Complete Noob looking for my first RX/TX SDR

Hello everyone,

I’m a new member as well as a COMPLETE noob on anything SDR/HAM/etc. A few years ago I stumbled onto SDR on the web and was captivated by Michael Ossmann’s design proposal of an TX/TX affordable (relative term) sdr, so I purchased an rtl-sdr from NooElec to see what is was all about and it sat in my office desk unused until earlier this year; Now retired and with a bit of time on my hands, I decided to try this little gem and got hooked on spectrum browsing.

So now I’m thinking that I would like to work towards my HAM (tech) license and upgrade to an rx/tx sdr; So for my budget of ~$300 there’s Michaels (now a product) HackRF and LimeSDR. There’s a lot of info on HackRF form many sources but much less on the LimeSDR.

I’m currently leaning towards the LimeSDR mainly do to it’s board design and newer componentry (FPGA vs CPLD, 12b vs 8b, USB3 vs USB2, etc) and upgrade path via FPGA, but I would appreciate some clarification of my thoughts on a couple of noob questions:

  1. What is between 3.8Ghz-6Ghz that I would be missing with LimeSDR.
  2. Will I need to buy/rent firmware (FPGA) for normal use or is that (Ubuntu Snappy Core store) only for special purpose radio apps.

Thanks in advance…

1> Since you mention ham I’ll guess that you are in the US.
It really does depend on what you are interested in. Take a look at these two links and decide if there is anything that interests you.

Once you are in the microwave frequency range, then RF can be directed into narrow beams and transmitted by parabolic dishes, I would guess that most of the spectrum is used for line of sight point-to-point communication links, wireless LANs (5170US/5725WW <-> 5875 MHz ISM band) and Satellite communication.

2> The FPGA gateware for the LimeSDR(USB) is fully opensource ( ) so I see normal use not requiring access to the app store. But I suspect that would depend on skill set and knowledge.

EDIT: I should add that there will be an future expansion board for the LimeSDR, that uses a LMS8001 as an up/down converter to boost the range up to 12GHz ( ).

Thanks for the fast reply; Wow, just looking at those .gov docs forced me into a second vodka toddy last night; I’ve a lot to learn… My mind was kind of made up to go with LimeSDR but the clincher was that 12Ghz addon coming next year, not sure I need it but it’s nice to know that I could go there.

I’m going to pre-order today…

As a ham (and not from the US, @mzs :slight_smile: ), I have not seen a clear enough statement about performance in the lower bands, specifically UHF, VHF and HF. I have seen enough conflicting information that I am at best cautious. The original design specified filtering that drastically reduced sensitivity at the bands that most hams would be interested in.

I am going to wait until I see reviews of actual production boards… I was very bullish about this device until I read some of the threads on the front-end configuration… now, sadly, I am less so.

The boards some of us have for development have band pass filters which reduce sensitivity greatly. These are not the same boards as will be shipped in a month or so - at least that’s what I’ve (we’ve) been told.

@gerryk I personally find that most Radio amateurs outside of the US, do not generally refer to themselves as a chunk of pork preserved through salting :confounded: But maybe my personal observation is flawed.

But I do fully agree, it is new hardware and the only useful performance information I’ve seen is two graphs for the RX LNAL and LNAH inputs Noise Figure and Gain versus Frequency:

But when the boards ship, I’m sure that there will be a lot more measurements, comparisons and generally seeing how far the LimeSDR can safely be tortured, stretched and pulled outside of specification.

Yes, I did see those plots… two things still concern me, though… there has been enough conflicting information from Lime Micro to leave things ‘uncertain’, and the plot starts around 100MHz, which doesn’t say enough about HF/VHF performance. I want to believe…

Maybe someone has done a comparison with airspy in the frequencies of the filters? I read that there is a filter for best reception in 800-900Mhz area. How Limesdr compares to airspy in these frequencies?


I’ve had my LimeSDR since February of this year and have performed A LOT of testing on it. I have to agree with Simon (G4ELI) that the matching networks on the board - currently - aren’t optimized for HF and will be improved in the next spin. I’m willing to give Lime Microsystems the benefit of the doubt and see what the performance of the redesigned matching networks will be, because when it’s all said and done everyone is going to either like the performance they have - stock - or they’re going to rip off the matching networks and roll their own to make it perform better in their band of choice (HF, VHF, UHF, SHF).

