One of the GPS units is likely sending a saw-tooth message out the serial
line that exactly describes the 0 to 100ns drift. This is why they call
it "saw tooth" the function ramps up slowly then falls to zero. A device
like a GPSDO that uses the PPS would need access to the serial data to read
t
Voltage is proportional to the product of resistance and absolute
temperature. As an experiment place a voltage across a high value
resister like say one 1M raise the volts until you are near the limit of
the resister and connect it via a coupler cadaster to an audio amplifier.
You will hear whi
1) I have my TAPR M12 Kit working now next to my lucent RFTG-U REF0/1 pair. I
was comparing the PPS outputs triggering on the Lucent as channel 1 and the M12
as channel 2. I can’t tell which is moving around but the symptoms are that at
T0 (not the top of the minute or hour) they are in sync w
Where do digital sensors (e.g. ds1820 and some more recent parts from TI)
fit into this ?
On Mon, Jun 5, 2017 at 12:59 AM, Attila Kinali wrote:
> Moin,
>
> This discussion is kind of getting heated.
> Let's put some facts in, to steer it away from
> opinion based discussion.
>
> On Sun, 4 Jun 2
trojancow...@gmail.com said:
> A roof antenna with preamp that could drive 100 feet or so of foam RG-58 is
> required.
RG-58 is very lossy at GPS signal frequencies.
The sweet spot on the cost/performance chart is RG-6. It's widely available
as low loss cable TV. It's slightly larger diamete
Yes, I have a TEC mounted on a convection heatsink that illustrates that point.
Initially ice forms on the cold surface but eventually the heatsink temperature
rises sufficiently that the ice melts. A larger blown heatsink or perhaps a
water cooled heatsink would be necessary if this setup was in
I'd recommend a GPIB-USB-HS adapter. There are tons of them on eBay, e.g.
http://www.ebay.com/itm/322360711342
http://www.ebay.com/itm/321957086926
These will work well with both PN3048 and HTBasic. I've purchased them from
both of those sellers in the past. They appear to be genuine, unlik
Hi
Many times people underestimate the amount of heat sinking required with a TEC.
If you get into fans, they
introduce a whole new set of issues ….It’s not just the heat you are getting
out of the “oven”. The TEC it’s self
makes a pretty good thermal short (compared to foam insulation). You ha
On 6/4/17 4:59 PM, Attila Kinali wrote:
Where did you get the idea to use a 1 k load for an AD590?
Jim was refering to a circuit _he_ used in a satellite. Not to your circuit.
We've also used 3k. It's more about supply voltage, expected
temperature range, and the ADC you're using (if an
Really??
The circuitry employed is something of a joke surely?
Relying on the MOSFET characteristics to limit warm up current is unwise.
The temperature sensor also would appear to suffer from large variations in
output from one part to another.
Bruce
>
> On 05 June 2017 at 01:21 "R. K
My concern with using a TEC is that, heating or cooling, you are left with one
cold surface and that surface will collect condensation which is a source for
corrosion.
John WA4WDL
> On June 4, 2017 at 8:12 PM Attila Kinali wrote:
>
>
> Moin Chris,
>
> On Sun, 4 Jun 2017 13:49:29 -0700
> Chr
The other issue that needs to be considered is the drift in temperature sensor
characteristics when operated at a constant temperature (as is typical in a
continuously operated crystal oven). High quality thermistors can achieve
drifts of around 1mK/month. Its unlikely that something as complex
Moin Chris,
On Sun, 4 Jun 2017 13:49:29 -0700
Chris Albertson wrote:
> We used the pelter because we preferred a cool "oven" to a hot one. The
> theory has that we get less electronic noise so we ran the TEC in cooling
> mode. But for your use a resistive heater would be cheaper. But in
>
Moin,
This discussion is kind of getting heated.
Let's put some facts in, to steer it away from
opinion based discussion.
On Sun, 4 Jun 2017 08:44:33 -0700
"Donald E. Pauly" wrote:
> I stand by my remark that thermistors have been obsolete for over 40
> years. The only exception that I know of
Hi
A thermistor has *no* output unless it is in a circuit that biases it up. A
thermocouple
is the one that has an output when no bias is present….
Take a 10K thermistor and a 10K resistor and put them in series. You will get
roughly Vcc / 2 at 25C
at the junction of the two parts.. The output
On 6/4/17 1:49 PM, Donald E. Pauly wrote:
I own several Fluke 52 stereo thermometers with K themocouples. They
run 40 μV/C°. All thermistors have tiny outputs without op amps.
They also suffer from self heating. AD590 sensors give AT LEAST 15
mV/C° without op amps. If a regulated 3,000V suppl
We are finishing a pair of HP5061B cesium standards which we have up
and running. We would like to acquire a GPS disciplined oscillator
with 5 or 10 mc output for comparison with the cesium clocks. 1 pulse
per second would be nice but is not mandatory. A roof antenna with
preamp that could drive
I own several Fluke 52 stereo thermometers with K themocouples. They
run 40 μV/C°. All thermistors have tiny outputs without op amps.
They also suffer from self heating. AD590 sensors give AT LEAST 15
mV/C° without op amps. If a regulated 3,000V supply is available they
can give 2 V/C° into a 1
Look at the temperature coefficient of your XO. Then figure a very simply
control loop and a thermistor will keep a block of aluminum within 0.1C of
a set point. Use a decent size block and insulation
We drilled a deep hole then epoxied the thermistor. I think this step is
important as you want
I am trying to set up an HP 3048 system and
have read the KE5FX web page on the software.
