mcHF clones from China

So much has happened in the time since I last posted – I have moved house (and workshop), changed employers, etc, etc, and not been in a position to do much SOTA work, but thats ok – At least I have this amazing hobby to keep me happily engaged in technology.

A while ago I brought an interesting SDR HF radio from eBay. It turned out that it was a copy of an awesome project called mcHF, developed by M0NKA. There is a heap of bad press about these radios, as the Chinese distributors simply copied M0NKA’s 0.4 version of his open source project, which is not helpful at all.

I have sent an email to Chris about either purchasing an 0.6 version of his boardset to allow me to contribute to the project, or simply making a ‘licence’ payment to ensure that he benefits from those of us who made an error.

In any case, I have a really neat little radio that is in an unknown state.

What an awesome ‘fixer upper’ 🙂

So – Firstly, Chris identified a couple of problems when he posted about the clones in September 2017;

The sampling capacitors in exciter and detector are not the correct type –
1. (C84, C85, C86, C87) Exciter Farnel 221-1120
2. (C68,C69) Detector Farnel 221-1120
The PA Bias circuit may be incorrect.
The use of Multi Layer inductors in the BPFs was identified as wrong by Chris
1. L1 – 2.2uH Farnel 166-9889
2. L2 – 1uH Farnel 166-9882
3. L3 – 0.47uH Farnel 166-9913
4. L4 – 0.33uH Farnel 166-9911
5. L5 – 4.7uH Farnel 166-9896
6. L6 – 2.2uH Farnel 166-9889
7. L7 – 1uH Farnel 166-9882
8. L8 – 0.68uH Farnel 166-9915
9. L9 – 2.2uH Farnel 166-9889
10. L10 – 1uH Farnel 166-9882
11. L11 – 0.47uH Farnel 166-9913
12. L12 – 0.33uH Farnel 166-9911

I will sweep the Bandass filters before I replace the indicuors so that I can identify how much of an issue the use of incorrect inductors actually was.

In summary, for the next couple of months, I think I will tear down the radio and spend some effort on identifying the changes between what this boardset actually is, and what I need to do to bring it up to spec based on the mcHF errata pages.

I shall keep you updated.