Author Topic: Symmetricom S200 Teardown/upgrade to S250  (Read 50206 times)

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Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #150 on: May 13, 2024, 12:21:53 pm »
Hi!

Got my S250 in the mail today and inspected it. Unfortunately a no-options unit, so no OCXO and no Rubidium reference. It's GPS is a Furuno GT-8031F module, need to figure out, if it shows a date. For now, I do not have any 12V antenna, but I will hook it up to my GPS splitter and let the old GPS reference power the antenna.

This unit seems not to receive any satellites. It is mounted to a GPS antenna splitter from SV1AFN that is powered by 5V from another receiver that works fine. The S250 is connected passively, so my 5V antenna will survive ;)
Unfortunately the S250 doesn't see any satellite nor does it lock to anything. Status says: Antenna: Good, Satellites: 0.
I'll probably opt for one of the modern replacements from France.

Only big question i have:
Is there any datasheet of the original MC597X4-040W OCXO? I could not find any details about it's precision, regulation voltage and such.

Because I want to use the system as my lab 10MHz reference, I'd prefer higher stability and better phase noise from a good OCXO over the ramping up and down of a TCXO and the high maintenance cost of an old used Rubidium reference.
So I'd like to adopt a OCXO in the lower ppb range.
« Last Edit: May 13, 2024, 07:03:03 pm by Astralix »
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #151 on: May 15, 2024, 07:38:56 am »
Seems like all of you have their units running... I still have an issue, so may be someone's willing to help a bit?

I have the S250 receiving GPS with it's Furuno receiver. I use a BIAS-T to cut out the 12V and supply external 5V to the Symmetricom 58532A antenna.
The Furuno seems to need quite a signal, so I have set up a crude but working configuration...

Antenna -> 30m cable -> BIAS-T 5V -> 50M..4G 13dB amp -> active 4-way splitter -> S250

The problem I still have is, that the 10MHz output of the S250 is still in "tracking mode". It does not lock to the GPS. The 10MHz output is is tracking +/- 10kHz up and down.
The counter is set to its internal high stability OCXO, the input is driven by an R&S SMIQ 03B set to external reference. It's external reference is connected to the 10MHz ouput of the S250.

Can anyone confirm that behavior, or if that goes away with the Huel PCB installed? Are there special setting required to get the TCXO synced to the 1PPS?

Thanks!
 

Offline DavidKo

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #152 on: May 15, 2024, 08:22:06 am »
I think that this is already described in pages before. Your unit will not work on GPS. You need GPS module update. Same was on my side, after installation of Heol design module the unit is locking to GPS. I do not remember the exact rollover date when Furuno stopped working, but I think that it is also mentioned in the thread.
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #153 on: May 15, 2024, 08:51:23 am »
Interesting, as the 1PPS signal is not related to the date information. That is sort of dumb design.
I'll test my old Trimble GPSDO, if that is still working, as these modules had been supplied with different GPS receivers, including some Furuno types.
Would be an interesting test as the modules are still sold on eBay.
 

Offline DavidKo

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #154 on: May 15, 2024, 12:16:01 pm »
I speak only about GPS. 1PPS, 10MHz or NTP should work without upgrade. You only need to configure it, but I have never tried to use different source that GPS or ntp.
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #155 on: May 15, 2024, 09:49:04 pm »
Hi!

No, that is the reference sources for the time server. It is not the outgoing reference clocks for something else.
The 10MHz output clock is tracking, i.e. the control loop is trying to sync the clock to the GPS, but the GPS delivers no reference.
Probably the 1PPS signal is missing and so the control loop is open.

I have another issue, as the 58532A antenna is only receiving L1 band. As the antenna position is not very optimal, it gets in trouble if there are not enough GPS satellites in sight. I guess that will be much better with a multi-band antenna and the modern module replacement.
 

Offline Johnny B Good

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #156 on: May 16, 2024, 06:16:20 pm »
Hi!

Got my S250 in the mail today and inspected it. Unfortunately a no-options unit, so no OCXO and no Rubidium reference. It's GPS is a Furuno GT-8031F module, need to figure out, if it shows a date. For now, I do not have any 12V antenna, but I will hook it up to my GPS splitter and let the old GPS reference power the antenna.

This unit seems not to receive any satellites. It is mounted to a GPS antenna splitter from SV1AFN that is powered by 5V from another receiver that works fine. The S250 is connected passively, so my 5V antenna will survive ;)
Unfortunately the S250 doesn't see any satellite nor does it lock to anything. Status says: Antenna: Good, Satellites: 0.
I'll probably opt for one of the modern replacements from France.

Only big question i have:
Is there any datasheet of the original MC597X4-040W OCXO? I could not find any details about it's precision, regulation voltage and such.

Because I want to use the system as my lab 10MHz reference, I'd prefer higher stability and better phase noise from a good OCXO over the ramping up and down of a TCXO and the high maintenance cost of an old used Rubidium reference.
So I'd like to adopt a OCXO in the lower ppb range.

 I started my diy gpsdo adventures some five years ago with my very first ocxo (a 13MHz cmos output ocxo) that I'd picked up at (afaicr) the 2019 Blackpool NARSA mobile radioham rally for a mere £4.

 I was really looking to buy a 10MHz unit but, rather surprisingly, no one else had thought to bring any to their table of wares so when I spotted this only example of an ocxo of any type amongst a rather eclectic collection of 'junk', I was so desperate to acquire an ocxo that I took a punt on it after persuading the seller to reduce his £5 asking price to the £4 I paid for it.

 I had a vague notion that I'd be able to generate a 10MHz square wave locked to its 13MHz with a bit of TTL trickery to allow me to start experimenting with a home brewed 10MHz gpsdo reference. Indeed, this vague notion did prove to be true and so was able to breadboard a gpsdo using the uBlox M8N I'd previously purchased a couple months earlier to act as a (high jitter) calibration frequency reference by which to check (and if necessary adjust) a Kenwood TS140s HF transceiver that had last been calibrated against the then receivable WWVB broadcast some thirty or more years ago (rather gratifyingly, the transceiver proved to still be in calibration after all those years).

 Anyhow, the only problem I had with this "CQE" 13MHz ocxo was the lack of any pin out and supply voltage requirements data. The best I could find was for a 12v 10MHz Vectron datasheet. This confirmed the pin out but left me guessing as to whether it was a 5 or 12 volt part. Since this was my one and only example of an ocxo, I played it safe and tested it with 5 volts. It had a rather sluggish (5 to 10 seconds or so) startup to even show its 13MHz output on the breadboard's "5 volt" (actually 4.85v) before stabilising to a 4v p2p square wave trace some 7 or 8 minutes later when the peak current draw of 280mA finally subsided to 180mA or so. At that time, I did not yet possess a variable lab bench supply to experiment with so played it safe by running it off a Vcc of 5.14v where it sprang into life within just one second of powering it up.

 In the meantime, I kept searching for a datasheet with no luck other than discovering a UK based ebay seller offering the 10MHz sine output versions for just a fiver each (still without any voltage specification in their description). Despite this, I bought three to try out, followed by placing an order for another four before alerting the EEVblog membership to this cheap source of 10MHz ocxos >:D

 My impression at that time had been that they were of a much higher quality than most other low priced ocxos being sold on ebay. An impression that eventually proved to be justified when I spotted this teardown video

https://youtu.be/zkzMtLyqju4?t=852

 Where the ocxo being used in this Symmetricom time and frequency receiver showed the exact same DOC1478 number (as well as the blue circular sticker with similar nn/n code (presumably a date code) as the ones stuck to my own set of ocxos).  I believe these "CQE" marked ocxos were originally an AEL product.

 Having now obtained more than a single sample of the 10MHz unit I felt I could take a chance on destroying one with a 12 volt "overvolting" test and proved that they were indeed a 12v part. One big clue that this would most likely be true was the fact that they were even more sluggish in producing an output than the 13MHz unit had been, even when powered from a 5.1v rail.

