[time-nuts] Z3816 Oscillator Saga
GandalfG8 at aol.com
GandalfG8 at aol.com
Fri May 2 09:08:33 EDT 2014
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?
In a message dated 02/05/2014 13:31:41 GMT Daylight Time,
syseng.greenfield at btconnect.com writes:
On 05/01/14 08:51, Peter Schmelcher wrote:
> 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.
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
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
pic, but if you ever have to do that, a jpg would be appreciated. It's
difficult to find info on these units, and haven't been able to find a
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
replacing the oscillator, though one would expect that to be an auto
within the firmware. The fact that the efc always returns to the most
at power up and not do a sweep through the whole range might suggest
this is not
Anyway, powered up the original 260-0558 oscillator on the bench today,
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
~$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,
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...
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