NanoVNA as a synthesized CW signal generator

Performance of a NanoVNA operated as a fully synthesized signal generator. Provides a very stable and accurate CW signal source for testing receivers, etc. Output level control will need an attenuator...

[@__--JY-Moe--__]

glad you're here, thanks for the video!

[@wd8dsb]

Great demo showing the amplitude versus frequency using your spectrum analyzer. The NanoVNA-F (V3.1) uses a TCXO (temperature controlled crystal oscillator) which makes the NanoVNA-F frequency very stable and pretty accurate with a published frequency accuracy spec of < 0.5ppm. With output frequency set at 10.000000 MHz my NanoVNA-F (V3.1) measured output frequency into a 50 ohm load was 9.999996 MHz (measured with a calibrated frequency counter traceable to NIST) and the square wave output into a 50 ohm load measured 2.6 dBm at 10 MHz (close to what you saw). I often use my NanoVNA-F as a portable signal generator out in the field for testing directional antenna patterns, it really is an amazing tool.

[@MegawattKS]

Thanks. I hadn't looked up the specs on the TCXO. Wow - 0.5ppm is awesome - and explains why it is within a few Hz of zero-beat on the FT817 tests. !

[@ebaystars]

I'm not into my current work on EMC/tempest protection yet, just setting up the basic lab but this thing is amazing for its price functionality and portability, (ive a tiny SA as well) amazing how kit has come on in the last 10 years, I expect sometime they may include an extenal clock source sync (for your rubidium or GPS) but whats the point the TXCOs of today are really cool :-)

[@acestudioscouk-Ace-G0ACE]

Really good information imparted here. Thank-you!

[@MegawattKS]

Glad it was helpful!

[@ebaystars]

Great video thanks, amazing for its price, I had to leave all my HP test gear back in UK when I retired to thailand now building an electroncis/radio lab and finding things have really come on in the last 10 years suits my limited EMC/EMI testing purposes a treat. One has to be careful of chinese copies especailly of the Tiny SAs, they do exist in large quantities consult all sites before buying your Tiny devices... But the way things are going between US and China you may find these things become banned and on the Munitions List !!!

[@felixcat4346]

Nice video. Thanks

[@acestudioscouk-Ace-G0ACE]

This is going to be useful. At present all my kit is packed away as I'm ripping out the old photographic darkroom from my studio which will eventually become my ham radio shack and electronics lab. I think my 2020 VNA will be very old kit by then but it will be good to learn on. If I accidentally kill it, it won't be as bad as writing off a new model. Thanks again for your help.

[@MegawattKS]

Thanks. With the NanoVNA out now (some going even to 6 GHz), things aren't as expensive as they once were :-) I actually bought two of the 'companion' "TinySA" spectrum analyzers, which include signal generation as well. I use one for that purpose. But the NanoVNA still works for higher power signal generation, as long as the squarewave isn't a problem and the frequency is low enough (< 300 MHz for my unit). Great to have both - for signal generation as well as their original purposes of network and spectrum analysis. Amazing how affordable stuff has become (for VHF and lower UHF work)...

[@Linas_LY2H]

A very informative video, thanks! (Subscribed!). I’ve just got a nanoVNA-F from Deepelec with the latest firmware on it and it’s got an even one more nice feature, like regulated RF output when used in CW mode. The menu allows to chose the +1dBm, -1dBm, -4dBm and -10dBm output levels. I wonder if this would allow for not using attenuator in at least some cases? I don’t have a spectrum analyser though and can’t check how accurate these levels are. I would like to use my VNA for the receiver testing on strong adjacent signal influence, what level of CW signal from the VNA ,in dbm, would be most close to the “real” strong signal on the air, you think? Thanks! 73! Linas LY2H

[@MegawattKS]

That's neat, and interesting. I wonder how they vary the level. Maybe the main synth chip in the unit has that ability itself. -10 dBm is still a _very_ strong signal. but such levels can occur in some situations. So it might give some information. That said, I doubt many receivers would be able to handle it without "blocking" the weak desired signal if the strong signal is close to the desired signal's frequency. If it's outside the bandwidth of the preselector in the receiver however, it should be able to deal with it. A case in point is in my area there is a super strong FM radio station in line-of-sight to our house. It shows as about -10 dBm on my SA and completely blocks the signal my wife wanted to receive (a quite weak PBS station about 10 MHz away) with most receivers. But I found one that was able to handle it, as it had a so-called tracking-preselect design. One other thought - you could invest in a few SMA attenuators. I bought a set including 1 dB, 2 dB, 3 dB, 6 dB, 10 dB, and 20 dB ones (giving ability to hit 1 to 40 dB in 1dB steps with some appropriate cascades) for about 40 dollars US. Or you might be able to find just one or two of these for maybe 10 dollars somewhere to get maybe 10, 20, and 30 dB options... 73

[@Linas_LY2H]

@@MegawattKS Thanks a lot for an advice! I will experiment with -10dBm in the begining to simulate a strong adjacent station but will also buy a bunch of SMA attenuators later. 73!

[@elioalcala4371]

Where & how much you país x it?

[@elioalcala4371]

You paid for it ? Thks

[@Linas_LY2H]

@@elioalcala4371 Hello, I bought it at Depelec store, I think on e-bay, but it is available on other platforms too, just google for Deepelec nanoVNA-F. It is important though to come accross the exactly Deepelec store, otherwise you can bump into one of numerous clones :). Good luck! Linas LY2H

[@glasslinger]

Very surprised that the output is square wave. I wonder how much this affects the various readings the nano makes. HP instruments put out a sine wave so no harmonics to add to the readings.

