Test Equipment Anonymous (TEA) group therapy thread

[med6753]

bitseeker...we need that rabbit hole incorporated into our TEA Glossary. 

[bd139]

What's the pot for?

Pot is to trim the OXCO frequency. Voltage controlled frequency offset. It's got an adjustment range of about 8Hz either side of 10.0000000MHz to offset for crystal aging.  Ideally should be a 10 or 25 turn trimmer but they are in the cupboard and I couldn't be arsed to get one out.

Incidentally this is what will be fed from the PLL that will lock it to the GPSDO.

[med6753]

What's the pot for?

Pot is to trim the OXCO frequency. Voltage controlled frequency offset. It's got an adjustment range of about 8Hz either side of 10.0000000MHz to offset for crystal aging.  Ideally should be a 10 or 25 turn trimmer but they are in the cupboard and I couldn't be arsed to get one out.

Incidentally this is what will be fed from the PLL that will lock it to the GPSDO.

See, and now you just introduced a level of uncertainty. What are you gonna do? I encounter same with volt nut. Getting a backup helps but still doesn't eliminate it.

Wish I wasn't so anal. 

[bd139]

What's the pot for?

Pot is to trim the OXCO frequency. Voltage controlled frequency offset. It's got an adjustment range of about 8Hz either side of 10.0000000MHz to offset for crystal aging.  Ideally should be a 10 or 25 turn trimmer but they are in the cupboard and I couldn't be arsed to get one out.

Incidentally this is what will be fed from the PLL that will lock it to the GPSDO.

See, and now you just introduced a level of uncertainty. What are you gonna do? I encounter same with volt nut. Getting a backup helps but still doesn't eliminate it.

Wish I wasn't so anal. 

Well there's relative certainty and absolute certainty. Relative certainty is that the TF930 and the OCXO track well. Absolute certainty is that they might be both be equally wrong compared to everyone else's opinion of 10MHz. Now that's where the GPSDO comes in because that will lock the OCXO to the lovely little network of space-borne rubidium frequency standards in the GPS satellites thus making sure they reference the same absolute standard.

Then time nuttery is won 

Volt nuttery is harder because there's no absolute reference that doesn't involve a transfer standard of some kind.

[Mr. Scram]

Pot is to trim the OXCO frequency. Voltage controlled frequency offset. It's got an adjustment range of about 8Hz either side of 10.0000000MHz to offset for crystal aging.  Ideally should be a 10 or 25 turn trimmer but they are in the cupboard and I couldn't be arsed to get one out.

Incidentally this is what will be fed from the PLL that will lock it to the GPSDO.

That's what I was worried about and I have the same complaint as med6753.

I've been contemplating a GPSDO for the same reason. You've essentially won time nuttery at that point, although I would possibly prefer to do it with a rubidium oscillator. Although apparently there's some complications with shorter term phase noise over longer term stability.

[bd139]

You can lock the OCXO to a rubidium standard. This OCXO has decent phase noise performance:

-120 dBc/Hz at 10 Hz
-130 dBc/Hz at 100 Hz
-140 dBc/Hz at 1 KHz
-145 dBc/Hz at 10 KHz
-145 dBc/Hz at 100 KHz

LT do a decent buffer IC although I can't remember the part number. That doesn't add any phase noise and give you two antiphase or in phase outputs depending on a pin config and has decent load isolation. MSOP package was the only problem.

Only problem with Rubidium is cheap Rubidium sources are cheap for a reason: they have a finite lifetime left. You might get lucky. It might last a month.

[glarsson]

Only problem with Rubidium is cheap Rubidium sources are cheap for a reason: they have a finite lifetime left. You might get lucky. It might last a month.

Unless you find that unique deal. I bought a sa22c development kit with rubidium oscillator, interface board with PSU nd drivers, heatsink, cables, mounting hardware and printed manual. Only used for evaluation and then put aside. Only £140.

[Specmaster]

I finally managed to dig some photos of my daily driver PC that has to live under my desk/bench because it is huge and I need as much working space as I can muster. I did think that the PSU was 750W but it's actually 850W so I have plenty of headroom there and do it runs really cool, I don't think I have ever heard its fan spool up and with the large 5 140mm cooling fans in the case the whole PC runs cool and very quiet.

The biggest problem is the case is that's so bloody heavy but has loads of future expansion space, I have space for 8 3.5" internal HDD, 4 x 2.5" SSD. It has 3 5.25" drive bays, 2 are filled with a Bluray rewriter and a DVD rewriter and the third has a hot swappable frame that will accept both a 3.5" HDD and either a 2.5" HDD or SSD.

I just love the cable management on this there are numerous grommets where power cables from the PSU can be taken through and routed through the back chamber which has a depth of 25mm to accommodate the cabling and the 4 SSD bays and others can be clipped to the back plate if required. Not a cheap case at all and it is the best case that I have ever purchased, I love it, the drive bays are toolless.

