QCX assembly Rev 1.08
129
7.3
Transmitter power output
The transmitter RF power output varies depending on the power supply voltage. It is also
dependent on band. Your results may vary depending on your Low Pass Filter inductor
construction! If the cut-off frequency becomes too low, then you can start to get attenuation at the
operating frequency. In this case you can remove a turn or two from each toroid.
The following charts show the power measurement using the oscilloscope to measure the peak-
peak amplitude across the 50-ohm dummy load.
Operation at output power levels above 5W is NOT recommended, as it will put too much strain on
the BS170 output transistors which may result in failure. For this reason, limiting the supply
voltage to not more than 15 or 16V is recommended.
Note that these measurements do not take into account the D3 1N5819 reverse polarity protection
diode voltage drop (approximately 0.3 or 0.4V). In other words, the measurements were done in a
transceiver with D3 bypassed by a wire link.
Summary of Contents for QCX 5W CW
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