© 1999 QRP2000 Design Team
The QRP2000 is a transceiver based on the KK7B R2 single signal direct conversion receiver and it's companion T2 phasing exciter. Using these two modules together with band pass filter, PA and LPF modules from Hands Electronics we aim to produce a CW/SSB transceiver covering all amateur bands from 1.8-30 Mhz. A prime objective is for us to build a high quality radio which any reasonably experienced home constructor can reproduce from easily obtainable parts. Our major contribution is our own design DDS VFO which allows the KK7B modules to be used on more than one band without the complications of changing the RF phasing networks and amplitude balance. We will also be putting effort in integrating the modules from Hands Electronics and Kanga US into a working product.
The first radio I made was George Dobbs's Sudden direct conversion receiver from the Kanga UK kit in 1995. It worked surprisingly well on 20 Meters and sounded so much nicer than a superhet. As a result I became a direct conversion fan. Sometime later I came across Rick Cambell's articles on the R2 and its T2 companion exciter. I began to wonder if a multi band version was possible and thought to give it a try.
Doug Faunt brought me over a set of the excellent Kanga US kits in 1997. I read everything I could get hold of on the R2/T2. All the indications were that multi-banding it would be difficult. As I was pretty new to Amateur Radio and home brewing I had clearly bitten off more than I could chew. So I put the modules in a safe place and built some simpler radios.
Sometime in early 1998 news trickled through to the QRP-L reflector about the AD9850 DDS Synthesiser Chip. Jan Verduyn, G0BBL, and I discussed the possibility of using two of these to produce a VFO for my project. Leon Heller, mean while, was thinking along similar lines. He had obtained some pre mounted AD9850s and sold us two. Jan and I thought some more. We had been thinking about using PICs for ham radio projects for a while. A fellow Trowbridge and District Amateur Radio Club member, Alan Rowe G7PUB, was producing pretty impressive projects using PICs so we brought him a beer and enlisted him into what had become a project team.
After much scratching of heads, drinking of beer and coffee we came up with a plan of campaign. I was to make the R2 board and a chassis, Jan would design the DDS and PIC Hardware and Alan would write the PIC Software. More beer was drunk. We ate large numbers of biscuits (I think they are called cookies in the colonies) drank much coffee and worked pretty hard. By October we had a working multi band R2 with buggy firmware. It took first prize in our clubs Constructors cup. We took it to the GQRP Club's convention at Rochdale where it was well received (pardon the pun) by George and the gang. They were especially impressed by the performance on 40 Meters at night - the acid test for receiver performance. Without any front end filtering there was no sign of overloading - which is more than I can say for my ICOM706Mk2. We also discussed kitting it with Sheldon Hands whilst consuming a huge oriental banquet.
Its now early March. We have spent a lot of effort perfecting the firmware and the DDS design. They are now in a position to be released. We still have work to do on the Band Pass filtering and the transmit side. We will post regular progress reports and design information as it becomes available. Our prototype RX will be on the GQRP Club stand at Dayton for you to see.
For those of you still with me here is a detailed technical specification of the firmware for the DDS VFO. This tells you the most about what we have achieved. It should be enough for you to decide if you want to make one or not. The links section will point you at info on the R2, T2 and Hands Electronics.
Shameless Plug for MPC Data, Bradford on Avon, Wiltshire, UK Alan Rowe, our PIC Guru (or should it be Sensei), is a big wheel at MPC Data. We could not have got as far as we have without the use of their facilities. Also they have the rights to all of the code that Alan cuts however they have agreed that it will be put in the Public Domain rather than charge for it. So, we owe a vote of thanks to MPC Data, check out their web site. if you are interested in high quality developers for Embedded Systems.