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So I backed the LimeSDR crowdfunding.
Now I'm eagerly waiting for my unit and hoping for the crowdfunding for it to succeed. Funded!
This page documents stuff I do relating to LimeSDR, be it software, electrical or mechanical. 

I forked the official MyriadRF LimeSDR repository on github for doing my own experiments with it. 
My fork can be found here: https://github.com/2ftg/LimeSDR-USB

Mechanical .STEP model of the LimeSDR pcb with reduced component count so that you don't see separate details for all the +280 capacitors and +100 resistors. Some resistors on board edges, all connectors and all large components have been kept. 
This was done to make cad design of cases for LimeSDR easier. 
The .step file can be found here:

I wrote a tiny bit about the LimeSDR frequency response based on my limited knowledge here:

But because I like content here's a reproduction of it.
Do note that this was/is for ver 1.2 of the pcb, current revision is 1.4 with slight changes.

The RF matching components are size 0402. 
So while doable with a steady hand and sharp eye, we are getting in to the microscope, micro tweezers and preheater territory. 
While I might be ready to stack some caps on top of the existing 100nF one's for improved LF response, I'm unsure how many others would be ready to do so.

Some stuff based on reading the schematics and googling: 
TC1-1-13MA+ balun transformer is used for 30 MHz-1.9 GHz branch, 700 MHz-900 MHz branch and on the 700 MHZ-2.6 GHz branch. Both TX and RX.
Datasheet shows that it is specified for 4.5 to 3000 MHz. https://www.minicircuits.com/pdfs/TC1-1-13MA+.pdf

TCM1-63AX+ balun transformer is used in the 2-2.6 GHz branches for both TX and RX.
Datasheet shows that it is specified for 10 to 6000 MHz. https://www.minicircuits.com/pdfs/TCM1-63AX+.pdf

The coupling caps in the 30 MHz-1.9 GHz branch are 100nF, which should be usable on HF, but might be too little at LF. 
I think the HF branch should work well for most of the HF bands and the 700-900 MHz branch should also work reasonably on 2m/70cm.
If the LimeSDR folks say that it will cover 100kHz-3.8GHz I'd say it does it, but the performance might be degraded at the band edges, this is my guess as an amateur and general radio hobbyist.
Here's a screencapture of the RF section for those without Altium or windows to run Altium viewer.https://i.imgur.com/GhfW6vr.png 

Other random info and links relating to my LimeSDR adventures:

Official MyriadRF LimeSDR wiki page. This should have tutorial and stuff.
To suggested "first test" with the internal loopback and WCDMA sample did not work for me on Win7 Ultimate as my LimeSDR some how only shows up on USB2 instead of USB3.0.
I had more success with GNU Radio companion .grc flowgraphs from Tatu OH2EAT and the WFM transmit flowgraph I made with his guidance. Those actually worked. I used AOR AR8200 as test receiver.

So far I have worked OH2EAT on 70cm PSK31 and Feld Hell and 13cm Feld Hell with LimeSDR.

The official LimeSDR board is 60mm x 100mm in size, has 12layers and is 1.6mm thick. 

Elecrow has cheap 10pcs 10cm x 10cm 4 layer boards:

Right First Time - a Practical Handbook on High Speed PCB and System Design, by Lee Ritchley

yxSDR The Case compatible but retarded cousin of LimeSDR.
Alisivut (1): yxSDR