I’m going to give you my take on this for the board I have (and it’s NOT the optimized version for HF). The board I have is a completely, as originally designed, LimeSDR and has a vintage of production presumably in late 2014 or 2015 - this LimeSDR thing has been going on for awhile now (it began its life as ‘SoDeRa’). It seems to have great receive performance in the VHF, UHF, and SHF bands - and that would make sense since the matching networks are optimized there. The original intent of the SoDeRa (pre-LimeSDR) was to be a reprogrammable cellular radio/Wifi appliance for IT and other ISM business purposes. I designed and built over 300+ HF upconverters for the RTL-SDR over the course of 3 years taking the RTL-SDR into the HF band through 120 MHz upconversion. In late-May of this year I extended that same HF upconverter module to the untouched front end of the LimeSDR in a way to see the HF performance as upconverted on the LimeSDR. The performance was on-par with the RTL-SDR with those matching networks in place - pretty good and I could hear things on the Lime (again, as upconverted) that I couldn’t hear on my Flex 5000A (and it’s supposed to be the ‘industry standard’ for Amateur Radio digital transceivers). Later on, the Lime Team got HF working natively on the LimeSDR and I removed the HF upconverter and natively tuned the HF band. As I thought, the performance wasn’t as good because the untouched matching networks were not optimized for that band, and even as I tried to tune 75m (around 3970 kHz) the performance really fell off. But, again, that’s with the UNOPTIMIZED matching networks. While the performance at 75m wasn’t stellar, it seemed that the 60m to 6m (and up) receive performance was pretty good considering everything and in some instances in the 20 - 10m bands (when those bands were active) was on-par with the Flex 5000A - it just fell off sharply between 60m to 75m.

So with the plots I saw around June of this year I’m banking that the performance in HF will be better in those lower bands than with the STOCK LimeSDR I have. But then again, as I said earlier, someone will not be happy with the performance because they can’t hear a 50mW WSPR station transmitting from Wake Island and will rip the matching networks off the board, roll their own, and publish the data so others can consider making that change. That’s the beauty of Open Source radio - - you’re free to make it better and then capitalize on it. I did that for RTL-SDR to make it REALLY work in the HF bands for HF upconverting and direct injection tuning.

Hope this puts things into perspective for the LimeSDR. Frankly, since I’ve had A LOT of time spent with this board over 2016, its worth every penny of the $289 that it’s being sold for considering its existing, and future, potential.

73, de Marty - KN0CK

Marty et all … Im looking for the schematic for the LimeSDR … i thought i had once found it and D/L it but i cant find it now …

I was interested in locating what you meant by “matching networks on the board”. I was thinking that you might of meant band pass filters – that might also pose as a matching network …

Ill keep looking … cant be that hard to find … i just need to get another cup of coffe’’

Ok… found -again- , i assume that your using LNAL_A for HF.
The only difference between broadband and lowband is L9/L17 (that i can see). With L9 X2 the value of L17 … perhaps a 100nH for L9 would do … TC1-1-13 is definitely not the issue … I use that part in my UHFSDR.

Id like to see the upper end of highband pushed to 12Ghz … and operate on the 3rd harmonic into a X-band setup.

Im not 100% sure how L9, C14 and C18 function in/as a filter … series? T?

Hi Marty
I’m not sure if you have any experience with the Ettus B200? I have this board and I’m really on the fence in purchasing a LimeSDR. I’m primarily interested in VHF on up in frequency range.
My B200 works well and I use Simon’s SDR Console V3 (great always improving software) but is plague by images.
I’m wondering if you or anyone on this board can offer a opinion regarding the LimeSDR and B200 performance.
Also, do you have the acrylic or metal case for your LimeSDR? Thank you and anyone else for their input.



Thanks for writing - I have no experience with the Ettus Research SDRs but I can tell you that Simon doesn’t like the way the Ettus boards are programmed or accessed. I’ve heard his comments on it and he’s no fan of those boards - He’s mentioned that the LimeSDR is much easier to set up and run than the Ettus boards.

