Author Topic: OCXO Reference devolopment - or a story about scaleability  (Read 938 times)

Offline Da_Stier

  • High Voltage Technician
  • ***
  • Posts: 182
  • Karma: +12/-0
    • View Profile
OCXO Reference devolopment - or a story about scaleability
« on: February 04, 2024, 07:56:55 PM »
Hi all,

long time no see. I spent the better part of the last year on developing an OCXO based frequency reference.
Since it got a little out of hand and I learned a lot in the process, I thought why not tell the story here.

Let's start from the beginning. Last year I had some trouble sleeping so at one point I decided to make the best of it and let "night me" develop something instead of staring at the dark ceiling.
After thinking a bit I decided to tackle a problem that I had for a while now.
My QO-100 HAM radio station needs several reference frequencies - one at 25MHz for the LNB and one at 40MHz for the SDR transceiver I use. They also need to have different amplitues and can't have a lot of jitter.
My old setup used a dual channel GPSDO, made by Leo Bodnar - which is a great device - but I didn't like the dependence on a GPS signal.
I had trouble before with not being able to operate due to the setup being under a roof of some sort.

I previously tried to use two of my little PT7C4511 breakouts to sync everything to a common 10MHz source.
As the source I came up with a very simple OCXO brekout with an integrated 6dB divider.





While it looked promising on the oscilloscope, it turns out, that there is way to much jitter on the outputs to be of any use.
This caused me quite a bit of confusion first, since I couldn't figure out, why nothing would lock on to these signals, unitl I realized the horrible jitter.

Next I remembered the SI5351 IC that is very commonly used for all kinds of reference purposes, from both hobbyists as well as in actual commercial products.
The most common one that can be found on a lot of cheap chinese breakout modules is the SI5351A which is the 3 output version that runs off of a external chrystal.
These modules look like this:



These are pretty nice and can basically do what I want, however I didn't like the 3 channel limit or the clock source being a chrystal at some random frequency.
After looking at the datasheet, I realized, that there is a SI5351C version available, that offers up to 8 outputs and can run from an external single ended input.

PERFECT.  :)



These chips are controlled via a simple I²C interface, run off a single 3V3 supply and need almost no external components.
So I got myself a few of them on Digikey and build a little breakout board.
Since I didn't want to wait for PCBs to arrive, I decided on a deadbug breakout, which is a nice challenge in itself, considering the 4x4mm 20 pin QFN package.



I reused the OCXO board from earlier and built a first mockup of the basic system I wanted to create.



I found a great arduino library to control the SI5351 series of ICs by NT7S.
If anyone is interested, it can be found here:
https://github.com/etherkit/Si5351Arduino

As a controller I chose to use an ESP32, since it runs at 3V3, is pretty cheap and easy to assemble.
After getting the proof of concept version going, I started to work on an actual board.
I wanted it to be a rather clean looking unit and decided to use a Hammond enclosure, since I used them before and they are affordable.

So after a couple of nights, "night me" came up with the first design, orderd all the parts for a few prototypes and a couple of weeks later, "day me" received everything and started the assembly.
This is what the first board looked like:



It also fitted nicely into its enclosure.





For software devlopment and debuggind, I like to make a "sceleton version" of the enclosure.
This offers access to all the LEDs, measurement points, etc., while making sure that it will stay at the final formfactor.





After this came  A LOT of firmware nights to get all the features going, that I wanted.
This includes:
- serial terminal via USB connection with a command line interface for setup
- saving all settings to memory
- recalling all the settings on startup
- two LEDs for status
- setting all eight channels in frequency and amplitude
- an external 10MHz input / output, depending on the mode it works in

It didn't take long for the first issue to come up.
During the hardware design I planned to use a dedicated programmer to flash the ESP.
This worked fine but by then I preferred to flash it via the same USB that is used for the CLI (command line interface).
Therefore I did my first mod on the protoype units and added a small auto reset addon.



With this mod I was now able to flash it via USB - much more comfortable.
By then I got most of the firmware going, the code looked horrible but it worked.
At this point I sent one of the units to Gregory - a friend of mine, over in Brazil.

He runs a youtube channel and did a review / gave some comments on one of my prototypes.


I also attached one of the units to my QO-100 setup and it worked the first try.  :D
This was a great success for me, especially since all of this came out of boredom basically.
The unit attaches nicely to the tripod I use for the satellite dish and I am finally independent of any third party signal - except the satellite of course.




At this point I thought I am done with this project, I built 5 prototypes, with one being in Brazil ... but it turned out, I was far from done.
I will split up the post here to make it a bit easier to type out.


