I would like to make a unit with multiple 10 MHz 50 Ohm outputs to feed my
various bits of test equipment. I am thinking about some practical
considerations.
1) It would be great if there was a circuit published which can give 50 Ohn
output impedance from a 12-15 power supply, which
a) Doesn't
In message 20141123153744.biokf...@smtp16.mail.yandex.net, Charles Steinmetz
writes:
First, mount the LTE in a cast aluminum box (not thin sheet metal,
something with some heft). [...]
Charles' design has some good points, but I don't agree with it.
What you are trying to do is to
Dave wrote
But given the TCXOs sensitivity to temperature changes, I don't
know whether it might be preferable to mount the LTE lite in its own box
without any power supplies in it - perhaps with some thermally insulting
material around the LTE lite so the crystal doesn't experience any fast
NIST did something similar for their WWWV site, where they used bottled
water in its staple packaging to build a thermal mass. They measured how
their atomic clocks and rig behaved before and after, and could see the
difference. Very neat way of using off the (store)shelf components for a
I'm writing a short simulation program to generate samples from a analog
system with some op amps, etc., and I'm wondering if anyone has some
practical experience on picking parameters for the generator.
I'm generating minutes worth of data sampled at 1 kHz, and my opamps
have their
Hi
On Nov 22, 2014, at 11:02 PM, paul swed paulsw...@gmail.com wrote:
Thanks I just like the idea that its leveling out instead of always
climbing.
Yup, that’s what you want to see.
Granted there are all these noisy spikes but I think thats just the way it
is and most likely not bad at
Hi
If all the “good stuff” runs on the 90 MHz, the 5 MHz issue may not be
important at all. It’s just something to watch for. If you start seeing data in
two groups, each one 20 ps wide and separated by maybe 200 ps, you are seeing a
problem from the 5 MHz.
Running the box for a while before
All:
I am enjoying this thread. These are all very interesting ideas.
Hoping to power up my first unit later today
I'm putting my LTE-Lite in the recommended HAMMOND box. That takes care
of the box with air. I was then considering proportional heating of the
surface of the box, like I
Dave wrote:
It would be great if there was a circuit published which can give 50 Ohn
output impedance from a 12-15 power supply, which
a) Doesn't load the TCXO
b) Doesn't degrade the phase noise.
WRT loading the TCXO, someone should establish quantitatively how
high the load impedance must
Hi
If you have a basement in your house / building
—and —
it’s dry and reasonably draft free (no garage doors opening up from time to
time)
— and —
At least one side / corner is well buried in the ground
— and —
You can get at that corner / side.
Move your thermal baffle gizmo up
Hi
About all I’d say is that if Jim Barnes said that’s the way to do it. then
that’s the way to do it. There are only a very few people who I’d say that
about.
Bob
On Nov 23, 2014, at 9:05 AM, Jim Lux jim...@earthlink.net wrote:
I'm writing a short simulation program to generate samples
In message c9e99c83-aaa9-4d50-9729-b86a79af2...@n1k.org, Bob Camp writes:
At least one side / corner is well buried in the ground
But be aware that such a corner may be dry only when empty.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP
In message 20141123174632.kvk4s...@smtp18.mail.yandex.net, Charles Steinmetz
writes:
And good luck fitting a cubic foot box with a surround of bricks into
a 3U rack cabinet, or any other relocatable (much less,semi-portable)
enclosure.
I didn't say it doesn't work, I said that I don't
Hi
What you have in the LTE is a TCXO rather than a bare crystal or an OCXO. It’s
got a compensation circuit that corrects the FT curve of the crystal. The net
result is likely a 5th or higher order curve when you plot frequency over
temperature. Every TCXO off that production line will have a
I am scratching my head here.
From what I see the LTE is a good unit but does swim around a bit. The
conclusion I might get from this thread is that lots of insulation will fix
that.
I suspect not.
The LTE in use down at 2.8 e-10 according to its output.
I have put it in a small cardboard box
Hi
Yup, that’s another good reason for the plastic bag :)
If moisture might be an issue in your area, cover up the corner for a while in
the rainy season to check for that problem before the project begins. Depending
on the bag is not a real good idea.