[@MegawattKS]

Interesting question. So far I have been very impressed with the unit - relative to the 8753's used at work. Architecturally, they seem to get away with using the squarewave because the mixing scheme places the mixing product from the fundamental around 5 kHz, but the product from the harmonic components of the squarewave is something like 15 kHz or more. So as long as the DSP filter is high-order (and ADC distortions don't creates spurious), it works well I think.

[@glasslinger]

@@MegawattKS I would think a signal at X3 or higher odd multiple would also produce the 5 khz. I'll find out when my unit FINALLY???? arrives. Been 4 weeks now.

[@elioalcala4371]

Very nice, I can see you have an original nanov with Sharp edge box! I am shopping for one but The makers were complaining about fake nanos all around and were talking about ,new versión over $150-?where did you got yours?

[@MegawattKS]

Thanks. I bought it from Amazon which has a number of different versions from many different "sellers". I mainly went for the one I got because it had a 4 inch screen and a metal case and the reviews on Amazon for that unit looked fine. It was pricey compared with the 54 buck ones, but compared to ones I used at work, it was still super cheap :-) I have noticed there are now 3 GHz versions available and have thought about getting one of those, but don't have a strong need at the moment. Some even have big N-type connectors - which frankly I don't want. I just put SMA male-female adapters (aka connector savers) on mine. Even that's not needed if one is careful. N connectors are fine for a benchtop unit, but I don't want them on a small portable like this that will see light to moderate use :-)

[@bat_bsvoriginal]

метод нулевых биений называется. я в 1996 году в училище еще проходил.

[@minazulkhan8287]

Can i use telescope antenna with nano vna and measure rf output with tinysa, wirelessly?

[@MegawattKS]

Technically yes. With an antenna on each unit, the TinySA will easily receive the NanoVNA's port 1 signal from a distance of a meter or more. BUT - legally, the NanoVNA is a bit too much signal level at some frequencies (it's about +2 dBm below 300 MHz), and it also has a squarewave output, so it throws harmonics out too. A better alternative is probably to have two TinySA units and set one to output mode to be a transmitter, with the output power adjusted to something low enough to not cause issues. Hope that helps.

[@HalfLife2Beta]

is the level the same for all frequencies? whats the accuracy of the power output level ? thx in advance

[@MegawattKS]

Its reasonably constant at about +2 dBm up through 300 MHz where the first harmonic is used. But note from the spectrums that its really a squarewave. The 2 dBm level is my estimate of the power in the first harmonic (the fundametal). The third and 5th are about 13 and 17 dB lower. As for accuracy - it's probably better than my spectrum analyzer since the squarewave is generated from a voltage-regulated supply rail. But it does fall off some as frequency goes up (and there's a huge jump of -13 dB when you go above 300 MHz as seen in the spectrums).

[@HalfLife2Beta]

@@MegawattKS ok so its not stable from Mhz to Ghz range. thats bummer.

[@MegawattKS]

@@HalfLife2Beta You might consider getting a TinySA. It's neat and it has a signal-generator mode in addition to spectrum analysis. And - it has some built-in attenuators to control output level over a limited range. (I haven't tested to see how accurate it is though)

[@ebaystars]

@@MegawattKS what does he expect for 50 bucks ???? and the video clearly and precisely states how it uses harmonics to get beyond 300MHz and the level change accordingly !

[@ijontichy6070]

Hi! a screwdriver as antenna of my Xiegu and my body as antenna in port 1 and done!

[@MegawattKS]

Interesting setup ;-) Do you have a TinySA too? I've switched to using the TinySA as a signal generator. It has built-in level control and AM and FM modulation modes. And there's an upgraded TinySA Ultra coming out this month. 73

[@ijontichy6070]

@@MegawattKS Hello! I have a standard NANO VNA ,na this device van generate only CW signal about +2 dBm.Your Tiny gives more:) good luck by 73!

[@mrgreenswelding2853]

I just the version 2 of this, it goes to 3mhz.

[@MegawattKS]

Awesome. It is nice to see they've extended operation to 3 GHz ! I suspect it uses the same design/chips and employs higher harmonics to stretch to 3GHz. So don't expect fundamental-frequency outputs above 300 MHz though. Anyone know ?

[@dayleedwards3521]

RF leakage will make it useless as a small signal source.

[@MegawattKS]

Good point. I partly agree - although useless may be subject to what one is trying to do. Just going from memory, I think measured values with attenuators attached tracked OK down to maybe -80 dBm. Or maybe -100 dBm. I.e. with use of 80 dB or 100 dB of attenuation. (I'd have to re-run the experiments to confirm if it's -80 or -100, or what the minimum is). So I agree - if we're looking for really low level stuff, its a problem for that small a signal. Mine is in a metal case, so I actually attributed that to cable leakage (I was using RG58, etc). But true, if one wants to get to -140 dBm or something, it would probably be necessary to do the attenuation inside the unit. Honestly, since the TinySA and TinySA Ultra products came out, I've been using them as signal generators. They have built in attenuators that will take them down to about -70 or -100 dBm respectively. Again, not exact values, and the cheaper TinySA isn't real accurate. But they're great for a quick-look and if I added 40 dB atten to the Ultra, I think we'd have a good -140 dBm minimum. BUT - if the NanoVNA is all one has, it's still a decent option for some applications. Recently I used the NanoVNA for testing my new scope. As shown here, it puts out a nice squarewave with fast edges up to 300 MHz, so it's still good for rise-time measurements of "100 MHz" scopes. 🙂