Thursday, February 19, 2026

FX-4CR evolves into a smaller, more QRO radio

From Yu BG2FX:

"A new design (of the FX-4CR) is underway. Thinner volume. Dual-fan cooling. The maximum SSB transmission power is designed to be 50W. The new MCU microcontroller provides more functionality."
 
Yu will also be providing a matching external ATU for the upcoming radio.
 
VFO tuning will be via Up/Down buttons rather than with a traditional rotary encoder in order to reduce the height. 
 
No info yet on a projected release date or price. 
 
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Height comparison: FX4CR vs New Radio

 
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11 March, more photos and commentary from Yu: 

 

The PAs were tested, and those between 80M and 10M all reached the 50W standard without any problems, while the 6M version could reach approximately 10W.
 
It seems that heat dissipation is the primary concern. I'm currently designing a dual-fan system, hoping that the dual fans will provide better cooling.
 
At the same time, the circuit of the PA section was improved again, referencing the circuit design adopted by modern commercial machines.
 
We aim to reduce current consumption while meeting power output requirements.
 
Once the new fan system design is complete, it will be tested again using the new PA board. Meanwhile, the design of the main circuitry (frequency converter and signal processing) is also about to begin.
 
Based on everyone's suggestions, we replaced the buttons with a high-quality mechanical encoder.
 

 
 


 
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14 comments:

  1. This is exciting for sure..

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  2. Very interesting, love to see another compact portable rig! Curious to see what it can do on digital modes, dimensions and weight as it gets completed.

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  4. I'm hoping the CW performance will be improved over early versions of the FX-4CR. Maybe the latter versions of the current radio have better CW performance - I know that F5BUD has written improved firmware that fixed other issues but I've been out of the loop on the FX-4CR for a while now.

    If this one offers good CW performance, I'll definitely be a buyer. I believe POTA is changing what many of us look for in a radio and I'm excited to see where the development of this one goes.

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  5. It's interesting for sure. I think I'd be willing to not have the reduced height in order to get a knob for tuning, even if it 'clicks' instead of a smooth rotary encoder. Push-button tuning just seems so slow and clunky. It's also small enough that I'd give up some of the compactness for an internal tuner.

    I'll certainly be waiting on the sidelines on this one though and if the reports of CW performance are good and the price is reasonable I'll probably have to try one. Hopefully it comes with a nice hard case like the FX-4CR series does.

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    1. Normally I'd prefer a rotary encoder but if the radio is used for a specific application I think I'd be okay with switches. For POTA/SOTA ops, we mostly tune to a frequency and then stay there for the duration. All of KD1JV's designs use this method of tuning, although you can also key in the desired frequency in Morse via the paddles.

      I do wish an ATU could be built-in though. Every time I mention that, someone asks "Why not just use resonant antennas?" Because resonant antennas are less convenient than what I might want to use in a portable scenario.

      73,
      John

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    2. I wonder if the 2 holes between the buttons are for small rotary encoders?

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  6. Am I the only one to be a little sceptical? Safely and reliably running 50W from such a tiny form factor seems like a big ask to me, but I’m here to be proven wrong. There better be excellent protection built in. And I’m certainly not a fine of button-tuning (especially if there’s still no 500Hz step).

    73, Tom, M7MCQ.

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    1. Tom, I must have missed it - I didn't see anything about the tuning step size. Where was that mentioned? I agree with you about 50 watts in a small package, but with fans blowing air constantly from one end to the other...maybe? And that's for SSB, not CW or digital. With SSB's low duty cycle, I think it'll be okay.

      73,
      John

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    2. 500 Hz steps available with F5BUDs FW among tons of other goodies..

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  7. Something you can throw in your pocket without the knobs. Looking forward to it.

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  8. Perhaps an on-board connector could provide for a shaft encoder in parallel with the up/down buttons as a DIY addon?

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  9. I'm ready! I have his FX4CR and I really do love using it on SOTA and POTA outings. 50 watts and this size is astounding!

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