New board: LimeRFE

An RF Front End Module for the LimeSDR Platforms, with integrated PAs, LNAs and filtering.

Key features

  • Filtering
    • Each band has appropriate filtering both for RX & TX
    • Selectable AM/FM notch filter
  • Fully Open Source Software
    • Firmware
    • API support
    • GUI
    • LimeSuite integration
  • Control & Configuration
    • Firmware programmable via Arduino IDE
    • Arduino Nano-compatible microcontroller (ATmega328)
    • FT232RL USB-to-serial converter
    • Host serial connection via USB mini Type B connector
  • Power & SWR Meter
    • 1 – 4000 MHz power & SWR meter (external directional coupler required)
    • Cellular bands TX power meter (internal coupler)
  • 10-pin Interface to SDR
  • Power and ground
  • I2C (SDA and SCL)
  • 2x GPIO connected to on-board microcontroller
  • 4x bi-directional level shifted I/O
    • 1.2 – 5.5 V
    • Each I/O has a high voltage and power Darlington drive stage for inductive loads (e.g., coaxial relays)
    • Individually switchable direction (input/output)
  • Power Supply
    • Single 12 V supply
    • Optionally supply microcontroller and RX channels via USB

Preliminary specifications

HAM Bands

No. Name Frequency (MHz) Output P1dB (dBm)*
1** HF** 1.6 – 30** 35
2 2 m 144 – 146 36
3 70 cm 430 – 440 34.5
4 23 cm 1240 – 1325 30.5
5 13 cm 2300 – 2450 33.5
6 - 3300 – 3500 26.5

Cellular Bands

No. Name Duplex Downlink Freq. (MHz) Uplink Freq. (MHz) Modulated Output Power (dBm)
1 Band 3/DCS-1800 FDD 1805 – 1880 1710 – 1785 24
2 Band 2/PCS-1900 FDD 1930 – 1990 1850 – 1910 24
3 Band 1 FDD 2110 – 2170 1920 – 1980 24
4 Band 7 FDD 2620 – 2690 2500 – 2570 24
5 Band 38 TDD 2570 – 2620 2570 – 2620 24

Wideband Channels

No. Frequency (MHz) Output P1dB (dBm)*
1 1 – 1000 27.5
2 1000 – 4000 25.5

For more info and to register interest:


I am excited & willing to Beta if needed. 2 LimeSDR-USBs (Later versions), scope, sig gen, spectrum analyzer at hand.
I have 8 shelving units of RF parts & assemblies just waiting.


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@andrewback - Andrew,

I WANT IN…! BRING IT…! #BETA :slight_smile: !!

73 de Marty, KN0CK

Nice! any ideas on pricing?

Great news :wink:

Have one small objection:

F2 on RX path should go 110 to 170 MHz
LPF2 on TX path should be at last 170 MHz
Yes I like to have Air band, Marine band voice and AIS options if possible…
Ordering 2 units… of Alpha edition.

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Thanks for the feedback! Will forward this to the engineering team for consideration.

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I have gathered most of the parts & pieces to work 1.8MHz to 440 MHz. BPFs, LPFs, attenuators, amplifiers, Etc…
Of course, with SMA relays & much larger components, mine needs a rather large container, compared.
I can test it against tried & true components.
I can also drive it into an FT-857 PA chassis (BPFs, LPFs, bandswitching, TX/RX control) for 100WHF-50MHz, 50W for 144-148MHz & 20W on 440 MHz. It is controlled with a simple shift register. With many of the driver transistors for these being unobtanium, more will be available.
I was also planning to use an arduino or 2 to control all of the junk required. I’ll pull out m notes this weekend.


Also, I noticed no provisions for 50 MHz& 70 MHz, or does that just fall under the 2 meters LPF/BPF?


