mcHF

This site is the home of the mcHF QRP transceiver. It is a small, home-brewed amateur radio project. Firmware is released as open source and most project files are released as well, with the only restriction of not commercial use (manufacturing and sales of kits or complete product).

Looking at the block diagram (Fig1) it should be clear that my design goal was to make it as cheap as possible – without sacrificing functionality – and include the ability to add new features via simple software update.

block_diag    Fig1: mcHF block diagram(click for a larger view)

The choice of architecture is a direct conversion receiver and transmitter, with a small micro-controller to provide control and DSP functions. The analog blocks in this implementation were kept to the bare minimum. Shifting, as much as possible, functionality into the digital domain. Some datasheets with more detailed description of the design concepts of individual blocks are available at the Downloads page.

Features

  • Standalone and compact embedded transceiver
  • Continues RX coverage 2-30 Mhz
  • 5W output power
  • CW, SSB, AM and FM – transmit and receive
  • 300/500 Hz CW and 1.8/2.3 kHz SSB filters with adjustable passband centering
  • 3.6 kHz “wide” filter plus 5, 6, 7.5 or 10 kHz “extra wide” filters for SSB/AM reception
  • SSB/AM Transmit Speech processor
  • DSP noise reduction
  • DSP automatic notch filter
  • Spectrum scope
  • Waterfall Display
  • Highly configurable with a wide variety of menu items

mcHF Kit

It took some two years to the moment i can offer the mcHF in kit form. It consists of two boards with populated SMD parts and extra components supplied in plastic bags. The kit does not include speaker, final MOSFETs and enclosure.

It is worth pointing out that the kit requires some advanced soldering skills and knowledge in electronics as mods might be required. Also extensive tuning and calibration might be needed, or sometimes debugging of problems. It is not recommended as first kit or if you expect to be on the air after few M3 bolts tightening.

72 thoughts on “mcHF

  1. Chuck

    Hi Chris, I just wanted to stop by and say THANK YOU for a quality kit & great design. I have almost completed the kit now, just a couple more components left to mount.
    -Chuck

    Reply
  2. David Finell

    I would gladly have paid a few extra pounds for a couple of extra of each of the caps, resistors, inductors, diodes, and transistors. This might be a good option. I do recognize that there are a few extra components in some of the packs. I am finding that on occasion a component snaps out of my tweezers.

    Reply
    1. m0nka Post author

      Hi David,

      The actual management of putting extra parts, keeping in mind how many components we have in BOM, is a huge task. So we try to add extra components when we can, but is not intentional or managed. Also those components go out of stock constantly with the supplier, so it is not easy to source for each batch anyway.

      73!

      Reply
  3. N7CXI

    Hello, a couple of questions.
    (1) Is there any way to switch an external 160M LPF? I really like the concept of the rig, but as a die-hard 160M user I keep getting stuck on the lack.

    (2) Does the AM TX work at the “extra wide” filter settings, or if not how does that work?

    Thanks!

    Reply
  4. mvs sarma

    Chris,
    Congrats on release of Ver 6.
    Few points for consideration.
    The dc feed thin track , to the power amp, might still be causing interference.
    Secondly , the PTT circuit element using mosFET to switch the opto , I fear, is an overkill. during Rx mode , the gate appears floating,without any termination, picking all sorts of induction.

    I admire removal of LM386 completely.

    regards
    sarma
    vu3zmv
    (i do have the Ver4 boards still to be completed.)

    Reply
  5. Michał

    Hi Chris!
    on question , rfboard 0.5 firs to uiboard 0.4?
    i’m buy second hand mchf , and rf board is in bad condition i think it’s good idea to make new one.
    thansk SQ9MYQ Michal.

    Reply
  6. Josep Mallafre Sala

    Hi Chris.
    Before ( in my 4 equips ) I was loading the DfuSE to prepare the CPU and then with the mcHF manager was loading the corresponding update. Now the thing has changed and I am confused and do not see the sequence clear. I am going to mount 5 º equipment and it wanted to be able do exactly like to prepare the CPU and to load Andreas’s new updates. Where it is explained?
    Thank´s
    Josep
    EA3BDD

    Reply
  7. ahmed METWALLY

    Hello Chris,
    I just placed one kit order , but I missed and used wrong shipping address , I sent you an email to your Paypal email account to explain that with right UK shipping address , please check and reply my email .
    Ahmed

    Reply
  8. Alex RK6AJE

    Hello Chris.
    I’m Alexander. Hamcall RK6AJE.
    I am interested in your development and created a topic on the Russian forum cqham.ru

    http://www.cqham.ru/forum/showthread.php?33633-QRP-SDR-%F2%F0%E0%ED%F1%E8%E2%E5%F0-M0NKA-mcHF

    Forum topic I created for advertising and promotion of your design of the transceiver.