 By then, I'd already had the 13MHz ocxo fitted into my MK I gpsdo and running off its 5.14v rail so didn't immediately test it with a 12v supply. I left that until I'd made up a MK II version before stripping the MK I down to retrieve its ocxo for testing. I'd have preferred to keep the MK I intact to compare against the MK II but its construction had made it difficult to isolate the Vcc pin from the rest of the circuitry without virtually stripping it all apart anyway.

 Incidentally, all seven of these 10MHz units had measured within a millivolt of 5.128v on their reference pins (according to my Mestek DM91A 9999 counts hand held meter) versus the 3.2 ish volts reading from the 13MHz when powered from a 5 volt supply (in retrospect, another big clue that it too was a 12v part). I did eventually get round to doing the 12v test on this unit, by which time I couldn't care less about burning it out (it had served its purpose and would never ever be used in a 10MHz gpsdo ever again - too much TTL generated noise on the Vcc rail without resorting to an add-on 10MHz crystal filter to get rid of the close in spurs and their harmonics).

 I tried a tin eye image search with no luck but you might do better by cropping out an individual ocxo from the attached image file. :)

« Last Edit: May 16, 2024, 10:48:42 pm by Johnny B Good »
John
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #157 on: May 16, 2024, 10:37:38 pm »
Hi!

It should not be too big of a deal to drop in a different OCXO. There are a few high quality brands and prices reach from 85USD into 1800USD per piece. The Symmetricom S250 never had an dual-oven Trimble OCXO even you probably could throw it in as the DAC voltage is 0..5V I guess. There are 3ppb and 2pbb below 200USD available that fit the original mounting holes. But I need to know the pulling range and the pulling voltage range. If the pulling range is far different or the center voltage is 2.00V instead of 2.50V the regulation loop may go nuts.
The available OCXOs can be ordered in variants like control voltage is 0..4V or 1..4V, 1..5V, 0..5V and different center voltages.

I can't see anyone having tested the behavior so I may try hacking in a HP OCXO from my 10 MHz distribution boards or spend 85USD in the name of science. I can record the voltage versus the frequency that the unit is trying to control with.
Reminds me that I even own an HP PLL Analyzer, that I never used before in my life... Should be fun!
« Last Edit: May 16, 2024, 10:40:09 pm by Astralix »
 

Offline Johnny B Good

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #158 on: May 17, 2024, 01:14:22 am »
 I rather doubt the tuning rate would be much of an issue with these ocxos (casual observation during the initial lock in phase, after the gps receiver module had achieved a lock with the minimum of 4 good gps svs suggested a positive tuning rate of ~3Hz/volt). The required tuning voltage for 10MHz ranged from a high of 4.49 down to a low of 2.34 volts (this last being the one I used in the MK II gpsdo which has drifted down by just 15mV over the past two or three years).

 A recent test using a bench meter on its Hi-Z setting (10G ohms) suggests an infinite dc impedance on the EFC pin. Most likely simply something like a 10MR/100nF LPF connection to the the reverse biased varactor tuning diode which consequently accounts for the positive tuning rate (as is typical of virtually every electronically tuned XO regardless of whether they're just a tunable xo (Siglent 1000 and 2000 AWG series), a tcxo or an ocxo).

 Also noteworthy is the use of input clamp diodes to limit the EFC tuning voltage between ground and Vcc. I remember testing that  5 volt powered 13MHz ocxo using a 9v battery (with a 10K current limiting resistor) to see if it would tune past the 5 volt limit. It didn't so I concluded it must have had clamping diodes. This test btw had been inspired by the Vectron datasheet's mention of a 10v upper tuning range voltage limit.

 I don't recall repeating a similar test with the 12 volt powered 10MHz units (most likely because the worst case requirement was safely below the 5 volt limit of the PLL's output giving me no urgent cause to check this out). However, having now mentioned this, I'll repeat this 9v tuning test on the 4.49v ocxo some time soon to check out my clamping diodes hypothesis ::)

 The point I was trying to make was that if you happen to chance upon a seller offering these ocxos at a sensible price (sub 30 dollars), they'd be worth taking a punt on (assuming the seller has a decent 95 + % rating of course).