Bob
On Nov 23, 2014, at 9:50 AM,
Jim,
Find myself providing guidance in both the 2010 and 2013 threads, and
they are still valid starting-points.
For music synthesizer applications, flicker noise have been done, such
as on this schematic:
https://rubidium.dyndns.org/~magnus/synths/friends/stopp/asm1ns.pdf
The work is
Anders,
The counter runs on a Pipistrello. I looked at the information on the web
about time taggers before starting. I decided to try an oversampling
scheme described by a group of Italian? physicists for a multichannel time
tagging instrument. They used 4x oversampling. My version is
Poul-Henning wrote:
Charles' design works great from the outside, but doesn't do anything
with respect to the thermal energy expended by the encapsulated
device themselves, which will cause convection in the inner box.
I have been using the technique for 30+ years, including with many
OCXOs
I was about to comment on this. As you interpolate among the 8 phases,
time errors in the routing might need to compensated for in order to
represent a flat stepping of time-compensation. It will not be perfect
naturally.
Cheers,
Magnus
On 11/23/2014 03:57 PM, Anders Wallin wrote:
Anders,
On 11/23/14, 7:21 AM, Magnus Danielson wrote:
Jim,
Find myself providing guidance in both the 2010 and 2013 threads, and
they are still valid starting-points.
For music synthesizer applications, flicker noise have been done, such
as on this schematic:
The short-term performance is 10x worse if you don't shield the TCXO from air,
even if the ambient air is still. I suggested Said sell the product with some
sort of engineered shield in place. Instead each of us will solve the problem
in our own way; which is ok for a dev kit.
For plots and
On 23 Nov 2014 14:45, Bob Camp kb...@n1k.org wrote:
Hi
If you have a basement in your house / building
I do not.
—and —
it’s dry and reasonably draft free (no garage doors opening up from time
to time)
My lab is a room which is part of the garage! Just about everything is
against me with
What's the latest opinion (data) on available low additive phase noise 10
MHz amplifiers for 10 MHz distribution?
Regards and thanks.Bill
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Thanks all for the replies. After a couple of replies and the reference
to terminal server a light bulb came on and put it all into
perspective, including a vague recollection of some previous postings.
cheers, Graham ve3gtc
On 2014-11-22 19:59, Chris Albertson wrote:
On Sat, Nov 22, 2014
Hi
I believe the DMTD mentioned is the one done by Bill Riley. It’s at:
http://www.wriley.com/A%20Small%20DMTD%20System.pdf
That paper has way more info on the device and it’s signal processing than is
worth going into on the list. There has been some discussion about the limiters
used here
Hi
If you want to go sub-nanosecond there are other ways to do the TDC in an FPGA.
Numbers in the 60 to 140 ps range are fairly easy to hit with 2010 era FPGA’s.
The results need to be corrected for temperature and voltage if either one
moves very much. The routing delays drop out as part of
In message canx10hb0kdrnaayzgvm1gkduj7gklth0acdxczg894hxbus...@mail.gmail.com
, Dr. David Kirkby (Kirkby Microwave Ltd) writes:
He installs ground source
heat pumps for the geothermal energy. He says that they actually work
quite poorly in many cases.
There is a BIG difference between
On 23 Nov 2014 17:49, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message
canx10hb0kdrnaayzgvm1gkduj7gklth0acdxczg894hxbus...@mail.gmail.com
, Dr. David Kirkby (Kirkby Microwave Ltd) writes:
He installs ground source
heat pumps for the geothermal energy. He says that they
In message canx10hcaob-5gysbr7sdxwl7dyh7qubmhxwmi9xdrcf3mdm...@mail.gmail.com
, Dr. David Kirkby (Kirkby Microwave Ltd) writes:
Geothermal means you drill at least 50m (Iceland) or more likely
half a kilometer down, in order to harvest water at near boiling
point from the Earths
Graham,
There are a number of WiFi to serial modules like the one I use on my
Thunderbolt monitor: The Microchip WiFly RN-XV-171. Once configured (typically
using a PC), they will present a TCPIP port (TCP or UDP) from which you can get
and send data directly to the serial port.
