Products > Test Equipment
FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
rhb:
I sent F***Tech 4 photos taken of the screen of an HP 8560A SA of the output of the 33622A and the FY6600 without identifying which was which. I deliberately chose the output levels so that they looked almost identical.
The 33622A was used from Keysight's eBay store, so not as much, but still 30X the 6600. But also 120 MHz rather than 60.
F***Tech told me I had lifetime support and similar BS for about 6 months without actually doing anything about the problem.
Not too sure that FOSS FW for the 6600 will help F***Tech. Relative to a DSO the FPGA code is simple. So writing a complete FOSS FW suite might well lead to a lot more competition. To date I've spent over $1k setting up for the DSO FW project. Right now I'm debating whether to also get a 1102X-E now or later. I already have an Instek GDS-2072E for testing. But long experience has convinced me that writing and testing SW on multiple platforms in 50-100 line increments avoids lots of bugs and other problems..
In a JDS6600 thread, a poster purporting to be with JDS said that they hired the guy who developed the F***Tech AWG who with another member of their staff designed the JDS6600. Interestingly, the FY6600 uses a DAC and the JDS6600 uses an R2R ladder.
Johnny B Good:
--- Quote from: rhb on December 02, 2018, 12:36:14 am ---I sent F***Tech 4 photos taken of the screen of an HP 8560A SA of the output of the 33622A and the FY6600 without identifying which was which. I deliberately chose the output levels so that they looked almost identical.
The 33622A was used from Keysight's eBay store, so not as much, but still 30X the 6600. But also 120 MHz rather than 60.
F***Tech told me I had lifetime support and similar BS for about 6 months without actually doing anything about the problem.
Not too sure that FOSS FW for the 6600 will help F***Tech. Relative to a DSO the FPGA code is simple. So writing a complete FOSS FW suite might well lead to a lot more competition. To date I've spent over $1k setting up for the DSO FW project. Right now I'm debating whether to also get a 1102X-E now or later. I already have an Instek GDS-2072E for testing. But long experience has convinced me that writing and testing SW on multiple platforms in 50-100 line increments avoids lots of bugs and other problems..
In a JDS6600 thread, a poster purporting to be with JDS said that they hired the guy who developed the F***Tech AWG who with another member of their staff designed the JDS6600. Interestingly, the FY6600 uses a DAC and the JDS6600 uses an R2R ladder.
--- End quote ---
I'm quite surprised F***Tech didn't gift you a new AWG with the latest firmware for you to review alongside of the 33622A. Any company with a functioning marketing division wouldn't have let such an advertising opportunity slip through their fingers like that.
BTW, the penny has only just dropped regarding your use of F***Tech.:) At first I just thought you were avoiding the use of their name to signify your reluctance to give it the "Oxygen of Publicity" but I guess you're simply expressing an expletive variation where the F*** is an anagram of FCUK (another company where their Branding division realised they could create a suggestive and memorable acronym from the initial letters of their company name, "French Connection UK").
Sounds like you bought the 33622A for around half price. Here in the UK, RS and Farnell/Element14 are selling it for £5854.80 after the VAT is added on, some 77 times more than I paid for the FY6600-60M. JOOI, I checked Newark element14's one off price which was $6,856.00. I've no idea whether that was a tax paid price or not but I'd seen more than enough to make my eyes water (only metaphorically you understand - I'm not made of money so there's no way I'm going to spend 77 times more for a box that's by volume no more than 50% bigger).
They say it's money that makes the world go round. If that's true, all I can say is that Keysight Technologies seem to be going above and beyond in keeping the world in a spin (mind you, Tektronix are no slackers in this endeavour either).
I'll take your word on the simplicity of coding a FPGA. My coding expertise only extends to BASIC and Z80 assembler and I haven't done any coding since the mid 80s. You might want to put off getting the Siglent till later (and maybe pick the SDS1202X-E instead ;D).
There's a damn good reason as to why the JDS6600 is cheaper (just!), the lack of a dedicated 14bit high speed DAC with laser trimmed resistors in its ladder network to maintain monotonicity throughout the whole range of sample values, is its downfall. I've seen the youtube review showing the artefacts on its sine wave output as a result of this nasty bit of cost cutting.
There's cheap and then there's so cheap it not only can't be any good, it actually isn't any good. The FY6600 falls into the former category whilst the JDS6600 is most firmly stuck in the latter.