 Also worth mentioning is the fact that the oscillator output must be unbuffered since my injection locking to an external 10MHz source in the one I'd used to upgrade my cheap Feeltech FY6600 only worked by injecting into its output pin, that plus the fact that I had to add a 100 ohm resistor across the output of the MK II's ocxo to eliminate a puzzling jitter on the resulting square wave output from the 74HC14 no matter how I trimmed the mid voltage bias on the gate's input pin (I'd connected directly via a 1nF cap without any load in order to get the maximum voltage swing into the 74HC14).

 I guess the oscillator had been designed with a 50 ohm loading in mind (possibly including a 75 ohm loading requirement) to prevent clipping induced jitter effects such as the one I'd experienced where it had taken the form of a change in duty cycle every alternate cycle. The 100 ohm had been chosen as a compromise between highest possible voltage swing without this peculiar jitter effect. At least one other EEVBlog member had also reported a similar peculiarity with another brand of sine wave output ocxo which vanished when he tried my solution.

 In retrospect, a better choice of resistor would have been 75 ohm. I had made a crude test of the output impedance of these ocxos and got figures ranging from a high of 90 ohms down to a low of 76 ohms, hence my choosing the 100 ohm option as an initial compromise value which seemed to be sufficient to eliminate this weird jitter behavior on the first try.

 One other thing worthy of mention is the useable voltage range these will function with. If you don't need the thermally stabilised voltage reference, you can use 6 to 13.2v (tested to a maximum of 14 volts btw) otherwise it's 11.5 to 13.2 volts if you need the 5.128 or so volt reference. Since the heater current is limited to a maximum of 280mA, a lower voltage can ease the initial startup power requirements at the expense of warm up time before it starts bouncing up and down as it over and undershoots the oven target temperature.

 In the end it makes no difference to the time they take to reach a sufficiently stable temperature some 20 minutes or so regardless of whether you use 5.5 or 13.2 volts. In your case, you've no such option to change the ocxo's supply voltage but in a DIY gpsdo project this can be an important consideration with regard to the power ratings of a 2.6 to 5.5v input boost to 12v output converter module feeding both the ocxo and a buck converter  module powering the 5 volt logic rail all powered from a 2.1A continuous rated 24v max input buck converter supplying it and a float charged at 3.85v protected LiPo cell that happens to have completely discharged to its cut off point.

 Using three dc-dc converters like this allows me to power the MK II from a minimum of 4.5v (below the cut off point of a battery bank) to a maximum of 24v (5 to 15 volt 10 watt rated wallwarts and 19 to 22 volt laptop charging bricks for example). ::)

 I've no doubt you're wondering why I've gone to so much trouble but the long and short of it is that I was getting totally pissed off by the ocxo's oven controller's boot up behavior in response to even the briefest of supply interruptions (whether those caused by a wallwart  swap over or a cable rerouting exercise or the 10 to 20ms interruption when using the type of power bank that can act like a UPS (feeding the gpsdo via a 5 to 12v boost converter).

 The problem in this case being due to the oven controller's "Shoot first, ask questions later." startup algorithm where it blindly assumes a literally cold oven startup requiring the maximum heating current to reach operational temperature before it checks whether such an extreme response is really necessary. In this case the result is a massive overshoot, followed by the inevitable under/overshooting that requires another ten minutes before the PLL stands any chance of winning this game of chasing "Will o' the Wisp". The two or three seconds for the gps receiver to regain lock is tolerable enough but the disruption caused by the ocxo's hot startup behavior is anything but. >:(

 I modified the 5 to 12v boost converter to 'paper over the' deficiency of a battery bank's brief interruption during any power source changeover or loss of its input power but realised this still didn't solve the problem caused by swapping out to another power source or a supply lead rerouting exercise so opted for the internal back up "battery" solution using one of a couple of LiPo cells I'd acquired for free.

 I only needed a mere 5 minutes of autonomy which could have been served with a couple of expensive 200F supercaps so it was a 'no-brainer' to make use of what I already had to hand, landing up with even only a 60% charged LiPo cell providing some 110 minutes of autonomy (now reduced to 90 minutes with the GNSS/RTK multiband timing antenna upgrade. Still an order of magnitude more than I required.

