Products > Test Equipment
FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
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battlecoder:

--- Quote from: aneevuser on July 16, 2019, 07:44:59 pm ---
--- Quote from: FuzzyOtter on July 16, 2019, 07:31:09 pm ---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.
--- End quote ---
It's coming from the unit: I've attached an image of the same setup but with the FY6800 switched off at the mains.


--- Quote ---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.

--- End quote ---
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.

--- End quote ---

I tried with my unit and the freerunning waveform shows some peaks of around 30mV. That goes down to around 14mV with 20MHz BW limit.
If I trigger on the spikes, and zoom into the periodic "noise", I'm getting a 10mV, 6-7Khz nonsense.
beanflying:
Just how are you getting the signal from the Feeltech into your Rigol? It matters!

Some time ago I built a BNC - Probe adapter (can also be brought online) https://www.eevblog.com/forum/beginners/o-scope-probe-to-bnc-adaptor-(dave-uses-on-in-642)-where-to-findbuy/msg2287812/#msg2287812

Fixes a bunch of induced noise source issues compared to incorrectly terminated scope inputs.


Have a trawl through this youtube search too https://www.youtube.com/results?search_query=oscilloscope+termination
radiolistener:

--- Quote from: aneevuser on July 16, 2019, 07:21:36 pm ---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?

--- End quote ---

I read that other users also have experienced with such noise from switching power supply. It may leak through ground wire, so it may be  hard to get rid of it. I think the only way is to replace it with linear power supply, but it will require better ventilation in order to cool down power supply.
aneevuser:

--- Quote from: beanflying on July 17, 2019, 01:43:35 am ---Just how are you getting the signal from the Feeltech into your Rigol? It matters!

--- End quote ---
I'm not sure how that is relevant to my problem, though.

I'm typically taking the signal to a breadboard with the BNC-croc clip cable provided with the FY6800. However, the noise that I see is present at the BNC connector on the device itself; it's not radiated noise that is picked up by the cable. So I can't see how any different cable would improve the situation (unless there's some kind of fancy filtering on it, and I don't think that you're suggesting that?). Maybe I'm misunderstanding you though.

Anyway, the figure posted earlier by battlecoder suggests that this noise is not untypical, so I guess I'll have to live with it, unless I can figure out how to replace the power supply.
aneevuser:

--- Quote from: battlecoder on July 17, 2019, 01:33:59 am ---I tried with my unit and the freerunning waveform shows some peaks of around 30mV. That goes down to around 14mV with 20MHz BW limit.
--- End quote ---

Thanks. Not different from what I see. I guess that it's a design problem, rather than a one off quirk of my unit.


--- Quote ---If I trigger on the spikes, and zoom into the periodic "noise", I'm getting a 10mV, 6-7Khz nonsense.

--- End quote ---
Not sure what you mean here - what's the "nonsense"?
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