Alternately,
Discrete component designs using suitable silicon BJTs offer the lowest
phase noise. Reworking some old designs to incorporate lower noise dc
biasing (particularly collector/emitter current ) can significantly reduce
close in PN.
Bruce
On Sunday, November 23, 2014 08:47:44 AM Bill wrote:
My unit didn't come with right-angle pigtails as shown in the doc (and
Tom's photos). Did anyone else get straight connectors?
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Thanks Didier,
Good suggestions and I have been considering something similar.
cheers, Graham ve3gtc
On 2014-11-23 13:26, Didier Juges wrote:
Graham,
There are a number of WiFi to serial modules like the one I use on my
Thunderbolt monitor: The Microchip WiFly RN-XV-171. Once configured
Schomandl -- the company which made the first indirect synthesizers in
the sixties in the past century -- used buried crystal oscillators as
standard frequency source, 12meter deep in the companies yard in the
Belfort Strasse in Munich, Bavaria Germany, ...Rohde Schwarz also had
buried
I've read about die-hard microwave hams burying their master oscillators
for a long time . . . .
On 11/23/2014 11:46 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
On 23 Nov 2014 14:45, Bob Camp kb...@n1k.org wrote:
Hi
If you have a basement in your house / building
I do not.
—and —
Interesting comment about the geothermal.
I have to take continuing education courses in order to maintain my PE;
one was in geothermal.
Intuitively, great for cooling, even (especially!) in Florida.
Intuitively, not so hot for heating, especially in PA, and especially
with the price of
Did you use one-ply, two-ply, or three-ply TP?
More seriously, your LTE-Lite differs in a couple of respects from the
batch of production ones, or at least my example. Your TCXO seems to be
in a metal package (shiny gold colour) and open to the air, if I'm
interpreting the photo on your LTE-Lite
My first unit came with straight connectors. I can manage.
On 11/23/2014 1:50 PM, Paul wrote:
My unit didn't come with right-angle pigtails as shown in the doc (and
Tom's photos). Did anyone else get straight connectors?
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time-nuts mailing list
Bill,
Check out the Ettus Octoclock. Its probably without competition at their $900
price point:
https://www.ettus.com/content/files/Octoclock_Spec_Sheet.pdf
Its very compact and quite useful. Is it the lowest noise amp ever built? No.
But its state of the art for low-cost distribution of
Didier has a good suggestion as to the serial to Wifi adapter. I may
order one for my Z3801. Looking on Amazon, I see these two units that
are more reasonably priced:
http://www.amazon.com/Keynice-Ethernet-Intelligent-Communication-Wireless/dp/B00JTUVA0G/ref=pd_sim_sbs_e_1?ie=UTF8
All:
I appreciate all the responses to my post earlier today. Very informative.
First: DownEast Microwave sells a nice kit for distributing 10 MHz.
Specs are on their website, but basically, one in, four out -- each
individually buffered and filtered.
Second: I will use the 20 MHz from
Hi guys,
this is the kind of lively discussion I was hoping for! I enjoyed this.
Some comments (these are my opinions only):
* Thanks much for Tom publishing the plots, and spending a lot(!) of time
evaluating and helping improve the units significantly. Tom's unit was a
pre-production
Ok, this got a bit tangled with various email addresses linked to here and
there. Let’s see if it works better this way.
Hi
On Nov 23, 2014, at 1:04 AM, Perry Sandeen sandee...@yahoo.com wrote:
List,
Wrote: Surplus OCXO’s are well … surplus. A significant percentage of the
Hi
For any “real world” source being distributed, simple high speed CMOS buffers
will not add enough noise to matter at 10 MHz. That of course also assumes that
the target gear is the normal bunch of instruments that we all play with.
Bob
On Nov 23, 2014, at 11:47 AM, Bill
Hi
If your target frequency error is in the 1x10^-10 to the “hopefully 1x10^-11”
range, You should consider your very requirements carefully. I tossed up some
frequency plots of the KS boxes and of the Z3801 a while back. They are OCXO
based boxes running in a very good thermal environment.