 Since I had to add a third dc-dc converter to the power train, I took the opportunity to extend the low voltage input limit from 6.8 down to 4.5 volts to maximise the benefit of all this radical modification effort.

 Anyway, there you have it : all you really need to know (and then some!) about these "CQE" ocxos should you chance upon a cost effective source. :)
« Last Edit: May 17, 2024, 03:10:18 am by Johnny B Good »
John
 
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Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #159 on: May 17, 2024, 08:05:00 am »
John,

a big thank you for all the details about your experiments! I totally agree about your findings and will inherit them to shorten my trail of experiments to adopt a different OCXO into my S250. I did not think about the real speed limiting factor of the control loop, which is the GNSS reference, not the OCXO.

The design of the S250 has a series resistor planned, even people using a retrofit original OCXO just bridged it. If I opt for a new OCXO, I could optimize the signal with a matching serial resistance. But it is still intriguing to use one of the low hours double oven OXCO from the LTE development system powered by the 12V supply meant for the Rubidium reference.

The goal should be to compile your detailed information and my practical approach into something that is repeatable for everyone to revive his S2xx / 3xx / 6xx units. It will take a few weeks from now on, due to workload and holidays, but with the Huel GNSS replacement arrived, the S250 will "unlock" all it's capabilities again.
 

Offline dj831

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #160 on: May 20, 2024, 11:06:22 am »
Hi there,

Apparently, I missed a lot of things on that 'official' ;D S200/300 thread (I don't know why notifications were turned off...). Anyway:
  • For those who need to install an OCXO on their S200/S250, I had success with a cheap OCXO found on FleaBay: the Vectron C4550A1-0213. However, buyers's beware: purchasing them is a lottery. Of the 8 I purchased, one is perfect (hardly no drift), 3 drift in their limits, 3 drift too much (off limits then), and one is stellar on how much it drifts - totally unuseable. Chinese seller was either a moron or makes everything possible not to send you replacement parts (I gave up with him). Testing method: the 10MHz clock output of my PM6685R (Rb) feeds my PM6680, and I ran Timelab for 24 hours, after a warm-up of several hours. I adjusted EFC for all 4550's, sometimes several times, and I let run the whole thing. Note that EFC is set with a trim pot and a 4.096V reference. The PM6680R was checked against my S250 with an Rb inside (factory installed)
  • I recently purchased an S300 for cheap, with a faceplate slightly damaged, but still useable, but with no power supply inside. In a previous post, i guessed that a Cisco power supply should fit. And it fits. I saw the original power supply of an S300 with an Rb inside on a blog, and it outputs +15V (a Cisco one outputs only 12V). As I have no Rb inside that S300, I still decided to test it, and it works like a charm - absolutely no issues so far.
  • S200, S250,S300 and S350 owners (i.e. almost everyone reading that topic ;) : BEWARE of original power supply! As the display in my cheap S300 was in pristine condition, I decided to swap it with my second S250, with OCXO added in it (the S300 is intended as an NTP server, so no need of a nice display ;) ). While tearing down the S250, I noticed a slightly bulged Nichicon capacitor. As it would have been a shame to leave it this way, I replaced it. Surprise: it had popped up from the bottom - unnoticeable until the replacement. So, please take 5 minutes to check capacitors of your power supplies ;)
I purchased since a 53132A from a nice German seller, and I will use it with one of my FE5680A in an enclosure as frequency reference, to replace the PM6680 and 6685R, though I'm building an option 010 for it, with a 10811 inside (no more used crap oscillators >:().

Hope it helps.
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #161 on: May 28, 2024, 11:37:43 am »
Question for the group...

There are three options to replace the old Furno module:
1) ~300€ The more expensive ProStudio Connection module with FPGA and what not.
2) ~170€ The French Heol Design module that, at least on the picture does not show any lable on the GPS module.
3) ~90€ An original LEA-M8F ublox module and some sort of self built controller for initialization, if required at all.

As my focus is on 10MHz reference clock output, not an accurate time of my server, it is interesting to see, that Heol tells about a 100ns jitter of their 1PPS signal, ProStudio says 2..6ns and ublox specifies their M8F module around <5ppb.

