It has taken almost 2 years but I finally did a local test on 30 Meters of the modified combo-star radio with a STM32F4 based digital codec board running the last port I could find of Codec2. There is still a lot of work to be done packaging, winding the rest of the filters, and completion of the high power sections. Must of the time was spent on independent projects and assembly of the combo-star was quite a undertaking. Although a hacked combo-star which I’m sure most of them are in the end given the home brew nature, I’ve got something now I can work with that is all integrated. Eventually I’ll even have it in a ready to go box.
After installing my 5 point harnesses it became apparent that the belts were not going to stay put on the rollcage without some assistance. I designed and built (3D Printer) these RZR Harness keeper clamps to fit the RZR S rollbar and hold my harness straps in the correct location. After several revisions this is what I have come up with. Its the perfect size. It looks factory and barely noticeable once on the rzr.
You can barely see the keepers installed and they look factory.
I purchased a HP 5328a counter off ebay for a decent price. It arrived a few days later and I’d say cosmetically its a 9.9/10. After putting it on the bench and turning on the unit I released it didn’t have the oven based oscillator. It did have channel C option and GPIB interface. After checking channel A I was really glad to see that things were working correctly. I moved over to test channel C. All was well I thought until I noticed that the connector on channel C seems to work intermittanly. After pulling the cover off I was pleased to see the unit was very clean inside. I removed the channel C card by taking a single screw out from the rear to remove the top cover. Removing the BNC was just a simple process of removing the nut. After taking the connector apart it was tarnished quite a bit. Some cleaning and I did apply a bit of pressure. After assembly the C channel was working perfectly.
I’ve got a ton of emails about the adapter for the Kenwood TM-D710A. The microphone on this unit uses a digital pulse counter based on 4017 logic IC’s to determine, over a single wire, which key is pressed. This same principle can be use in other projects to read a keypad, control LED’s etc with on a pin or two from a microcontroller. For reference below, are the articles on the TM-710A Adapter and associated projects.
http://www.shaneburrell.com/?p=688 – Keyboard Adapter itself – This board is line powered from the microphone cable. It effectively sits between the Kenwood radio unit and Microphone. It allows you to place a keyboard in between the two to allow functionality that Kenwood never intended per say.
The theory of operation: The microprocessor in the radio head unit sends pulses to the microphone. On each pulse the line is pulled low which the microcontroller spies on via another pin attached to the pulse pin. On a scope, it’s very easy to see the line being pulled low depending on the keypress. In hacking the pulses, its just a matter of seeing what key generates what pattern. In the TM-D710A adapter I used a AVR to talk to the microphone and read a standard keyboard. The One Signal Wire board design above was used to Emulate the mic controlled by the AVR.
Below is a video some Arduino code I initially developed to scan the microphone patterns driving the Kenwood Mic from the AVR. If you look at the scope this should give you a good idea how the pulse counter is working.
The TM-D710A keyboard hack was a really fun project and hit multiple stages of hack/design. The 4017 counter is a pretty neat way of reading/controlling things using on 2 pins from a micro-controller.