EFRATOM device identification - Page 1
Forum section: electronics / testgear

author: daqq
author_rank: Super Contributor
timestamp: January 09, 2015, 10:11:08 pm
content: Hi guys,do you have any ideas about what the device on the picture is? It's not a distribution amplifier as far as I can tell, it's not a standard probably... I havent a clue.Thanks,David

author: edpalmer42
author_rank: Super Contributor
timestamp: January 09, 2015, 10:30:39 pm
content: It's a controller to lock the frequency of a Rubidium standard to the frequency of a radio signal. I have an Efratom FRT Rubidium Standard that looks like it's the same form factor. The EFR is mentioned a few times in the FRT manual.Ed

author: daqq
author_rank: Super Contributor
timestamp: January 09, 2015, 10:33:02 pm
content: So essentially a part of PLL controller for a Rubidium clock?

author: edpalmer42
author_rank: Super Contributor
timestamp: January 10, 2015, 02:12:37 am
content: Yes, I guess that would be a fair description.I'm just guessing by what I see in your pictures, but it looks like you feed the output of the Rb standard into the controller. The controller would then compare the 10 MHz to a signal derived from the received radio signal and adjust the Rb standard as necessary. You could use a quartz oscillator instead of a Rubidium standard. You'd have to try it to see how good it would be.Google might be able to find some more about your unit.Ed

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 10, 2015, 01:32:11 pm
content: As it's built in Germany, I assume it's intended for our DCF77http://en.wikipedia.org/wiki/DCF77.Therefore, you'd need a suitable active ferrite antenna for operation.Should also work well in Slovakia.Frank

author: babysitter
author_rank: Frequent Contributor
timestamp: January 10, 2015, 02:01:13 pm
content: Dont immediately connect a Ferrite rod antenna! The device supplies a voltage to the antenna to operate a amplifier, the winding on a ferrite rod would short it, really go for a active!Use a DC block for the first experiments, series capacitor at least.Are you able to feed a sig generator into the antenna port, DC-blocked ? You might see the control voltage output stuck at one limit at too low frequencies, changing to the other limit at too high frequencies. This might help you identify if it is for DCF, MSF, 10 MHz WWVB...

author: edpalmer42
author_rank: Super Contributor
timestamp: January 10, 2015, 02:56:22 pm
content: The manual for my FRT Rubidium standard lists DCF77, HGB, and WWV as sources for the EFR. There's likely switches or jumpers somewhere in the EFR to select which one since they're on different frequencies.David, if you can't find any more info on the unit, pictures of the boards would help others give you ideas.Ed

author: daqq
author_rank: Super Contributor
timestamp: January 10, 2015, 07:41:00 pm
content: Thanks guys for the info. It's not mine, I just saw it on a local auction site, was wondering what it was. I'm not gonna buy it, seeing as I don't have the more interesting bitsThanks,David

author: oyibo
author_rank: Newbie
timestamp: February 02, 2015, 03:29:35 pm
content: Actually, I have purchased this "Efratom EFR receiver controller" from the auction site. It was originally tuned to the BritishLF radio standard MSF (60 kHz), so I was little bit surprised how the unit got to Czechia.After some reverse engineering efforts (there is quite detailed manual for Efratom FRT / FRK on the web, but nothing on EFR), I have managed to retune the unit to DCF77 (77,5 kHz). Then, have tried it with active TAK antenna (also retuned to DCF77) and with autonomous X-tal generator of 10 MHz clock. The LF receiver seems to work OK and the oscillator control voltage changes periodically, as can be expected for open-loop operation. Unfortunately, I don't have any suitable Rb clock (like LPRO-101) yet, to test performance of the controller in the locked mode.

author: babysitter
author_rank: Frequent Contributor
timestamp: February 02, 2015, 05:01:23 pm
content: Go, get a cheap Morion OCXO with EFC from ebay! There are a lot of expensive, broken and just and plain "wrong" cheap Rbs out there

author: oyibo
author_rank: Newbie
timestamp: February 02, 2015, 05:53:04 pm
content: Well. As a matter of fact I already have an older secondary frequency standard with OCXO, synchronised by OMA/DCF77.Therefore would like to test something different. If I get Efratom/Datum LPRO-101 Rb clock with Lamp voltage >6V, it can stillrun for couple more years (interrupted service period). Yes, the only issue is to find reliable enough Chinese fellow tobuy it from.