I know that the jitter will not be reflected 1:1 to the 10MHz output as it is dampened by the 10MHz OCXO regulation loop.

Any thoughts on that?
 

Offline dj831

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #162 on: May 28, 2024, 12:23:54 pm »
Hi, if it helps ...:

3) I would go for a LEA-M8T, since it is timing oriented. And such a thing should exists, since an eBay seller sells upgraded S200/S250/S300/S350 with a LEA module in it. BTW, a home built module with a LEA module in it should give full control over GPS offset (and why not, store that offset on an external socketed DIL EEPROM, and reprogram it 20 years later ;))
4) ~240€, an original GT-8736, NOS from eBay (186459605590), that should stop working in circa 2035 (it was built in 2016). Anyway, I still don't know if S200/S300 series can still run past 2038.

About your question, actual HEOL module is made from a Furuno GT-88, with specific firmware as this module does not officially support M12 protocol as per datasheet - but support it though, since this module works flawlessly. And I have a datasheed with M12 protocol for the GT-88. About jitter, why don't ask Olivier Descoubes from HEOL? He is reachable via support contact, if it helps, and should answer you.

That being said, I never checked the PPS output, since I never needed it - only the 10 MHz out for reference purposes, and NTP server for the 300. But 100ns seems huge and very strange.
« Last Edit: May 28, 2024, 12:30:35 pm by dj831 »
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #163 on: May 28, 2024, 01:26:10 pm »
LEA-M8T and M8F are for timing purposes.
The F also includes a direct external (VC)OCXO PLL control without any DAC needed. You can just tack the OCXO to the M8F and you're good to go if you only need a precision reference clock.

For the HEOL modules, if they are using GT-88 modules, the jitter is specified with 4.5ns. High probability that Heol specifies something else, likely the timing messages, not the 1PPS pulse? I'll ask them and then we see.
« Last Edit: May 28, 2024, 02:02:50 pm by Astralix »
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #164 on: June 10, 2024, 03:15:48 pm »
Question...

Does anyone know exactly the model number and firmware release the Symmetricom Rubidium reference shall be?
There are a few out there in the bay.

And I read about a guy who can update the firmware in these modules if required, but I cannot find a contact or the firmware itself for trying to do that myself...

For now it is just theoretical, as the Heol Design GPS upgrade was stolen from my front door, so I have to wait till the second one comes in. And after it has been plugged, I want to experiment with some OCXOs. But I may get in contact with someone who is able to build and re-fill rubidium modules what opens up almost endless options ;)
 

Offline tusentack

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #165 on: June 12, 2024, 10:07:20 am »
Hi I have a Symmetricom S200 with Rubidium Oscillator that I have sucsessfully upgrade with a new GPS-module.

My problem is that I can not get the (hardware clock status) to Lock. It stands as Unlocked all the Time under the timing. The GPS input is locked and the gps is the current sync source. The GPS time i valid and the Antenna status is good. I sync to 9 satellites. I have tried to do a factory reset and I also tried to reinstall the image to the card but it does not solve the problem the hardware clock do not lock. Does any one have any help or advice to what I should do to get the Hardwareclock to Lock.

I have attached pictures from the unit.

Thanks
 

Offline dj831

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #166 on: June 12, 2024, 07:30:05 pm »
Hi, I just powered my S300 with antenna not viewing satellites, and though S300 is acquiring satellite (no satellites in view), hardware clock is locked. So:

  • Can you check logs and see if you see something?
  • Did you upgrade device by yourself, i.e. replaced the oscillator by an Rb one?
  • Can you SSH the device, and retrieve hardware settings (same program used to tell device that hardware has changed)?

Worst case: Rb oscillator dead. For the X72/X99, I don't know, bur for the SA.22c, there is a 'Service' pin that tells the oscillator is EOL. Since most, if not all, Rb oscillator has an 'health' pin, I guess that if it exists, the S200 detects that Rb is dying. Another idea: Rb oscillator is bad, and DAC is out of range to adjust EFC pin of X72/X99 and reports the issue.

Note that these are ideas only, and I may be totally wrong. But are a good start for investigations  ;)
 

Offline tusentack

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #167 on: June 13, 2024, 02:56:01 pm »
Hi thanks for the help.