Mention of 'interesting facts' raises the question as to why a seven thousand dollar, less a bit of pocket change, AWG comes with only a 2ppm XO as standard with a 0.1ppm OCXO as an optional upgrade. At that price point you'd expect to see a 0.1ppm TCXO as standard with an option to upgrade to a 3ppb OCXO at the very least. In fact, at a factory fitted option price of $715 why isn't the OCXO a 3ppb rated one? It seems, on that basis, that my 20 dollar 0.1ppm TCXO board is too good a bargain to be true. I sincerely hope that's not the case. BTW, do you happen to know which timebase option is installed in your 33622A? You may have got a better bargain than you'd thought.
One final item I feel is worth mentioning, in view of my earlier ramblings about the anomalous power consumption readings I'd noticed in recent days, is that the problem has definitely progressed in that the average power consumption has increased ever so slightly with it spending more time now consuming exactly 10 watts. It now looks more and more like a mundane crappy PSU smoothing cap issue than the result of some rather exotic anomaly in the main and front panel boards.
I guess it's time I stopped talking about testing the caps and actually get some testing done before it's too late and I'm left with no choice but to fit untested replacements.
Regards, Johnny B Good
rhb:
I'm surprised you didn't catch the F***Tech allusion sooner.
I was quite surprised that I offered to do several thousand dollars of consulting and marketing for under $400 and they ignored it. That's when I started referring to them as F***Tech.
It's really easy to store corrected coefficients at final test. But you have to care. Why do you rate the JDS below the F***Tech? I've not seen a good comparison, despite a number of people in this thread having both.
The 33622A is the only one of my HP instruments that does not have the OXCO option. But as I'm about to hook everything to a GPSDO it shouldn't matter.
Subsequently I saw Keysight offering a 33622A for about $2800.
Johnny B Good:
--- Quote from: Johnny B Good on December 02, 2018, 04:37:39 am ---
====snip====
One final item I feel is worth mentioning, in view of my earlier ramblings about the anomalous power consumption readings I'd noticed in recent days, is that the problem has definitely progressed in that the average power consumption has increased ever so slightly with it spending more time now consuming exactly 10 watts. It now looks more and more like a mundane crappy PSU smoothing cap issue than the result of some rather exotic anomaly in the main and front panel boards.
I guess it's time I stopped talking about testing the caps and actually get some testing done before it's too late and I'm left with no choice but to fit untested replacements.
--- End quote ---
Following up on the above, I picked out a couple of 16v 470μF caps to replace the 220μF ones used by the 12v rails and a nice pair of 6.3v 1500μF (actually proved on testing as 1860 and 1920 μF) from my salvaged caps collection to replace the 10v 1000μF and the 16v 220μF used in the Pi network filtering on the 5v rail.
Unfortunately, the PSU switching chip didn't take kindly to all this extra capacitance and refused to start up (similar overload current foldback symptoms I'd seen with my fullwave rectification upgrade experiment).
After double checking I hadn't bridged any tracks during my resoldering of the replacement caps, I figured that maybe I'd placed too much smoothing capacitance into the secondary circuit so replaced the 1500μF cap on the output of the 5v Pi filter with one of the 220μF caps and tried again (the tall 1500μF cap had made accessing the output header a little awkward, making it my first choice for reverting to the original value).
This proved a sufficient enough remedy to allow the PSU to fire back up and, since the wattmeter showed no change for the worse, I boxed the job off to carry out ESR tests on the other three caps that I'd pulled from the PSU board. They tested ok on ESR compared to the other caps I'd used as replacements so they're no longer suspect. The one I was obliged to revert to and wasn't able to test seems to also be ok since I haven't seen the wattmeter readings get any higher than about 9.8W, typically varying between 9 1/3 W and that high water mark.
That happened last night and this morning, I managed to catch a glimpse of the power level suddenly, yet smoothly, transitioning upwards by a tenth of a watt from just over the 9 1/2 watt mark. Over the next 5 or 6 hours it remained clear of the 10 watt mark by a good 5th of a watt whilst I was running some more tests on the AWG. However, after shutting it down so as to restart it with my last default settings, it refused to power up in a repeat performance of the excess capacitance episode.
It was only after allowing things to cool down for 20 minutes that it started up again so I knew I'd have to pull out the remaining "1500μF" cap and revert to the original 1000μF cap so yet again I'd have to delve into the AWG's innards.
