Let me start off with my soldering disclaimer. I am one of those only use one soldering tip for everything. It is the biggest chisel type tip that Hakko makes for my soldering iron. For this build I was forced to change over to something a lot smaller. I also included a picture in the image gallery of the tips I used.

This build could go really fast if you did not maximize the full protentional of your build. According to KababFPV there are 2 mods that can made a noticeable difference “The XT30 gives you about 30-40% more performance overall. Swapping out the wires will give you another ~10-20% of added performance.”
Go and read KababFPV’s build guide to read more in details about it: https://kababfpv.com/2019/01/16/build-guide/

So, if you do not do those modes your can finish they build even faster because there is a lot less soldering to do. You can simply plug in the motor wires instead of soldering it directly.

My first impression of the GEPRC 12a AOI FC/ESC is that is looks great. I do wish they had more 5v and ground pads to use. I had to share one for the VTX and FPV Camera. I also have to say that the instructions on GEPRC website showing you how to wire a TBS Nano Crossfire RC is WRONG! Instead of using the SBUS pad for UART RX, use the R2 pad that is directly above the T2 pad.

The next problem I encounter was the VTX. I am still unsure what went wrong but I could not get the TBS Nano VTX to power up. The FC was putting out 5 volts as it should, but I did not see any video signal being broadcast when I checked with my Fatshark goggles. As a test I switched to an Eachine VTX03S and everything worked fine. Maybe I got a defective VTX? I also tried powering up the VTX with a Pololu 5v 1a Step Down Voltage Regulator and still nothing! I guess it is worth the extra 1.5g of weight since the VTX03S can output 200mw compared to the 50mw from the TBS Nano.

When you look at the image gallery, it might seem confusing because there are so many different weights shown for the quad. This lightest is when I used the 2 blade props with TBS Nano VTX and that weighed in at 41g. Then I switched out the props to the Emax Avan Rush 2.5x1.9x3 and the total weight increase to 45g. Since I was not able to get the TBS Nano VTX working I switched it out for an Eachine VTX03S and now it weighs 48g. I happen to have other props, so I tried using the Gemfan 2540 and if lowered the weight to 46g.

There are a few reasons why I did not stay with the 2 blade props. For some odd reason the motors were running a lot hotter. But when I used a 3 blade props the motor was cool after running a full pack and it is a lot quieter too. Another obvious difference is that the 2 blade props will have less thrust. I have not done a flight time comparison between the props but I can not imagine the 2 blade getting much better results.

Here is a video of the Primo with the Gemfan 2540 Props: