On Nov 23, 1:07*pm, highlandham wrote:
In the 78 issue there is one as you describe. *The broadband torroid sensors
are about standard in the autotuners and in some radios because they tune up
at low power. *They are small and don't add much inductance. *You might even
build it into a qrp rig and use a multi function meter scrapped out of an
old tape recorder or a led bar graph.

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High intensity LEDs (for example those as used in traffic lights ,225 ea
per light) already light-up at 45 microampere and hence can be directly
used as a reflected power indicator instead of a meter.

Problem is, you don't get any visual output until the 1.6V biases the
LED, much higher than a germanium or silicon detector diode in a
traditional bridge. Some of the high-efficiency LED's are even higher
forward voltage drops, and can exhibit weird visual hysteresis effects
too at low current - meaning that they turn on at some current but
don't turn off until a much lower current.

Many QRP'ers use a clever idea of using an auditory output from the
bridge. For example Fig 7.46 in EMRFD. Works very well in night-time
QRP'ing, and tuning to reduce the squeal is incredibly intuitive.

Tim N3QE