FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator

[Johnny B Good]

You are assuming the big fat Earth pin is connected inside the box   

Has anyone managed to get hold of an FY6900 to check this out yet?

AFAIK, they're still only pre-booking orders.

 I thought this was the case but I wasn't sure so I posed the question anyway.   

JBG

[Johnny B Good]

Hello, new here to this forum.  I had just purchased an FY6800-60M and ended up returning it.  The DC offset was over 35mV when set to 0.  There was a lot of jitter in frequencies above 20 MHz or so.  Amplitudes were way off into a 50 ohm load; there was considerable distortion in the output into a 10 k load.  Square waves started to look more and more like sine waves as frequencies got past 15 MHz.  Etc. Etc. Etc.   I haven't read all the posts in this thread yet, so I don't know if any of these problems have been experienced by others, but I am curious to know what others have found in actual use, i.e. tied to a real circuit and not just an o'scope.  Any input will be appreciated.

 Others have already mentioned the jitter and rounded square waves issues so I'll only address the issue of "DC offset error". I've put this in quotes because there's every chance that Feeltech introduced the problem when they upgraded the mains socket to a 3 pole earthed one to address the howls of rage over the half mains live voltage leakage with the FY6600 inevitable with any class II smpsu, courtesy of the 1nF EMC bodge capacitor mandated by EEC regulations, and made the skoolboy howler of hard linking the ground rail to the protective earth instead of using it to suppress the 100 or so volts of 'touch voltage' when powered off a UK/European 240/220 volt supply.

 If they'd inserted a 1K to 10K "drain" resistor between chassis ground and the protective earth tag on the mains socket to load down the touch voltage to either 50mV (1KR) or 500mV (10KR) with such a 'static drain resistor', this would have neatly  attenuated such external galvanic and/or thermo-couple generated DC offset voltages via the unfortunate effect of the mains earthing ground loop circuit whilst attenuating such unwanted effects by some 60 or 80dB, allowing you to actually see the millivolt or so of DC offset produced by the FY6800 itself.

 It's a pity you didn't discover this thread before going to the trouble of shipping your FY6800 back to the vendor. You may have saved yourself the trouble as a previous contributor did some months back when he followed our advice to test with the safety earth disconnected and discovered the true source of his high "DC voltage offset" problem.

[Edit]  Found the relevant post here:

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2202948/#msg2202948

JBG

[GerryR]

Thank you for finding that; a very interesting read.  With all the free engineering that has been done here for FeelTech, maybe the YF6900 will not have these same issues! 

[Johnny B Good]

Thank you for finding that; a very interesting read.  With all the free engineering that has been done here for FeelTech, maybe the YF6900 will not have these same issues! 

 It's just possible but looking at the way they implemented the C14 switched socket upgrade on the FY6800, I rather doubt it. In view of my observations on the changes to the Pk - Pk voltage limits shown in the 6900's manual, I'd rather take my chances with a 6800 where I know I won't be swindled out of a 20Vpp capability that goes up to 20MHz rather than with a 6900 model which may or may not suffer from the same (very fixable) ground loop issue but be swindled on the Pk -Pk capabilities in the 10 to 20MHz range (extremely unfixable).

 The rather questionable (have they upgraded the PSU board to one with +/-15v voltage rails?) 24Vpp rating (who would benefit from that?) in the DC to 5MHz range is just a marketing exercise imho to distract their customers from the more serious limitations they've now imposed to disguise the shortcomings of their over-stock of the very shite THS3002i dual opamps they're seemingly determined to use up come Hell or High Water.

 TBH, that downgrade on Pk to Pk voltage capability is such a detriment that even the original FY6600 would be a much better bet as a "Fixer Upper". There, at least, all the shortcomings are fixable. When the 20Vpp frequency range goes up to 20MHz, an opamp upgrade is well worth the effort but when it falls woefully short at just 10MHz, there's very little point in attempting such a marginal improvement. As I said, it looks like they've elected to downgrade the spec rather than upgrade the opamps. What's the betting that this new 6900 abomination will also sport an 85 ohm attenuator to serve the 0 to 500mV output range? 

[EDIT]

 When it comes to the voltage output specifications published in the two FY6600 manuals and the single FY6800 manual, Feeltech (Feelelec) appear to have perpetrated a mistake since they all quote exactly the same levels and frequency limits (excluding the FY6900's 24Vpp upgrade in the 0 to 5MHz frequency range), despite the truth being a 20Vpp limit extending all the way from 0 to 20MHz for the sine and square wave forms at least.

 In this case, the manuals can't be relied on as authoritative guides to their performance and this might well (probably does) apply to the FY6900 as well. Obviously, we won't know until someone finally manages to acquire an FY6900 to test the actual frequency limits that apply to the 20Vpp setting and report their findings here or the other FY6900 thread that was started just two days ago.

 https://www.eevblog.com/forum/testgear/fy6800-vs-fy6900/msg2521413/#msg2521413

JBG

[Johnny B Good]

The only differences I see are the increased max Vp-p of 24V and the elimination of the 100uV step in the amplitude setting.  I guess we'll wait for a teardown to see what they've done for the power supply this time--but I'm not expecting much!  Meanwhile, the prices of the FY6600-60MHz have hit $40 on eBay, so if you like the idea of multiple synced units, now is the time to pick some up.

 If you ignore the rather questionable 24Vpp "upgrade" for the DC to 5MHz range, it basically amounts to a downgrade on the FY6600, let alone the FY6800 (which is basically just an FY6600 with a C14 switched socket and a revamped front panel with nicer to touch buttons - most likely still using the same SMD momentary action switches underneath though, but at least they can be replaced if any get worn out).

 The 24Vpp rating does suggest the possibility that the PSU board now sports +/-"15v" rails as opposed to the +/-"12 volt" (+/-11.7 volt actual) rails of the earlier models. However, that rather flies in the face of the claim of 5 watts or less consumption when the previous models typically consumed some 7 or 8 watts (un modified) against the previous 10W maximum claim. Does anyone get the feeling that their "Marketing Department" is doing what all marketing departments do as a matter of routine, which is making up their own figures without regard to actual test measurement data? 

 Anyhow, regarding your mention of those forty dollar FY6600s on Ebay, I was intrigued enough to investigate what was on offer for myself. I did check out the prices on the FY6800s btw, before placing an order just half an hour ago on a FY6600-60M from Hong Kong for a mere £40.41p (just over half of the £75.66p I'd paid for my now much modded unit some seven months ago).

 I didn't fancy paying a 30 quid premium just to get a slightly nicer revamped front panel and a big butch switched C14 socket on what is essentially still an FY6600 inside. Besides which, it's a case of "Better the Devil you know." and it makes for a very cheap "Spare". The only concern with these "last available FY6600s" being whether they're unsold stock of all those models which had been afflicted by the version 3.0 firmware bug. Hopefully not but I should be able to determine that in some two to three week's time. 

JBG

[vince53]

I was fortunate to be able to retire a few years ago and one of the first missions was to set up a basic electronics bench for playing with radio control planes and amateur radio.  It didn't take long before I missed the resources and expertise I had enjoyed for decades, test equipment, metrology lab, machine and sheet metal shop.  One purchase was an old 5MHz function/ sweep generator.

I used it to align some AM radios but now I wanted to align the 10.7MHz IF sections.

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.

I'm testing and hear a high pitched squeal.  The LM337T failed and blew out one of the new op amps.  I reinstalled the original op amp .  Currently running off a bench supply with the board sitting an a cardboard box.

It appears to work like new.  So I'm back to playing with the sweep.  For now, it's not raining so outside I go.

It's been a pleasure to read all of this thread.  KC8AAC

[bdunham7]

 Anyhow, regarding your mention of those forty dollar FY6600s on Ebay, I was intrigued enough to investigate what was on offer for myself. I did check out the prices on the FY6800s btw, before placing an order just half an hour ago on a FY6600-60M from Hong Kong for a mere £40.41p (just over half of the £75.66p I'd paid for my now much modded unit some seven months ago).

 I didn't fancy paying a 30 quid premium just to get a slightly nicer revamped front panel and a big butch switched C14 socket on what is essentially still an FY6600 inside. Besides which, it's a case of "Better the Devil you know." and it makes for a very cheap "Spare". The only concern with these "last available FY6600s" being whether they're unsold stock of all those models which had been afflicted by the version 3.0 firmware bug. Hopefully not but I should be able to determine that in some two to three week's time. 

JBG

I agree that it looks like the original FY6600 with the latest firmware is the best option at this point--unless a teardown of the FY6900 reveals a new level of excellence.  I actually ordered two with the cheapest-option AU plug since I plan on converting them to  US/C5-C6 and adding a 10K resistor to the existing Y-cap and running it to ground.  Then I'll see how it works and if my EMI and noise is acceptable.  I have a use case for two--or three--using either the sync feature or using one to control the other thru the VCO port.  I paid a total of US$84.86 for two, shipped, so I can't imagine a better deal.  I can live with the output limitations--20Vp-p at 20MHz (let alone 60) is pretty hard to do with an inexpensive op amp.  And this thing has two channels!  I'd like to see a comparison with more expensive DDS AWG models--I've seen some at over 10X the price that don't seem to do as well as the lowly (and now dirt cheap) FY6600. If I need more power I'll get or make an amplifier.

[bdunham7]

I used it to align some AM radios but now I wanted to align the 10.7MHz IF sections.

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.

I also want to repair/restore/adjust/align/fiddle with some FM receivers.  I'd be interested how you make out.  Is it necessary to have such high outputs that new power supplies, op-amps, etc are needed? 
Also, I'm trying to synthesize a usable FM multiplex stereo test signal.  I have an RF signal generator with an FM function, but the multiplex signal is complex and I'm still trying to figure out the best way to do it.  Any ideas?

[Johnny B Good]

====snip====

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.

I'm testing and hear a high pitched squeal.  The LM337T failed and blew out one of the new op amps.  I reinstalled the original op amp .  Currently running off a bench supply with the board sitting an a cardboard box.

It appears to work like new.  So I'm back to playing with the sweep.  For now, it's not raining so outside I go.

It's been a pleasure to read all of this thread.  KC8AAC

 I'm sorry to hear of your misfortune with the blown supply and one deceased opamp. Those analogue regulators are supposed to have over-current/temperature protection to prevent such disasters. Did you install a cooling fan btw. Most (possibly all) of the previous PSU modders took the precaution of fitting a fan once they realised just how hot these generators were getting even before having the extra thermal loading from an analogue PSU upgrade imposed upon them.

 Indeed, I'll be fitting a 50mm cooling fan to my 40 quid prize once I've allowed a few months of "hard use" to prove it isn't harbouring any "Infant Mortality" failure mechanisms. I don't want to risk invalidating the warranty or the Ebay money back guarantee too soon like I did with the first one. A cooling fan mod should take priority over any other mods you might be contemplating imo.

JBG

[Andbro]

Hi,

If the 6600 to 6900 are not good. Do you have any suggestions???

Thanks

[GerryR]

Personally, I didn't think that the 6800 that I had purchased wasn't worth much past 20-to-25 MHz (As mentioned above, I ended up returning it.).  I found a descent BK Precision 4045B (20 MHz unit) on ebay for a few dollars more than the 6800.  It doesn't have all features claimed by the 6800, but what it does have works!  I must admit that I am a little bit funny about my test equipment; if something doesn't perform to the mfg's spec, I lose confidence in the whole instrument.  It's OK to make a hobby project out of an instrument, but .....
I had an HP34401A multimeter that I paid $1100.00 for about 18 years ago.  While working on a project, I found that it couldn't measure the DC offset of a sine wave.  My cheapo hand-held meters could make the measurement, but this fancy piece of gear couldn't!  The people at HP (now Keysight) said it was a "quirk" that I ran into, and I should just trade it in on something newer.  Lost all trust in the meter...Up for sale!

[bdunham7]

Hi,

If the 6600 to 6900 are not good. Do you have any suggestions???

Thanks

I think the best choices are:

A.  Buy a 6600 and use it in the grounded configuration and don't expect more than 10Vp-p output.

B.  Buy a 6600 and modify it if you absolutely need floating configuration.

C.  Spend a LOT more money and maybe get something that really isn't any better.

These are not precision function or pulse generators or low distortion audio signal generators, they are versatile and useful Arbitrary Waveform Generators.  They are very handy for a wide variety of things.  There may be a few bugs, quirks, anomalies or shortcomings, but I've seen equipment that costs 1000X as much have just as many issues.

