#129 

Back so soon! :) Another excellent video. I'm thinking of getting myself one of those from your previous video, but having seen this, i think i'll go for the MAX one as it'll suit my needs better. The USB spectrum analyser is also a good piece of kit, as you reviewed it previously and could do with one now and then, so may treat myself to one of those too :) I may even put the signal generator in a box and put the analyser inside that too and have them as a rack unit, as im not too keen on PCB kit, so it will sit on top of another piece of test equipment. Happy 2021!

The increased noise and spikes is just because it is sweeping faster. If you set it to sweep the same slow speed as the other it will look about the same. The 'noise' is because neither of them does a real frequency sweep but increases the frequency in steps, which in itself creates all sorts of sidebands and spuria. On top of that the transition between one frequency step and another is quite chaotic (in both versions) . Apart from the gap between the end of one frequency and the start of the other there's quite a lot of stuff going on, I think it is partly because the PLL goes out of lock and takes some time to lock to the new frequency. If you are sweeping slowly this chaotic period is only a very small proportion of the time. However as you make the sweep faster and faster the chaotic part remains the same duration while the useful part is getting shorter and shorter, so at the fastest speed almost half the time is spent in the chaotic state between one frequency step and the next.

With regards to the transition between square and sine there is not actually one. It is square throughout the whole range. What you are seeing as a transition from sine to square is just the bandwidth limitation of the oscilloscope which limits the harmonics thus rounding the square wave. Keep in mind that the first significant harmonic is the third, which means that at 150MHz the first frequency component that contributes the squareness is 450MHz which is well beyond the bandwidth of the oscilloscope and will be highly attenuated. Observing on a 1GHz oscilloscope even at 500 MHz it looks more like a poor square wave than anything resembling a sinewave. At about 650MHz it is something between a square and a sine not really any one of the two, though again this is a limitation of the scope not the output actually becoming a sine. At about 1GHz it is indistinguisahable from a sine to the untrained eye but in FFT I still see the presence of a third harmonic, even if much attenuated. Keep in mind that below 3000MHz the output is not from the oscillator but from digital frequency dividers which can of course only produce square waves. This device should not really be considered an RF signal generator and using it as such can lead to unexpected results unless one applies filters to its output to suppress the harmonics. It is more of a digital clock generator.

Thanks for sharing this video and the PLZ-PLL-MAX doc and sw. You're a real lifesaver. Seems the MCLK is internal reference clock. Whatever it measures (mine was 26MHz) is what you need to configure the REF Clock for otherwise the output frequency will be wrong.

Tony have you played with the 6GHz version of this? I have some amazon vouchers to use and thinking of getting one.

Hello Tony, to your experience, which one was generally more accurate in timing (Fq counts)? MAX2870, ADF4350 or 4351?

Would be good if you can set your spectrum analyzer span to 1mhz and compare the two units for phase noise

Hello Tony one curiosity if take off the power the last memorized freguncy stay on place? or reset automaticaly? I apreciate one comment abaut this board.Regards.

Thank you for comparing these two devices - great video. Could I have a link to the software plz?

The fact that it is not looking like a square may be the bandwidth of the oscilloscope, not the generator. You need to have a bandwidth at lest five times (or more) greater than your square wave to see it.

Thank you for your work. It was very intresting video.

I just got the MAX2870. Not sure I understand the whole "waveform" setting. It never lets me change it. When I first got it, it says "Sine/Square". After using it a bit, it now says "Square" and is permanently stuck there. Changing frequency or power cycling doesn't do anything. Either way, I think it's just driving fast edges, so everything looks square until you approach the bandwidth of your equipment/interconnects. Wondering if I can have more control talking to it over USB. Is it a simple serial connection?

This is really interesting. I have a different version of the ADF4351 that has an adjustable sweep speed as well as step, in uS increments for the step. Now I have to add the MAX generator to my wish list, to get up to 6GHz. As far as the noise goes, with the sweep, I'm wondering if it could be one of two things. First, maybe the processor square clock harmonics are mixing with the generated signal. I say that because I'd expect the processor to have to send a bunch of commands to the generator during a sweep, where it wouldn't on a fixed frequency output. Second, I'm wondering if the sweep could be somehow aliasing with the internal sweep of the spectrum analyzer? I don't know how to check the former easily, unless you were to separate the boards and put a bunch of ferrite on the lines, but for the second, if changing the spectrum analyzer sweep speed changes the noise, it might be some sort of artifact. Either way, very interesting stuff, thank you for posting these.

