Thursday, April 30, 2015

The mcHF HF SDR Transceiver - 1


This is one of my current projects still under construction.
I started building it couple of months ago and is still under progress due to limited time availability.

mcHF is a standalone Software Defined Radio designed by a ham from UK, M0NKA (Chris) which is getting popular at an unimaginable pace. Unlike SDRs which requires a computer to operate, mcHF being a standalone SDR doesn't require a computer to operate with. It has its own processor, ADC, DAC etc. It has got a wide coverage all along from 3.5 MHz to 30 MHz and is capable of delivering 10 Watts of output power.

Coming back to the basics of Software Defined Radio, I have seen many getting confused between a Software defined radio and a Software controlled radio.Software controlled radios are nothing but the same analogue radios that we have been used to, but with a digital interface. Software is just used for controlling various functions of the radio. The functions like digital control of VFO, AGC, RF gain, AF gain, LCD display to show the frequency, SWR, power etc are some examples.

But on the other side, the working principle of a Software Defined Radio(SDR) is completely different.Here the software itself has been used to model the radio. In layman's terms, you could say that the building blocks that make a radio are implemented by Software program. Changing this software program can change the working of the radio completely. Say you have a software defined radio built to receive FM signals. You could just change the software inside to make it a AM, SSB or a CW radio without any changes in the hardware.

Most of the SDRs after down converting(some high end SDRs are exception) the receive frequency, they sample the signals i.e. they convert it to digital format consisting of just numbers. Digital wave forms which are nothing but a series of numbers can easily be processed by the processor. After this point, it is pure mathematics which does our job with the help of DSP. All the basic processes inside a normal radio like Mixing, Filtering, Noise reduction etc can be achieved in digital world with out much effort.

back to mcHF :)

mcHF consists of 2 boards, UI Board and RF board. 
The UI board mainly consists of the processor (STM32F04), the codec(WM8731), the TFT LCD (HY28B) and other UI related components. The project is not available as a KIT. As of now, the boards along with the LCD can be bought from Chris(M0NKA), the designer of this radio. Below is the website of M0NKA where the order can be placed.

http://www.m0nka.co.uk/

And the components, in India can be sourced from 

http://in.element14.com/ 

or 

http://kitsnspares.com/

Few parts like the RF Power mosfets, torroids etc will have to be sourced from abroad. Both the boards are SMD double sided boards. Do not fear away from this project all because it is SMD. Both the boards can be assembled using a normal soldering iron following any of the many SMD soldering styles or may be by using a Hot Air soldering iron as I did. There are lots of videos available in Youtube showing different soldering techniques.

I would suggest not to take this project as your first Homebrew Transceiver Project since it is not a plug and play kind of kit. But if you have built any analog radios before, mcHF build will amaze you for sure :).

Below is the YouTube video of my mcHF UI board coming to life few months ago.







Friday, April 17, 2015

Ham radio and me


To introduce myself, I am  an 

Electronics and Communication Engineer by Graduation,
Software Engineer by Profession
and a Ham Radio Homebrewer/Operator by Passion.

I cannot remember when I started loving this amazing thing called Radio. 
If I look back towards my childhood days, during early 90s, I had always been loving radios and I still remember seeing walkie-talkies used by the police used to leave me wonder struck.
I used to dream to possess one of those walkie-talkies. Those were the days when there were no mobile phones and not even in your distant thoughts you could imagine that such a device would come in future to the hands of a common man.

During my childhood days, my uncle who was doing his civil engineering at that time, used to build electronics stuffs like Audio amplifiers and home-theaters. I used to be his assistant while soldering the electronic boards and I enjoyed it.This gave me a lot of exposure to electronic components, soldering and all those basic stuffs. And all these helped me in doing many hobby electronics circuits myself during my school days. Also I had a chance to build many basic AM,FM receivers and transmitters of low power levels during those days.


And this same love towards electronics and radios took me to pursue my Engineering in Electronics and Communication at National Institute Of Technology Calicut (NIT Calicut). 

Engineering provided me a different perspective of electronics, a mathematical one. Considering today's educational system, an electronics hobbyist and electronics engineer are at opposite banks of a river. But the home-brewing activities and the passion for radio circuits helped me bridge the two.

Even though I never kept away from home-brewing or electronics circuits, I could not spent much time for applying and getting a HAM licence during my college days.

Once I started working after completing my graduation, I started spending serious time into home-brewing after office hours and took the time out to get my license and thus became a licensed Amateur Radio Operator with the call sign VU3LTB. Till I got a license, I never got a chance to meet any HAMs in person and it was only me and my circuits. The license gave me a chance to meet and socialize with other Hams.

This being my first blog, I would like to thank my Ham friends who had suggested to start this blog and also  Ham friends who have been encouraging me for my home-brewing activities. I would also like to thank VU2LVJ, VU3CPE, VU2SCE, VU3ARP, VU3MOG, VU3MPK, VU2KBX, VU2SVF, VU2LSW, VU3SMZ, VU3ISJ, VU2UMX, VU2RZA, VU2YNT and the list goes on.


I hope more articles would see light through this blog.