Diode Detectors

Many circuits use Germanium 1N34As and or Schottky 1N5711, but will a Si switching diode like a 1N914 (or a 1N4148) work?

Shunt detector is cap(0.1uF) , diode shunt, big resistor (100K), filter cap in shunt (0.1uF)

Series detector is DC block (0.1 uF), 100K shunt, series diode, filter cap shunt(0.1uF)

What about voltage doubler configurations?

 

The note from Wenzel (below) recommends the 1N5711 (small signal Schottky) or Germaniums like 1N60, 1N34, 1N270. Ordinary silicon diodes like the 1N914 haave a 300 mV offset when measuring peak voltage, where as 1N5711 is 100 mV and Ge diodes are 60 mV. Voltage probes read low when measuring large voltages with significant errors measuring voltages below about twice the offset. The note describes a simple DC offset circuit.

1N914 has Max C of 4pF typical 1 pF. Schottky mixer diodes will be less...

Square law response below 100 mV and match is really appalling so people building detectors put pads, etc. Biasing through a several kohm resistor lowers dynamic resistance

What about if you calibrate it, though?

What is the temperature dependency?

 

References:

http://www.wenzel.com/pdffiles/detect.pdf Measuring RF Voltages with a VOM - Wenzel Associates

http://engphys.mcmaster.ca/~elmer101/rfpower/rfpower.html Discussion of measuring RF power,voltage, and current from QRP radios (i.e. Norcal 40)

http://www.qsl.net/ve3mcf/elecraft_reflect/Small_Diode_Notes.txt - descriptions of small diodes from elecraft reflector

radio/diodedet.htm - 14 Jan 2003 - Jim Lux