The FX-4L QRP SDR HF transceiver is on order!

This year, I’ve had a couple of readers very kindly offer to loan me their FX-4C transceivers to take to the field and review.

Those offers have been very temping because I’ve only heard positive comments from owners of this wee feature-packed SDR transceiver designed by Yu (BG2FX).

Earlier this year, I learned that Yu was retiring the FX-4C and would be introducing two new radios, so I decided to hold off on an FX-4C review for this reason.

My buddy, Don, informed me that the new radios were now available for pre-order, so I checked out the option on Yu’s website, and placed an order.

Details (features and specs) are still a little sparse because BG2FX is still finalizing the design and lining up production, but here’s a snapshot of the two models based on Yu’s preliminary info:

The FX-4CR

I was very pleased to read that my buddy John (AE5X) has one of these on order.

The FX-4CR can push 15-20 watts on most bands according to John, which is most impressive for a one pound radio that fits in the palm of your hand! It covers 80 – 6 meters, sports a color screen with a 48 kHz wide waterfall display, an internal sound card for digital modes, built-in speaker and microphone, 9 – 18 VDC input range, and even sports Bluetooth!

That’s an impressive array of features for $550 US (on pre-order).

The FX-4L

I pre-ordered the FX-4L and am told by Yu that it should ship by end of October or early November 2022. I wouldn’t be surprised if that’s an optimistic projection.

The FX-4L is essentially a more basic QRP version of the FX-4CR; it’s maximum output power is around 5 watts.

It’s very similar to the FX-4CR in many respects: it has the same display from what I can tell, covers 80 – 6 meters, has a wide voltage range 9 – 18 VDC, sports an internal sound card, and is super compact and lightweight.

The FX-4L doesn’t appear to have Bluetooth. Lu doesn’t mention a built-in speaker or microphone, but there’s an obvious speaker grill and even a small hole that might be a microphone. I’ll try to confirm this. Yu does note that there’s room in the chassis for the user to add a battery or ATU.

I’ve been more interested in the FX-4L because, as you likely know, it’s very rare for me top operate over 5 watts of power.

That said, I certainly see the appeal of a 15W+ radio like the FX-4CR.

(Many thanks to Yu for sharing all of the FX-4L photos above.)

Stay tuned!

I’m really looking forward to checking out the FX-4L and also reading AE5X’s assessment of the FX-4CR.

I’m curious if anyone else has pre-ordered one of these radios. Also, if you’re an FX-4C owner, I’d love to hear your comments!

49 thoughts on “The FX-4L QRP SDR HF transceiver is on order!”

    1. It’s been my experience that in this field radio world, there is no “safe” time to come out. It’s better to just not resist. 🙂 At least, that’s my game plan. Ha ha!

  1. The day seems fast approaching when a tiny sdr: with low draw, long-lasting internal chargeable battery, internal ATU, Bluetooth, 10-80m, touch color display, multimode, keyer, rugged, waterproof, mind-reading, fit in your pocket, gps, rtc, and integrated linewinder, CapKey, with a smarter SIRI, IOS compatible (did I miss anything.) will hit the market… and yes, I will buy the latest, greatest!

    Thomas, you need intervention (Hi, hi!?). And apparently, so do I…

  2. Sounds interesting. Thanks Thomas.

    But you can’t have them all. Or at least I can’t. So I am just going to concentrate on mastering my 705 for now.

    Maybe someday as I have a dream…a dream of a radio that fits in the palm of my hand with an internal battery and ATU so that I can just take the radio and and a piece of wire into the field and play radio.


  3. Good to see the reviews, lets us know what is in the QRP rigs.

    I’ve decided to stay with my IC705 and maybe use my X6100 on accusations just for the fun. I dont think I can do better, can do just as well, but no better.


    73, ron, n9ee

  4. The FX-4L seems interesting for sure.

    It’s current price of $385 makes me right away compare to the Xiegu G90. Of course the G90 is larger and outputs 20W but it’s still plenty portable for POTA and is of a similar price point.

    I’d be interested to see what pros/cons are to going with the FX-4L over the G90. My thought is the G90 would be a better radio for someone looking for their first HF rig and the FX-4L might be for someone who is specifically interested in QRP & portability.

  5. FX-4CR on order and a TR-45L too. My TX500 has been setting in Reno awaiting parts for four months so will see which one arrives first.

