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Good day. I am curious how did you measure a 70 dB return loss? That is an extraordinary measurement indeed, Thanks.
________________________________ From: [email protected] <[email protected]> on behalf of tuckvk3cca <tuckvk3cca@...> Sent: Sunday, August 4, 2019 7:46 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] NanoVNA Under The Covers Thanks Gary. I contacted my supplier, EBay and ask if I could get another set of cal8bration loads. No luck. The 50 ohm was of very high quality, return loss -70dB compared to -40dB from another source I had, up to 1GHz. Anyone knows where to get such loads? Sent from my Samsung Galaxy smartphone. -------- Original message --------From: Gary O'Neil <n3go@...> Date: 04/08/2019 08:55 (GMT+01:00) To: [email protected] Subject: [nanovna-users] NanoVNA Under The Covers Having expressed accolades to AliExpress supplier Guangyi0016 store... I felt duty bound to provide a thorough overview of the hardware itself. I also think I missed the "i" in the supplier's ID, so I corrected it here. :-)If the attached photos are of insufficient resolution, I can attempt uploading them at higher definition. I first removed the top and bottom covers and observed that both are constructed of double sided copper clad PCB material (appear to be FR4), and both are painted on both surfaces. The external surface of each are both stenciled, but don't appear to have a clearcoat finish to protect them from wear. Users might want to remove and spray them with a clear acrylic for added longevity. I then photographed both sides of the board and made the following observations:1. The front-end shielding provided is mounted in blade standoffs, such that they can be readily removed if repairs are warranted. I removed them forthwith and photographed that side of the board again for completeness.2. It is unclear whether or not a footprint exists for an SD card reader, but I don't believe there is. The internal LIPO battery pack is secured in place with double sided tape, where such a footprint would likely reside. 3. There is not an on-board LIPO charger, but rather a tiny sliver of a PCB is afixed (presumably taped) to one end of the LIPO battery and wrapped in Kapton. 4. Brass standoffs are used to suspend the covers above and below the board. The paint on the covers prevent them from serving as a ground references, so the covers only serve to provide electrostatic shielding. 5. The mixers are SA602's, the processor an STM32F072CBT6, The codec an AIC3204, and the clock an SI5351. It looks to be a pretty faithful clone. 6. The PCB is stenciled, and marked under the battery as "NANOVNA V3.1".I secured the shields back into position, reattached the covers, and verified all was well.I performed a couple of 1 port calibrations, plugged it into my Windows 10 machine and verified that it communicates with the NanoVNA Sharp GUI. From there I was able to download the attached Firmware info.Navigating the hardware is pretty intuitive. The NanoSharp GUI not so much. :-) I'll stop here before I accidentally delete everything I've composed here again... Yikes! Fortunately it was autosaved as a draft. Phew! For the first few hours out of the box an all in all very positive experience. 72/73Gary, N3GO |