I have successfully installed both PN3048 and
the HT Basic port of RMB. The programs basically
appear to run correctly on my Windows 7 desktop.
HOWEVER, I don't have a GP-IB card. According to
KE5FX, both
Hi
I think you have thermistors and thermocouples a bit mixed up. You can get
quite substantial output voltages from a thermistor bridge….
Bob
> On Jun 4, 2017, at 11:44 AM, Donald E. Pauly wrote:
>
> I stand by my remark that thermistors have been obsolete for over 40
> years. The only excep
Hi
Ok, when you wrote the specification for your crystals what was the tolerance
on the angle
for those crystals? What did the suppliers who quoted to your spec say about
the angle tolerance
you specified? When they shipped against your volume requirements how did they
do against the
specific
I stand by my remark that thermistors have been obsolete for over 40
years. The only exception that I know of is cesium beam tubes that
must withstand a 350° C bakeout. Thermistors are unstable and
manufactured with a witches brew straight out of MacBeth. Their
output voltages are tiny and are t
I've bought dozens of them over the years and talked to crystal
engineers for tens of hours. I watched them plated and tuned at a
crystal filter company in Phoenix. I own Virgil Bottom's book on the
subject and understood half of it.
πθ°μΩω±√·Γλ
WB0KVV
-- Forwarded message --
F
Maybe you want to check out the work of Hans Summers he has done some
impressive low cost stuff:
http://www.hanssummers.com/ocxosynth.html
http://www.qrp-labs.com/ocxokit.html
Ralph
On Sun, Jun 4, 2017 at 07:19 jimlux wrote:
> I recall some years ago folks were talking about putting a PTC
> the
hi
I have been having great results with my M12 and Lady H. I (foolish me)
had tried to cobble up a Perl program at first... just browse through some
of the 400+ pages of heathgps.cpp to see why that was a bad idea! Both my
M12 and my Tbolt are controlled by Heather running on two PI3s.
Now, i
Hi
If you have not done so already, you might try bumping the temperature a bit to
search for the
upper turn in the crystal curve. Based on the data in the plots, you do have an
AT that is cut
with an upper turn.
Bob
> On Jun 4, 2017, at 11:30 AM, Dan Rae wrote:
>
>
The attached plot shows the sort of improvement in warm up time and
stability of a simple "oven" made by attaching a Darlington heater
transistor and thermistor to a Crystek 100 MHz oscillator, adjusted to
set the osc temp to around 35C and wrapping it all in foam. In this
application, a DDS c
Hi
There is no way to know how every outfit makes their products. My guess is that
the temperature compensation “stuff” is pretty stable. At least it has been on
all
the product I’ve designed :) I’d bet that the crystals in the TCXO’s are the
culprit.
In some of the factories I’ve visited, the
Mark -
Yes, it does. :-)
The "S" and "!" menus are the most frequent menus I use with LH.
Jerry is using SynTAC.
After a few e-mail exchanges, off-list, problem was antenna location.
gb
===
So does Lady Heather... the "S" menu control things like self-surveys, entering
fixed position coordinates
Bob, at the same time, look at all the guys here who absolutely insist that
the only way to use a double-oven OCXO is to put it in a tightly
temperature controlled environment. "Nuts", yes, but that's why we're here!
I myself have been extremely disappointed with the aging characteristics of
low-e
Hi
The gotcha is that you have multiple systems working against each other. The
crystal in the TCXO has
one temperature characteristic. The compensation in the TCXO has a temperature
characteristic. They
cancel each other out to a limited degree. The residual slope may (or may not)
be as shallo
My SDR-1000 showed substantially less "WWV drift" after adding
the PTC thermistor to the TCXO. Sorry, no measurements because
that was before I had a GPSDO.
Mikr - AA8K
On 06/04/2017 08:13 AM, jimlux wrote:
I recall some years ago folks were talking about putting a PTC
thermistor on the T
We did this years ago on a 430 MHz data radio with an utterly uncompensated
crystal that would drift through the passband. After building our own for a
while, we discovered that Yaesu had something even better available through
their replacement parts shop -- a spring clip with PTC that snapped
Hi
Have you ever tried to actually *buy* a crystal built to a specification? There
is a
tolerance on them. That has a profound impact on what you can *buy*.
Bob
> On Jun 4, 2017, at 12:56 AM, Donald E. Pauly wrote:
>
> You have a fundamental misunderstanding of the AT curve family. See
>
I recall some years ago folks were talking about putting a PTC
thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the frequency
as a sort of poor-man's OCXO.
It's also referenced at
http://www.setileague.org/askdr/xtaloven.htm
where he says "order of magnitude improvement" with no number
In message <3ca81847-63c4-f803-994d-8e07c9973...@earthlink.net>, jimlux writes:
>Modern RTDs all are 0.00385 ohm/ohm/degree at 25C. Typically, you have
>a 100 ohm device (although there are Pt1000s), so it's changing 0.385
>ohm/degree. 1 part in 3000
Depending how much money you want
On 6/3/17 9:56 PM, Donald E. Pauly wrote:
It was only in the early 70s that Analog Devices invented the AD590
solid state temperature sensor. It made thermister bridges obsolete.
There is a difference between something like a platinum resistance
thermometer (PRT or RTD) and a thermistor, but
You have a fundamental misunderstanding of the AT curve family. See
my QBASIC plot at
http://gonascent.com/papers/hp/hp5061/photos/newxtl.jpg . The
commonly described AT cut is shown as the largest sine wave in the
blue rectangle. The left side of the rectangle is -55°C, the center
is 25° C and
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