    Unfortunately I do not have the opportunity to buy at once a complete set of the transceiver. But I have an interest in creating a new PCB design and new / different ideas of the front panel. I think to do now is only the receiving part. I have a few critical components from a list of elements. (Processor, LCD, codec, eeprom, etc.)

    Please help save time in the development of new PCB. Send me please the source device circuit in Altium Designer.

    I do not design for commercial profit, but only for his own amusement.

    Reply
    1. m0nka Post author

      Hi Alex,

      Thank you for the interest in the project and making it more popular among Russian hams! I have read the thread as much
      as I can, need to brush up on my Russian, as it is relevant to the 1980s more or less.

      The reason i have not shared the Altium files is because i would like to retain control of the hardware part of the project,
      so any new changes are approved by me, and new software versions work on all revisions of the hardware. Also PCB sales help me
      work on this project full time and add improvements and updates. Releasing the PCB files will result in hundreds of clones and
      incompatible versions.

      Drop me a mail if you want to talk more (djchrismarc@gmail.com).

      73!

      Reply
  9. Kostas

    Nice project! Has anyone investigated the receiver’s sensitivity across the HF spectrum?
    Also, can it transmit outside the ham bands by applying a mod (I am sure it can!)?

    73

    Reply
      1. Dave

        It is a legitimate question for those with intentions for MARS operations. Is it modifiable for out-of-band operations?

        Reply
        1. m0nka Post author

          Hi Dave,

          The project is Open Source, you can re-compile to TX anywhere, as long is not too much outside of the pass band of the filters.

          73!

          Reply
  10. jason

    hi there this seems like a great little kit however i note the full kit is not so full and requires extra parts what exactly is missing and where would be likely places to get them.

    also what is the final output power once built

    kind regards

    73’s

    m3xno

    Reply
    1. m0nka Post author

      Hi Jason,

      The things missing:

      – speaker – removed to reduce weight of the package, can get from Farnell, order code in BOM
      – final MOSFETs – difficult to source in large quantity, can get from reputable ham stores online
      – casing – it is personal preference what type casing to use, most hams prefer fabricating one themselves.

      Output power by design is 5W, but there are mods that allow for slightly more.

      73!

      Reply
  11. Dean Kozel

    Sounds great Chris. I will order tonight and I look forward to becoming part of your technical community.

    73, Dean

    Reply
  12. Dean Kozel

    Please give me an idea of shipping cost to Hawaii so I have no surprise when I order. I look forward to building the kit.

    Respectfully,
    Dean Kozel….KB5HVJ

    Reply
    1. m0nka Post author

      Hi Dean,

      Sorry for the delay in response, i think the hosting was down. Shipping is the same, worldwide – 10 GBP
      for International Recorded Delivery.

      73, Chris

      Reply
    1. m0nka Post author

      Hi Jim,

      This was implemented by Clint, so can’t remember the exact figure, but i am sure it is
      somewhere in the User Guide. I have it on my Downloads page.

      73

      Reply
  13. Alan

    Hi Chris,
    Thanks for your comments. The rig is ver 4 hardware running 219.26.4 firmware.
    I initially thought I had a general issue, but your comments made me go back and take another look at the transients. When I looked at the I2C data and clock lines to the audio codec (at R20, R21 & R22) I found the data was actually sent in the quiet period immediately after the “splat” and before the carrier ramps up as it should, so although my suggestion should have worked it would have been for the wrong reason.
    Also the transient at the start of the sideband transmissions takes a different form in that there are 2 distinct pulses during the first 50mS of transmission giving the blip on the spectrum display.
    The AM and FM modes come up very cleanly but always drop out for 10ms after the first 100ms of transmission.
    These measurements can be made using a scope on C7a and/or C8a on the UI board with a trigger taken from the junction of R13 and R14 (PB1 or PTT in the cct diag), as I have found that the output tracks these signals very closely after all the mixing etc.
    I must admit that I have only the one radio to look at so I have to make sure what I am seeing isn’t because of my soldering.
    Thanks again and 73
    Alan

