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Hi Larry, thanks for the inputs.
Can you elaborate on the statement: big difference in noise levels. The second photo shows a closeup of the installed shields - big difference in noise levels! If you are doing just one port measurement, then I assume lower noise implies less uncertainty in the readout of the S11 parameter. Less bouncing around in it's value. Is that correct? Or if it is S21 and you are using a 4 track machine and measuring S21 then this big difference in noise would result in a lower noise floor in the THRU measurement and greater dynamic range. Below ~ 200 MHz I see about 70 dB or better and at frequencies approaching 900 MHz, there is a fairly linear degradation in the black nanoVNA. However, the largest limit in DR appears to be the cables themselves. I'll elaborate on that in another message. Thanks, Alan ________________________________ From: [email protected] <[email protected]> on behalf of Larry Rothman <ac293@...> Sent: Tuesday, July 9, 2019 2:55 PM To: [email protected] Subject: [nanovna-users] Adding Shields and an SD-card slot [Edited Message Follows] I have been hacking my Gecko unit to add shields and I also decided to add an SD card slot I removed from an old Blackberry cellphone. As I mentioned in a previous post, old 2-way radios and cellphones have a treasure trove of re-usable parts. The first photo shows a pile of shields from several old Motorola HT1250 portables. Cellphone shields are similar. I got the TF card slot from an old Blackberry. Use a heat gun to remove them as well as switches. TIP: Heat the opposite side of the PCB when removing parts to prevent heat damage. The second photo shows a closeup of the installed shields - big difference in noise levels! The third and fourth photos show the TF card slot where I had to scrape some ground plane solder mask for securing it. In the upper left corner, you can see the push button I installed on the BOOT solder pads. I know the firmware doesn't support the SD card - yet - but that is what hacking is all about! Now, I'm waiting to receive the Black (Original design) version with the USB-C connector . BTW, that old Motorola cellphone battery lasts well over 4 hours. |
