re: [3400] NE40-40 Questions


From: Luke Enriquez (
Date: Sat Nov 02 1996 - 04:16:12 EST

>ohms, if my math serves me correctly. At this level, the PA gets very
>warm to the touch after a SLOW 2x2 CQ. Q6 output is not quite
>sinusoidal, somewhat triangular. Filter output is clean sin wave. Is
>this normal?

        Assuming the device is designed properly, check your VSWR as
this will heat up the device. Hot to the touch might just be the
normal operating temperature. Some devices function well up to 150 to
200 deg cel. The final transistor is probably running class-C,
which would explain the triangular waveform. Remembering that a
triangle is just made up of many different sin waves of different
frequencies, the output filter is simply attenuating the "higher"
frequencies. Eventually you end up recovering the sine wave which
is of one particular frequency. Triangle waves are often called
complex signals because of frequency components that make it up.
        One of my personal gripes is when people call an AM envelope
a modulated carrier. If you observed the "carrier" component of an
AM envelope on a spectrum analyser you will see it definantly
doesn't modulate! Once again, the envelope is made up of the
carrier and the sidebands (the sum of them) and it too is a
complex signal.


 Luke Enriquez VK3DLE      	  	   "I only cook with Non-violent   
 3rd Year Electronic Engineering    	    fruit that pulps itself." 
 Latrobe University, Victoria, Australia.

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