On 23 Nov 2014 16:25, Tom Van Baak t...@leapsecond.com wrote:
For plots and photos showing performance with, and without, and with
insulation see:
http://leapsecond.com/pages/LTE-Lite/
The difference is dramatic, especially if you are used to working with
OCXO where this sort of effect does not
Hi
Well the answer is obvious:)
You simply need to turn on the air-conditioning full blast for more months of
the summer in … ummm ….. e …. Denmark … hmmm…..
Heat only or cool only systems seem to be more practical when the heat sink is
a flowing body of water or an ocean. Unfortunately
Hi
There are two plots with activity changing at 300 seconds. The second plot
(purple) is the removal of the paper at 300 seconds. The fourth plot (red) is
the addition of the paper at 300 seconds.
The last plot (green and blue) is ADEV with and without the paper. Blue is ADEV
with paper.
Paul
Mine came with right angles.
It does make for a nicer arrangement.
Regards
Paul
WB8TSL
On Sun, Nov 23, 2014 at 2:26 PM, Jim Sanford wb4...@wb4gcs.org wrote:
My first unit came with straight connectors. I can manage.
On 11/23/2014 1:50 PM, Paul wrote:
My unit didn't come with
Tom,
From the looks of the plots these may be from the first proto unit with early
software no? Also was this with the indoor GPS antenna setup?
The production units with outdoor or windowed' antenna should have
significantly improved average performance from the first unit and its early
GPS
Hi
A lot of these parts are designed for use in a system environment rather than
sitting out on a bench. That’s as true of the KS boxes (forced air cooling) as
it is of the LTE’s. In 90% (and likely 99.9%) of the places a TCXO gets
used, it’s packed tight in with a bunch of other stuff. Not
Hi
Actually that was Bob trying to explain Tom’s plots simply from looking at
them. I *think* I got it right, but it’s Tom’s data and his LTE part. Others
have commented that Tom’s part looks different than theirs.
Maybe Tom needs a Microsoft Windows Update on his GPSDO firmware :) For some
by us in central California, we get 1kW/h square meter average around
the year, the south even more, el Cajon will have today +29C° in the
afternoon as of 23 of November 2014
73
Alex
On 11/23/2014 9:49 AM, Poul-Henning Kamp wrote:
In message
Running very nearly continuously for about 4 days now. The self-measured
jitter is mean 0 and sdev of 8 ps. I don't think there is a problem with the
Morion. I'm using my newly acquired cs source and a couple of z3801's for
checking. 1 bit on the SR's frequency calibration dac seems to be about
Hi
That sounds fine. Without knowing just what they did or didn’t do, it’s always
worth being a bit careful.
Bob
On Nov 23, 2014, at 6:40 PM, Don Latham d...@montana.com wrote:
Running very nearly continuously for about 4 days now. The self-measured
jitter is mean 0 and sdev of 8 ps. I
No question about that. The morion does run a little warmer than the old unit
apparently did. Fan is temp-controlled, so I think OK. will monitor box temp
with a digital :-) thermometer, very poor resolution, but probably ok.
When I get the last obs done. will do a little blurb to the group.
Don
Did we answer the q? about schematics?
All of SRS's products have their block diagram and parts list with a
detailed circuit description in their user manual. Sneak preview: its all
resistors.
NS
On Sun, Nov 23, 2014 at 4:22 PM, Don Latham d...@montana.com wrote:
No question about that. The
Hi
About the only other question would be the proper resolution for the DAC.
There’s not much of a way to to answer that one without playing with a woking
original OCXO.
Bob
On Nov 23, 2014, at 7:22 PM, Don Latham d...@montana.com wrote:
No question about that. The morion does run a
A Hint about avoiding convective cell heat transfer,
If you keep the spacing between two planes less than 5/16 then you will
be unlikely to have convection cells forming. The stationary air is a good
insulator
but thermal radiation will be the dominant heat transfer process.
This is true for
Hi
I believe that if you go back a few years in the archives, you will find a
thread that ultimately stops with a swimming pool full of mercury. Needless to
say, we’re been down this road once or twice before.
Bob
On Nov 23, 2014, at 7:59 PM, Neville Michie namic...@gmail.com wrote:
A
Said wrote:
The 10MHz units have a different RF output than the 20MHz units. The
20MHz units have a 50 Ohms series-terminated and buffered RF output,
while the
10MHz units have the TCXO output drive the MMCX connector directly without
series impedance matching. Both drive the line with 3.0V
Schematics in KO4BB magnificent storehouse.
