Open HT Surgery Gives Cheap Transceiver All-Band Capabilities

Watch out, Baofeng; there’s a new kid on the cheap handy talkie market, and judging by this hardware and firmware upgrade to the Quansheng UV-K5, the radio’s hackability is going to keep amateur radio operators busy for quite a while.

Like the ubiquitous Baofeng line of cheap transceivers, the Quansheng UV-K5 is designed to be a dual-band portable for hams to use on the 2-meter VHF and 70-centimeter UHF bands. While certainly a useful capability, these bands are usually quite range-limited, and generally require fixed repeaters to cover a decent geographic area. For long-range comms you want to be on the high-frequency (HF) bands, and you want modulations other than the FM-only offered by most of the cheap HT radios.

Luckily, there’s a fix for both problems, as [Paul (OM0ET)] outlines in the video below. It’s a two-step process that starts with installing a hardware kit to replace the radio’s stock receiver chip with the much more capable Si4732. The kit includes the chip mounted on a small PCB, a new RF choke, and a bunch of nearly invisible capacitors. The mods are straightforward but would certainly benefit from the help of a microscope, and perhaps a little hot air rework. Once the hardware is installed and the new firmware flashed, you have an HT that can receive signals down to the 20-meter band, with AM and SSB modulations, and a completely redesigned display with all kinds of goodies.

It’s important to note that this is a receive-only modification — you won’t be transmitting on the HF bands with this thing. However, it appears that the firmware allows you to switch back and forth between HF receive and VHF/UHF transceive, so the radio’s stock functionality is still there if you need it. But at $30 for the radio and $12 for the kit, who cares? Having a portable HF receiver could be pretty handy in some situations. This looks like yet another fun hack for this radio; we’ve seen a few recently, including a firmware-only band expansion and even a Trojan that adds a waterfall display and a game of Pong.

Thanks to [KC] for the tip.

29 thoughts on “Open HT Surgery Gives Cheap Transceiver All-Band Capabilities

  1. > It’s important to note that this is a receive-only modification — you won’t be transmitting on the HF bands with this thing.

    It’s still very useful given the unreasonable price of HF full mode capable portable receivers/scanners.
    Having a small receiver that covers a wide spectrum is an important tool in a home lab; Back in the day I spent countless hours with my old scanners (a Black Jaguar first, then a Alinco DJ-x3, both gone now) not just receiving for fun but also testing circuits I built. Does this thing oscillate? How good is the modulation? does it produce nasty harmonics at a given frequency? I need a quick receiver for this and that to test a demodulator for X, or setting it up as a IF+AF to test a converter for other bands, etc. Some of these tasks are indeed best accomplished with an oscilloscope, but in the 80s and 90s RF capable ones were out of reach for young hackers.
    Too bad the mod requires SMT capable hands and equipment, but I can see potential for a business if someone would sell them already modded, or mod them on request, at a good price.

    1. This is exactly what I do as well.
      I use my AR8200 more ofthen than not on SSB to check if clock oscilaltors start and if there is anything weird with their tone.
      With SSB receive UV-K5 now also sometimes fills that role when my AR8200 is elsewhere.
      The spectrum analyzer function available in some UV-K5 firmwares is also very convenient when checking clocks and other RF things.

    2. Could you not just use a ~$75 portable shortwave radio with SSB if you want a HF full-mode capable portable receiver? Granted most of them will not receive FM in the HF bands but that is a very limited niche case.

    1. What is an ISO unit?
      Assuming you mean SI units, they are already there: The 2 m, 70 cm, 20 m mentioned are the wavelengths.

      If what you actually want is frequency, then you’ll need the knowledge that the speed of light is 300E6 m/s, and the ability to do arithmetic.

    1. Both Yaesu and Kenwood both make HTs with wide band receive? Kenwood even does SSB, and the Yaesu at least does AM. Granted I still think most of their products are 20 years behind UI wise, but still.

  2. Nice! There is a link to buy the mod. I ordered two PCB’s. And it go into my ( hopefully not ) list of unfinished projects :)

    Even with the Receive only firmware, I think it’s a great piece of hardware. You can set it listen to a set frequency; while you hunt for active frequencies on your HF Transceiver. Considering the risk of spurious emissions, I won’t transmit on it, with modified firmware.

  3. There are UV-K5 ads on Amazon that claim 20-1000MHz capability, so what’s the difference with this mod?

    BTW, this is part of a comment about one of those radios: “This radio does in fact have the extended frequency range as described excrpt [sic] for one thing the description failed to mention that is this radio will transmit as well as receieve [sic] on all frequencys. [sic]”

    1. From the description of the video:
      “After this mod. you can receieve AM/SSB signals from Long Waves up to 30MHz(CB included)”

      So it goes way lower than 20 MHz after the mod. From around 27 minutes onward on the video you can see 40m reception for yourself.

      It will not transmit on those lower bands, but will work just as a receiver.

        1. The hardware that’s added for those frequencies is an all-in-one receiver chip and wouldn’t have anything to do with whether the original tx hardware could work there. Which it shouldn’t be able to, given that the limits of the txrx were why the extra receiver was added. Unless I’m missing something, of course.

      1. “From the description of the video”

        In the video’s notes at YouTube below the video which I didn’t watch. However, my fault since I just quickly scanned the article and just caught the “HF” part.

  4. “Once the hardware is installed and the new firmware flashed, you have an HT that can receive signals down to the 20-meter band”

    The firmware-only limit is 18MHz, and the 20m band is around 14MHz, so if that were true that wouldn’t be much of an improvement. This 4732 chip is used in cheap shortwave/AM broadcast receivers like the ATS-20, and in those it does NOT stop at 20m but actually is supposed to be able to tune all the way down to longwave (a few hundred kilohertz). Due to not having any strong clean longwave signals to listen to, I can only personally verify that it gets down to the medium wave AM band.

  5. this mod only goes down to 14MHz, i want my radio to go below 500KHz so for HF/shortwave listening i would rather just get a radio that was made for MW/SW with SSB right out of the box,

  6. Transmitting on HF with these modified radios, even firmware only, is a bad idea. Output power is micro watts, and harmonics in police, aircraft and ambulance frequencies are higher power than HF. So do not try transmit using the radios on HF.

  7. Ah, my esteemed listeners, allow me the immense privilege of recounting to you the audacious exploits of those who, in their boundless arrogance and reckless disregard for the law, have seen fit to tamper with their transmitters in defiance of all that is right and proper in the world of amateur radio.

    These scofflaws, these miscreants of the ether, brazenly flout the regulations that we, the noble and upright operators, hold sacred. With their illegal modifications and their insatiable lust for power, they seek to dominate the airwaves, heedless of the chaos and interference they sow in their wake.

    But mark my words, dear friends, for justice will not be denied. The vigilant eyes of the FCC, those guardians of the spectrum, stand ever watchful, ready to mete out swift and severe punishment to those who dare to transgress their hallowed rules. And let us not forget the righteous fury of our fellow operators, those paragons of virtue and rectitude, who will not hesitate to cast out the impure from our midst.

    So let us stand tall, my brethren in the radio fraternity, and condemn these vile transgressors for their wanton acts of defiance. Let us uphold the honour and integrity of our beloved hobby, and strike down those who would seek to tarnish its noble reputation. For we are the keepers of the airwaves, the stewards of the spectrum, and woe unto those who would dare to challenge our authority.

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