All the units are based on the same hardware. This from "A Guide to the NanoVNA":
The current design of the NanoVNA and the name was created several years ago by a Japanese ham under the pseudonym “edy555”. His first design ideas with a different DDS (frequency generator) seem to date back to 2013, but the current design with a significantly reduced parts count and based on the Si5351A was published by him in 2016. Edy555 himself references a German kit, the VNWA3 which was based on the concept of using a cheap computer soundcard, published by Tom Baier, DG8SAQ in the Mar/Apr 2007 issue of QEX ("A Low Budget Vector Network Analyzer for AF to UHF"). In the summer of 2016, edy555 announced to produce the NanoVNA, which was apparently done afterwards, but the kits were predominantly sold in Japan. Edy555 was also involved in the original firmware and continues to support the firmware (see chapter Two). He decided to open-source hardware and firmware to avoid bad clones, which undoubtedly was key to future development and the current popularity of the NanoVNA. It was not until a Chinese ham, Gen Hu (pseudonym ''hugen'') adapted the design slightly by changing the power supply and started to mass market the NanoVNA, that the device created international interest. In agreement with Edy555, hugen sells his product under the name NanoVNA-H. Hugen also runs his version of the firmware.
Schw?rzler, Christoph; Schw?rzler, Maximilian. A guide to the NanoVNA (pp. 9-10). Kindle Edition.
Bob
KN6UXD