Neil Schroeder
Did we answer the q? about schematics?
All of SRS's products have their block diagram and parts list with a
detailed circuit description in their user manual. Sneak preview: its all
resistors.
NS
On Sun, Nov 23, 2014 at 4:22 PM,
From the manual, I infer the dac is 10 bit. ( 4096 max count) Span is 5 volts.
I've connected the gpsdo and the clock error light does not light; I'm
assuming the morion is locking to the gpsdo OK. I do have the original, was
going to open it up sometime. I suspect something wrong with the heater.
No but a little math based on your ocxo's range can help... but measuring
it in person does give you the best numbers.
More precision and more bits WON'T hurt here and the application notes from
the leading crystal makers suggest a DAC front ended by a precision op amp
with and that the xo be
Hi Jim:
It turns out that ground water that's being pumped is very similar to pumping
oil. It's a limited resource.
There's a web page showing the GRACE satellite maps of California and that we
are running out of ground water.
This isn't the page, but gives the idea:
Hi
The ADEV of the reference source (OCXO / external reference) will most
certainly impact the performance of the counter. The device is just comparing
the input signal to the reference. Which ever one has the worse stability will
limit the measurement. At some point (inside the 90 MHz VCXO’s
Hi
The main question is - is there a PLL between the external ref and the OCXO? If
so does it go through the DAC?
If there’s a PLL through the DAC, then bits do matter. If the DAC is simply a
replacement for a trim pot, then it may not matter much at all. The OCXO will
likely age more in a
Thanks to all for the response but the distribution amp additive noise can be a
real problem since the 10 MHz to be distributed is -170 dBC/Hz at 10 KHz and
needs to be preserved if at all possible.
BTW, the Ettus Octobox doesn't have a spec for additive phase noise, so that's
out.
Again
If you feel like building :
http://www.ti.com/tool/tida-00226
You can integrate that further than a cots one
On Sunday, November 23, 2014, Joseph Gray jg...@zianet.com wrote:
Didier has a good suggestion as to the serial to Wifi adapter. I may
order one for my Z3801. Looking on Amazon, I
Hi
While OCXO’s that have -170 dbc/ Hz specs are fairly common, they normally go
deep inside a box of some sort. It’s a rare off the shelf device that takes in
the output of a distribution amp *and* requires that sort of phase noise.
What’s your target device(s)?
Why do I ask? Well, a device
On 11/23/14, 5:46 PM, Brooke Clarke wrote:
Hi Jim:
It turns out that ground water that's being pumped is very similar to
pumping oil. It's a limited resource.
There's a web page showing the GRACE satellite maps of California and
that we are running out of ground water.
Back east where that
Charles,
Any buffer options added to the board would have caused either additive phase
noise or added power consumption, and possibly yet another low noise LDO to be
required.
On the 20MHz units there is already a strong buffer that can drive 50 Ohms
terminations so adding a buffer in front
In message 54723237.7070...@pcscons.com, Alex Pummer writes:
by us in central California, we get 1kW/h square meter average around
the year, the south even more, el Cajon will have today +29C° in the
afternoon as of 23 of November 2014
Yes, the latitude means a lot for ground
Hi Bob,
Thanks for your comments.
The devices in my lab that can benefit from the low phase 10 MHz source are 1)
the spectrum analyzer(s), 2) a Comstron direct synthesizer, 3) the synthesized
signal generators and the test source(s) used to drive microwave multipliers
and signal sources. All
I did some checking around for low noise buffer amps earlier
this year. They needed to have 200 MHz bandwidth, so this
isn't directly applicable to 10 MHz. I also needed isolation.
About the only information in print is from the usual suspects
at NIST. They wrote a series of papers taking a
The 90 MHz is multiplied up from the 10 MHz, no pll. Done with a 10 mhz rate
5 ns pulse and a filter chain, followed by a comparator and buffer.
from the manual:
The SR620 has a rear panel input that will accept either a 5 or 10Mhz external
timebase. The SR620 phaselocks its internal timebase to
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