Testing in the 3-4GHz range is not the most fair comparison because the V2 Plus4 only has guaranteed performance specifications up to 3GHz.
Limit the design if you don't want customers to run beyond 3GHz.
Again to be clear, I had made a test cable to try and identify the problem as well. My last attempt had used a linear power supply driving a linear regulator powering the V2Plus4. This also caused the increased noise. Basically, as I had said, if don't run it from the internal battery, the noise goes up. Measuring the voltage with this cable, I get 5.014V
Your custom cable has too much resistance, and operating at 4.6V is way too low for the mixer.
I don't have the standards in front of me but first hit from Google:
According to the USB spec, and illustrated in Figure 1, the minimum available voltage from a USB host or powered hub at the peripheral end of the cable is 4.5V, while the minimum voltage from a USB bus-powered hub is 4.35V.
I would have assumed you would design the product to meet the USB minimum voltage requirements. You mention my cables high resistance. The cable drops 21.5mV @ 398mA or 8.6mOhm or so. Even with the 5.014V measured internal of the V2Plus4, the noise is poor. Blame the cable if you like.
I suggest reviewing the Arinst VNA-DL or VNA-PR1. Both reach 6GHz at low cost, have better performance, and are designed from scratch by people that know what they are doing who don't need to rip off other's designs.
I would not waste my time with that device. Similar to Jan's, they did not document the communications requiring the use of their software. The hardware could rival the best VNAs on the market today but without good firmware and software, they have little value to me. Of course, you are welcome to procure what ever VNAs you like to create your own reviews. You could even cherry pick the parameters to skew the data.
The LiteVNA copies my design without permission and only substituted some parts to extend the frequency range.
I've asked you several times for proof that any laws were broken in your country, so far all I have received is a constant stream of lecturing from you. It comes across rather rude, childish and unprofessional. And while you may feel you have some say in how I conduct my reviews, you don't.
If I wanted to create something novel and planned to turn it into a product to capitalize on it, I may patent the IP or I may hold it as a trade secrete. I would NEVER make it open source!
Once the product is designed, social media seems like a good choice for advertising to the hobbyist market. I setup a mail group to attract potential customers. I would never consider is locking the group to potential customers! You have stated that was a mistake. That is what Jan stated as well. Really bad choices.
I decide to reinvest some of my earnings into my next product and make an announcement to stir up some interest. The one thing I would never do is make a public announcement that I am walking away from it unless I plan to walk away from it! It's the story of the boy and his ball walking off the playground. It shows a lack of maturity on your part.
It's just a hobby project at this point since all I've seen indicates the market is so small that you shouldn't take it too seriously. Or I may just go and take the 6 figure job at a big technology company doing cutting edge R&D and be gone with this race to the bottom crap, maybe I'll decide that's where I want to be in life instead.
https://www.eevblog.com/forum/testgear/nanovna-v3-(6ghz)/msg3847775/#msg3847775Let's assume I had placed my design in the public domain and someone improves the idea and capitalizes on it. These changes were obvious to one skilled in the art. I would ask myself, I had the design done and all I needed to do was make these simple changes to obsolete my own product or add to my product line and increase my market share. Why didn't I?
From my perspective the problems you are having are a reflection of the poor choices you have made. I'm responsible for the choices I make. If there is something I don't like, I change and move on. You seem unable to learn from your mistakes and change course. It's not the competition you need to be concerned with.