[bdunham7]

Personally, I didn't think that the 6800 that I had purchased wasn't worth much past 20-to-25 MHz (As mentioned above, I ended up returning it.).  I found a descent BK Precision 4045B (20 MHz unit) on ebay for a few dollars more than the 6800.  It doesn't have all features claimed by the 6800, but what it does have works!  I must admit that I am a little bit funny about my test equipment; if something doesn't perform to the mfg's spec, I lose confidence in the whole instrument.  It's OK to make a hobby project out of an instrument, but .....
I had an HP34401A multimeter that I paid $1100.00 for about 18 years ago.  While working on a project, I found that it couldn't measure the DC offset of a sine wave.  My cheapo hand-held meters could make the measurement, but this fancy piece of gear couldn't!  The people at HP (now Keysight) said it was a "quirk" that I ran into, and I should just trade it in on something newer.  Lost all trust in the meter...Up for sale!

I saw the 4045Bs on eBay, that is a lot off the new price for a 'current' unit.  But how does the square wave actually look??  They list a 20ns rise time, which is more than 3x worse than the FY6600.

[GerryR]

I saw the 4045Bs on eBay, that is a lot off the new price for a 'current' unit.  But how does the square wave actually look??  They list a 20ns rise time, which is more than 3x worse than the FY6600.

My Rigol DS1102D shows the rise and fall times to be about 13 ns;  Square wave looks good to about 15MHz and gets very "siney" after that, though rise and fall times remain around 13 ns out to 20 MHz.  The 6800 square wave got  looking like a sine wave around 15 MHz, as well.  Everything I've checked on the 4045B, so far, is dead on.  Good price from one seller on ebay ($124.95 shipped) and the unit I received looks new.

[bdunham7]

My Rigol DS1102D shows the rise and fall times to be about 13 ns;  Square wave looks good to about 15MHz and gets very "siney" after that, though rise and fall times remain around 13 ns out to 20 MHz.  The 6800 square wave got  looking like a sine wave around 15 MHz, as well.  Everything I've checked on the 4045B, so far, is dead on.  Good price from one seller on ebay ($124.95 shipped) and the unit I received looks new.

My FY6600 gives me 8 ns or so and still looks pretty square.  Perhaps your FY6800 underperformed--or how did you connect it?  I have a 50cm RG316/BNC cable direct from AWG to DSO.

However, there is a jitter issue with high frequency square waves with a period that is not a multiple of 4 ns!  See second photo.  I think this is just an unavoidable result of a 250 MSa/s DDS.  If you need a precise, low jitter square wave, this limitation would be significant.

Does the BK unit appear to not have this issue?  It only has 50 MSa/s, so if it can produce a reasonable 9.999999 MHz square wave, then is must not be using the DDS for the basic sine/square/triangle/ramp functions.   

[GerryR]

The Spec sheet says the following:

"The true arbitrary waveform section generates point by point waveforms with lower jitter, high
resolution, and true representation of the required waveform."
"Due to the arbitrary waveform capability of the 4045B, the instrument is able to generate low-jitter square waves with greater edge
stability. The improved signal integrity allows these generators to be used for simulating reliable clock signals, generating triggers, or
validating serial data buses."

I haven't been inside it yet to see what is going on, but I don't see any jitter on through 20 MHZ, unlike the 6800, and the jitter I saw on the 6800 got really bad at the higher frequencies.  I may have gotten a poor unit, but it did have the 1.7.1 firmware.

[bdunham7]

So to answer my own question, it appears the BK 4045B uses a 50MSa/s DDS for "general" AWG duty and a "True AWG" with a variable clock (probably up to 50 MHz) for the advertised low-jitter sine/square/triangle/ramp functions.  I might just "need" one.  BK Precision does have some nice stuff if you can get it cheap enough. 

https://bkpmedia.s3.amazonaws.com/downloads/datasheets/en-us/4045B_datasheet.pdf

https://www.tegam.com/wp-content/uploads/2015/10/AN4011.pdf
 

[bdunham7]

I haven't been inside it yet to see what is going on, but I don't see any jitter on through 20 MHZ, unlike the 6800, and the jitter I saw on the 6800 got really bad at the higher frequencies.  I may have gotten a poor unit, but it did have the 1.7.1 firmware.

Were you looking at sine or square waves?  Square waves (and others) will have the jitter I described just because of the way DDS works, but on mine the sine waves are rock steady.

[GerryR]

I'm talking about square waves; sine waves are clean, triangle waves show some distortion at higher amplitudes on the down slope(frequencies are fine).  I haven't done a full inspection of all it is supposed to do, but so far, it looks pretty clean.  I am going directly from the generator to the scope thru a 50 ohm terminator at the scope.  Oh, the DC offset, when set to "0," is about 1.35 mV, much better than the 35 mV of the 6800, which of course, there is a remedy for by some hacking.

