my "Rubi's".Btw: Could you take a pict. of the tool you used to "Countersink" the heatsink screws with ?/Bingo

author: Cones
author_rank: Regular Contributor
timestamp: October 12, 2013, 05:07:04 pm
content: Hi,Yes it is in the previous set of pictures.I think it is intended for woodworking, but it works fine on the soft alloy of the case.ThanksMark

author: gerrysweeney
author_rank: Regular Contributor
timestamp: March 01, 2014, 11:04:50 pm
content: Hi Cones,Just came across your project, its looking good. Nice to see others build these up, they are so useful and so cheap to do, they make a fun project too. Glad you got on with the PIC code.Gerry

author: linux-works
author_rank: Super Contributor
timestamp: March 02, 2014, 03:46:46 am
content: what timing! (lol, get it?)I was just watching your video today, gerry (not a short video either, lol) and I liked what you did.doing real work is hard and its nice to watch someone else do it for a changeanyway, the box you chose was not hard to find on the bay at a reasonable price, so I snagged one in prep for a similar project as yours. I may follow your layout pretty closely, too; I was saying the same things to myself, as I was watching the video, that you ended up concluding.I wonder how quiet this video dist system is, though. any phase noise or shifting? I worry a bit about having a rock stable 10mhz clock going into a 'video amp' and I wonder how jittery the output will end up being? is there any way to easy check for jitter changes? I guess you could put it thru a spectrum scope and see what kind of sidebands come up.it would also be interesting to see if you get better performance if you disable some of the output buffer stages. who needs THAT many?anyway, I'll start on this project at some point. just bought one of the boxes so I guess I'm now semi-comitted.thanks for the cool idea and entertaining video, man./bryan

author: Cones
author_rank: Regular Contributor
timestamp: August 11, 2014, 08:17:51 pm
content: Hi,No not really. I ended up with another eBay find of an AT&T RFG-RB which only needed a loose chip plugging back in to fix it.I can at least check them against each other. I get 8.3886235 Mhz out of the fe5680a unit from the internal socket.Sorry to not be able to help.Mark