Offline Da_Stier

  • High Voltage Technician
  • ***
  • Posts: 182
  • Karma: +12/-0
    • View Profile
Re: OCXO Reference devolopment - or a story about scaleability
« Reply #1 on: February 04, 2024, 08:18:01 PM »
So at this point, both Gregory and I had some ideas on what to improve, how to get better firmware going and also on what to get out of the project.
So once again "night me" opened KICAD and worked on the next iteration.
By far the most motivating reason for this was, that Gregory suprised me by completely rewriting the firmware and making it way more responsive and overall way better.
So while being at it I decided this would be a perfect opportunity to see how a project like this would scale up.

And while "day me" was still a little unimpressed by the thought to go all out and build a lot of these references, "night me" was collecting quotes from manufactures and working on a breakout box for testing.
This breakout box made it really easy to work with the device, since it drastically reduced the amount of wires and other clutter needed on the desk.
It has LEDs on all the outputs, switches on all the inputs and banana jacks for everything else.





This picture also gives a preview on the next change, I got some screenprinted enclosures, custom made for me by Hammond.
Their service was really helpful and it was pretty easy to get them printed.
.... and still cheaper then the standard  version off of Digikey.   :o
I don't think I mentioned this before but the endplates for the enclosures are actually aluminium PCBs.
I found this to be by far the cheapest way to get CNC milled, black lids with custom screenprinting on them.

So what was the plan from here ... make 50 units of course.
This is when the real work began, I got myself 50 boards of version V1.1.
Why? To learn how to scale things up, to see, what works and what doesn't if you have to do it 50 times.
Also to see what is important for getting boards populated.
I guess I'm in a rather lucky position here, since the company I work for actually has a PCB assembly line.
This meant that I was the one populating these boards, which meant I had all the possibilities to learn from it.



And while 50 pieces didn't sound too bad at first, I quickly realized, how much 50 actually is.





So the very first thing I learned is to reduce manual work as much as possible.
I think I did a good job by getting all the lids professionally made, by using SMA pigtails that just need to get plugged in, etc.
However some other parts, like having no mechanical index for the edge launch SMA connectors for example, turned out to be a timely oversight.

On the software side of things, Gregory did an outstanding job by implementing a Web UI on the ESP.
This means that you can either configure the device via the CLI and forget it or to have a live Web UI to change all the settings.
This expanded the use case of the unit from a "dumb" reference to an actual signal generator for lab use.



This also meant that I got a lot of new ideas on where to go from here.
For example I implemented a proof of concept IQ function to have up to two IQ channels, providing signals at 90° phase offset.

So where am I at right now?
The 50 units are built up but not yet calibrated or tested.
After thinking about how to do that, I decided on building a teststand for the unit.
This makes testing a lot easier, since it saves me from connecting and disconnecting a million SMA connectors.
I came up with a "quick connector" consisting of an aluminium shround and a pogo pin.
The goal being to have a "drop in a board and push it closed" kind of device.



So that's basically it for now, I will keep posting updates as soon as I got some more work done.
Also, if anyone is interested in getting a reference like this, feel free to contact me, I have a few.  ;)



Greetings,
Michael

Offline Mads Barnkob

  • Administrator
  • Executive Board Member
  • *****
  • Posts: 2246
  • Karma: +70/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: OCXO Reference devolopment - or a story about scaleability
« Reply #2 on: February 06, 2024, 07:29:29 PM »
That is some project!

From the faucet style heat sink of the QFN package in dead bug style to a finished product with a web interface. Very nice, but take care and do get some sleep. Too much night-me sounds unhealthy :)

I got a project myself, with a 10MHz reference, but its GPS based like what you came from. I have a Meinberg GPS170 sitting in a box, that really should get in a minirack and live on the bench.
https://kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics
https://www.youtube.com/KaizerPowerElectronicsDk60/join - Please consider supporting the forum, websites and youtube channel!

High Voltage Forum

Re: OCXO Reference devolopment - or a story about scaleability
« Reply #2 on: February 06, 2024, 07:29:29 PM »

 