[Specmaster]

Arh, yes, so you will have won time nuttery but what are going to spend your time on now then because that really wasn't much of a battle was it, unlike volt nuttery which just goes on. I mastered time nuttery in a far simpler way except that I can't distribute that to my gear, I just went out and purchased a radio controlled watch that is locked to the atomic clocks around the world 

[Mr. Scram]

You can lock the OCXO to a rubidium standard. This OCXO has decent phase noise performance:

-120 dBc/Hz at 10 Hz
-130 dBc/Hz at 100 Hz
-140 dBc/Hz at 1 KHz
-145 dBc/Hz at 10 KHz
-145 dBc/Hz at 100 KHz

LT do a decent buffer IC although I can't remember the part number. That doesn't add any phase noise and give you two antiphase or in phase outputs depending on a pin config and has decent load isolation. MSOP package was the only problem.

Only problem with Rubidium is cheap Rubidium sources are cheap for a reason: they have a finite lifetime left. You might get lucky. It might last a month.

That's a problem to keep in mind, although I think that the ones lasting a month may have been murdered by mishandling by their new owner.

[Wolfgang]

You can lock the OCXO to a rubidium standard. This OCXO has decent phase noise performance:

-120 dBc/Hz at 10 Hz
-130 dBc/Hz at 100 Hz
-140 dBc/Hz at 1 KHz
-145 dBc/Hz at 10 KHz
-145 dBc/Hz at 100 KHz

LT do a decent buffer IC although I can't remember the part number. That doesn't add any phase noise and give you two antiphase or in phase outputs depending on a pin config and has decent load isolation. MSOP package was the only problem.

Only problem with Rubidium is cheap Rubidium sources are cheap for a reason: they have a finite lifetime left. You might get lucky. It might last a month.

... a month, thats a bit pessemistic. The cheap stuff is from old mobile radio stations and has worked there for about 10 years. I bought two LPRO101s and they still work after 3 years with quite some lamp voltage left.

[bd139]

Arh, yes, so you will have won time nuttery but what are going to spend your time on now then because that really wasn't much of a battle was it, unlike volt nuttery which just goes on. I mastered time nuttery in a far simpler way except that I can't distribute that to my gear, I just went out and purchased a radio controlled watch that is locked to the atomic clocks around the world 

Well there's no point in doing something unless you're going to use it, so now I'm going to spend my entire time as a member of the "drift nazis", whining about other people's transmit frequency offet being wrong and the transmit drift on WSPR!

1Hz drift in 30 seconds - GTFO! 

That's a problem to keep in mind, although I think that the ones lasting a month may have been murdered by mishandling of their new owner.

That's a possibility for sure. Usually "ham radio dude attacks it with a Weller soldering gun he uses on antenna grounds".

... a month, thats a bit pessemistic. The cheap stuff is from old mobile radio stations and has worked there for about 10 years. I bought two LPRO101s and they still work after 3 years with quite some lamp voltage left.

Like I said it depends. I worked for a defence contractor who bought a nice brand new standard and it dropped dead after a week 

MTBF has a large standard deviation

[Mr. Scram]

That fits the bathtub curve nicely.

[med6753]

Volt nuttery is harder because there's no absolute reference that doesn't involve a transfer standard of some kind.

Don't I know it and makes me crazy. 

[Cubdriver]

Volt nuttery is harder because there's no absolute reference that doesn't involve a transfer standard of some kind.

Don't I know it and makes me crazyier. 

Fixed it for you.   

-Pat

[Mr. Scram]

Well there's relative certainty and absolute certainty. Relative certainty is that the TF930 and the OCXO track well. Absolute certainty is that they might be both be equally wrong compared to everyone else's opinion of 10MHz. Now that's where the GPSDO comes in because that will lock the OCXO to the lovely little network of space-borne rubidium frequency standards in the GPS satellites thus making sure they reference the same absolute standard.

Then time nuttery is won 

Volt nuttery is harder because there's no absolute reference that doesn't involve a transfer standard of some kind.

Well, there is. You're just not going to find it on Ebay any time soon or pay for it with the income of a mortal.

[bd139]

I live up the road (3 miles) from National Physics Laboratory aka everything-nut central. I reckon hanging around in the local pubs may be a profitable exercise, at least in the long term 

http://www.npl.co.uk/electromagnetics/electrical-quantum-standards/

Edit: actually a bus goes from outside my door right past it

Edit 2: LTC6957 was what I was considering for buffering the reference. See: LTC6957-3: https://www.analog.com/media/en/technical-documentation/data-sheets/6957fb.pdf

Edit 3: just bought another OCXO as a spare ... link here if anyone wants one. They still have 476 pieces available: https://www.aliexpress.com/item/NEW-1PC-Disassemble-parts-OCXO-NV47A1282-10MHZ-low-phase-noise-high-stability-thermostatic-crystal-5V-sine/32884007601.html - currently £12.90

[tggzzz]

I live up the road (3 miles) from National Physics Laboratory aka everything-nut central. I reckon hanging around in the local pubs may be a profitable exercise, at least in the long term 

http://www.npl.co.uk/electromagnetics/electrical-quantum-standards/

I have a university friend that works there.i have suggested NPL should duplicate the PTB's outreach at the Hannover maker fairs, without success.