Here are the answers.

Can you check logs and see if you see something?

I am attaching the messeges logs. Maybe you can see whats wrong?

Did you upgrade device by yourself, i.e. replaced the oscillator by an Rb one?

The Oscillator was there when I bought the unit. The only upgrade I did was the GPS-card.


Can you SSH the device, and retrieve hardware settings (same program used to tell device that hardware has changed)?

I can SSH into the unit but I do not know the commands to see the hardware settings.


Thanks
 

Offline dj831

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #168 on: June 13, 2024, 07:33:54 pm »
Hi,

Jun 13 04:35:03 SyncServer alarm: Thu Jun 13 02:35:03 2024  Alarm 1715693008: Type: Timing Source Lower Accuracy Input Alarm, Class: Timing, Level: Notify, Action: Clear Alarm, Flags: 0x4
Jun 13 09:23:37 SyncServer alarm: Thu Jun 13 07:23:37 2024  Alarm 1715693009: Type: Timing Oscillator DAC Range Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x4

=> Does that mean you had no alarm for circa 5 hours (i.e. that the SyncServer worked flawlessly)?

Jun 13 09:23:38 SyncServer alarm: Thu Jun 13 07:23:38 2024  Alarm 1715693010: Type: Timing Oscillator DAC Range Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x4

=> Can you monitor DAC output of S200 (or EFC / C-field input of X72 - reply #118 of that topic)? You may have either a timing issue from GPS (but I never had any problem with the two HEOL cards I own, they are reliable), either your X72 started drifting significantly.
=> DO check service the pin too (reply #118 of that topic too).

If it helps, you have all details about seeprom utility given by Sandra from post #62 onwards, but you may not need it since you didn't change any hardware (apart GPS card that is plug & play)

Note: I may not be able to answer you prior July,1st  ;)
 

Offline Astralix

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #169 on: June 16, 2024, 07:11:28 pm »
Finally, the Heol Design module has arrived and works fine for now. There is an issue with my antenna but the new one was not available when I tried ordering it.

I tried the Acquisition Mode that the switched to Position Hold the next day. That looks nice, but it shows 0 satellites and also does not show any satellite in the GPS overview.
So, to get an overview myself, I switched to Dynamic Mode and I'll report on that.

I also added an Abacron 10MHz reference OCXO (AOCJY3A-10.000MHZ-E). It is a 5V type with CMOS output. Fron what I read from Jonny, I set a 68R resistor at R121. Next I set JP3. Finally I changed the shadow file to gain root access and used seeprom to configure the oscillator type. After a reboot, the system still shows TCXO in all the places, and for a while it also had the DS3 lit, the LED besides the TCXO. Now that DS3 is off, but the DS2 near the OCXO is not lit. I checked the OCXO output and it has a nice stable square wave 10MHz signal.

Probably I need to wait until the system has got some sats to lock onto and trim the OCXO, I guess?

Does anyone use a battery for the Heol Module to get faster AOS?

[Edit]
This morning I have GPS reporting 8 satellites but the timing source is still unlocked.
The oscillator is still shown as TCXO and there are still precision alarms in the log.

