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H4 microSD card slot

This page was last updated : 29-Jul-21 00:00:08

When I got my hands on a used NanoVNA H4 I couldn't resist looking inside to see if it was using shielding for the RF components. Turned out it did so I bought the right one. But one thing I noticed was the component silkscreen for a micro SD-card slot without the slot it self and because it still contained the original software which didn't mention anything about saving images to SD cards, I didn't do anything with it. 

Recently I updated the NanoVNA H4 with new firmware from the groups.io/g/nanovna-users group found in the file section "Dislord's Nanovna -H Firmware". That version does support writing the screen and the SP1/SP2 data to the SD card. So I searched my junkbox for a micro SD-card slot donor and found one on a WEMOS  micro sd card shield (which is cheaper then buying a new slot). using a little patience, solder and desoldering I removed it without damage from the donor.  

The H4 board had all the pads for the slot filled with solder so some I removed that with desoldeer strand and cleaned up the area (on the picture i looks awful but it's nice and clean). 

For soldering the slot to the PCB I used my trusted 1985 Olympus 10x/20x microscope because even with my magnifying lamp I can't clearly see tiny fine pins.  

A few minutes later the slot was in place and ready to be tested. 

I connected a QRP-Labs NanoVNA adapter to the H4 and recalled the 30m BPF calibration settings. Double tapped the lower mid area on the screen (indicating bw:1000Hz 401p) and a notification told me that a image was stored. Took the SD card out of the H4 and looked on my computer to the result. Turned out  everything works as expected. 

Then I need to add a opening to the case to allow access to the micro SDcard and was a little to fanatical with the file.  

 Overall I like this mod allowing to simple take screenshots from what I see on the NanoVNA H4 instead of using the computer software. 

 

 

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