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Teardown: GW Instek SFG-2110 Function Generator.

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Kibi:
I was after a function generator the other day. I looked in the usual places, RS, Farnell etc. but I wanted one right away. A quick Google search revealed a supplier about a kilometer away from my house. Nice.

I walked in and made some enquiries. The company does consulting and sells test equipment online, they were really not geared up for "walk-in" customers. They were however, extremely helpful and I walked out with a good function generator at a lower price than RS. Awesome.

I took the lid off to take a few quick pictures before putting it to work.







I like this thing, it's easy to use and does just what I want it to do. 10MHz is plenty of bandwidth for me for now.
I have measured the output witch my Fluke 287 and the selected frequency reads spot on with the Fluke up to about 175KHz before the Fluke's bandwidth is exceeded at 181KHz and then totally stops measuring.
When I've got a moment I'll post pictures of the output on the 'scope.

Kibi:
OK, so I have taken some screenshots of the output of the SFG-2110 at different frequencies. I started at 1KHz and worked up to 10MHz.

Sine wave output.

1KHz




10KHz




100KHz




1MHz - Some attenuation starts creeping in.




10MHz - Noticeably attenuated with noise. Although the shape of the waveform is reasonably faithful.




Triangle wave output

1KHz




10KHz




100KHz




1MHz - Distortion at the peaks. Also, the party stops here for the triangle waveform on this device.




Now, for the Square Wave

1KHz




10KHz - Not too bad so far.




100KHz - Distortion is more noticeable now.




1MHz - It's going wrong.




10MHz - Oh shit. That's supposed to be a square wave!



All of the above measurements were taken out of the the main output terminal of the generator.

However, the square wave is much better on the TTL output as below.

1MHz - TTL Output




10MHz - TTL Output.




Overall though, I am very impressed with this unit. One shouldn't really be using equipment at the very limit of it's capabilities, so the distortion at the upper end of the spectrum is really not a problem and should actually be expected.
I think the SFG-2100 range represents really good value.

alm:
Does terminating it into 50 ohm improve the square wave? I'm surprised they spec the square wave up to 10 MHz if the output is so bad. It looks like it will barely meet its <= 25 ns rise time spec.

SeanB:
Nice buy! There is a little jitter at the top, probably expected. Most of the time it will be used at the lower end so no problems, and you are aware of it anyway.

Looking at the output it was done with a 10x probe direct to the socket, with a very short lead length.

I take it you are not living in Bob's lovely handbasket, but are another expat living in the UK.

Kibi:
I used a 50 Ohm terminator and it made no difference with or without it.


--- Quote from: SeanB on April 08, 2012, 08:13:00 pm ---I take it you are not living in Bob's lovely handbasket, but are another expat living in the UK.

--- End quote ---

Ja, I've been living in the UK for 14 years now. I went back to Zim at New Year, it was nice to go there on holiday, but I wouldn't live there any time soon.
Where abouts in SA are you from?

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