The Si5351A data sheet specifies its maximum output frequency as 200MHz but the designers have found that in practice most of the chips are able to operate to 300 MHz. As the outputs from the clock generator chip are square waves they are rich in odd harmonics and by generating LO and test signals whose third harmonics are spaced by 6 kHz it is possible to extend the frequency range to 900 MHz.

Extending the Frequency Range

Over the past year newer versions of the firmware have appeared on Github and the Nanovna IO group that extend the frequency range of the unit up to 1500 MHz by using the fifth harmonic of the Si5351A output. I was curious to see how well it would work and so I re-flashed the firmware in my unit with the DFU files uploaded to Github by Dislord, [1].

There are extensive guides to flashing firmware to STM32F microcontrollers on the internet and Youtube so I will not cover it here.

Conclusion

Overall the unit has become useful as an indicator of performance at frequencies in the 23cm amateur band and the additional capacitors have reduced the noise on the traces at frequencies in its original operating range improving the dynamic range there as well. There may still be some scope for further noise reduction.

We all like cheap instruments, whether they are a logic analyser, an SDR, a spectrum analyser, or whatever. Sometimes the cheap products are based upon open source projects, such as the NanoVNA vector network analyser we looked at a while back, but it’s important to be aware that just as often they are clones of commercial products that have had a huge research and development applied to create them.

There may be some open-source enthusiasts who would respond that all such things should be open source hardware anyway, and that the devices have been somehow “set free” by the cloners.

Here is my latest video, using the nanoVNA-F.

Verification of nominal values of inductors and capacitors is a useful function of the nanoVNA. In this video I measure the actual values, compare to the marked component values, and then verify the accuracy of the method used to obtain the readings using an LC resonant tank circuit and some S21 measurements. Does a test fixture make measurements that much more accurate as opposed to using simple alligator clip leads?

nanoVNA – Alligator Clip Leads vs. VNA Test Fixture Kit – Measuring Inductors & Capacitors
https://m.youtube.com/watch?v=Y2_aytTVvFw&feature=youtu.be

LiteVNA current has two versions: LiteVNA 62 and LiteVNA 64. Besides LCD screen sizes (2.8 inch for the 62 model versus 3.95 inch for the 64 model) and battery capacities (1.3 Ah for the 62 model versus 2 Ah for the 64 model), all other technical aspects are identical. The model I got here is the LiteVNA 62.

Unlike the NanoVNA-F V2 which is enclosed in a metal case, the LiteVNA comes in a plastic case with no additional shielding. But the build quality looks quite decent.

https://eleshop.eu/litevna.html

The LiteVNA is a portable 50 kHz – 6.3 GHz vector network analyzer which design is based on the NanoVNA and SAA2. This vna is designed to measure equipment reflection and transmission coefficients without the need for a large analyzer. The LiteVNA uses one mixer which enables S11 and S21 measurements through RF switching and TDR/DTF measurements through IFFT calculations.
The analyser has a 2.8″ touch-screen display that can show the measurements in 10-1001 data points. Furthermore, the analyser has a built-in 1300 mAh battery and can be connected to an android phone or PC. Connecting to a phone or PC allows for controlling the analyser and displaying the measurements.