    Reply
  14. Alan

    McHF Tx Splatter:
    Havng built one of these kits (V4) on behalf of a freind I was examinimg the Tx characteristics when I noticed (initially in CW mode) an 8mS Full Power “Splat” before the transmitter generated a clean signal. This “splat” gives rise to the spike that appears on the spectrum display when keying up in side band mode.
    I traced the source of the “splat” back to the audio codec IC U1 where it appears to be the data signal setting up the codec for the change from Rx to Tx appearing on the LOUT and ROUT lines (pins 12 and 13 respectively).
    I would suggest a simple fix is to delay the switching of the PB1 signal until after the data has been sent to the codec chip instead of before it. All the supply and PTT switching resulting from this signal happens very quickly and is stable by the time a stable carrier is generated, you may get the noise burst appearing on the Rx audio, but at least it isn’t being transmitted at full power (this is irrespective of the power level selected as the power control ccts don’t have time to react).

    Reply
    1. m0nka Post author

      Hi Alan,

      Thanks for your input. I think i have seen somebody reported this issue in the group as well, it might have been you.
      I think this would be very firmware version related. The last time i was playing with the CW function, we were at
      v 0.2 of the boards, and more or less very basic functionality in the code. And i haven’t seen this(or maybe missed it even then?) At this stage, many changes on the boards and firmware extremely bloated. So it is possibly that was introduced later.

      Is this an issue with the reference firmware i provide for download for new users or with the latest builds on Github
      as well ? If the latter, maybe is good idea to post as issue there, as i currently don’t take part in their development.

      73!

      Reply
  15. Claudio

    Hi cris, buying the kit already assembled the firmware is already uploaded and ready to use? I would like to ask you if there are any changes to make because I read in some posts that some hams has made changes after you have finished Assembly. Thank you Claudio iv3alf

    Reply
    1. m0nka Post author

      Hello Claudio,

      I am sorry, but the mcHF is a project, not a complete product. If you need something Plug and Play – best to go for the KX3. As for mods, yes, there are many mods offered by the German ham group, they have it explained on their GitHub page.

      73

      Reply
  16. Kees Talen

    I believe Chris, M0NKA, has really hit the nail on the head with this mcHF project. After 2+ years, there must be quite a qty of these kits out there and the enthusiasm to jump in and make modifications and enhance the code is exceptional and enviable (we started the SDR2GO project a few years ago and handed it off to Dave where it evolved into the STM32-SDR). I would attribute the mcHF success FIRST to Chris’ overall design point and features (and price ….although lower is always better). I even see some hams jumping in to offer very nice CNC machined enclosures. Every contributor has their area of expertise and there are a number of experts out there willing to contribute their time. Fantastic and Thank You.

    As with all new designs, there will be some changes needed …..RF spurs detected, filters which could be better, Amplifier stability, unwanted noise, new TFT displays, better AGC algorithms,etc. In addition to those, there is an additional “wish list” which is a whole lot easier than writing working firmware, and handling fixes has to take priority over it all. I see an excellent rundown by Andreas, DF8OE, on recommended changes for the Rev 4 boards. Is there a similar list for Rev 5 ?. I see that Clint, KA7OEI, is handling some code changes/fixes/upgrades for Rev 4 …. and Rev 5 ? Is he the control point and is there a list of firmware levels ? similar to what Andreas has ?

    I think “many cooks” is great but that can result in multiple directions and is confusing to the rest of us who are new to the project. I would like to see continued and structured support for the mcHF for many more hams to build with the kits and boards offered ……and not have it fade into the ether. Maybe I’m just easily confused.

    With more people wanting to contribute. what is the centralized (hopefully) control structure ? Who does what ? where is that posted ? ….hunting through all the emails does not cut it. …..what design changes are officially recommended, what code is tested and integrated into the latest official release, etc, etc.

