Hi Chris I've got some results to hand for three samples of the fluke.l MTI-260-0624-C oscillator, if that's the one you mean?, and for 5 MHz output they all require an EFC input on pin 1 between 2.8 and 3.1 Volts. That's with a 12 Volt supply on pin 5, which gives approx 6 Volts out on the Ref Volt Out pin, pin 2. So it would seem, in this respect at least, that they are quite close to your original oscillator, although I don't see any figures for EFC sensitivity in those particular results, but I wonder if there's any possibility of an initial adjustment in the Z3816, either hardware or software, that might limit the EFC range to more closely match individual oscillators? Regards Nigel GM8PZR In a message dated 02/05/2014 13:31:41 GMT Daylight Time, syseng.greenfi...@btconnect.com writes:
On 05/01/14 08:51, Peter Schmelcher wrote: > Chris, > This hi res pic might help you. I modified my Z3816A to improve the > performance. I changed the grounding and added a few extra capacitors. > This pic is close to the start so very few changes. > -Peter Peter, Thanks very much for sending that. The damage is in fact to the underside of the board, not the top side. I was using a solder sucker to remove the solder around each oscillator pin, which was then free enough of solder to use pliers to wiggle each lead side to side to free up. Unfortunately, the pliers slipped and sheared off ~3 parts from the underside of the board. It's not clear if all the parts are resistors or caps, though one is a cap for sure. It's too much to expect you to strip your board out just to send a pic, but if you ever have to do that, a jpg would be appreciated. It's really difficult to find info on these units, and haven't been able to find a schematic. It's not clear what all the pins of the header are for, though some may be to flash the cpu with firmware. There may also be added factory commands for things like replacing the oscillator, though one would expect that to be an auto function within the firmware. The fact that the efc always returns to the most recent value at power up and not do a sweep through the whole range might suggest this is not the case. Anyway, powered up the original 260-0558 oscillator on the bench today, with a helipot of the efc input and get the following: EFC Frequency, MHz ---------------------- 0v 5.000 003 54 1v 5,000 002 59 2v 5.000 001 57 3v 5.000 000 55 4v 4.999 999 53 5v 4.999 998 51 6v 4.999 997 35 Voltage for exactly 5Mhz output = 3.5413v So the oscillator looks good and the fact that the Z3816 doesn't lock with that in place suggests that some of those damaged parts are needed :-(. Have another of Ebay fluke seller's MTI 260-0664 ordered. The original is in the Z3816 and don't want to take it out again until i'm sure that it's necessary. At ~$18 each, it good to have a spare and will characterise that on arrival to see what the differences are between that and the 260-0558. Knowing my luck, probably find the efc is the opposite sign, or negative, but time will tell. Have posted this to the list as well, in case the info is useful... Regards, Chris _______________________________________________ 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.