HI Andrew
This is a marvellous addition!
As a Radio Amateur in Region 2 may I suggest that filtering be added to cover:
50 - 54 Mhz Region 2 4 Mhz ***
144 - 148 Mhz Region 2 4 Mhz
222 -225 Mhz Amateur 1.25 m band often ignored by the big 3 Japanese radio makers (!)****
420 - 450 Mhz US 70 cm band (a bit smaller in Canada )
902- 928 Mhz Amateur 33 cm band ****
1240 - 1300 Mhz (as mentioned)
2304 - 2450 Mhz (as mentioned)
3300 - 3500 Mhz (as mentioned)
I know it might be a stretch but adding extra band filters would certainly help the Amateur Community greatly, as this technology will replace racks of gear in basements across the world…its super disruptive!
If you do that, there a thousands of us who would love to put this system to work for VHF UHF SHF operations in Region 2.(not to mention R3 and of course R1)
(Now if it would only get to 5.7 and 10 Ghz ! ) - transverter board still around??

73 Dana VE3DS (One of the guys from VE3ONT Off the Moon with the Algonquin Radio Telescope) 25 yrs ago…

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Oh and maybe 50 - 72 Mhz>>>> 6 and 4 m…

All great suggestions and as with so many things, it’s a balancing act. I’ll certainly be discussing all this feedback with the team and if additional filtering branches don’t make it to the final production design, it won’t be because we were not listening.

I am more than willing to consult with the engineers on the ham radio aspect 1.8MHz to 440MHz.
As for the 50/70 MHz, use that frequency as the “HF” LPF. Many LDMOS amplifiers will do 1.8MHz to 60 or 70 MHz.
We as hams can always break open a defunct rig to pillage LPFs & BPFs for HF/50-70 MHz(I have mine from a TS440SAT).
I am building one as a mobile touchscreen ham radio @ 100W, using the FT-857 PA deck.
I am building another in a G5 MAC case, with full water cooled limit amps from HF to 2M & 650W on 440 MHz.
We as hams love to experiment. Some also collect vast amounts of junk (Ask my wife). All I am waiting on is a couple LNAs & a lull in work to get it all finalized.

Of course, there will have to be coordination with the Software Developers, to get this off of the ground.


So, is there any advice from the Devs, as to HF TX? I would guess that with the RFE board, there would be certain settings for cleaner TX.
It might be nice to let the software Devs know.
My guess is lower drive in the Lime & adding the predrivers outboard?


Not sure that I follow. Could you explain in a little more detail and if there is work to be done here, I imagine that @Zack could advise.

I was excited about this until I saw that it didn’t include the 222 MHz and 902 MHz bands.

It is hard to consider it for serious amateur VHF & Up work when those bands are not included.

Not having those bands included makes it look as though it was spec’d by someone without real experience or knowledge about this segment of our bands.

Here is hoping that those bands can be included. See VE3DS Dana’s excellent note for further suggestions.



Notice that there are 2 amplified outputs with no filtering. Other filters can be added there.


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Indeed. We will review all the feedback provided and consider accommodating requests for new features where possible, but the line will have to be drawn somewhere. E.g. it would have been nice to have integrated filtering for all the HF bands, but this would have made the board quite a bit bigger and more expensive. Meanwhile you can more easily pick up HF PA LPF and receive BPF boards.

You should know me and some of my fellow hams are also very interested in this new board. We’ve been doing some work trying to implement simplified GSM on ham bands based on the OsmocomBB software stack, and one of the obstacles was the terminal RF frontend: PA, proper filters and antenna switching… I think this is a step forward in that direction, great to see work being done here.


863-928 mhz would be useful for SRD (max 500 mw/ 27 dbm) in EU & 902-928 MHZ in us (max 1W / 30 dbm).

It is however usually quite close to very strong cellular signals (central bandgap in EU), and i don’t know how big the market is, so i guess it must be prioritized against everything else.

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Yes, there will always be more use cases and it would be possible to widen bands until eventually we just have a wideband RFE with no LPF or BPF… Which actually will be a supported mode of operation :smiley:

Interested by @9a4db’s suggestion of widening out the 2m band branch to cover 110 to 170 MHz, so as to include air/marine/AIS… Any thoughts on this, @VE3DS, @AA7QQ, @martywittrock ?

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