* Recent Topics and Posts

post Re: Syntherrupter - A Feature-rich, Polyphonic Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Mads Barnkob
Today at 07:25:48 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
malte0811
Today at 01:38:21 PM
post Re: Mid-sized DRSSTC build with freewheeling
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 05:33:49 AM
post Re: Small UD3 Coil project (including CAD data)
[Dual Resonant Solid State Tesla coils (DRSSTC)]
TMaxElectronics
Today at 02:52:07 AM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
TMaxElectronics
Today at 02:43:08 AM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Kevindk9
Today at 02:25:30 AM
post Kaizer VTTC 1
[Vacuum Tube Tesla Coils (VTTC)]
Mads Barnkob
February 23, 2024, 06:59:58 PM
post Re: Syntherrupter - A Feature-rich, Polyphonic Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
February 23, 2024, 06:20:27 PM
post Re: Mid-sized DRSSTC build with freewheeling
[Dual Resonant Solid State Tesla coils (DRSSTC)]
AstRii
February 23, 2024, 09:58:10 AM
post Mid-sized DRSSTC build with freewheeling
[Dual Resonant Solid State Tesla coils (DRSSTC)]
markus
February 23, 2024, 08:43:42 AM
post Re: UD2.7 Thru Hole Capacitor Selection
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
February 22, 2024, 01:06:19 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
February 22, 2024, 12:53:22 AM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 21, 2024, 11:37:47 PM
post Re: ESAB Bantam TBH 140 Welder Restoration
[Laboratories, Equipment and Tools]
rikkitikkitavi
February 21, 2024, 10:58:53 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
February 21, 2024, 09:13:05 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 21, 2024, 09:04:11 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
February 21, 2024, 08:53:07 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 21, 2024, 07:48:47 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
February 21, 2024, 07:28:29 PM
post Re: LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 21, 2024, 06:58:39 PM
post LabCoatz Staccato QCW No straight sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
February 21, 2024, 02:31:59 PM
post UD2.7 Thru Hole Capacitor Selection
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
February 21, 2024, 02:30:10 PM
post Re: DIY X-RAY generator made of eBay parts
[X-ray]
PhotonLab
February 20, 2024, 03:14:58 PM
post Re: DIY X-RAY generator made of eBay parts
[X-ray]
alan sailer
February 19, 2024, 06:08:05 PM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
February 19, 2024, 03:03:37 PM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
AstRii
February 19, 2024, 04:34:22 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
davekni
February 19, 2024, 04:27:28 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
AstRii
February 19, 2024, 03:59:51 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
davekni
February 19, 2024, 03:45:51 AM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 19, 2024, 03:30:09 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
AstRii
February 19, 2024, 02:38:49 AM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
February 19, 2024, 01:52:20 AM
post Re: Lathe Restauration
[General Chat]
TMaxElectronics
February 19, 2024, 12:47:27 AM
post Re: VS-GP250SA60S IGBT suitability - no flywheel diode
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 18, 2024, 10:32:36 PM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 18, 2024, 10:06:58 PM
post Re: VS-GP250SA60S IGBT suitability - no flywheel diode
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hydron
February 18, 2024, 11:43:44 AM
post Re: VS-GP250SA60S IGBT suitability - no flywheel diode
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Keybored
February 18, 2024, 03:41:12 AM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
February 18, 2024, 02:43:37 AM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 17, 2024, 10:45:17 PM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
February 17, 2024, 10:29:30 PM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 17, 2024, 10:20:39 PM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 17, 2024, 10:14:20 PM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 17, 2024, 08:56:42 PM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 17, 2024, 08:52:45 PM
post Re: DIY X-RAY generator made of eBay parts
[X-ray]
PhotonLab
February 16, 2024, 09:20:44 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 16, 2024, 03:50:58 AM
post Re: Ramped DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
February 16, 2024, 03:27:18 AM
post Re: DIY X-RAY generator made of eBay parts
[X-ray]
klugesmith
February 16, 2024, 01:55:48 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 15, 2024, 07:11:20 PM
post Re: DIY X-RAY generator made of eBay parts
[X-ray]
PhotonLab
February 15, 2024, 11:31:42 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
davekni
February 15, 2024, 06:01:49 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
AstRii
February 15, 2024, 05:13:13 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
davekni
