John:

I have just completed some analytic evaluation of the clamping of the PCB generously to the side edge of the Baseplate, as in the revised design shown to you on the E05 60 Module, its new designation.

The model consists of a 80x80mm PCB, with 72x80mm freely hanging away from the Baseplate. One model uses only a single 1.4mil copper ground plane layer and has the IC mounted 52mm from the clamped PCB to the Baseplate. The second model uses a dual 1.4mil copper ground plane and has the IC mounted 20mm from the clamped PCB to the Baseplate.

I ran a series of four power levels in the IC, 0.25W, 0.50W, 0.75W, and 1.00W. The IC temperatures are fairly linear with power for each case. In the first case with the IC mounted pretty far away, 1.00W of power caused a temperature rise of 38.4°C above a 20°C Baseplate and enclosure. For the more closely mounted IC, the temperature rise for the 1.00W case is 28.6°C above the 20°C of the Baseplate.

You can detect that the temperature rise does not seem to be very linear with the distance from the Baseplate. As this data is still quite new for me, I do not have an explanation for this effect. I did, however, want to make you aware of the data so that you can start to plan to see what you can do in the URx redesign. I plan to do some variations on these two cases to try to understand the processes more completely. I do, however, have to wrap up this data process so that I can complete my presentation in Pittsburgh.

I hope that this information will be of use to you.

’73, Dick Jansson, KD1K mailto:kd1k@amsat.org kd1k@amsat.org mailto:kd1k@arrl.net kd1k@arrl.net