  6. Say after me, “Resist, resist, resist, resist, resistance is futile….”.

    Oh no, last week the TR-45, now this…

    Richard M0RGM

    1. I saw your video, Alan. Well done. I am curious though, at that price point, does it do all of the things it can do well, or is it a compromise rig? I’d prefer to have a great CW-only rig than an all-mode rig that performs in a mediocre manner. The 4L and the latest Mountain Topper are similarly priced, yet one seems much more featured than the other. I am not doubting the 4L’s specs, build quality, etc., but you are getting a lot of radio for the money compared to the seemingly modest specs of the Mountain Topper.

      1. I think it does SSB very well – filtering works great, and really good TX audio reports. RX audio is pretty good considering the tiny speaker. For CW, it also works well, with the only complaint being that strong adjacent signals (within 5-10kHz) can cause some overload and AGC pumping. Otherwise, seems to work well with both straight key and iambic (only tested to about 18-20wpm). Not quite full break-in, but close.

  7. I really wanted an FX-4a back in the day, but at the time, LNR had a waiting list, and I had a small windfall, so bought a KX3. I wonder how the rig works for CW? I think I will wait for your review on that. Thanks.

  8. Great writeup Thomas. I have the FX-4C and enjoy it. In fact, I have two of them! I’ve posted up a couple small videos over on the FX-4C Facebook page. Lots of good info there as well on the new radios that Yu is coming out with. A well-known Youtuber has been working with Yu and writing the instruction manuals and that can be found on his webpage which you mentioned. I’m sure he’ll keep working with him on the new rigs as well. Rigs are firmware updateable and Yu has been responsive to adding features as needed. (Maybe that’s why the FX-4C was retired and the new FX-4CR came about).

    Now gota consider letting the NIB FX-4C go to fund the 4L 😉

    72, Todd KH2TJ

  9. Curious to know how usable the display is outdoors in sunlight. Also whether it’s polarized (like my favorite sunglasses, which is not a good thing).

  10. I too am very interested in the FX-4C.
    Yu looks serious in these builds but not very talkative.
    I contacted him for more details on this radio and I got brief answers.
    I would like to see interior photos and a technical description: mixer, filter, quartz, adc dac cpu, ..


  11. Ooh… I’d been on the verge of ordering a Xiegu g106, but the FX-4L with built-in sound card looks interesting as even better value (on specs basis anyway). Xiegu hasn’t got a great reputation for firmware updating, and this designer Yu apparently does better with updates? I’m interested in QRP digital modes. Any suggestions which radio might be the better bet? (I’m only getting one of them!) Thanks in advance.

      1. Thanks, Damian. While many seem happy with the Xiegu G106 when paired with the DE-19, my key aim will be VARA HF for Winlink regional EmCom, so a single device rather than two is my preference, which is why I’m holding out for an FX-…

        The FX4CR is indeed getting nice reviews after the initial fix, and the builder seems really committed to quality. I’m a little concerned it’s a one-man business, but the price is right and if the quality is there, it’s a solid-state device after all. I’m hoping the “baby brother” FX-4L gets released to good reviews soon, as 5W is fine for my goals, and I don’t need the bluetooth feature. So I think I’ll be buying from Yu, it’s just a question of which… and when.

  12. I ordered the FX-4CR about six weeks ago and they were to originally ship mid October. I guess I expected the delay. The whole of China is now off work for one week to celebrate China day I doubt that will help :-). The latest update I got was that the prototype unit has been built but the cases have not been sent from the factory so as yet it has no housing. I believe it started out as 20 -30 watt output and now its a more realistic 15 -20 watts. I like the wide voltage input range and the XT60 connectors as this will suit the 4 cell lipo batteries which are quite inexpensive from Hobby King etc. It will be interesting to see if the blue tooth capabilities are more like the IC-705 or the X6100. Thomas you’ll have to get a blue tooth enabled morse key!

  13. Things I wonder…

    Are the FX4-C available on Ebay “real” BG2FX versions or outside clones? I notice that the pictures of these don’t have backlit buttons so I wonder how representative of the BG2FX radios they are? (I will probably wait for BG2FX website availability, just curious)

    I also notice that the pictures on BG2FX website under FX4-CR are actually of a FX4-C. Will the CR version be the same size and look the same as the FX4-C? The FX4-L pictures look different from the form factor of the FX4-C (one large knob rather than two small ones, holes rather than slits for speaker, white plastic (?) end caps of some sort). What size will this radio be? Will this different cabinet be used on the CR version also? If the manufacturer doesn’t even have a prototype to photograph, how realistic is a October/November timeline?

