Kontron/Tabor 6010 universal counter still worth getting?

[0xdeadbeef]

I'm looking for a universal counter but don't want to spend too much money (ideally <200€). It should have at least a TCXO time base with like <= 1ppm but also allow to use an external 10MHz reference.
Doesn't have to support GHz stuff, I'll mainly use it to check drift of 10MHz time bases like OCXO vs. GPSDO and things like this. So anything <= 100MHz will certainly do. And well, the smaller the better. I already have too much gear and not enough space.

So I first looked into Racal/Dana counters like 199x but what I found was still rather expensive and in pretty bad condition and for counters from big brands like HP/Agilent it's even worse.
That's why I currently think about getting a moderately prized Kontron/Tabor 6010 with a TCXO time base. I assume the 60x0 counters were produced from the late 80s to the late 90s or so. Maybe even longer.
My understanding is that they were built by Kontron first, then that business was sold to Tabor or maybe Tabor produced them as OEM or whatever. Anyway, the seem to have been produced for quite some time and you can still download datsheets, drivers and manuals for them from the TaborElec web site.

Anyway, I'm unsure if it's really worth getting such a counter which will be at least 20 years old, maybe even older. Like there's the chance of dying the death of dried electrolytics, the TCXO probably drifted quite a few ppm over the decades, the calibration is fully manual and I'd need to get some GPIB to USB adapter if I ever want to control it from a PC. Actually I figure I need to open the 6010 to calibrate it and to configure stuff like the 10MHz reference output to input.

So in a nutshell, is it still worth getting something like this for like <= 200€ or should I rather get my hands on something new like a TTI TF930 with USB and electronic calibration but costs more like 420€ (incl. VAT)?
To be perfectly clear: I don't consider buying an old counter because I'm into vintage stuff. It's more like I hope to get good gear for a good price in this case.

[EDIT]
The Tabor 60x0 was obviously also also sold under names like Keithley 776 and Racal 2202.

[perdrix]

I'd say so - they are good counters, were badge engineered as Racal in the 2022(R)!

Dave

[don.r]

You might also want to consider older HP gear like the 5315/5316. The 5316 has a 10Mhz external input. These can be found for under $100 frequently.

[jpb]

It might be worth looking out for a second hand TTi TF930. These are simple reciprical counters with no interpolation but do produce continuous counts and have a reference input and a computer interface via usb. They can do 10 digits on 100s or if you use the computer interface you can collect data continuously over longer gates.

One drawback is they have no backlight on the display.

New price is a bit excessive but they seem to be sold second hand for under £100 from time to time. There is also the TTi TF960 which is more recent.

The other thing to say is that the reference input is a bit deaf - it needs TTL or 1Vrms AC and a lot of sources are less than this which is a bit annoying.

[0xdeadbeef]

Yeah, I mentioned the TF930 in my initial posting. Problem is that I couldn't find anything cheap yet. Actually the few ones sold on eBay are much more expensive than a new unit from RS (including VAT) which is around 420€ and a bit more than I'd like to spend.
Besides, I don't think I like the external reference input on the front and I guess some thinks like Phase A/B are missing (which I don't really need though) compared to the 6010.
Then there's the issue that there are two inputs, but the B input is only for >80MHz. So I couldn't even use stuff like Ratio A/B with a 10MHz OCXO vs. GPSDO.
Again, not a total showstopper. It's just that this makes the 2nd channel more or less useless for me.
The only measurements that the TF930 has but the 6010 doesn't are pulse width and duty cycle measurement. Dunno how much sense these make though as they depend on rise/fall times and threshold.

About the old HPs: my impression is that these are at least 10 years older than the Tabor 6010 and the ones that are in the <200€ range don't seem to have a TCXO.
Anyway my chances to get a mint unit for a good price are better for a less known brand like Tabor.

[jpb]

Yeah, I mentioned the TF930 in my initial posting. Problem is that I couldn't find anything cheap yet. Actually the few ones sold on eBay are much more expensive than a new unit from RS (including VAT) which is around 420€ and a bit more than I'd like to spend.
Besides, I don't think I like the external reference input on the front and I guess some thinks like Phase A/B are missing (which I don't really need though) compared to the 6010.
Then there's the issue that there are two inputs, but the B input is only for >80MHz. So I couldn't even use stuff like Ratio A/B with a 10MHz OCXO vs. GPSDO.
Again, not a total showstopper. It's just that this makes the 2nd channel more or less useless for me.
The only measurements that the TF930 has but the 6010 doesn't are pulse width and duty cycle measurement. Dunno how much sense these make though as they depend on rise/fall times and threshold.

About the old HPs: my impression is that these are at least 10 years older than the Tabor 6010 and the ones that are in the <200€ range don't seem to have a TCXO.
Anyway my chances to get a mint unit for a good price are better for a less known brand like Tabor.

You make some valid points.
If you are looking at 10MHz ratio then you just use one as the reference - I used to set my 10MHz OCXO by using it as a reference and measuring the 1pps from a GPS averaged over 100 seconds - one nice thing is the lowest frequency is 1mHz so measuring 1Hz is fine - some other counters start well above 1Hz.
I agree though that you'd be wasting the second channel.
I generally don't use  the second channel but recently I bought an RF generator on ebay and was glad to be able to go up to 3GHz (I have a much more expensive Tektronix Counter FC3100 but that only goes up to 300MHz).

I bought my TF930 from TTi themselves as an ex-demo model, it cost me £190 I think.

I am not particularly pushing the TF930 though, it definitely has its flaws such as the non-backlit display, the ref port on the front (as you say) and the fact that you need a high level (3V+ TTL or 1Vrms sine). Also it is a bit lightweight with plastic rivets rather than screws. But it also has some good points - very light, draws little current so can be powered from its internal batteries or from the USB port and the fact that it has no dead-time and is a proper reciprical counter.

[0xdeadbeef]

Yeah, for <= 200€ I'd really consider buying one but I don't see this happen at the moment.
Side note: some sellers seem to show a version with different front layout (older version???)
https://www.ebay.de/itm/AIM-TTI-INSTRUMENTS-TF930-FREQUENCY-COUNTER-TIMER-3-GHZ/271964144601?epid=1026587164&hash=item3f525383d9:g:X2UAAMXQatBSa78h

And while we're at it: while the TaborElec site and the datasheet speaks of a "Standard TCXO stability Oscillator", the manual than can be downloaded there clearly describes the TCXO as Option 1.
So at least older versions of this counter seem to have a standard oscillator (5ppm) that is not a TCXO. Actually the device shows all installed options at power up after the display test.
It should display "6010-1" for TXCO or "6010-1.2.4" for TCXO, 1.3GHz input and GPIB interface. Then again, confusingly, the datasheet lists Option 1 as "10x clock multiplier".

[0xdeadbeef]

OK, I was tired of looking for other options, so I bought a Tabor 6010 for 150€ which looks pretty much like in mint condition on the pictures even tough I guess it's most probably from 1992 or so.
The seller confirmed that the TCXO is installed even though it doesn't show option 1 during startup. Can't wait for it to arrive so I can take a look inside

There's another eBay seller who sells a Kontron and (!) a Tabor 6010, both in very good condition but without the 1.3GHz option installed for 123€ (each). As I don't really need the 1.3GHz input, my main reason not to save ~30€ was that he couldn't confirm that the TCXO is installed.

Side note: the 6010 is working in reciprocal mode up to exactly 10MHz (whatever that means). If it really quits reciprocal mode at 10.0000001MHz or so this might be a bit of a nuisance but still I guess that it's quite a bargain for a solid 9 digit counter with two 125MHz inputs, a TCXO and both, GPIB option and the 1.3GHz option installed.

[0xdeadbeef]

So the world is bad. Even though I was explicitly assured by the seller that the TCXO is placed, it simply isn't.
There's just the 5ppm standard oscillator on the PCB which is also connected to the rear panel 10MHz reference output (and input - configurable by jumper).
Besides, using the according trimming capacitor of the 5ppm oscillator changes the measurement so there's absolutely no doubt that the 5ppm standard oscillator is used.
Still the seller claims that I should just open the case and I would see the TCXO in a "black housing". Dunno what he thinks the TCXO would look like but IMHO there is no TCXO and anyway, it's absolutely 100% certain that the 5ppm oscillator is used.
Still, the device in nearly mint condition and works flawlessly. It's hard to believe that it must be at least 20 years old. So I'm hesitant if I'd like to keep it or not.
As a side note, the reciprocal mode doesn't seem to work near 10MHz. At least I didn't get it to work. But I guess I could live with that.

[Ash]

This is a photo of the inside of my 6030, showing the time-base module. You can see that the 5ppm oscillator you highlight is not fit in this case.

Ash.

[0xdeadbeef]

Yeah, this is what I expected to see for the TCXO option
But then again, you don't have the GHz input board

Good thing is that I convinced the seller that he's wrong in the meantime. So I will get a refund this way or the other (either send it back or keep it and get some money back).
I mean it's not totally unusable even with the 5ppm oscillator. I could calibrate it to a few LSDs (i.e. the 9th digit changes driftes counts up and down) and I can't tell if the drift comes from the oscillator or the GPSDO.

While we're at it: did you ever try to jumper the 10MHz output to input? I wonder if it will need the 10MHz reference input all the time then or automatically detects its presence and switches from the internal timebase to the external if there is a signal connected.

[Ash]

Yes, the channel C input is a little bit of a lesson for me 

I assumed it had it because the connector was there, but it wasn't. That in in line with the manual, and the seller didn't say it was fitted when I bought it on eBay. But no matter I got it reasonably cheaply because there was an error with the unit where it wouldn't read correctly. Turned out the PLL that takes the 10MHz and converts to 500MHz (on the 6030, not sure about the 6010) was broken - the first divider was dead. I was able to source a replacement and was all good. I also took the precaution of replacing the electrolytics..

As for the External/Internal switching, I'm not sure about the 6010, but if the 6030 is anything to go my, it is a manual switch - you need to move jumpers around inside the instrument. These are located on the left side of the module.. There is no auto switching  In my case the instrument runs at 500MHz derived from a PLL, so the external 10Mhz would have to be constant..

On my long list of "projects to do when I get a chance" is to break out the jumpers to either a small relay daughter board or even add a toggle switch on the back..  marginal at 10MHz tho.

I also intend to make or re-purpose a divider board to bring the C channel up. I'm reasonably sure there is the ability to go to higher frequencies as some of the pins to the daughter board set the divide ratio so the firmware can correctly display the frequency. the 6030 is labelled at 2.4GHz..

If you have a GPSDO, just setup as an input, and you will be more accurate than me

I don't know what the differences are between the models, but if they share common hardware, I have a copy of the 6030 EPROM if you want to play with it..

Ash.

[0xdeadbeef]

I already have a cheap Chinese GPSDO and used it to calibrate the 5PPM oscillator. However I somewhat dislike the idea of using a GPSDO as (permanent) time base for the counter.
My idea is to create a small PCB with an 10MHZ OCXO plus trimmer, voltage supply and the like and either mount it internally or to the external input (after using the jumper to configure it).
Maybe I could even use the internal jumper J4 to supply the PCB.
Anyway, I understand that if I had the TCXO option (1), the external reference could be 1MHz, 5MHz or 10MHu but without it, only 10MHz is possible (since the PLL 74HCT4046 is on the TCXO board).

One  drawback of this solution compared to the TCXO board is that I won't have the 10x multiplier. With it, the counter is 10 times faster (8 digits per second instead of 7) and the maximum frequency for reciprocal counting is increased to 100MHz. Well, theoretically, I guess I could try to figure out the pinning of J4, create the 100MHZ signal and apply it to the correct pin but I'm not sure if this is worth it.

About the EEPROM: I think the 6030 has higher specs so I doubt  using the 6030 SW in a 6010 would do any good even though the HW looks very similar.

[Ash]

I downloaded the manual for the 6010 (available on the Tabor site), and looked at the pin-out of the connector, its all documented.