All that aside, I can’t give you an assessment on the comparison of the Ettus SDRs and the LimeSDR since I’ve only been using the LimeSDR since late January of this year and fairly consistently since then. Since you’re mostly interested in VHF, you will find that the LimeSDR handles that band pretty well and has real nice receive sensitivity. I haven’t taken scientific measurements with it, but it does have similar performance to other radios that I own (VX-8DR, VX-2DR, FT-757, etc). Seems to have similar receive performance to those commercially available radios. I’m more fixated on the HF band and I know that the matching networks they have on the board are not optimized on the receiver I own, but will be when they start shipping in November/December - it will have no effect on the performance on the V/UHF bands on that SDR.

Again, wish I could give you a side by side comparison of those SDRs but I haven’t owned an Ettus yet and from everything I’ve read and heard I’ll just stick with my LimeSDR for now in terms of higher performance SDRs. I’m sure the Ettus radio has good qualities, but having played with the LimeSDR a lot this year I’ve come to find that its performance in the V/UHF bands has been pretty good all things considered (antennas, band conditions, etc).

Thanks again for writing and hope you join the LimeSDR fray soon…!

73 de Marty, KN0CK


I’ve yet to get my hands on the schematic of the LimeSDR - I know that it’s open source and somewhere on GitHub (at one time) but I haven’t taken the time to look at the input circuitry enough to know what we have there. Andrew Back corrected both Simon Brown and I about (what we referred to as ‘filters’ a few months ago) what’s at the input and referred to them as ‘Matching Networks’. Since Andrew is part of the Lime Microsystems Team, I’d have to take him at his word - but I’m also now even more interested in studying the schematic to look at the input circuit and see how it might be changed - or supplanted altogether with a different auxiliary board - for better HF performance of what I have now. It remains to be seen what we’ll receive in November/December with the modified ‘matching networks’.

And you are correct on the LNA_L Port A on the board - that’s what I’ve been using for my HF work. The wideband port (as Ricardas mentioned awhile ago) is primarily used for ‘sniffing’ (and while wideband, it’s really not suitable to use as a primary port for receive…more for just seeing ‘…is anything out there?..’ kind of use) and the LNA_H port has better U/SHF performance than the LNA_L port that appears to be suitable for V/UHF work and capable of SHF. LNA_L is the one that they will change to make for better HF response even though the plots really show the performance curve starting at 100 MHz - again, we’ll just have to see. I’m of the mindset that there will be changes necessary (in the form of an auxiliary PC board I’m planning to design) that will optimize for HF and add about 22dB of gain to that receive port. I’ll just have to see how to remove passives and tap into it.

Keep me apprised of your efforts there and I’ll also start pounding the ground for the schematic, too.

73 de Marty, KN0CK

Thanks Marty for the reply
Yes I and the many Ettus owners using SDR Console are aware of Simon’s comments.
I think I will take the plunge and purchase a LimeSDR.
Marty can you comment on you have your board in a metal enclosure or the acrylic one? I trying to decide which one i will get. Thanks again.


One thing I must say - there’s been a new guy at Ettus for some months now (goes by the name of Derek), he really has helped with the codebase for Windows users. My B200 is working well, I expect to get the full 60MHz bandwidth by the end of the year. Myself I don’t have a case for the LimeSDR, I would like a good, professional metal case similar to the one I bought from NI for the B200.

I am looking forward to the official LimeSDR - should be funky.


Right now I cobbled together a Hammond Industries case (Part Number: 1455A1202RD) around my original LimeSDR and the pictures of that can be seen in the thread here ----> Hammond 1455 V2 aluminum case for LimeSDR Just look for the pictures I posted of the LimeSDR being cased up. It’s kind of a hack, but it fit like a glove (it’s a little tight) and I had to chew part of the case away on my version of the Lime. If you look further down the posts, a user Luftek has created A REAL NICE CASE from a little larger Hammond chassis. Again, refer to the link I posted here and then follow the discussion - it’ll give you the informed decision on casing up the LimeSDR.

I also want to go on record that I have a LimeSDR running WITHOUT ANYTHING (not enclosed in acrylic or metal) that I’m listening to on the 20m band right now and it’s playing fine. But I really think you’d be better off with a metal case for your LimeSDR and Luftek has designed one that - I think - is going to meet most (if not all) of the requirements of LimeSDR users. Just post a note to Luftek (his real name is Ziga) and see if you can gather the BOM and other details from him - he’s been great about sharing that. Also, I believe he’s selling on EBay, too, but do check with him on that. The link to the EBay listing is here ----->

Keep in touch if you have any other questions, Vincent -

de Marty (KN0CK)

Thank you Marty,
Have a great weekend