After completing my VGA Generator project a while back, I’ve embarked on a new electronics project: building a simple 6502-based homebrew 8-bit computer on a breadboard. There are a bunch of similar projects online from which to draw ideas. Some projects set constraints such as only using contemporary parts of the 8-bit era, no FPGAs, no microcontrollers etc. In my case, I opted instead to keep the constraints minimal and the project simple.
What are you thinking — I am not trying to break any world record? My XYL asked me that question today — why are you building another rig? Followed up by a snide comment that I had so many rigs now why do I need another one. Well the answer plain and simple because I can!
For the longest time in the late 60’s early 70’s my success rate with homebrew SSB transceivers was miserable. At that time I lacked the more sophisticated test gear and let’s face it some of the technology wasn’t that great. Crappy Analog VFO’s were high on the list of impediments! I also had to work and to give a fair share of my time to the family — it is that balance thing.
But today that is all changed –better test gear, better technology like Digital VFO’s and a bit more time. The latest project is to demonstrate that some of the components out of boat anchors can indeed be reworked to provide a very modern, very capable rig.
Having seen the Apache-labs version of the PIHPSDR I wanted to customise it to fill my needs, so I needed to build my own
All the needed information , with the software, is at John Melton’s github site github.com/g0orx/pihpsdr The hardware shopping list includes. RaspberryPi 3, 7″ Official Raspberry Pi LCD, 8 push buttons, 4 rotary encoders, case and power supply.
All the items were mounted in a 12x7x2″ aluminium case obtained from Mouser, The display was held in place with plastic channel finishing strips from B&Q.
I have created a simple 50 Ω dummy load to test transmitters. I also added a simple RF diode detector so I can measure the peak voltage, and calculate the power.
The dummy load consists of eight 100 Ω resistors rated at 2 W so the load should handle 16 W, at least for short periods. I constructed the dummy load using a combination of ugly construction and Manhattan style, by gluing pieces of PCB (as isolation pads) on top of a ground plane PCB. Then I soldered the components directly on the copper without drilling holes.
Several months ago, Georges F6DFZ sent me pictures of a Manhattan project he had just completed, using Rex’s MeSQUARES, and I have waited far too long to share it with you. It began life as a copy of the Ten Tec 1253 regen, but George said that the results and usability were very poor. One thing that must be said about regens is that the ones which don’t work well are very dispiriting. However, when you come across a good design and build it well, the performance can be very satisfying indeed. Luckily, Georges didn’t let his initial regen experience put him off, and he ended up turning the project into a receiver based on the Kitchin-inspired Scout Regen. He normally uses PCB software to design custom boards for his projects, but decided to try Manhattan construction for this receiver.
I like how his project was obviously the result of considerable careful planning
Powerpole voltage and current monitoring is quite nice to have. One can buy commercial meters, but due to the availability of nice and cheap modules, it is very easy to make them oneself.
To the right you’ll see my combined voltage and current meter as well as my volt-meter on top of the power supply.
Today we complete most of the mechanical work and the only item remaining is the RC Filter to turn the Square Waves into Sine Waves for the tune signal. We have had it on the air in the current box as you always worry that even though it worked on the bench there is always a danger it won’t work in the box.
This rig has a lot of soul as some of the boards were used in the 30M CW transceiver and then moved over to the LBS on the bread board and now this radio. The main tuning knob was purchased in St Louis some 20 years ago and now is now controlling the encoder.
Just in case you are wondering this is not a BITX design but does use bilateral amplifiers originally designed by Plessey. The driver stage is from EMRFD and the intermediate bi-directional amp is my own design as is the 40M Band Pass Filter and the microphone amp. The Low Pass Filter is from W3NQN.
I woke up one day eager to build something simple (at least I thought is was simple) and opened up the first chapter in EMRFD and decided to build the 40m direct conversion receiver. I already had most of the components in my junk box. By the way, Experimental Method in RF Design (EMRFD) is the best book about homebrewing amateur radio gear. You should get it if you don`t have it.