Get a transfer standard, have a short break in Hannover. Cheaper than getting RS to do something like calibrate it

[beanflying]

Volt Nuttery deals in PPM and certainties and stability

Time Nuttery deals in PPB and deviation

the next illogical leap is unclear but

Then, one day, a student who had been left to sweep up after a particularly unsuccessful party found himself reasoning in this way: If he thought to himself, such a machine is a virtual impossibility, it must have finite improbability. So all I have to do in order to make one is to work out how exactly improbable it is, feed that figure into the finite improbability generator, give it a fresh cup of really hot tea... and turn it on!

[mnementh]

Vinegar seems to be the choice as it is a Hydroxide residue. Anyhow tomorrow job the top came off beer number 2  and Slim Dotty is sitting locked and tracking the last digit over a range of values.

Got NFI what to do with her long term and to good to break down maybe bodge a switchable clock option onto the display using the BCD the bus runs between the upper and lower halves

Vinegar is pretty active in its own right and requires careful rinsing afterwards. Windex contains alcohol as well, which seems to help with keeping contaminants in suspension rather than just smearing them around. But hey, it's your party; you get to pick the booze.

mnem
*Need-Coffee zombie*

[bd139]

I live up the road (3 miles) from National Physics Laboratory aka everything-nut central. I reckon hanging around in the local pubs may be a profitable exercise, at least in the long term 

http://www.npl.co.uk/electromagnetics/electrical-quantum-standards/

I have a university friend that works there.i have suggested NPL should duplicate the PTB's outreach at the Hannover maker fairs, without success.

Get a transfer standard, have a short break in Hannover. Cheaper than getting RS to do something like calibrate it

And as Specmaster found out, RS can't actually calibrate anything anyway 

Talking of which, I'm sending my 87V off for cal next month. Decided I need at least one thing in cal.

[mnementh]

Well my OCXO finally arrived and with an interesting packaging. Nope they didn't desolder it, just cut round the damn thing with a band saw 

Fingers crossed it works.

*Cries a little inside for the donor*   

*Sends a little prayer to Ifni that the crystal didn't get its brains pulverized by the vibration from dumbasses with power tools*

I think I'm becoming a time nut 

By the time you start thinking this ... it's too late.

I was just thinking that... 

mnem
ERROR: INSUFFICIENT CAFFEINE LEVELS FOR CONSCIOUS THOUGHT. HULK SMASH COFFEE BEANS NOW!!!

[tggzzz]

I live up the road (3 miles) from National Physics Laboratory aka everything-nut central. I reckon hanging around in the local pubs may be a profitable exercise, at least in the long term 

http://www.npl.co.uk/electromagnetics/electrical-quantum-standards/

I have a university friend that works there.i have suggested NPL should duplicate the PTB's outreach at the Hannover maker fairs, without success.

Get a transfer standard, have a short break in Hannover. Cheaper than getting RS to do something like calibrate it

And as Specmaster found out, RS can't actually calibrate anything anyway 

Indeed. Let me just say that I asked RS a few simple questions, and the responses were sufficient to persuade me to go to Hannover

[mnementh]

What's the pot for?

Pot is to trim the OXCO frequency. Voltage controlled frequency offset. It's got an adjustment range of about 8Hz either side of 10.0000000MHz to offset for crystal aging.  Ideally should be a 10 or 25 turn trimmer but they are in the cupboard and I couldn't be arsed to get one out.

Incidentally this is what will be fed from the PLL that will lock it to the GPSDO.

See, and now you just introduced a level of uncertainty. What are you gonna do? I encounter same with volt nut. Getting a backup helps but still doesn't eliminate it.

Wish I wasn't so anal. 

Well there's relative certainty and absolute certainty. Relative certainty is that the TF930 and the OCXO track well. Absolute certainty is that they might be both be equally wrong compared to everyone else's opinion of 10MHz. Now that's where the GPSDO comes in because that will lock the OCXO to the lovely little network of space-borne rubidium frequency standards in the GPS satellites thus making sure they reference the same absolute standard.

Then time nuttery is won     Volt nuttery is harder because there's no absolute reference that doesn't involve a transfer standard of some kind.

*Looks at his wristwatch* Ummm... yeah.

I'm semi-retired. If I need more precision that that, I'll reach for the big pocket watch; which incidentally, is also locked to that same time constant y'all are on about... 

mnem
Time is a puppy begging for scraps at the Cosmic BBQ. Watch out for mommy.

[bd139]

I prefer the 21st Century pocket watch: