HOMEBREW RADIO 9Y4AR
ANOTHER DIRECT CONVERSION HF SSB TRANSCEIVER
(last update: 26th March 2007)
|PLL VCO||DDS VFO|
|Tayloe Mixer/Detector||Exciter & Receiver Audio|
Over the past five years I have developed an interest in Direct Conversion receivers. Among my recent successful projects are the KK7B MiniR2 and T2 direct conversion kits. These were driven by a PIC stabilized Huff and Puff VFO. I was very impressed with the performance of the receiver and thus I became addicted to the phasing type ssb approach with the direct conversion process. Over the pass several years I have experimented with the first, second, third and even "fourth" method SSB.
Recently, I have been experimenting with the Dan Tayloe N7VE Detector and got some very satisfying results using it as a receive detector. Compared with the diode DBM and other types of mixers it displays good sensitivity and superior large signal handling capability. So impress was I that I decided to build a transceiver using this device.
The parts count of this transceiver is far from being small. As a matter of fact some areas are a bit complex and instead of naming it a direct conversion transceiver which is what it is, I thought a Zero I.F. transceiver might be a more befitting name. What I have presently, is a prototype model on which several modifications have been made over the months. The transceiver is of a modular construction as shown in the General Description. If I wanted to change the audio phase-shift filters, I just need to change that board. Recently, to effect small modifications, instead of rebuilding a module, I just added a small PCB with the additional circuitry, either to the side of the original board or sub-mounted it as a daughter board. The experimentation has been exciting and fun filled as I have gone through several VCO's, PLL configurations etc. What I am presenting here may not be the final issue. However, it works and I am delighted to share my experience at this point in the attached pages. The choice of some components may appear to be a bit odd but they just turned out to be what I had available in the "junk box".
Credits go out to several hams from whom I have borrowed (or stolen) ideas and I thank them for the contributions they have made available both via the Internet and in Amateur Radio related publications.
73's from Arnim Rudder, 9Y4AR
Member: Trinidad & Tobago Amateur Radio Society (TTARS)