Symmetricom/Datum FTS-1050A Disciplined Frequency Standard
I've been scrounging around in the OCXO department and found two of
these that I likely pulled from something junked out long ago. I found
the MTI website, current catalog, model line etc, but of course no
mention of this specific version, or anything close, numerically. I
can't make any sense of the sub-model numbers, so assume this was a
custom version for somebody, or long obsolete. Does anyone know of this
particular model version, or if there's a "system" to the sub-model
numbering scheme?
Frequency 10 MHz
Model 250-0709-B
Part # 010209-0709
I believe the date codes are 1997 and 1998
The notes I made on them say they're +12V powered, which I must have
figured out back when I pulled them.
One thing different about these versus the current ones pictured is they
have no screw-plug port to access mechanical/coarse tuning - they're
solid all around. It might be that the "-B" suffix deletes this access.
I suppose that this could be a good or a bad thing, depending on use.
Maybe it's very stable, long term, or maybe it has a very wide EFC
tuning range.
I'm hoping it's an SC-cut, sine out, for lowest available phase noise
and utility for my needs. Worst case would be AT, HCMOS, poor phase
noise and excessive tuning range, so of course, that's most likely.
If no info is available, I can fire it up and check the output type easy
enough. Also, as I recall, you can tell the cut by the frequency
behavior during warm up, but I forget which does which. Any suggestions
on how to assess this definitively?
Anyway, here's hoping there's some actual data available, and it's a
good one for my needs.
Ed
Hi
For most oscillator manufacturers, the OEM numbers are simply
assigned in sequence. 0709 was the next one after 0709 and the
one before 0710. It does not relate to anything other than when
(relative to the rest) it was done. The “root number” may or may
not relate to a package size ….
Bob
On Jul 18, 2022, at 4:59 PM, ed breya via time-nuts time-nuts@lists.febo.com wrote:
I've been scrounging around in the OCXO department and found two of these that I likely pulled from something junked out long ago. I found the MTI website, current catalog, model line etc, but of course no mention of this specific version, or anything close, numerically. I can't make any sense of the sub-model numbers, so assume this was a custom version for somebody, or long obsolete. Does anyone know of this particular model version, or if there's a "system" to the sub-model numbering scheme?
Frequency 10 MHz
Model 250-0709-B
Part # 010209-0709
I believe the date codes are 1997 and 1998
The notes I made on them say they're +12V powered, which I must have figured out back when I pulled them.
One thing different about these versus the current ones pictured is they have no screw-plug port to access mechanical/coarse tuning - they're solid all around. It might be that the "-B" suffix deletes this access. I suppose that this could be a good or a bad thing, depending on use. Maybe it's very stable, long term, or maybe it has a very wide EFC tuning range.
I'm hoping it's an SC-cut, sine out, for lowest available phase noise and utility for my needs. Worst case would be AT, HCMOS, poor phase noise and excessive tuning range, so of course, that's most likely.
If no info is available, I can fire it up and check the output type easy enough. Also, as I recall, you can tell the cut by the frequency behavior during warm up, but I forget which does which. Any suggestions on how to assess this definitively?
Anyway, here's hoping there's some actual data available, and it's a good one for my needs.
Ed
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Am 2022-07-19 2:59, schrieb ed breya via time-nuts:
I've been scrounging around in the OCXO department and found two of
these that I likely pulled from something junked out long ago. I found
the MTI website, current catalog, model line etc, but of course no
mention of this specific version, or anything close, numerically. I
can't make any sense of the sub-model numbers, so assume this was a
custom version for somebody, or long obsolete. Does anyone know of
this particular model version, or if there's a "system" to the
sub-model numbering scheme?
Frequency 10 MHz
Model 250-0709-B
Part # 010209-0709
The family data sheet states that you can get just about everything
that fits into the box.
Someone here on time-nuts tried to get info on a MTI-260 subtype
and even called them with no real result. Info would only be given
to the original customer, i.e. nobody, since the customer should
not have to ask what he had ordered.
It's in the archives.