At $125.00, you surely do need one! 

[vince53]

FM IF Sweep.

Getting this working was more about learning how my scope worked than my FY6800.
I produced these nice filled traces by using infinite persistence and adjusting the number of points.  I suspect other scopes may need to be adjusted differently.

First photo:  The purple trace is the generator output from channel #2, 1kHz sine wave with the amplitude at 6.2v and offset at 2.7v
Green trace: sweep of 10.2MHz to 11.2MHz using VCO mode with a cable from output #2 to VCO In at the back of the generator. 
Red trace:  FFT math function of green trace.

Second photo: Purple trace, input to VCO IN
Green trace: 1MHz wide sweep with the center at 10.7MHz.  The signal is fed through a Yaesu receiver prefilter.

Third photo: measurements for the control ramp.  DC coupling.  6.2v peak to peak, with 5.7 volts for the positive peak and and -0.57v for the negative peak.
The spec for the VCO In is 0-5vdc.  To get the full sweep I needed to start below 0vdc and ramp to about 5.3vdc.  This is consistent with an earlier post.  To get the full sweep I had to use 6.2v for the amplitude and 2.7v for the offset.  VCO IN maximum frequency is 500Hz but I had to go higher to get the trace on the scope.  Values may vary but it can be made to work.
1 Megohm input impedance of the scope was used. 

I couldn't figure out how to use the "Insert Image" tool so I'll try Attachments.

Vince KC8AAC

[Johnny B Good]

 Anyhow, regarding your mention of those forty dollar FY6600s on Ebay, I was intrigued enough to investigate what was on offer for myself. I did check out the prices on the FY6800s btw, before placing an order just half an hour ago on a FY6600-60M from Hong Kong for a mere £40.41p (just over half of the £75.66p I'd paid for my now much modded unit some seven months ago).

 I didn't fancy paying a 30 quid premium just to get a slightly nicer revamped front panel and a big butch switched C14 socket on what is essentially still an FY6600 inside. Besides which, it's a case of "Better the Devil you know." and it makes for a very cheap "Spare". The only concern with these "last available FY6600s" being whether they're unsold stock of all those models which had been afflicted by the version 3.0 firmware bug. Hopefully not but I should be able to determine that in some two to three week's time. 

JBG

I agree that it looks like the original FY6600 with the latest firmware is the best option at this point--unless a teardown of the FY6900 reveals a new level of excellence.  I actually ordered two with the cheapest-option AU plug since I plan on converting them to  US/C5-C6 and adding a 10K resistor to the existing Y-cap and running it to ground.  Then I'll see how it works and if my EMI and noise is acceptable.  I have a use case for two--or three--using either the sync feature or using one to control the other thru the VCO port.  I paid a total of US$84.86 for two, shipped, so I can't imagine a better deal.  I can live with the output limitations--20Vp-p at 20MHz (let alone 60) is pretty hard to do with an inexpensive op amp.  And this thing has two channels!  I'd like to see a comparison with more expensive DDS AWG models--I've seen some at over 10X the price that don't seem to do as well as the lowly (and now dirt cheap) FY6600. If I need more power I'll get or make an amplifier.

 Hi bdunham7,

 Apologies for the tardy response. I'm not sure how I overlooked your reply but, after reviewing the recent postings here, I realised my oversight hence this response.

 One thing that did catch my attention was your reference to attaching a 10KR to the Y cap. Presumably (just to be absolutely clear on this point), connecting the resistor between the protective earth pin on the C6 connector and the side of the Y cap going to the zero volt rail and the BNC grounds rather than across it. 

 The Hong Kong dealer I bought mine from was out of stock of the UK plug versions so, since the crappy UK plug with C8 lead was destined for the scrap bucket anyway, I chose the (no doubt equally crap) US option (sadly, no additional discount for this cheaper mains lead option).

 At an effective price of $42.43 each, you got an even better bargain than my own £40.41 'prize' which equates to a 49 dollar price tag (give or take a dollar or two). However, we Right Pondians have long since come to accept this disparity in pricing between the US and UK markets for 'foreign goods' so it still represented a massive reduction on the £75.66 I'd originally paid for the first one some seven months earlier.