I realised several days ago now that I'd best not bother refitting those four long screws that hold the case halves secured lest I totally wear the screw threads out by the time I've finished all of my planned modifications, so it's now just a matter of unclipping the top of the case from the front panel. I've gotten quite adept at this now with all the practice I've had recently with half of a cut up credit card as a spudger. :)
Anyway, this latest modification to my last PSU modification seems to have dialled the capacitive loading back to a more tolerable level for the controller chip to get on with its job. I've had it running flat out for the past 5 or 6 hours and my hot power up tests checked out ok so it looks like I've modded that PSU to within an inch of its life (hopefully... I don't want to do any more back pedalling or I'll be right back where I started. high performance rectifier diodes upgrade and transformer mod aside). :)
That brings me to a rather curious feature of Feeltech's design wherein the relay switched attenuator network creates a horrible impedance mismatch when it cuts in at P2P levels of 500mV and below. I noticed this effect, which only produces a discontinuity when driving into a 50 ohm load, after I'd been perusing the reverse engineered circuit diagram of the main board trying to work out exactly just how the relay switching was meant to function.
What happens is that for levels at or below 500mV, the THS3002 (or replacement 3091 or 3095 or 3491) opamp(s) are bypassed and the output from the OPA686N is routed to the output sockets via a kakmaimee attenuator network consisting of two 100 ohm shunt resistors linked with a 510 ohm series resistor element. When I first saw that suspiciously high value resistor, I had to assume it had been a transcribing error for a 51 ohm resistor even though that would still have resulted in a 10% mismatch error of 45 ohms.
When the AWG is driving a 50 ohm load, there's a huge jump in output voltage at the transition from 500.0mV level to 500.1mV level and beyond. When I repeated this test without the 50 ohm dummy load, the transition was seamless. Intrigued by this, I tested the output impedance with a DMM to measure the resistance of the output channels either side of this transition level and obtained readings of 52.7 and 84.7 ohms on channel 1 and 54.7 and 85.9 ohms on channel 2 for settings above and below the critical 500mV mark respectively.
No wonder there was such a discontinuity in level when driving 50 ohm loads! It turns out that the series element of this attenuator is 510 ohms after all, rather than 51 to the zeroeth power of ten as I'd thought would be the more likely scenario. Those measured resistance values were in close agreement with my calculated value of 84.45 ohms for the resistor values shown on the circuit diagram.
Anyone using this AWG only for driving Hi-Z loads at audio frequencies would never notice this "Skoolboy Howler" in the design of this final attenuator resistor network which Feeltech chose to "fix in the firmware" and hope nobody would notice their sleight of hand rather than sort it out properly with a new BoM for the attenuator resistor network.
Luckily, for those with an interest in radio frequency work requiring properly terminated loads, this mismatch effect doesn't effect signal level settings above the 500mV mark. The obvious work around when millivolt test signals are required is simply to employ an external 20dB/40dB attenuator instead of the rather shoddy built in one.
I did, btw, figure out that the other relay switching was to bypass the high voltage output current feedback opamp stages for output levels of 5V p2p or less. These high output opamps are only used for outputs when p2p levels above 5v are selected otherwise the OPA686N chips drive the output terminals directly or via those kakmaimee attenuator resistor networks.
I did notice a problem with sub 50mV level signals with common mode interference from the PSU board (if it had been switching ripple on the voltage rails it would have reappeared when the attenuator cut out at the the 500mV transition point). Most likely a problem exacerbated by my 'curing' the half live mains leakage issue when I removed that class Y1 EMC bodge capacitor the other week. :(
BTW, I still think the JDS6600 is a bag of shite. It's merely a tarted up poor man's FY6600 imho and not worth its £62.48 plus £6.99 economy delivery price tag.
Regards and a merry Xmas, Johnny B Good
rhb:
--- Quote from: Johnny B Good on December 04, 2018, 04:04:17 am ---....snip...
BTW, I still think the JDS6600 is a bag of shite. It's merely a tarted up poor man's FY6600 imho and not worth its £62.48 plus £6.99 economy delivery price tag.
Regards and a merry Xmas, Johnny B Good
--- End quote ---
I'm going to have to read through all your ramblings on the F***Tech. It's both entertaining and educational. But you still didn't give a reason for your denigration of the JDS.
Still, it's a great pleasure to encounter someone who both knows what they are writing about and writes well. My BA is in literature, so I have done a lot of reading.
If I didn't have an Instek GDS-2027E sitting open on my bench while I try to sort the JTAG and TTY port I'd have the F***Tech open and follow along.
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