Gerhard
On 7/18/22 5:59 PM, ed breya via time-nuts wrote:
I've been scrounging around in the OCXO department and found two of
these that I likely pulled from something junked out long ago. I found
the MTI website, current catalog, model line etc, but of course no
mention of this specific version, or anything close, numerically. I
can't make any sense of the sub-model numbers, so assume this was a
custom version for somebody, or long obsolete. Does anyone know of
this particular model version, or if there's a "system" to the
sub-model numbering scheme?
Frequency 10 MHz
Model 250-0709-B
Part # 010209-0709
I believe the date codes are 1997 and 1998
MTI-250 is a standard series for Milliren
http://www.mti-milliren.com/pdfs/250.pdf
The catalog (page 20) lists a dozen or so variants (the chart extends to
Page 21) does give some examples, so maybe you can figure out a pattern?
http://www.mti-milliren.com/pdfs/mti_catalog.pdf
Given that there's a series of 0788, 0789, 0790, 0791, 0792, I'd guess
the last 2 digits are a sequential number to successive orders or customers.
The notes I made on them say they're +12V powered, which I must have
figured out back when I pulled them.
One thing different about these versus the current ones pictured is
they have no screw-plug port to access mechanical/coarse tuning -
they're solid all around. It might be that the "-B" suffix deletes
this access. I suppose that this could be a good or a bad thing,
depending on use. Maybe it's very stable, long term, or maybe it has a
very wide EFC tuning range.
I'm hoping it's an SC-cut, sine out, for lowest available phase noise
and utility for my needs. Worst case would be AT, HCMOS, poor phase
noise and excessive tuning range, so of course, that's most likely.
If no info is available, I can fire it up and check the output type
easy enough. Also, as I recall, you can tell the cut by the frequency
behavior during warm up, but I forget which does which. Any
suggestions on how to assess this definitively?
Anyway, here's hoping there's some actual data available, and it's a
good one for my needs.
Ed
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Hi
On Jul 18, 2022, at 7:28 PM, Gerhard Hoffmann via time-nuts time-nuts@lists.febo.com wrote:
Am 2022-07-19 2:59, schrieb ed breya via time-nuts:
I've been scrounging around in the OCXO department and found two of
these that I likely pulled from something junked out long ago. I found
the MTI website, current catalog, model line etc, but of course no
mention of this specific version, or anything close, numerically. I
can't make any sense of the sub-model numbers, so assume this was a
custom version for somebody, or long obsolete. Does anyone know of
this particular model version, or if there's a "system" to the
sub-model numbering scheme?
Frequency 10 MHz
Model 250-0709-B
Part # 010209-0709
The family data sheet states that you can get just about everything
that fits into the box.
Someone here on time-nuts tried to get info on a MTI-260 subtype
and even called them with no real result. Info would only be given
to the original customer, i.e. nobody, since the customer should
not have to ask what he had ordered.
It's in the archives.
MTI is hardly unique in not sending out OEM data sheets. Most outfits
have similar rules. In some cases OEM’s go to pretty great lengths to
assure that nobody can get the specs on the parts they use. The main
idea is that it makes their end products harder to clone. Same thing that
got them dropping schematics from manuals ….
Bob
Gerhard
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On Tue, Jul 19, 2022 at 5:42 PM Bob kb8tq via time-nuts <
time-nuts@lists.febo.com> wrote:
MTI is hardly unique in not sending out OEM data sheets. Most outfits
have similar rules. In some cases OEM’s go to pretty great lengths to
assure that nobody can get the specs on the parts they use. The main
idea is that it makes their end products harder to clone. Same thing that
got them dropping schematics from manuals ….
A bizarre attitude. Surely someone going to the trouble of cloning an
instrument is going to see reverse-engineering the schematic as a pretty
minor job.
Slightly more reasonable to keep things secret when one of the components
is a quartz crystal with proprietary parameters and no public source.
On 7/19/22 10:19 AM, Adrian Godwin via time-nuts wrote:
On Tue, Jul 19, 2022 at 5:42 PM Bob kb8tq via time-nuts <
time-nuts@lists.febo.com> wrote:
MTI is hardly unique in not sending out OEM data sheets. Most outfits
have similar rules. In some cases OEM’s go to pretty great lengths to
assure that nobody can get the specs on the parts they use. The main
idea is that it makes their end products harder to clone. Same thing that
got them dropping schematics from manuals ….
