2.
Some simple tools written in
JavaScript for the QRP/SWL HomeBuilder Minimal input error checking.
A. Calculate DC Voltage Divider Bias
Enter Voltage:
Enter R1:
Enter R2:
Bias
voltage =
B. Calculate Inductive Reactance
Enter Inductance in uH:
Enter Freq in MHz:
XL (ohms) = C. Calculate DC Current for a Current
Mirror
Enter VCC:
Enter RC in ohms
Current (mA) =
D. Calculate # of Turns To Obtain a Desired Inductance on a Ferrite Torroid
Enter Inductance in millihenries:
Select Core:
Turns =
The AL for this ferrite core is =
E. Calculate Cut off
Frequency for an RC Low Pass Filter
Enter resistor value in ohms:
Select capacitor values in uF:
3
dB down frequency (Hertz) =
F. Calculate Power in
dBm and mW from Peak to Peak Voltage
Enter measured peak-to-peak voltage into a 50 ohm load:
dBm,
mW
Application Note: This web site follows the EMRFD standard for dBm power measurement.
dBm = the power delivered into a 50 Ohm resistive load which is temporarily substituted at that point in the signal chain.
G. Calculate Lm and Cm For a
Crystal using the G3UUR Method
Enter frequency in MHz written on crystal (series
resonant
frequency):
Enter measured frequency in MHz with switch open:
Enter measured frequency in MHz with switch thrown:
Enter crystal capacitance in pF:
Enter open switch circuit capacitance in pF:
Cm
= femto Farads ,
Lm =
Henries
Supplemental web page for this applet: Crystal
filter measurement and adjustment Link
H. Calculate Decibel Power Gain or Loss from
2 Peak-peak Voltages
Enter voltage 1:
Enter voltage 2
dB
gain or loss =
I. Calculate Decibel Power Gain or Loss from
Input and Output power
Enter input power in watts:
Enter output power in watts
dB
gain or loss =
J. Calculate dBm and mW from RMS Voltage (50 ohms)
Enter RMS voltage
dBm mW
K. Calculate Return Loss and VSWR (50 Ohms
Detector)
Enter the detector signal in pk-pk volts when the unknown port is terminated in
an open circuit:Enter the detector signal in pk-pk volts when the unknown port is
terminated in the unknown impedance:
