Posted by
Kevin Simmons-2 on
Nov 01, 2006; 4:00pm
URL: http://elecraft.85.s1.nabble.com/KX1-KXB3080-Q7-voltages-tp394979.html
While tracking down a low power output after installing the KXB3080 into the
KX1, I was checking the voltages at Q1, Q4, Q5, Q6, and Q7 during transmit into
a dummy load. Page E-6 of the KX1 manual states there should be 0.7VDC at the
base of Q7 during transmit with a KXB30 (not KXB3080) installed. I would get
between -1.5 to -2.7 VDC at the base of Q7 with the KXB3080. I found no mention
of this change in the voltage in the supplied manuals. In fact, looking at the
KXB3080 manual, page 18, figure 15, the circuit around Q7 is not what I have
installed. The diagram shows the base of Q7 connecting to R2, a 1Kohm resistor.
I don't find this change in the procedures. The KX1 manual shows Q7 base
connecting to R28, a 1.8Kohm resistor.
I resolved the low power output issue (yay!) and the voltage at the base of Q7
during transmit is still ~-2.5VDC. The question is "What /should/ the voltage
be?" If it should now be something other than 0.7VDC, then there should be a
reference to that in the KXB3080 manual. Do others think the circuit diagram on
page 18 is inaccurate?
--
Kevin
KF0JX
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