The Sine / Square section just tests your 'scope, not the signal generator. You need at least a 500MHz 'scope to properly show a 100MHz squarewave.

Hello back after this nice video 2 years ago ! I noticed there is a new version of this 2870 signal generator with a modified menu. In the description on aliexpress, the field for entering the reference frequency seems to be missing. There is a new button labeled "gear" that i don't know what it is for. Does anybody here have information? It might also be possible to change the reference frequency by the software, but i wonder if this is maintained after power cycling.

A 200 MHz scope cannot display a 200 MHz square wave. We should expect it to begin to look like a sine wave long before 200 MHz and pretty much a perfect sine wave by about maybe 250 MHz. Not saying the generator is still producing a square wave, just saying that you can't know with that scope. Nice scope BTW. I have the 4ch version and love it.

Hi Tony, any chance you could do a video on creating a Two Tone SSB test (27mhz SSB CB radio) with either one of these units to feed into a radios microphone?? Aparently you have to make a little summing circuit to mix the 2 channels.. I think a lot of people would lile to see this. Thanks in advance.

I'm currently working on programming a ADF6106 that can also get up to 6Ghz.

I did test it and it does indeed do 5.9GHz ( I have industrial oscilloscope but it works best with a microwave amplifier* PLEASE DO NOT try to amplify at home you WILL burn your routers ( wifi ) trust me 20Db 6GHz amp => 24dbm in total( your microwave oven is 20DB wich is quite powerful ( enough to warrent a non ionizing radiation sticker) ( but anything above 3GHz( without ext clock) is sin wave) and Max chips are meant for industrial app vs the adf is easy to knock off

Hi Tony. I got one of these boards with the small olead display and goes 23mhz to 6ghz. Its the Max 2870 version. Its got a 100mhz oscillator on the board and no external reference input. I'm wondering if using the software can I change that to 10mhz ? and will it stay at 10mhz after that? I would like to make it an external 10ghz ref. Also were do you get the software from? At the moment its not very good as its 25khz of freq at 1 ghz and it drifts around a lot..

Hey Tony, can use one of them for wireless data transmission. It is kind of urgent.

@Tony Albus Hello. From this video a saw that board generate square signal . Could you switch signal to sine on board and generate sine on 30, 50 or 100 MHz ?

Hi, in this device ADF4351 is the possibility to update the firmware ?? THANKS FOR THE REPLY

Tony thank you for your review, can you upload the app I bought the same unit, and I can't happen to find the application. If you can upload to google drive. Thank you , from argentina

How would one use one of these transmitters for there own project? Could you use this with a raspberry pi and how would you?

Its possible to change the ADF chip with the maxim IC without change the firmware ,i think the maxim have other commands, you have a link for flash the maxim firmware in to the mcu for use with touchscreen thx

The PLL filter components are different values with this new chip

Is the second port a reference frequency in? Does it accept 10M?

Hello, I'm misael from the Sumatran Institute of Technology doing my final project on the gsm signal jammer and I have a problem with how to connect the RF signal generator MAX2870 to ESP32? can you help me?

Can these generators be used to produce a carriersignal ?

Hi I need to generate a sweep signal from 50 to 70MHz. But i want to achieve this sweep in 10u sec. Is it possible?

Can I attach an antenna or to RF amplifier and it became RF transmitter?

Hi Tony. The legend has it frequency 150MHz is exeptionally good for human health. How to beam this frequency (to benefit)? Does it take a special antenna?

Hello，I am a Student .Can this MAX2870 frequency step reach 1KHz? How to determine the values of the resistors and capacitors of the loop filter above.

The RF stuff is interesting

what software are you using onm the screen I need this thing to have precision of 1 hz not 10khz

Hi Tony, could you tell me the supply voltage to Nihon Dempa SC00001 4HMz TCXO please. Best regards Rohitha

Hi I am new in RF i want to Build band 860 -970MHz can you provide me the code for MAX2870 Board i shall be very thank ful

Hi, in this device ADF4351 is the possibility to update the firmware ?? THANKS FOR THE REPLY