Tuesday, August 19, 2014

YAFP - The mcHF SDR HF Transceiver

Those who know me are already familiar with a four-letter acronym that I've used for many years:


Which stands for:


What, exactly the "F" stands for is up to you, but the sentiment is the same, regardless:  Too many fun projects, too little ($#!+) time!

Falling into this category is one that a friend of mine, Brett, N7KG, made me aware of and that is the "mcHF", a small, (relatively) inexpensive SDR-based HF (10 watts, 80-10 meter, SSB-CW) transceiver, based around the STM32F4 processor, designed by U.K. amateur Chris, M0NKA - see the web site:


This radio is definitely NOT a kit.

What you can get from from Chris is:

  • Two circuit boards
  • A full-color TFT LCD display
And from the web site:
  • Documented source code
  • Information on how to use the bootloader
  • Where to get the compiler and the various utilities.
  • Pre-compiled binaries
  • How to compile your own binaries
And that's it!

If you want to build the radio, you must get - on your own - all of the other parts to populate the board - which numbers around 480 or so!  Fortunately, the vast majority of these (numerically speaking) are things like surface-mount resistors and capacitors that are on the order of a penny or two each.

The web site above contains a "BOM" (Bill Of Materials) but for the U.S. amateurs, this is a bit awkward to use as it uses mostly Farnell U.K. part numbers.

Figure 1: 
The boards and LCD supplied by M0NKA.  At the bottom-left is the RF board while
the upper-right is the CPU/User-Interface board.
Other than source code, instructions and some binaries, everything else is up to YOU, including
the case which you must figure out how to get made using someone's 3-D printer!
Click on the picture for a larger version.
For the convenience of others, I've gone through the pains of cross-referencing those parts to Mouser Electronics part numbers (in most cases providing several alternates for the same part) and where the part was not available from Mouser, offered a Digi-Key alternative and some may even be obtained on Ebay:  This alternate Bill of Materials may be found in the "KA7OEI" folder of the FILES section on the M0NKA mcHF Yahoo Group which requires membership access, or you could send an email to me and I could pass it along.  Even if you were to choose not to obtain the parts from Mouser and/or Digi-Key, at least you can figure out the specifications of these parts and figure out what, exactly, they are and where to get them.

There are a few parts, notably the ferrites, RF output transistors that are not available from either Mouser or Digi-Key, and these may be obtained either via Ebay or other suppliers.  There are a few specific parts, however - the 3.5mm connectors for the audio input, output and key connectors and for the DC power connector - that do NOT seem to be available from ANY U.S. supplier and unless one "kludges" alternatives must simply be ordered via Newark/Farnell from their U.K. distributor!

There is some "support" in the form of a Yahoo group mentioned above and some exchange of ideas on the website forum itself, but this is, as they say, open source in terms of both hardware and software.

At the moment the only source of circuit boards is from Chris, M0NKA himself and a set of these, shipped to the U.S. along with an LCD will run about $68 (as of August 2014) - if he has them in stock.  As of this posting he does not currently plan to make the board layout files available, but since the schematic diagrams are published, there's nothing stopping anyone from laying out their own board!

This sort of project is definitely NOT for everyone as this is very far from "plug and play":  The software is a bit rough around the edges and the feature set presently extant is a bit sparse, but it is reportedly functional and open-source and a quick look at the source code reveals that it shouldn't be too terribly hard to add user-interface bells and whistles while the addition of other features like additional audio filter bandwidths shouldn't be too difficult, either.

What would take a bit more work would be the addition of things like DSP noise reduction, other operational modes like AM and FM and the addition of stand-alone support for digital modes like PSK-31, RTTY (to name but two) and the self-copying of CW, for example, although this sort of thing should be possible... in theory...

Where it stands:
Figure 2: 
The box into which the accumulating parts for the
radios are being tossed as they arrive!

Myself, Brett and Bryan, W7CBM are putting together four of these radios between us (I'm building two) and we have almost all of the parts on hand, missing only a few components on the RF board:  Those are on their way from Mouser or from the EvilBay vendor.  Meanwhile, the 3.5mm and power connectors are reportedly on their way from the U.K. at this moment.

The next step - which might be the most difficult of all - will be finding time for the three of us to get together and get these small parts on the board and do some assembly and testing!

As I said before:



This page stolen from ka7oei.blogspot.com

1 comment:

  1. Have you seen this?





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