FeelElec FY6900 Function Generator Review and making use of the VCO function - #047

#047
FeelElec FY6900 Function Generator

A long term review and detailed explanation of using the VCO (Voltage Controlled Oscillator) function.

Other videos featuring this instrument here:-
SDG Electronics Review

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[manisteve]

I like you didn’t replicate the same information capably presented by other reviewers. Your impressions of the usefulness and operational characteristics from your chair are most valuable to me. As a hobbyist, and new one at that, I don’t have much of a budget for “nice to have” but not essential kit. I appreciate your frank comments as what to expect from this unit.
I enjoy your video work and find them interesting and educational. Thanks for taking your time to produce.

[sneugler]

I’ve had mine for around a year now, it’s pretty great other than the lack of a power switch on the front panel. I’m not a fan of devices that “sleep” as does this, being used to older stuff that might decide to burst into flames in the middle of the night. I mainly use it as an RF generator for aligning AM radios, and it accomplishes that task very well.

[fredsmith]

I found using the VCO with a cable from Ch 2 was messy and not accurate. From what I've seen, the response of the VCO isn't quite linear and mine had to be pushed slightly over 5 volts with the ramp to reach the end frequency. The offset was also slightly off.

The best way was to use the FM modulation function, using Ch 2 as the modulating signal. I used it with a slow five step ramp and a frequency meter to check it worked, and it was pretty much spot on. There's also far less messing about. The falling edge of the ramp can be used as a trigger for a scope or you could use the ramp to drive the X axis in X-Y mode on the scope.

They produced a very sophisticated sweep feature with all sorts of options, but didn't add a sync pulse. At least I've not found any way of picking up a sync pulse in sweep mode. It's a bit like making a fantastic car, but not including a steering wheel.

[JohnStewart-fswz]

To reach the same functionality you can use the modulation of the fy6900. Only the freqence setup is slightly different. It can be set the middle freqency und a span. Its useful to find the center frequency of filters. The sweep rate configuration is simular to your setup, means CH2 ist set to ramp of 5V.
The benefit of this methode you need no Connection between CH2 and the VCO input.

Greetings

[holgerk.]

thank you. I power up my fy6900 almost ever over the usb port - that works perfect. The ratio between price and usability ist very, very good and i think for hobby and educational purposes it is a nice product.

[barbsblogs]

I’m thinking of purchasing one of these, but can I ask it is capable of outputting a 455khz tone mod at say 30%. So you can align IF stages of a transistor radio ie Roberts rambler ?

[German_byte]

Another great video Bill.
Is it possible to get a 455KHz signal modulated with say 400Hz or 2500 Hz out of this unit?
If I set Channel 1 to 455KHz and then press mod, the modulation is fixed to channel 2
I’m confused.

[dist]

Thanks for this interesting video. I too have a FY6900.

I have a question about impedance matching. If I'm not mistaken, the FY6900 has an output impedance of 50 Ohms. Did you set the input impedance of your Hantek scope to 50 Ohms too? Because I'm not seeing 50 Ohms terminators in your setup. Or are the frequencies you are using so low that impedance matching is not an issue?

Thanks for the videos! I'm subscribed :-)

[meoztekin]

do you recommend for a student and hobbyist man? Thank you good video.

[youtuuba]

"Bode plots" are mentioned a few times in this video, pronounced with a silent 'e'. However, the correct pronunciation is the way their inventor, Hendrik Bode, said his name, as "boh-dee".

[seantonnesen]

Can this generator output an AM modulated signal, say 600Khz w/ 1Khz Mod?

[walterwinnipeg]

I haven't purchased one of these FY6900 units yet, but I am VERY close. Some interesting ideas for doing frequency sweeps for filter and Bode plot measurements. The FM modulation idea from fredsmith5473 looks promising. I was wondering about another idea...
Let's say you set up a sweep on channel 1, for 10kHz to 100kHz, with a sweep rate of once per second. Then, on channel 2, you set up a square wave, with 1 Hz frequency. If you display both on a scope (triggering on the square wave), how will they appear relative to each each other? Will they drift relative to one another? Will they stay locked? Will the edges of the square wave be at some arbitrary position relative to the channel 1 frequency-sweep? If they drift, could you very slightly adjust the 1Hz square wave frequency so that the two waveforms stay in more-or-less sync? (Kind of like manually adjusting the time base on an old scope with no trigger. :-) )

[akontecetks]

I had my one going for calibration and I had it at Hz and now it’s at MHz and I don’t know how to change the frequency to go back to hertz damn. Anyone can help?

[victorkustov]

Why do you need so many different devices? Are you a collector?