Dave Richards AA7EE

August 29, 2011

A Very Early Look At The CC-20 Beta

A few days ago, a small flat-rate Priority Mail box showed up at my doorstep. It was pretty unassuming but it held great promise, as inside was the beta kit for the Etherkit CC-20 transceiver.  Jason has been working on this transceiver kit for quite a while now, and he’s overcome many challenges but finally, his version has a sensitive and stable receiver (superhet with crystal filter) with a DDS VFO that is rock-solid and free of spurs.  You can follow the fun of the beta-build over at the Etherkit forums.

The day after receiving my beta kit, I set about building it with gusto, but didn’t get very far.  Etherkit is billed as “open source amateur radio” so in the spirit of being open, I guess I should ‘fess up and tell you what I did.

Firstly, let me mention that the boards as received are not the final production boards. There will need to be some modifications made to the traces on the board, so Jason modded our boards for us by cutting some traces and soldering in some wiring so that we could use the PCB’s we had at this stage of the game. He also soldered in the DDS and micro-controller IC’s, as well as the 2 regulator IC’s, and checked that they were working before shipping them to us. All I had to do for the very first stage of building was to solder in a diode, an electrolytic capacitor and the power jack, and then check for 3.3V and 5V at the output of the regulators. Simple eh?

You’d think that a diode for reverse voltage protection would be a safeguard against bozos like me, but as well as connecting the power with the wrong polarity, I also soldered the reverse-voltage protection diode in the wrong way.

It just beggars belief. It really does.  Even I am asking myself why I did that.  The moment I connected the power to the board and saw sparks fly out of both voltage regulators I knew it was all over – at least for the time being.

When I build circuits myself from scratch I get things pretty much right because I am checking the circuit as I go. When I build kits, I don’t have to concentrate quite as hard because the instructions tell me what to do.  The problem is that as a beta tester, I should have reminded myself that although this will be a kit in the near future,  right now it is a beta, and I am expected to proceed carefully, checking myself as I go. Somehow, I convinced myself that I had wired things the correct way and didn’t bother to check the circuit board traces in order to make sure, leading to *poof*!

Rest assured that by the time the CC-20 is a finalized product, Jason will have ensured that the only way you could make a simple mistake like this is if for some odd reason, you really want to.

While waiting for extra parts to arrive, I started putting some thought into what to use for an enclosure. I have some 4″ x 6″ sheets of single-sided PCB material, some in blue and some in red, that I think that would look really nifty, so I laid out the board with the connectors in roughly the positions I envisage they will be. Bear in mind that in the final version, the colored side of the board will be facing outwards with the copper-clad side on the inside:

The red PCB material you see is 4″ x 6″, which should allow for a nice easy fit.  I’m thinking that the case need only be about 1″ high. I’d like to take advantage of the fact that the micro-controller outputs the operating frequency in morse code, allowing for a compact installation without a frequency display. Because the majority of the time I’ll be using it at home, I’ll fit an RCA jack on the back panel with an output to drive an outboard digital dial (probably the N3ZI Digital Dial), so when portable, can take a nice compact transceiver with me.

On the front panel, from left to right, is the AF gain control, the headphone jack, the command button, the frequency button (commands the micro-controller to output the operating frequency in morse code),  and the encoder to control the tuning of the DDS VFO. The back panel has the paddle jack, the antenna jack and the DC power jack. There will also be an RCA jack for an output to a digital dial.

I may even start building the enclosure this week while waiting for parts (possibly a new board) to arrive.

This is going to be one really neat little transceiver.

UPDATE:  The replacement voltage regulators arrived from Jason this morning and I was happy to discover that my misadventures with reverse polarity hadn’t fried the DDS and AVR IC’s.  The build continues!

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6 Comments »

  1. Thanks for the write-up Dave – I’ll be interested in your progress and results. I recently ordered a sheet of clear Lexan and some tools for working with it…for a long time now I’ve wanted to build a QRP rig into a transparent housing so, pending your results with this rig, I may have the candidate.

    Comment by John AE5X — August 29, 2011 @ 3:58 pm | Reply

    • As I think I mentioned John, the final board will look a bit neater than this one. In this one, a few traces have been scored and some extra wiring added in (you can see the blue wire-wrap wire). This is still the pre-production board, though close to what the final one will look like. I think it would really good in a Lexan case. Will keep you posted via this blog.

      Comment by AA7EE — August 29, 2011 @ 4:01 pm | Reply

    • John, would you mind emailing me? milldrum at gmail

      I might have an opportunity for you…

      Comment by Jason Milldrum — August 30, 2011 @ 5:55 am | Reply

  2. This looks FANTASTIC, David!! Keep me in the loop, PLEASE!!!! There is a CQ column that needs writing featuring this rig!!

    Comment by Rich Arland — August 31, 2011 @ 3:14 am | Reply

  3. Hi Dave,

    Would you mind sharing your source of colored PCB blanks? I’ve searched through Ebay without success.

    Thanks ~

    73 – John – ZL1AZS

    Comment by poweredbynature — July 23, 2012 @ 7:28 am | Reply

    • John – the guy’s seller name on the US ebay at http://www.ebay.com is abcfab The last time I bought copper-clad laminate from him was about 6 months ago. I looked the other day and noticed that he only had a very small quantity of blue board, and no red. He does have black, but it is only .03′ thickness. The board I normally use is .06″ which makes for a stout case. It might be worth shooting him a message, as the stuff he supplies is good quality.

      Comment by AA7EE — July 23, 2012 @ 2:27 pm | Reply


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