    73 Kees K5BCQ

    Reply
    1. m0nka Post author

      Hi Kees,

      Sorry for the late reply! Yes, it is a problem with such projects when they become popular, they got forked left and right, many new people have different ideas. This is why i wanted to keep control over the hardware production, i am very open to implement new ideas and changes, but to a certain point, without loosing the project in the process. Please drop me a mail for more detailed info, this comment section is not the best place (djchrismarc at gmail)

      73, Chris

      Reply
  17. Arnaldo

    Hello,
    I would buy the complete kit of ‘mcHF with payment via paypal.
    what is the procedure? You need to register? or just make payment via paypal?

    when available the mcHF pro?

    Bye
    Arnaldo ‘HJV

    Reply
  18. Adrian Zamfir

    Hi Chris,
    Congratulations for the project!
    I couldn’t find anything about the heatsink dimensions for the final transistors. Please tell me if it can be fitted in the 3D printed case?

    Thank you!
    73 de Adrian, YO3IQI

    Reply
    1. m0nka Post author

      Hello Adrian,

      I am finishing the new 3D case, where everything is different. There are two small alu studs aprox 24x14mm, that transfer heat to two external heatsinks 41x41mm big. Soon will publish all documents.

      73

      Reply
  19. G7NQL

    Hi Chris,
    very interesting project.
    Can you tell me what else is required to complete the full kit ?
    The RF output transistors and anything else ?
    Do you know where these can be purchased (UK/EU) ?

    There is an aluminium case for sale on ebay, 252285831337, for £120. Is it sanctioned by you ? Will it work with v0.5.
    73
    G7NQL

    Reply
    1. m0nka Post author

      Hello, transistors, best from reputable source, like Funk Amateur. Speaker from Farnell, or if you have one in the junk box. Those cases are not from me, I don’t mind them for sale, it is accessory. But i have one like this, needs a bit of modding. Sorry,can’t confirm v 0.5 compatibility, 73!

      Reply
  20. Roberto

    Hello Chris
    I had just send you order for complete kit
    but I had wrong address for delivery.
    My correct address is
    Amadesi Roberto
    Via Punta 5
    48024 Massa Lombarda Italy
    Please chek if all ok or tell me for any problem
    Many thanks
    Roberto

    Reply
  21. DIMITRIS

    Hello Chris

    Please send me the IBAN and SWIFT number for a Bank I pay to your

    My Paypal.. problem to capital control

    DIMITRIS

    Email:sv7boy@yahoo.gr

    Reply
  22. Bob

    Hi Chris,

    I ordered your boards and I am very excited to get to it. I just needed to chime in and say, yeah, I am a 160m guy, and I wish it had that band too.

    Keep up the great work and 73.

    Bob VE3UK

    Reply
    1. m0nka Post author

      It is maybe possible to add via mod of the filters and small software change. Try to post in the Yahoo group, i am sure somebody wanted this as well. 73

      Reply
      1. Bob

        Well, I am no expert but wouldn’t there be more required since the LO Si570 will only go down to 10Mhz? And the Tayloe uses a divide/4 making the lowest frequency 2.5mhz? You would have to divide again requiring more circuitry beyond filters?

        Just curious.

        73
        Bob VE3UK

        Reply
    1. m0nka Post author

      Hello,

      Thanks for the link, looks really impressive work! Those 7 years studying Russian at school were not for nothing. About 160m – few reasons – i have never TX on this band, so not very confident about adding it, then the small RF board – it is cramped as it is – another band means more toroids, two extra relays, etc. I don’t believe i can fit all in such small space ;(

      73, Chris

      Reply
      1. Jim Steelhammer

        I would be interested if I can afford the price!!! (Retired and not much money)
        So I am requesting the cost of this project and does the package include all of the discrete parts except what you have noted so far!( no final transistors and no cabinet!)
        Thanks for your help.
        Cheers,
        Jim
        WA6HAG

        Reply
        1. m0nka Post author

          Hi Jim,

          I understand. Yes, the kit has all parts, except the final MOSFETS, speaker and enclosure. The cheaper option for you would be to get the just the PCBs and buy the parts yourself, i have Farnell BOM on the Downloads page, also US centric BOMs available in the group from colleagues.

          Another saving option is to not fully populate both boards – you can do the UI board, then only the RX path and power supply on the RF board (no filters or relays and tx path).

          Or even cheaper option – get the UI board only, buy parts yourself and populate, then interface to a Softrock board, and use a makeshift power supply.

          73, Chris

          Reply

Leave a Reply

Your email address will not be published. Required fields are marked *