February 15, 2024, 04:26:00 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 14, 2024, 06:25:45 PM
post Re: DIY X-RAY generator made of eBay parts
[X-ray]
Luca c.
February 14, 2024, 03:33:25 PM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
AstRii
February 14, 2024, 12:57:01 PM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 14, 2024, 05:32:30 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
davekni
February 14, 2024, 05:22:35 AM
post Re: VS-GP250SA60S IGBT suitability - no flywheel diode
[Dual Resonant Solid State Tesla coils (DRSSTC)]
AstRii
February 14, 2024, 04:34:14 AM
post Re: VS-GP250SA60S IGBT suitability - no flywheel diode
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Keybored
February 14, 2024, 03:02:16 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
February 14, 2024, 01:58:17 AM
post Re: ZCS for SSTC without E class??
[Solid State Tesla Coils (SSTC)]
AstRii
February 13, 2024, 09:30:40 PM
post DIY X-RAY generator made of eBay parts
[X-ray]
PhotonLab
February 13, 2024, 03:54:23 PM
post VS-GP250SA60S IGBT suitability - no flywheel diode
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Keybored
February 13, 2024, 09:57:12 AM
post Re: TNY265 flyback issue
[Transformer (Ferrite Core)]
davekni
February 13, 2024, 03:50:05 AM
post Re: TNY265 flyback issue
[Transformer (Ferrite Core)]
AstRii
February 12, 2024, 07:30:42 PM
post Re: PLL "IHFSSTC" concept and schematic
[Solid State Tesla Coils (SSTC)]
Anders Mikkelsen
February 11, 2024, 10:30:38 PM
post Re: Help finding correct IGBT Module
[General Chat]
rikkitikkitavi
February 11, 2024, 09:41:57 PM
post Re: PLL "IHFSSTC" concept and schematic
[Solid State Tesla Coils (SSTC)]
Lucasww
February 11, 2024, 06:34:35 AM
post Re: TNY265 flyback issue
[Transformer (Ferrite Core)]
davekni
February 10, 2024, 03:55:35 AM
post Help finding correct IGBT Module
[General Chat]
cnichols
February 09, 2024, 09:34:13 PM
post TNY265 flyback issue
[Transformer (Ferrite Core)]
AstRii
February 09, 2024, 06:45:46 PM
post Re: Help Sourcing or Debugging My Small HV Module
[Transformer (Ferrite Core)]
michaelrcolton
February 08, 2024, 07:04:07 PM
post ESAB Bantam TBH 140 Welder Restoration
[Laboratories, Equipment and Tools]
Mads Barnkob
February 08, 2024, 06:47:35 PM
post Re: Anyone used iCCFL.com?
[Transformer (Ferrite Core)]
FPS
February 08, 2024, 12:27:47 AM
post Re: PLL "IHFSSTC" concept and schematic
[Solid State Tesla Coils (SSTC)]
Anders Mikkelsen
February 07, 2024, 09:49:11 PM
post Re: Anyone know of a good variable driver?
[Beginners]
NyaaX_X
February 07, 2024, 04:48:02 PM
post Re: Anyone know of a good variable driver?
[Beginners]
FPS
February 07, 2024, 08:17:37 AM
post Re: How much power?
[Spark Gap Tesla Coils (SGTC)]
Terry
February 06, 2024, 10:51:35 PM
post Re: OCXO Reference devolopment - or a story about scaleability
[Radio Frequency]
Mads Barnkob
February 06, 2024, 07:29:29 PM
post Re: Anyone used iCCFL.com?
[Transformer (Ferrite Core)]
MRMILSTAR
February 05, 2024, 05:18:33 AM
post Re: Anyone know of a good variable driver?
[Beginners]
Mads Barnkob
February 04, 2024, 09:16:25 PM
post Re: PLL "IHFSSTC" concept and schematic
[Solid State Tesla Coils (SSTC)]
davekni
February 04, 2024, 09:13:36 PM
post Anyone used iCCFL.com?
[Transformer (Ferrite Core)]
FPS
February 04, 2024, 09:00:30 PM
post Re: Anyone know of a good variable driver?
[Beginners]
FPS
February 04, 2024, 08:56:14 PM
post Re: OCXO Reference devolopment - or a story about scaleability
[Radio Frequency]
Da_Stier
February 04, 2024, 08:18:01 PM
post Re: Anyone know of a good variable driver?
[Beginners]
Mads Barnkob
February 04, 2024, 08:04:36 PM
post OCXO Reference devolopment - or a story about scaleability
[Radio Frequency]
Da_Stier
February 04, 2024, 07:56:55 PM
post Re: PLL "IHFSSTC" concept and schematic
[Solid State Tesla Coils (SSTC)]
Lucasww
February 04, 2024, 08:45:53 AM
post Anyone know of a good variable driver?
[Beginners]
FPS
February 04, 2024, 12:56:52 AM
post Re: looking for a pll sstc schematic with gate driver ic.
[Solid State Tesla Coils (SSTC)]
yourboi
February 03, 2024, 07:01:12 PM
post Re: SSTC bus inductance
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
February 03, 2024, 08:04:29 AM
post Re: SSTC bus inductance
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
February 03, 2024, 06:01:12 AM
post Re: is there a standard pinout of optical audio output connectors?
[Electronic Circuits]
Rafft
February 02, 2024, 05:04:44 PM
post SSTC bus inductance
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
February 02, 2024, 08:34:56 AM
post Re: How much power?
[Spark Gap Tesla Coils (SGTC)]
klugesmith
February 01, 2024, 07:03:41 PM
post Does anyone have a 3d print form for a spiral primary on 4" pvc?
[Solid State Tesla Coils (SSTC)]
yourboi
February 01, 2024, 06:23:45 PM
post Re: How much power?
[Spark Gap Tesla Coils (SGTC)]
Mads Barnkob
February 01, 2024, 07:53:53 AM
post Re: How much power?
[Spark Gap Tesla Coils (SGTC)]
klugesmith
January 31, 2024, 11:43:32 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Ranni81
January 31, 2024, 08:03:40 PM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal