WTB (UK) Fluke PM6690 / Pendulum CNT-90 Frequency counter/timer - Page 1
Forum section: electronics / general

author: picitup
author_rank: Regular Contributor
timestamp: March 01, 2018, 12:38:20 pm
content: Hi AllI've been wanting to upgrade my TF930 for some time and am hankering after one of the above.I don't know if I have enough cash yet, but I'm saving and selling kit as fast as I can.If anyone has one for sale, please let me know a price and I'll reply straight away.Thanks for reading...Steve

author: jpb
author_rank: Super Contributor
timestamp: March 01, 2018, 04:30:54 pm
content: Tektronix also sell this counter as the FCA3100 (equivalent to the CNT-95 I think - 50 psec resolution), I bought mine as refurbished stock from TTi who are the Tektronix reps in the UK. It wasn't cheap (£1500 inc VAT) but it came with an as-new warranty and was a lot cheaper than the Agilent top of line counters which were around £3k ex VAT or more even from the Keysight e-bay store (of course it is not quite as good as the Keysight which is 20psec resolution though it does timestamp both wave crossing whilst the Keysight only does the up-ones).I also upgraded from the TF930 though I've hung onto that as it goes to 3GHz and also its useful as a spare.It may be worth approaching Tektronix to see if they have any refurbished stock. (i.e. TTi in the UK - unfortunately the Tektronix ebay store doesn't ship to the UK)

author: DaJMasta
author_rank: Super Contributor
timestamp: March 01, 2018, 04:50:37 pm
content: That's right, the FCA3100 series is the CNT-91, but the FCA3000 series is the CNT-90 and is still sometimes available for a reasonable price.I'd sell my PM6690 if I could buy a 53230a for cheap...... but where I've been looking, that hasn't been for months. I'll mention if it comes up, but certainly don't hold your breath.

author: picitup
author_rank: Regular Contributor
timestamp: March 02, 2018, 07:17:37 am
content: Hi BothThanks very much for the info. I didn't know the Tektronix FCA series was the same as the Fluke/Pendulum series. I think the TF930 is an excellent piece of kit for its class with its 10 digit resolution.I found a Pendulum CNT-90 on a used equipment web site for £750.00 but when I contacted them it had gone.Well if anyone has one under their bench please let me know!CheersSteve

author: PTR_1275
author_rank: Frequent Contributor
timestamp: March 02, 2018, 10:58:30 am
content: There was a bloke in Israel a few years back with about 10 of them on eBay. I kept putting it off, then when I’d saved the money they’d all been sold.I still keep an eye out for them, but haven’t seen many come up since.I picked up a 53220 Agilent counter for a steal at a auction a few months back so I don’t think I’ll be needing another counter for a long time.

author: picitup
author_rank: Regular Contributor
timestamp: March 03, 2018, 08:20:59 am
content: Bummer. Hindsight is wonderful....The 53220 looks a very nice beast. There's a brand new one on eBay for £2K3 but still too much for me.I got an offer of a new one from from a used equip guy for £1700.00 but still too rich for me.CheersSteve

author: picitup
author_rank: Regular Contributor
timestamp: March 08, 2018, 04:16:17 pm
content: OK last request.I'm about to cough £1700.00 for one of these and eat grass for a few months.Any last minute offers gratefully received!CheersSteve

author: kj7e
author_rank: Frequent Contributor
timestamp: March 08, 2018, 09:16:20 pm
content: For that price I would look at a 53220A and put an oven in it;https://www.ebay.com/itm/Keysight-Agilent-53220A-350-MHz-Universal-Frequency-Counter-Timer-12-digits-s/323001851557?epid=661749371&hash=item4b34691ea5:g:0ccAAOSwkvFaW~U~

author: picitup
author_rank: Regular Contributor
timestamp: March 09, 2018, 08:15:22 pm
content: Thanks for the tip. It looks like a very decent counter. I can't quite find out if it's 12 or 15 digits - different data sheets say different things. I know it will work at 12 digits/s but I'm wondering about the total resolution.The CNT-90 is 14 digits and the price is for a new unit, calibrated with a 3 year warranty. Not that I mind second hand kit. I wouldn't need an oven as I have A GPSDO.I'm really half and half on whether to cough up. It's a lot of cash and grass isn't all that badCheersSteve

author: jpb
author_rank: Super Contributor
timestamp: March 09, 2018, 09:39:51 pm
content: £1700 for a CNT-90 seems quite high. I paid £1500 for the FC3100 which is equivalent to the CNT-91 (50psec vs 100psec plus other features) - it wasn't new but it was refurbished and with a 3 year warranty as new.The Tektronix store on ebay have The FCA3103 for US $2,044.00 with 3 year warranty but sadly they don't ship to the UK. ($2044 converted to £ and with 20% added on is £1,770). I know you couldn't take this option but it may be worth speaking to the TTi people - that is what I did and they were able to get a model from the US on my behalf.Having said that, compared to the list price £1700 inc VAT is cheap, so it is a fair offer but the CNT90/FC3000/etc is a very old model now so I think suppliers should be open to negotiation.

author: DaJMasta
author_rank: Super Contributor
timestamp: March 10, 2018, 05:49:01 am
content: The actual displayed digits with the CNT-90 varies with quantities of samples and measurement stability. If your signal is stable enough and you keep measuring, 14 digits will happen if your signal is super stable, but if it's varying by enough measurement to measurement, it will only display down to the least significant digit above the noise.In terms of actual timing, you want to look at digits per second (and basically everything mentioned is 12 digits/s), and then timestamp resolution (100ps for the CNT-90, 50ps for the CNT-91, 20ps for the 53230A). I don't know of a commercially available counter that can give you more than 12 digits/s or a smaller timestamp resolution. Then the additional digits are all up to software averaging, and if you wanted an arbitrary number of extra digits worth of averaging, it would be easy to do with a little custom software (though it would be only useful above the noise threshold of the variation between signals).I think the CNT-90 based counter that's your fallback is overpriced. The CNT-91 series units have been going for around 2k USD for a while, and there have been plenty of CNT-90 based counters that have gone for half that or less (though maybe not in the last few months, there's not a ton of volume). I know it's harder to find stuff in the UK, but I think a really good deal for a CNT-90 based counter is about half what you're considering - maybe something in between is more realistic, but 1700 pounds seems a bit steep from what I've seen of the market.

author: picitup
author_rank: Regular Contributor
timestamp: March 10, 2018, 11:09:42 am
content: oo that's embarrasing, it's 1700 +VAT so I guess much overpriced. After saying that, the other offerings aren't much different, with the 53220A on eBay being USD 2300 = GBP 1660 and it's second hand, no apparent warranty and no calibration.On the tek.com web site, the FCA3000 is USD 2510 which is GBP 1800 but as you say, they don't ship to the UK. The other issue with the US and China for expensive kit is if you get stuck for VAT (20%) and import duties + courier admin fee which can significantly hike the price.On rs uk the FCA3000 is GBP 2,500.Well now I don't know what to do. I could wait a while. Hmm.....

author: jpb
author_rank: Super Contributor
timestamp: March 10, 2018, 12:28:12 pm
content: I think it is worth e-mailing TTi and asking them if they can get a refurbished FCA3100 or FCA3000, saying you've seen one on the US e-bay store:https://www.ebay.com/itm/Tektronix-FCA3103-Frequency-Counter-/191938212406?hash=item2cb068b236and see if they can offer you a good deal - they may well have ex-demo stock of their own (I bought my TF930 from them as ex-demo as well) - they can only say no or come back with too high a price which you can turn down. In my case there was a US only deal being advertised but when I contacted TTi they agreed to give me the same deal on my refurbished FCA3100.Aspen electronics also sometimes have ex-demo kit, there is nothing listed on their site at present but if you contact them they may either come up with something or offer you some sort of discount.https://www.keysight.aspen-electronics.com/ex-demo-equipmentThe other thing is to ask TopLoser if he has anything in the pipeline.The Keysight ebay store is worth perusing. At the time I bought my counter (a few years ago) they had quite a few going. They don't have anything on the UK store at present though they do have them on their US ebay store and may be willing to ship to UK (they are generally very helpful, I bought a signal generator from them). Though the ones on the US store are the more expensive ones at present. You have to be a little careful if you want a warranty as they only do this on their "Premium Used" and not on their used though they do offer 30 days return.

author: bozidarms
author_rank: Regular Contributor
timestamp: March 10, 2018, 04:21:40 pm
content: HP 53310A could be more than adequate alternative:http://www.testequipmenthq.com/datasheets/Agilent-53310A-Datasheet.pdfhttp://www.gellerlabs.com/hp53310A.htm

author: picitup
author_rank: Regular Contributor
timestamp: March 20, 2018, 11:47:06 am
content: Well, firstly I'd like to thank everyone for their excellent advice. I've decided to go for gold and buy the brand new CNT-90 calibrated with 3 year warranty so look out for me bunging what I can on eBay so I can eat lol. I'll post up here when I list and it should be Monday coming as I'm away now.CheersSteve

author: MaxR
author_rank: Contributor
timestamp: April 16, 2019, 05:02:38 am
content: Hi,How is your counter?I have a CNT-91 and CNT-90, got them when a local lab was going out of businessMaybe you can give me some hints on the functionality?

author: testpoint1
author_rank: Frequent Contributor
timestamp: April 16, 2019, 11:55:10 am
content: I already listed it:https://www.ebay.com/itm/used-pendulum-CNT-90-frequency-counter-same-as-Fluke-PM6690/17386964613512 digits

author: jpb
author_rank: Super Contributor
timestamp: April 16, 2019, 05:06:44 pm
content: Quote from: MaxR on April 16, 2019, 05:02:38 amThere are a lot of manuals on line. Look at the Tektronix FCA3100 manuals (e.g. programmers reference manual) as well as it is the same counter.https://www.tek.com/frequency-counter-supplies/mca3027-manual/fca3000-fca3100-and-mca3000-series-0

author: MaxR
author_rank: Contributor
timestamp: April 16, 2019, 09:16:10 pm
content: Good idea. I'll try to ask service support for some application notes also.

author: MaxR
author_rank: Contributor
timestamp: April 16, 2019, 10:35:21 pm
content: To Testpoint 1, what options your cnt-90 has inside?Quote from: testpoint1 on April 16, 2019, 11:55:10 am

author: testpoint1
author_rank: Frequent Contributor
timestamp: April 17, 2019, 02:31:46 am
content: Quote from: MaxR on April 16, 2019, 10:35:21 pmtype CNT90/011, seems no option for that, I only use the external reference. and I do not suggest you use the OCXO option, the hot time is quite long.

author: testpoint1
author_rank: Frequent Contributor
timestamp: April 17, 2019, 02:33:36 am
content: all manual in here:https://pendulum-instruments.com/products/frequency-counters-analyzers/cnt-90-timer-counter-analyzer/

author: MaxR
author_rank: Contributor
timestamp: April 17, 2019, 09:03:09 am
content: Thx.Why do sell it?Do you have something better, it would be good to know 🤔

author: testpoint1
author_rank: Frequent Contributor
timestamp: April 17, 2019, 11:28:13 am
content: Quote from: MaxR on April 17, 2019, 09:03:09 amI have more, all from a moved factory.

author: MaxR
author_rank: Contributor
timestamp: April 17, 2019, 12:28:03 pm
content: Lucky you