Gang,
We all know that the RTL parts used in the calibrator are no longer being made. So, if your calibrator in your R4B goes kaput, then you're screwed. This year at the dayton hamvention I talked to Ron, WB4HFN, about the problem and he sent me a broken calibrator board. I needed the dimensions. So, after lots of paper and a few broken pencils, a prototype pcb has been made. Actually, three here made. Same foot print as the original. You have your choice of either 100, 50, or 25 kHZ markers. The marker pulses so you can find it on a crowed band so you're adjusting the dial to the marker instead of a SW broadcast. The pcb will have .100 MTA plug assembly that plugs into the board. It supplies the board with the necessary voltages, ground and output. There is no modification required to the radio, the front panel control will work just as before. A 3.2mHZ crystal is oscillated and divided by a 7 bit ripple counter. You can net the crystal freq with a trimmer on the pcb. There is an on-board regulator to keep the oscillator stable and an adjustment to control the speed of the pulses. This is a prototype board. The next run will have some corrections made and I am going to put in a jumper to select either a pulse output or no pulse (steady) output. The board is a hybrid. It has both through hole and surface mount components. The final cost of the pcb has yet to be determined. I don't know if I will offer it as a kit or fully assembled The surface mount parts are not the ones that look like paint dots, but they are small. If anyone is interested in the remaining two prototypes let me know and I'll assemble and test them. Right now, I don't have an R4B to install one, so will be looking for someone that can write up the procedure on how to install the new calibrator. Mike, WB8VGE Mike Bryce, WB8VGE the heathkit shop SunLight energy systems J e e p o|||||||o
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