On Wed, Mar 19, 2025 at 02:50 AM, Hans Summers wrote:
There was a report of a blown PA transistor(s) during Calibration. The phase pre-distortion measurement ramps up the PA from near zero to full power in DAC steps of 50. There can be up to 60 points in the vector but for 12V supply typically about 50 points are measured. Each measurement takes about 1.6 seconds (I will explain the technical details, somewhat later, about how I achieved this measurement). Previously there was 10 milliseconds of key-up in between tests. I have now changed that so that for DAC values 1200 and above (corresponding to about 6V PA voltage), a delay is inserted which is equivalent to the DAC value. For example as you get to larger values like 2000 for the DAC, that would cause a 2 second key-down between measurements. This will prevent overheating in the PA transistors.?
Hans,
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For my understanding, did you mean to say there is a "2 second delay between key down?"? I read the above as the transmitter is kept on for 2 seconds.
?
73
Evan
AC9TU
