Just to give back to the group, here are the connectors I chose from
Digikey to make the GPS MMCX antenna included with the kit detachable for
an enclosure:
1x ACX1499-ND CONN ADAPT JACK-JACK MMCX 50 OHM
1x 744-1715-ND RF CABL MMCX ML STR / ML RA 6
Cheers,
Joel
W0KGW
On Tue, Nov
Hal wrote:
So driving 50 Ohms inputs is not optimal here, 1M inputs are much
better for
this purpose.
That only works if you have a (very) short connection to the next stage.
Things get interesting if you have, say, 10 feet of unterminated coax.
Thinking that the output was a sine wave, I
The 20 MHz output should be OK, since it is series-terminated with 50 ohms
at the source and the buffer can source enough current. The driver sees a
100 ohm load (50 ohm resistor in series with 50 ohm coax impedance) for
that 32 ns round trip time, so it will increase power dissipation (as you
Charles,
The increased current for the driver will cause heating near the crystal in
both the CMOS driver and the 3.0V LDO as the LDO has to convert the excess
voltage into heat. This may or may not affect the crystal.
One could certainly try, this is why I initially said its certainly
Dave,
Exactly.
Sent From iPhone
On Nov 25, 2014, at 7:34, Dave Martindale dave.martind...@gmail.com wrote:
The 20 MHz output should be OK, since it is series-terminated with 50 ohms
at the source and the buffer can source enough current. The driver sees a
100 ohm load (50 ohm resistor in
Said wrote:
The increased current for the driver will cause heating near the
crystal in both the CMOS driver and the 3.0V LDO as the LDO has to
convert the excess voltage into heat. This may or may not affect the crystal.
There would be next to no additional heating in the CMOS driver,
That's why I said its up to the user to decide what they want their
trade-off to be.
For permanent installations I personally would not run the unbuffered 10MHz
output through more than about a foot of coax cable to the buffer.
The rise/fall time of the TCXO output is slow enough (typical
On 24 November 2014 at 03:44, Said Jackson via time-nuts
time-nuts@febo.com wrote:
On the 20MHz units there is already a strong buffer that can drive 50 Ohms
terminations so adding a buffer in front of the coax connector on that
version would have just added unnecessary phase and AM noise,
Correct, and thats why its all a bad trade off if you have to use 50 Ohms
termination. Either more heat or more PN, and more circuitry.
So driving 50 Ohms inputs is not optimal here, 1M inputs are much better for
this purpose.
I had discussed the advantages of CMOS open-ended termination some
To: Discussion of precise time and frequency measurement; Charles Steinmetz
Subject: Re: [time-nuts] Practical considerations making a lab standard with
an LTE lite
In message 20141123153744.biokf...@smtp16.mail.yandex.net, Charles
Steinmetz
writes:
First, mount the LTE in a cast aluminum box
Said:
Several times you've mentioned a low noise LDO regulator. I've not seen
a device specified -- can you share?
Also, yesterday, in response to my question about using an existing
antenna, you basically said, Try it. Well, I did -- working great for
over 24 hours. At this moment, I
Hi
The Linear LT1764 is a pretty good part. It’s nice and rugged / tough to kill.
Bypass the output with a few hundred uF of tantalum caps. Keep at least a volt
between input and output.
Bob
On Nov 24, 2014, at 7:12 PM, Jim Sanford wb4...@wb4gcs.org wrote:
Said:
Several times you've
Jim,
Bobs suggestion is good; look at for example the LT3060 for something that
needs less than 100mA.
Glad your antenna is working well. What C/No numbers is uBlox indicating?
Bye,
Said
Sent from my iPad
On Nov 24, 2014, at 16:28, Bob Camp kb...@n1k.org wrote:
Hi
The Linear LT1764 is
Said:
I'm seeing C/No numbers between 50.0 and 41.0 for the green birds.
I'm seeing 27.0 to 42 on the blue birds. Not quite sure what the
difference between green and blue is. UBlox is acting kind of funny --
it ignores any attempt to click on an icon or any of the menu bar
items. Yet it
It won't respond the LTE LITE is send only.
I found another program from the Chip manufacturer and it behaves teh same
as expected and mentioned by Said.
So putty works as well as anything.
OK my first external fun with the LTE.
Since I had no 74AS74 I used a 74HC74 chip running at 4.5V. This
Jim,
41 to 50dB is great.
The height difference may be MSL to GPS height?
Bye,
Said
Sent From iPhone
On Nov 24, 2014, at 18:39, Jim Sanford wb4...@wb4gcs.org wrote:
Said:
I'm seeing C/No numbers between 50.0 and 41.0 for the green birds. I'm
seeing 27.0 to 42 on the blue birds. Not
Said Jackson said:
Correct, and thats why its all a bad trade off if you have to use 50 Ohms
termination. Either more heat or more PN, and more circuitry.
So driving 50 Ohms inputs is not optimal here, 1M inputs are much better for
this purpose.
That only works if you have a (very) short
kb...@n1k.org said:
Maybe Tom needs a Microsoft Windows Update on his GPSDO firmware :) For some
reason the very thought of Microsoft getting involved in something like that
makes me shudderâ¦
For good reason. A friend's scope picked up a virus.
--
These are my opinions. I hate spam.
I once bought an HP16700 series logic analyzer off of Ebay that had a directory
filled with porn on it... but that is a Unix machine.
for good reason. A friend's scope picked up a virus.
___
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
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
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,
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
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
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
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
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
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.
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
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
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:
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
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