KPA500 keyed with no drive

[ANDY DURBIN]

An unexpected shut down of my station PC led to a cascading failure that caused my Arduino station logger to key my KPA500.    I was alerted to the problem by the KPA500 fan running a level 1.  Indicated temperature was 50 deg C.   I estimate that my KPA500 was continuously keyed with no RF drive for about 2 hours.

My system design error was corrected by adding a blocking diode between my Arduino station logger and the KAT500 key line so it won't happen again. (Arduino monitors the state of the key line but pulled it low when it lost power from the USB hub).

My question - Is there any possibility that my KPA500 suffered any harm from being keyed for such a long time with no drive?

73,
Andy, k3wyc
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[ANDY DURBIN]

In one off-line reply I was asked why the temperature rose to 50 deg C.

With a room temperature of about 25 deg C  the temperature of my KPA500 PA module when not keyed runs about 34 deg C.  Measured PA dissipation when keyed with no drive is 40.75 W.    It seems reasonable that 40.75 W could raise the PA module temperature from 34 deg C to the fan 1 trip temperature of 50 deg C.

The irony is that my Arduino data logger records KPA500 temperature at 3 different locations.  Had it been running I would have recorded some interesting data.   However, it was the fact that it lost power that caused the event.   Now, of course, I'm tempted to repeat the event with the logger running.

73,
Andy, k3wyc


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