 I had hoped to be able to report on the firmware loaded into my unit by now but it hasn't arrived yet, some two days after the latest of the estimated delivery dates. It looks like a cheap MESTEK 9999 Counts Digital Multimeter I ordered just four days ago is likely to arrive before the signal generator according to Yodel's tracking info[1] - there's no tracking option for the generator so its delivery is a matter of blind faith.  I guess I'll have to give it another week before I start pestering the seller/ebay over this delay.

 I have just one other ebay order in the pipeline race to my front door but that's just a 99p order for a pack of 10 SN74HC14Ns due to arrive by the 25th. Unbelievably, there's even a tracking number on this 99p order but ICBA checking the progress of a 99p package that will probably arrive before the ETA expires anyway and isn't holding up progress on any of my current projects (at least not yet!).

 Regarding whether the FY6900 actually shortchanges you on the 20Vpp in the 10 to 20MHz frequency range or not remains an open question since (apart from the 24Vpp claim for the FY6900), the same limitations are quoted in the manuals for the 6600 and 6800 models making the specifications published in the manuals rather suspect to say the least. We're not going to know the truth of the matter until someone finally gets hold of one to report actual test figures.

 As for the business of 24Vpp for the DC to 5MHz range, that appears to be an attempt at one-up-man-ship in the specifications battle. It seems to me a rather pointless distraction since, as you mentioned, this is nothing a linear amplifier couldn't address more effectively anyway if higher outputs are needed. The only thing about the 24Vpp figure, along with the extended +/-12v dc offset specification, is the implication that they've raised the PSU board's +/-12v rail voltages to +/-15v which may or may not be a good thing, depending on how they've achieved this.

 It seems rather doubtful that they've moved from a switching psu board to an analogue one if this is the case. The extra voltage will provide more margin but if they've simply rejigged the existing transformer windings to raise the voltage without using a beefier HV switching chip or adding a discrete HV switching transistor to take the load off the existing chip, this could all end up in 'Tears Before Bedtime' as far as the service life of the PSU board goes. I can't wait to see a competent tear down review video on this latest version of the FY6600 from Feeltech / Feelelec when it's eventually released to the market. 

[1] I just had another look at Yodel's tracking website and it's now, at long last, offering an ETA of Saturday the 6th (tomorrow) for that Mestek DMM so it looks like the result in the "Slow Boat From China" race as far as that FY6600 is concerned is going to be a draw at best. My money's on the Mestek winning this race but the possibility of a "dead heat"  for all three orders still remains intact, making this Saturday a little on the special side for me to look forward to. 

[EDIT]  The DMM arrived at 1pm but I'm still waiting on the cheap FY6600 and that pack of hex inverters.

JBG

[battlecoder]

Has anyone gotten the firmware update to work with PC Software version 6.0?
My FY6600 has firmware 3.1, PC Software says that the latest available firmware is 3.3, but when I click "update" it seems to download something but then it immediately throws the error "USB linkage fault".

[aneevuser]

I've attached an image of the signal that I get from my FY6800, channel 1, with the unit on, but with channel 1 disabled. There's noise at about 44 kHz of about 40 mV pp, which I'm guessing is from the SMPS.

My question is: is noise of this magnitude expected from this unit?

I'm finding that it's making it rather tricky to trigger on signals below about 100 mV reliably, but I'm too much of a noob to know if this is standard for a SMPS, or if I've got a dodgy device.

[FuzzyOtter]

I don't have one of these devices, but what does the scope show you with the unit powered off entirely? Is it the same, or does some/all of the measurement clean itself up? Just curious to know if it's actually coming from the unit, or if it's radiated from somewhere else.

You might try enabling the 20MHz bandwidth limit on the scope to knock some of the noise down if those spurs are giving you trouble with triggering.

[aneevuser]

I don't have one of these devices, but what does the scope show you with the unit powered off entirely? Is it the same, or does some/all of the measurement clean itself up? Just curious to know if it's actually coming from the unit, or if it's radiated from somewhere else.

It's coming from the unit: I've attached an image of the same setup but with the FY6800 switched off at the mains.

You might try enabling the 20MHz bandwidth limit on the scope to knock some of the noise down if those spurs are giving you trouble with triggering.

Yes, I've tried that but it doesn't really clean things up enough. I'm not sure if this is just something that I have to live with. It's a bit of pity if so, as the device itself can generate sub 10 mV signals, but they're swamped in the SMPS noise.