Jun 17 07:25:40 SyncServer httpd: Mon Jun 17 05:25:40 2024  Alarm 1718563484: Type: System Config Change Alarm, Class: System, Level: Notify, Action: Raise Alarm, Flags: 0x4
Jun 17 07:25:50 SyncServer alarm: Mon Jun 17 05:25:50 2024  Alarm 1718563485: Type: Timing Quality 1e-5 Alarm, Class: Timing, Level: Notify, Action: Clear Alarm, Flags: 0x14
Jun 17 07:26:09 SyncServer alarm: Mon Jun 17 05:26:09 2024  Alarm 1718563486: Type: Timing Quality 1e-5 Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x14
Jun 17 07:28:46 SyncServer alarm: Mon Jun 17 05:28:46 2024  Alarm 1718563487: Type: Timing Quality 1e-5 Alarm, Class: Timing, Level: Notify, Action: Clear Alarm, Flags: 0x14
Jun 17 07:28:49 SyncServer alarm: Mon Jun 17 05:28:49 2024  Alarm 1718563488: Type: Timing Quality 1e-6 Alarm, Class: Timing, Level: Notify, Action: Clear Alarm, Flags: 0x14
Jun 17 07:28:52 SyncServer alarm: Mon Jun 17 05:28:52 2024  Alarm 1718563489: Type: Timing Quality 1e-6 Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x14
Jun 17 07:28:55 SyncServer alarm: Mon Jun 17 05:28:55 2024  Alarm 1718563490: Type: Timing Quality 1e-5 Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x14
Jun 17 07:29:45 SyncServer alarm: Mon Jun 17 05:29:45 2024  Alarm 1718563491: Type: Timing Quality 1e-4 Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x14
Jun 17 07:30:28 SyncServer alarm: Mon Jun 17 05:30:28 2024  Alarm 1718563492: Type: Timing Quality 1e-4 Alarm, Class: Timing, Level: Notify, Action: Clear Alarm, Flags: 0x14
Jun 17 07:31:26 SyncServer alarm: Mon Jun 17 05:31:26 2024  Alarm 1718563493: Type: Timing Quality 1e-5 Alarm, Class: Timing, Level: Notify, Action: Clear Alarm, Flags: 0x14
Jun 17 07:31:36 SyncServer alarm: Mon Jun 17 05:31:36 2024  Alarm 1718563494: Type: Timing Quality 1e-5 Alarm, Class: Timing, Level: Notify, Action: Raise Alarm, Flags: 0x14


I switched the GPS to Position Hold mode now to test if that helps, but for now the timing source is still NTP instead of GPS.
« Last Edit: June 17, 2024, 05:36:17 am by Astralix »
 

Offline Johnny B Good

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Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #170 on: June 18, 2024, 01:47:08 am »
Finally, the Heol Design module has arrived and works fine for now. There is an issue with my antenna but the new one was not available when I tried ordering it.

I tried the Acquisition Mode that the switched to Position Hold the next day. That looks nice, but it shows 0 satellites and also does not show any satellite in the GPS overview.
So, to get an overview myself, I switched to Dynamic Mode and I'll report on that.

I also added an Abacron 10MHz reference OCXO (AOCJY3A-10.000MHZ-E). It is a 5V type with CMOS output. Fron what I read from Jonny, I set a 68R resistor at R121. Next I set JP3. Finally I changed the shadow file to gain root access and used seeprom to configure the oscillator type. After a reboot, the system still shows TCXO in all the places, and for a while it also had the DS3 lit, the LED besides the TCXO. Now that DS3 is off, but the DS2 near the OCXO is not lit. I checked the OCXO output and it has a nice stable square wave 10MHz signal.


 Just to address the issue of connecting a cmos output ocxo directly to a logic gate input, there's no need to connect a load resistor like there is with most sine output types. They're designed to connect directly to a logic gate input (just keep the connecting trace/wire short - just a centimeter or three).  :)
John
 

Offline Astralix

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  • Country: de
Re: Symmetricom S200 Teardown/upgrade to S250
« Reply #171 on: June 19, 2024, 09:31:35 pm »
A little update...

I had moved things around a bit and, bridged the R121 resistor and checked the OCXO to be seated correctly (I socketed it, as it was quite expensive).
I checked around in the menus and with GPS in "Hold Position Mode" it still showed "unlock". Then I tried "Dynamic Mode" again, but till now there is no lock, GT88 is still trying to find satellites.

It also continues to insist on having a TCXO.
It also refuses to lock onto an external 10MHz reference frequency...

Checking the Alarm page I got some errors, a script spread lines across the screen about "S350" is not supported. So I made a factory reset and hacked my way back to seeprom as described above. seeprom was showing option 9 as "S350" so I changed that to "S250" and rewrote the CRC with option 4.

Progress!
Again a reboot and now the Alarm page is back working and the system shows "OCXO".
It also locks to my generator applying 10MHz sine at 0dBm (it starts locking at -7.6dBm what is ~93mV into 50 Ohm)

So now I wait until it has locked to some satellites.
 


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