If you had a modern 100MHz TCXO (quick digikey search showed some 1ppm versions).. and buffered that you then feed 100MHz into the right pin onto the unit. There are 2 "sense" lines on the header used by the firmware to detect the option and adapt I guess. These are shown in the schematic for the option in the manual.

I'd be betting that it would all work fine, but you would have to disable the existing 10Mhz reference first. That should be as simple as pulling both the int/ext jumpers so there is no connection at all. This will leave the output driver active in one logic state, but this is capacitively coupled to the same line as the 100Mhz input from the TCXO option so hopefully shouldn't be a big issue.

You could probably test by just jumpering the right pins on the header so the firmware detects the option, but leave the 10MHz ref alone, the counter should then be reading 10x high.. If that happens, building your own 100Mhz TCXO should be straight forward. Looks like if you jumper pin 2 (OPT0) to pin 1 (ground) is all you need to do, pin 4 (OPT1) is left floating according to the schematic.

The manual does state that the options are field installable with no software changes needed. And section 5-2 details it.. however it says to pull U58, and the links LK1a/b, but I can't find U58, I'm guessing that they mean U57 which is the 10Mhz reference. Is that socketed?

Anyway - have a look over the manual and schematics etc, and I think you'll see it should be pretty straight forward to upgrade the unit. There is plenty of room inside to mount a TCXO board, or even a OCXO.. however if you have a 10Mhz you'll need to PLL up to 100Mhz. Like I suggested above it may be better to just go straight to a modern 100MHz osc. Guess it depends on how far you want to go. you could do a PLL and have some internal/external reference switching on the board as well.

Ash.

[0xdeadbeef]

Wow, thanks, how could I overlook the schematics in the manual? I actually searched for the Jumper 4 layout in the manual but didn't consider that the schematics were only graphics.
Anyway, I tend to think that the manual mixes up U56 and U58. While U58 is used in the analog output option, U56 is the 74F132 (Quad 2-input NAND Schmitt trigger) used in the 5ppm Oscillator. It's socketed as all the other ICs and I guess it would make perfect sense that the 5ppm oscillator isn't connected to the device anymore if it's removed.

I originally planned to use one of the 10MHz OCXOs I bought some time ago and I guess I could build some PLL circuit to crank it up to 100Mhz.
The benefit of this approach would be that I could also still use an external 10MHz (keeping the 10x multiplier) reference with an internal jumper.
But it's certainly much easier to try to get a 100Mhz TCXO (or OCXO) with <=1ppm. 
Now this really looks like it could be a piece of cake to build myself a fake option 1...

[EDIT]
On a 2nd thought, I guess using some off-the-shelf clock multiplier like the IDT ICS601M-01 I could actually re-use my 10MHz OCXO and keep the possibility to use an external 10MHz Reference.
https://www.idt.com/document/dst/601-01-datasheet
 

[Ash]

Wow, thanks, how could I overlook the schematics in the manual? I actually searched for the Jumper 4 layout in the manual but didn't consider that the schematics were only graphics.

Haha.. I guess I'm used to looking at old manuals which are scans of a photocopy of a printout...

Anyway, I tend to think that the manual mixes up U56 and U58. While U58 is used in the analog output option, U56 is the 74F132 (Quad 2-input NAND Schmitt trigger) used in the 5ppm Oscillator. It's socketed as all the other ICs and I guess it would make perfect sense that the 5ppm oscillator isn't connected to the device anymore if it's removed.

Ah yes, makes sense. I didn't have a lot of time to search for it. Now that you point that out, it would certainly make more sense to pull the NAND that is driving the 10Mhz output. Leave the oscillator there as you may need it at some point and that way you won't loose it

I originally planned to use one of the 10MHz OCXOs I bought some time ago and I guess I could build some PLL circuit to crank it up to 100Mhz.
The benefit of this approach would be that I could also still use an external 10MHz (keeping the 10x multiplier) reference with an internal jumper.
But it's certainly much easier to try to get a 100Mhz TCXO (or OCXO) with <=1ppm. 
Now this really looks like it could be a piece of cake to build myself a fake option 1...

That's the wonderful thing about this older gear - its well documented and can be modified and built upon 

[EDIT]
On a 2nd thought, I guess using some off-the-shelf clock multiplier like the IDT ICS601M-01 I could actually re-use my 10MHz OCXO and keep the possibility to use an external 10MHz Reference.
https://www.idt.com/document/dst/601-01-datasheet

You might want to be careful with that chip - it seems to be designed for direct crystal driving. It also states that the jitter and phase between the reference and output are not specified.

The external input is really useful I think and it is something I'd try to incorporate, but I'd be looking for a higher spec design. The problem is going to be the accuracy of your measurements will be directly affected by the jitter.

Let me know if I can help with anything. I find this lots of fun messing with old gear and I always learn a lot.

Ash.

[0xdeadbeef]

You might want to be careful with that chip - it seems to be designed for direct crystal driving.

It also supports clock in. X2 is just left open then.

It also states that the jitter and phase between the reference and output are not specified.

It's true true that the input to output skew isn't defined but I'm unsure why I would need that for this application.
Anyway, there is also a "zero delay" version available namely the ICS670 which however has a slightly worse phase noise specification (-124 dBc/Hz at 10 kHz for the 670 vs. -132 dBc/Hz at 10 kHz for the 601).

The external input is really useful I think and it is something I'd try to incorporate, but I'd be looking for a higher spec design. The problem is going to be the accuracy of your measurements will be directly affected by the jitter.

The typical output jitter (one sigma) is defined as 12ps for the ICS601 which is probably >100 times less than the time resolution of the counter. Actually I couldn't find any specification for the single shot interval resolution only the 10ps resolution for averaged (!) measurement with option 1 (TCXO). So probably even with the TCXO the single shot resolution is 500ps or more. Actually I think it could be as bad as 2ns.
I don't think a typical OCXO or TCXOs will have much better values regarding phase noise. E.g. I looked up a 100MHz VCTCXO from Abracon (ASGTX-D-100.000MHz-1 for 51,36€) and my understanding is that it has a phase noise specification of -116dBc/Hz at 10KHz for a 120MHz carrier.
So I'm not sure that an affordable TCXO or OCXO will have a much better phase noise or jitter than this multiplier solution.

[Ash]

The external input is really useful I think and it is something I'd try to incorporate, but I'd be looking for a higher spec design. The problem is going to be the accuracy of your measurements will be directly affected by the jitter.

The typical output jitter (one sigma) is defined as 12ps for the ICS601 which is probably >100 times less than the time resolution of the counter. Actually I couldn't find any specification for the single shot interval resolution only the 10ps resolution for averaged (!) measurement with option 1 (TCXO). So probably even with the TCXO the single shot resolution is 500ps or more. Actually I think it could be as bad as 2ns.
I don't think a typical OCXO or TCXOs will have much better values regarding phase noise. E.g. I looked up a 100MHz VCTCXO from Abracon (ASGTX-D-100.000MHz-1 for 51,36€) and my understanding is that it has a phase noise specification of -116dBc/Hz at 10KHz for a 120MHz carrier.
So I'm not sure that an affordable TCXO or OCXO will have a much better phase noise or jitter than this multiplier solution.

You are probably right. I wasn't really thinking through that stuff too much. 

I missed that you could drive the ICS670 with an external clock (I did look, but very quickly). For the price on digikey, I'd be very tempted to just give it a go given you already have a OCXO

Looks like a fun project. I'll certainly be following your progress if you share it!

Ash.

[0xdeadbeef]

Yeah, I'm like 95% percent sure I will do this sooner or later. It's just that I guess I want to design a PCB for this and even if I should do this in the next days it will take >6 weeks or so until I get the PCBs from China. And well, you know if I'm ordering parts it usually ends with days checking what I could order additionally now that I'm ordering anyway.
So don't expect an update on this too soon

[Ash]

Yeah, I'm like 95% percent sure I will do this sooner or later. It's just that I guess I want to design a PCB for this and even if I should do this in the next days it will take >6 weeks or so until I get the PCBs from China. And well, you know if I'm ordering parts it usually ends with days checking what I could order additionally now that I'm ordering anyway.
So don't expect an update on this too soon

We are all busy and sometimes the fun stuff has to wait a bit sadly.. I have a few of those projects myself. 

As for ordering, I'm normally frantically trying to figure out what else I should add to the order to meet the free shipping threshold to Australia.. That often takes much longer than getting the stuff I know I need

Best of luck!
Ash.

[0xdeadbeef]

Yeah, I need to get over 50€ to get free shipping. But I guess this won't be much of a problem - just time consuming

Side note: I looked a bit more into the schematic and it looks like simply connecting a 100MHz oscillator won't do the job.
There seems to be some +/-5V level shifting going on at the output So I guess I will replicate that circuit.

While I'm at it, I guess I will also replicate the 10MHz external reference input/output circuit using the 74F132 NAND-Schmitt-Triggers (funnily they are called Schmidt-Triggers in the manual which is actually the more common German spelling).

[Ash]

Side note: I looked a bit more into the schematic and it looks like simply connecting a 100MHz oscillator won't do the job.
There seems to be some +/-5V level shifting going on at the output So I guess I will replicate that circuit.

While I'm at it, I guess I will also replicate the 10MHz external reference input/output circuit using the 74F132 NAND-Schmitt-Triggers (funnily they are called Schmidt-Triggers in the manual which is actually the more common German spelling).

It appears to be a buffer/driver. On the main board, it is driving 2 ECL based NOR gates. There seems to be a biasing network around U25c(?) which along with the series resistor/capacitor R106/C69(?) for AC coupling is how the 10MHz signal gets through from a standard logic gate..

I can't see Q1 being a level shifter as the output is capacitively coupled (C3). I'm thinking its setup as a buffer and driver from the ECL VCO U7 (MC1648).

Q2 is interesting as well, it seem to be disabling the output if the phase comparator is generating longish pulses meaning that it is not locked. The zener is a 6.2V device, so when the output of U2a NAND goes high it will conduct and allow current into the NPN base and therefore shunt the output signal. If I'm reading that correctly.. pretty clever level shifting happening there

Maybe stick a scope on the line and see what the signal looks like using your current 10MHz osc on the board, then try replicate that. I'm guessing that a modern fast logic gate, capacitively coupled would work. If you have a signal generator you could mock up a driver using a gate and drive it from the sign gen and see the result on a scope.. check the output of the ECL NOR gates as well. Would tell you if it will work.

I don't have any experience with ECL, I'm sure there are others here who could glance at the schematic and tell you for sure what you need

Ash.

[0xdeadbeef]

Well, the output of the normal 5ppm oscillator and the external reference is definitely created vby a TTL NAND gate (74F132). When I follow this signal into the "Measurement Logic circuit", it's simply connected to the ECL NOR gate through a series 820Ohm resistor and 100nF capacitor. So I guess this is exactly what I need to connect my TCXO/OCXO output to the 100MHz input.
Quickly checked this with LTSpice and it looks somewhat promising:

[Ash]

Well, the output of the normal 5ppm oscillator and the external reference is definitely created vby a TTL NAND gate (74F132). When I follow this signal into the "Measurement Logic circuit", it's simply connected to the ECL NOR gate through a series 820Ohm resistor and 100nF capacitor. So I guess this is exactly what I need to connect my TCXO/OCXO output to the 100MHz input.
Quickly checked this with LTSpice and it looks somewhat promising:

Looks like it should work

Have fun!

Ash.

[0xdeadbeef]

Did some schematic design today. Mainly copied the circuitry from the manual and added my OCXO, a 3.3V supply and the ICS601-01 as multiplier.
I also replaced the 74F132 with a MC74ACT132 and the 1N4151 diodes with a (double) BAV99.
I also started with the PCB. It should fit quite easily into a 5x5cm PCB. I'm a bit uncertain if I should solder the shielded wire to the 10MHhz reference input/output directly to the PCB or use some kind of SMB connector.