Thumbnet is manufacturing RTL-SDR dongles for its own purposes, and sells surplus to the general public (official info here). Their latest receiver is called N3, shipping around mid-October.
I had an engineering/prototyping model for testing.
This is not a review or evaluation. Customers will get a different product, which, I fervently hope, will be probably very similar - I'll write a full review of a production N3 after it starts shipping.
Also, the N3 is not a commercially oriented RTL-SDR receiver, it is designed for the Thumbnet network. Just like the FlightAware ProStick and HackRF, be happy that it works like an RTL-SDR, and be merry that profit from sales go to good causes.
RTL-SDR architecture and components: engineers took a standard RTL2832U with R820T2 tuner and TCXO, then placed components on a 6x4 cm printed circuit board with alternative power supply options - N3 is twice as large as a full-size RTL-SDR dongle for better heat dissipation.
External DC power can be supplied via two pins (officially called a Phoenix connector, I used RasPi female jumper pins), takes 4.5V-5.5V, mobile phone or RasPi chargers (which are 5V), and power banks can be used.
Only data to the host computer with external power (= less noise from PC).
Important note: All testing has been conducted with external power, either a 4.75V 700mA charger or 20,000 mAh battery bank. Performance will probably be different if USB power from host computer is used, but my prototyping sample did not have that option.
F-connector: the only standard easily and cheaply available worldwide.
Just like external hard drives and higher-class SDRs, it uses a separate USB cable for data and power connection to the host computer. I still cannot fathom why every manufacturer feels compelled to reinvent the wheel every single time by not using MicroUSB: seriously, it's like the 90's for mobile phone chargers, move on fellas, every major consumer device uses MicroUSB (sans iStuff). Anyway, Thumbnet at least sells a suitable cable for a few dollars in the online store.
There's a metal dome (RFI shield/screen) above electronic components, which further increases heat dissipation area and acts as a Faraday cage / protects components from prying fingers.
Needs a metal case (official one is 4 dollars extra), electronic components on bottom of PCB are in a vulnerable position. Large corner holes take multiple screw options, and F connector means mounting into a makeshift box is easy with a nut and washer.
I had the distinct impression it's built to last, there's enough solder on the board to assemble 3 generic dongles.
Performance is similar to any dongle with a R820T2, but with much less noise on screen than any other RTL-SDR. Worked on shortwave with Ham-It-Up v1.3 upconverter, and on every frequency other dongles could tune. Only tested up to 1090 MHz, no issues, PiAware recognized the N3 as a regular RTL-SDR dongle and started sending data straight away.
Audio quality was superb on commercial FM and for SWLing. Can't comment on reliability, obviously, was powered on for a week whilst connected to outdoor antennas and had no problems.
Compared to: can't really compare it to anything, as it was not a final product, but from price alone it's clear the premium and satellite-oriented RTL dongle club has a new applicant. Can't wait to put it up against a v.3, SMArt and XTR+.
Preorder only at the moment, (link to store) bare board costs $25.75, flat rate shipping for 4.5 dollars worldwide.
Realistically, you'll add an RFI screen (+$2) and a metal case (+6), ending up with enough change from $40 to buy an F to SMA female adaptor.
Receiver only. No antennas, power/data cable, adapter, bias-T, LNA, direct sampling hole etc, but it's unlikely the target audience will care.
Who is it for?
I think the N3 will find favor at the advanced / enthusiast end of the market. $35 for a metal cased, RFI screened R820T2 TCXO dongle with external DC power is not too bad.
Don't draw conclusions
I had an engineering model, so production units will be different; I doubt major changes will happen in the next few weeks until it ships.
The N3 is based on the RTL-SDR platform, so compatible with existing software, and because of its architecture, offers several benefits and ... and I'm waiting for a production sample in a metal case as well, because as I really don't know how final units will perform. If close to this, I'm sold.