Re: Quick and dirty GPSDO build by F2DC and me.
A 25 MHz tcxo may be a good idea then, I guess.
Sverre La3za ons. 23. jun. 2021, 20:14 skrev Erik Kaashoek < erik@...>:
[Edited Message Follows]
[Reason: Typo]
The measurement time is adaptive based on the measured error. When the error is less than what can be observed in the measurement time the measurement time increases. With 400 seconds to count the 45MHz clock the error will rarely be zero as this represents above 1e-10 accuracy. It helps to thermally isolate or otherwise stabilize the temperature of the SI5351 module, in particular the crystal, to reduce drift and other disturbances.
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
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Re: Quick and dirty GPSDO build by F2DC and me.
The measurement time is adaptive based on the measured error. When the error is less than what can be observed in the measurement time the measurement time increases. With 400 seconds to count the 45MHz clock the error will rarely be zero as this represents above 1e-10 accuracy. It helps to thermally isolate or otherwise stabilize the temperature of the SI5351 module, in particular the crystal, to reduce drift and other disturbances. -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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Re: Quick and dirty GPSDO build by F2DC and me.
talks about potential problems with a 1PPS reference in GPSDO (GPS Disciplined Oscillator) circuits.? If using 1PPS to stabilize an oscillator
it seems that the best short-term accuracy might be + or - 1/2 Hz, unless one
uses some more analog like technique to add or subtract phase shift to get
sub-1Hz stability.? Several of the popular GPSDO circuits look more like the
H&P (Huff and Puff) circuits that were popular a few years ago.
I am not an expert at GPS disciplined objects.? Others may have better
answers.
Arv _._
On Tue, Jun 22, 2021 at 3:26 PM Sverre Holm < svholm54@...> wrote: I downloaded the PD0EK version of the F2DC software and have had it running for a while. I'm using it with the QLG-1 GPS from QRPLabs. What I find is that the measurement gate with time goes from ... 4, 8, 16, 32, 64, 128, 256, 400 seconds, but the measurement error never stabilizes, but shows -6, 28, and seldom 0 i.e. and therefore it is rare that the display shows "lock".
Is this normal? Or could I have a jitter problem in the 1 PPS pulse from the GPS?
Sverre
LA3ZA
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Re: Quick and dirty GPSDO build by F2DC and me.
I downloaded the PD0EK version of the F2DC software and have had it running for a while. I'm using it with the QLG-1 GPS from QRPLabs. What I find is that the measurement gate with time goes from ... 4, 8, 16, 32, 64, 128, 256, 400 seconds, but the measurement error never stabilizes, but shows -6, 28, and seldom 0 i.e. and therefore it is rare that the display shows "lock".
Is this normal? Or could I have a jitter problem in the 1 PPS pulse from the GPS?
Sverre
LA3ZA
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Re: Tuning a 2.5GHz cavity filter with home build VNA
On Sat, Jun 5, 2021 at 09:24 PM, <kerocool4719@...> wrote:
you could share the arduino firmware
I'm afraid it disappeared ? -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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Re: Tuning a 2.5GHz cavity filter with home build VNA
Hi
you could share the arduino firmware
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Re: A PCB for the W0SJ TDR
Gerry, I would, but unfortunately they are all spoken for. You can use the Gerber files to get boards made. I use JLCPCB. They are cheap and I've never had any problems with their work.
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John P.
WA2FZW
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Re: A PCB for the W0SJ TDR
I'm interested John. Would you ship to Ireland?
Edit: there is no license in the repository. Do you have any particular license in mind? As it stands nobody can legally make use of the designs.
Apologies... this is probably more hassle than you had in mind when publishing your designs.
/ Gerry
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Re: A PCB for the W0SJ TDR
I still have 2 PCBs available. Get 'em while they're hot!
--
John P.
WA2FZW
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In the May 2021 edition of QST Magazine, Stan Johnson (W0SJ) published an article describing a device one can hook to an oscilloscope to turn it into a time domain reflectometer (TDR). Stan built his basically out of parts from the junque box for which he deserves kudos!
?
I hate hand wiring stuff so I decided to design a printed circuit board for it. My board makes a few changes in Stan’s design which made the PCB layout a bit neater and added a couple of features, but otherwise it is basically the same as his design.
?
With a lot of help from Glenn (VK3PE), the PCB can be built using either through-hole components or SMD components or
a combination of both.
?
.
Also available there are two Android apps developed by Roderick Wall (VK3YC). One allows you to calculate the
length of a piece of coax and the other allows you to compute the velocity factor of a known length of coax.
?
I have a few extra circuit boards available should anyone want one. You can have them for $5 each (free shipping to the USA). If you'd like one, please email me (good on QRZ.com).
-- John P. WA2FZW
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File /iw5bsf adf4351 pll spurios/adf4351 spuriosa.jpg uploaded
#file-notice
The following files have been uploaded to
the Files area of the [email protected] group.
By: Roberto <iw5bsf@...>
Description:
original out adf4351 pll spurios
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Thanks everyone for the encouraging comments, I am thoroughly enjoying building something so seemingly simple but quite complicated when you get down to the details of it.
I had a look at the QST articles, yes very interesting project indeed. My DMM is not that versatile but I may in the future add some of the functionalities, will see. For now the voltmeter function is fully working, calibration not a huge issue, I have carefully selected the divider resistor values so that is ok. I am finding the protection part a bit interesting and challenging, it is something I never gave much thought before but looking at information from different sources it seems that the protection is the more difficult and clever bit, especially for the ammeter and ohm meter functionality.?
I haven't tested it with anything higher than 24VDC yet, next is to build the ac rectifier for ac voltage measurements. Eventually will replace it with a true rms module but a simple rectifier for initial testing will do I guess.
Elia, M0ZHN
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my folder file iw5bsf
Hello unfortunately the image with the lost spurious I solved it by welding a few pieces of sheet metal under the pcb and the central dissipation hole adf4351 the poor laminate lacks its ground plane those green colored boards always with adf4351 do not have this problem!
update phase noise?
or noise reduction just put two 1000uf 6.3v electrolytic capacitors on c30 and c31
73 de iw5bsf Roberto
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Re: Quick and dirty GPSDO build by F2DC and me.
I am still getting what must be a loss of pps at the nano. ?I tried the original code from F2DC where this condition drives the error factor to extremes and it does not recover.
Gary
W9TD
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Very cool project!
Yeah, Nick, I remember that series and have a copy somewhere in my stack of stuff. Also that same year QST had another 8-part series by Doug Demaw called “Learning to Work with Semiconductors”. I had gotten my novice ticket the year before and that series really hit the mark for me. IIRC you ended up with a QRP transmitter at the end of the series.
To bad QST no longer supports beginner projects such as these.
Don, K5DW
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On May 23, 2021, at 7:43 PM, Nick Kennedy <kennnick@...> wrote:
? Very nice.
Makes me think of a series in QST back in 1976 I think, that may have been called “Learning to Work with Integrated Circuits” or similar.? The heart of the thing produced a frequency counter, but other devices converted it to a DVM and other functions.? I didn’t get beyond the counter, but it was nice.
It was popular enough that they reprinted the series as a stand-alone booklet.
73-
Nick, WA5BDU
Good day everyone,
Just thought I would share something I started during the lockdown, nothing new or revolutionary but it has kept me entertained :)
My Fluke 77 has served me well since 1984 but is showing sings of age so I said to myself, why not build a bench DMM?
This is a simple DMM, old technology and uses 7 segment display. The heart of the DMM is MAX1496 ADC chip, an arduino controls the functions and range. It is still pretty much a work in progress, attached is a photo of it.
<IMG_20210520_221055499.jpg>
With pubs now open probably this DMM will wait for a while :)
Cheers, Elia, M0ZHN
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Re: Quick and dirty GPSDO build by F2DC and me.
Erik,
I may have figured out why I was getting the skips in the 1pps. I did not have the TP5 configured, just the default on the TP. In TP5, you can have the pulse output continue during system updates (frequency locked).
Gary
W9TD
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Very nice.
Makes me think of a series in QST back in 1976 I think, that may have been called “Learning to Work with Integrated Circuits” or similar.? The heart of the thing produced a frequency counter, but other devices converted it to a DVM and other functions.? I didn’t get beyond the counter, but it was nice.
It was popular enough that they reprinted the series as a stand-alone booklet.
73-
Nick, WA5BDU
Good day everyone,
Just thought I would share something I started during the lockdown, nothing new or revolutionary but it has kept me entertained :)
My Fluke 77 has served me well since 1984 but is showing sings of age so I said to myself, why not build a bench DMM?
This is a simple DMM, old technology and uses 7 segment display. The heart of the DMM is MAX1496 ADC chip, an arduino controls the functions and range. It is still pretty much a work in progress, attached is a photo of it.
With pubs now open probably this DMM will wait for a while :)
Cheers, Elia, M0ZHN
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Hi Elia.? Love the project!? Reminds me of being at university when we had to buy a specified multimeter kit (analogue).? We were provided (if my memory serves correctly) with the circuit, required ranges and the meter characteristics.? All the component values had to be calculated, then components of those values were provided and then we had to assemble the kit.? I remember my soldering was not to standard :(? Final test was to calibrate it.? I still have the pieces somewhere - the case was a very brittle plastic, maybe bakelite.? Even tightening up the case screws could crack it and the case certainly did not survive the accidental drop test, though it still worked electrically.
Incidentally I have a Fluke 77 issued to me when I started my job in 1986.? Various segments in the display became faint over time so a few years ago I took it apart and found that there is a sort of conductive rubber connecting the display to the PCB.? Carefully dismantling, cleaning everything up with IPA and reassembling restored most segments, second attempt fixed the lot - could be worth trying on your one if it has a similar issue.
73
Dave M0WID
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Sorry thanks info? adf4351 pll
73 de iw5bsf Roberto
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Re: Quick and dirty GPSDO build by F2DC and me.
I built the? Marcus one. Has been in service for over 3 years. As you say " Cheap and dirty " ....
Have never had to do anything to it. Is set for 10.000000 mhz. and stays there.
My freq counter? a DSI 5612 had a terrible time base osc in it. Was not accurate in any way.
Modified the counter with an OCXO osc on 4.0 mhz.
Now when it reads the GPSDO at 10 mhz is is dead nuts on .. Error is usually less than .2hz?
A great? "CHEAP " reference ..
Graham VE3WGW
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John P
Roberto
Gary W9TD
Don K5DW
Nick Kennedy