A bizarre attitude. Surely someone going to the trouble of cloning an
instrument is going to see reverse-engineering the schematic as a pretty
minor job.
Not exactly - you might not be cloning, you might be developing a
competitive instrument, and knowing the oscillator performance is useful
(e.g. "I know I can get one like that" or you can check your design to
see if using your oscillator, you can get the same performance).
Trade secrets are trade secrets - why give any secret sauce away...
A less common cause - the oscillator might be in a system that is
subject to export controls, and the oscillator specifications are export
controlled. It's easier for the oscillator company to just say "nobody
gets it other than the original customer", rather than having to make a
decision on a case by case basis.
Slightly more reasonable to keep things secret when one of the components
is a quartz crystal with proprietary parameters and no public source.
Pretty much every commercial oscillator in existence is made with quartz
crystals with proprietary parameters. Sure, a box might have a
commodity crystal in it, with published characteristics, but a packaged
oscillator? that is truly the oscillator mfr's secret sauce.
I fired one up, and found the following info:
Vs +12VDC works just fine, draws about 400 mA cold start, down to 150 mA
warmed up. Initial current draw rises with input voltage, up to about
11V, then constant, viewed up to 16 V.
Cold start frequency less than 9.999953 MHz, reaching normal in about
5-10 minutes.
Output is sine - haven't measured accurately yet but seems about right
on scope for the typical +9 dBm specs listed.
Tune reference about +8 V.
Frequency tune range about +12/-17 Hz, at Vt = 0V/+8V (Vr).
!0 MHz "exact" is at Vt = +3.096 V
Ed
Ed,
Thanks for this info.
Where you able to measure the phase noise of your MTI 250?
Erik.
On 22-7-2022 7:29, ed breya via time-nuts wrote:
I fired one up, and found the following info:
Vs +12VDC works just fine, draws about 400 mA cold start, down to 150
mA warmed up. Initial current draw rises with input voltage, up to
about 11V, then constant, viewed up to 16 V.
Cold start frequency less than 9.999953 MHz, reaching normal in about
5-10 minutes.
Output is sine - haven't measured accurately yet but seems about right
on scope for the typical +9 dBm specs listed.
Tune reference about +8 V.
Frequency tune range about +12/-17 Hz, at Vt = 0V/+8V (Vr).
!0 MHz "exact" is at Vt = +3.096 V
Ed
Been busy planning and rounding up parts and subsystems for my
multi-function box for looking at phase noise and stability etc mostly
on 10 and 5 MHz. The PN part will be kind of like Erik's recent project,
using those identical MTI 10 MHz OCXOs (the subject of my recent info
search) for initial experimenting. The baseband analyzer will be the
HP3561A (0-100 kHz).
The other part will be a fairly simple analog DMTD system, with fixed
100 Hz offset for 10 MHz, and 50 Hz for 5 MHz. I found I have a nice old
10 MHz OCXO that has mechanical tuning only, that will be committed
(built in) to this project. It's set now for 9.9999 MHz (10 MHz - 100
Hz). I have no suitable 5 MHz OCXOs for this, so figured on dividing the
9.9999 MHz by two when needed.
I recall many times over the years encountering talk about low noise
regenerative dividers, but now that I'm actually contemplating making
one, I can't seem to find much detail. I found a number of commercial
ones like at Wenzel et al, but not much in the way of design detail.
John M's ke5fx site has a good example for 80-40-20 MHz, but I can't
seem to find any of the linked papers and such that were the basis. What
I'm hoping is to find one or more examples of designs already figured
out for 10 MHz/2. I think there must be some out there.
Does anyone know of such?
BTW I finally pulled the trigger on acquiring an HP8663A, which I've
been wanting to get for a very long time. I've had a fully loaded (all
bands) HP11729C for many years, to go with it, and finally be of use. In
the TIM department, I have a busted HP5370A, and a good HP5372A.
Ed