Wednesday, 12 November 2014

New workbench!

It's about time that I updated this, spare time when you have kids seems in short supply!

I didn't have an area for doing my hobby, but this summer that changed. I have installed a simple workbench in the attic, consisting of two tables form Ikea. I bought one table and then decided that it would be great to have another one to put my Oscilloscope on. I made a small free standing shelf by using a shelf board, along with some adjustable legs, from Ikea. I already had an ESD mat and wristband. I bought an adjustable desk lamp with LED bulb, I find the colour of the light is excellent and the bulb runs very cool. It's nice to have a properly lit work area, the main lighting system uses dichroic bulbs, so I find it very easy to read the colour bands on resistors etc. I find that with traditional incandescent bulbs, it can be very difficult to distinguish the colour bands on resistors.

Despite having limited spare time, I have managed to complete a few projects over the year, although progress was painfully slow at times. Firstly I built a Manhattan style RockMite 40 as a surprise gift for Pete, G4ISJ ( After attending the Blackpool Radio Rally in April, I came home with a RockMite 80 kit (W1REX version) and an OpenQRP 7MHz CW rig kit from Kanga Products, I also commited to building two RockMites for another another ham. I finished the 'customer' RockMites and started to build my OpenQRP and RockMite kits in late spring, but then I put everything away for the summer. I spent my spare time in the summer doing stuff with the family, we had quite a few trips away and had lots of fun chasing the two Lancaster bombers up and down the country on their 2014 Two Lancs Tour. I heard about the Canadian Lancaster's tour of the UK and felt that I could not miss the once in a lifetime opportunity to see two Lancaster bombers flying together in formation.

With the establishment of my new workbench in late summer, I have recently finished a few of my projects. I got my OpenQRP rig working eventually after swapping out some of the components, I battled with VFO drift and problems with the firmware not booting correctly; I replaced the IC socket for the Arduino chip which cured the firmware problem and the drift was cured by replacing a capacitor in the VFO circuit. I finished building my NEQRP NEScaf audio filter which had been lying around since 2013! I also completed a 'customer' build of a Cumbria Designs MicroCode DSP CW reader, and my RockMite 80 was finally wired into it's Zomboids tin this week.

For the last year or so, I've had the ambition of building an SSB rig. I have always been fascinated by contacting hams in the USA, I don't know where this comes from, but it gives me a buzz whenever I manage a contact across the pond. I've had a few contacts across the pond with home built gear (read 'kits'), which I find magical, although I've never managed it with a scratch built rig, this is probably due to the fact that my scratch built rigs work on 30m. I find that for the times I operate, 20m is the best band for US contacts. (I really ought to build a home brew 20m CW rig!). I came up with a personal goal of having a contact with a US station using a scratch built SSB rig.

I have spoken to various hams about my idea and I decided upon the BITX design for my rig. I consulted Bill N2CQR of SolderSmoke podcast fame as he has built a couple of these rigs from scratch. Bill has hooked up with Pete Juliano N6QW for the last few episodes of SolderSmoke and Bill passed my email on to Pete. Pete very soon steered me away from using a traditional VFO for my BITX, suggesting that a DDS VFO would be better. At first I resisted, but I soon came to realise that, as I operate almost entirely from SOTA summits, I'd be using my rig in a VFO hostile environment. I have used my MKARS80 rig a couple of times for SOTA and the VFO tends to drift quite a bit, thankfully Steve, G6ALU the MKARS80 designer, had implemented a very neat solution for this problem in the form of Huff and Puff correction. The Huff and Puff circuit does a very good job at keeping me on frequency.

I have started work on my BITX20, I began by putting together the Arduino controlled DDS VFO, with much help from Pete N6QW (thanks Pete!). I used a cheap Pro Mini Arduino clone board, an AD9850 DDS module from Ebay, and the system drives a neat looking four line LCD display. The original code used in the Arduino was put out by Paul, M0XPD.

I hope to write up my progress with my BITX rig as I go along.

I want to end by expressing my thanks to Pete Juliano, N6QW, Bill Meara, N2CQR and Paul M0XPD who have been great in providing advice, resources and encouragement.

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