Re: Offtopic: nanoSA
|
Interesting.? Is there a schematic?
toggle quoted message
Show quoted text
Mike WY6K "... somewhere in the distance, there's a tower and a light, broadcastin' the resistance, through the rain and through the night..." On Tuesday, October 8, 2019, 7:52:03 AM CDT, erik@... <erik@...> wrote:
Would it be wonderful if there would be, next to the nanoVNA, a nanoSA or nano Spectrum Analyzer? Well I decided to test what the most simple SA could look like, just good enough to test the harmonics level of your signals till 400MHz and some other, not too complex, measurements. According to my estimate the BOM of the nanoSA on the photo would be around 12$ Main components are two SI4432 modules, one in RX mode at 443MHz using the RSSI as log detector, one as +20dBm LO for the mixer (443MHz - 886MHz), a 443mHz SAW filter as first IF filter, a Double balanced diode mixer and an arduino zero (3.3 volt) or compatible (arduino micro with 3.3v serial to USB module will also work), adding a LCD will still keep the cost below 25$ or 50$ retail. The measurement performance is surprisingly useful. Attached a scan of the harmonics and spurs of a SI5351 at 25MHz And a scan of the AD9851 ast 25MHz, both connected through a 30dB attenuator Specs: Range 0-400MHz (0-200MHz with unmodified modules) RBW selectable between 3kHz and 600kHz With RWB=300kHz noise floor below -90dBm Max signal around -5dBm Did not yet do the IIP3 measurement but the used ADE-25MH is supposed to be +13dBm Good enough for many measurements. Things to further improve: - 400MHz low pass filter at input - remove output filter of TX module to get full 400MHz bandwidth - Put everything in a box. I hope someone gets inspired and puts everything on a PCB with a LCD as a small standalone SA (nanoSA) |
WY6K Mike Watts