    I would really like to preorder, but so little info is available on the website as to the actual specs/physical arrangements of the new radios there’s not much info to go on. Considering that (unlike preorder/reserve list nominal fee for the 705 when it was introduced in this country) it appears that the preorder is full price, that’s a lot of “on faith” on the buyers part. Not to disparage Yu, it seems like he is a responsible guy. But maybe things are in a bit of flux…

    Of course, if I don’t preorder and can’t get one for a while after they are available, I will go all coo-coo for Cocoa Puffs 🙂 Ya can’t win…

    BTW, ordered a RGO ONE based on Thomas recommendation, so I am anxious for that, too.

    73, Kevin K3OX

    1. Hello Kevin,

      The FX-4C design is not open-source, so I don’t know of clones exist or not. The back-lighting of the knobs is momentary by default, so it is possible to see pictures of backlighting or not, depending on if the photographer recently hit a button or turned the backlighting on continuously.

      My understanding is that the FX-4CR is essentially an internal hardware update of the FX-4C, so the outside case will look virtually identical. I think he replaced the slide on/off switch with a soft-button power switch. So, the silk-screen and power switch may be the only way to distinguish them physically.

      The FX-4L is designed to be a cost reduced (L = low cost) version of the FX-4C. The display will be different as far as I know. It will roughly the same size as the 4C.

    2. I ref’d the Facebook page a few days ago. Yu has photos of the newer rigs posted and has answered a few questions. One of the questions asked was if CAT control was supported over Bluetooth, to which he answered yes…Also stated he was in the process of writing the firmware…

      Farcebook page here:

      73, Todd KH2TJ

  14. I ordered a FX4-L yesterday and can‘t wait for the delivery..

    Was no easy decision with the provided information.
    Hopefully the L Version will have a Waterfall in the Display as well.

    72 de Alex, DK4FT

  15. Where the hell do you get those side guards from?? I have an FX-4c and would love to get those attachments for more protection on the rig! Anyone? Is it available for 3d printing?

  16. KM9G is now tearing into this rig (FX-4C). Should be interesting. Look for his videos on youtube. Has 5 videos to date…

    72, Todd KH2TJ

  17. My FX-4CR arrived and I am beginning the process of evaluation but so far, despite some idiosyncrasies, it looks pretty good to me. Yu has been working diligently to fix things, but a slight problem is that I don’t think he is an avid on-air operator and doesn’t have the insights that an experienced op would have. But he seems to be quite willing to do what is requested to make the radio usable for us.

  18. Right now, there is no recognizable way to operate split RX/TX. Menu setting 8 is supposed to be split operation, but even with it engaged it’s a no-go. My guess is that Yu might have no real idea what should actually happen in split mode. When you think you might have it set up, the VFO’s net back to transceive when you TX. Yu apparently doesn’t speak English and uses translation software, fine for normal conversation but not so much for tech stuff, so it’s hard to know if and when this will be fixed in any way to allow reasonable split DXing. Just FYI.

  19. I have an FX4-CR with all firmware updates. It works great.
    Have used it with Winlink, Fldigi, and Vara. Trying to get it to work with JS8Call using a Mac with OS Sonoma. Can receive, but Cat control not working. Looking for help. It’s a wonderful rig.

  20. I ordered an FX-4L in September 2022 (expecting delivery in October 2022). In August 2023, we were told that it would be available soon. In April 2024, I contacted Yu to ask about production status. He replied:
    “Yes, it has been too long. [He offered to give a refund.] I will let you know as soon as FX-4L is complete。Because I can’t give you an exact time. I’m going to make some modifications to the FX-4L case. Give up using 3.5 specification data cable. Replace with TYPE-C data cable. I’m contacting another programmer so I can finish programming the FX-4L more quickly,Thank you for waiting patiently for so long.”

    Apparently, some FX-4CR units have been delivered, and Yu has made some improvements to that product. Perhaps the FX-4L will be well refined, if it ever reaches production.

    Is anyone else still waiting?

    1. I had a FX-4CR, but sold it because it was probably fine for SSB, but funky on CW, split operation didn’t work correctly and I mostly operate CW. No one else seemed too concerned about the CW issues, so I bailed. Perhaps eventually all the issues will be sorted and the FX-4L will become available. I think Yu is a good guy, but I think he is just swamped. I hope he works things out.

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