Amateur Radio Toolkit is the best app for ham radio hobbyists. It contains many calculators to help you design radios and antennas for all your projects.

Tools:
Q code - A list of common Q codes
92 Code - A list of common 92 codes
RST code - A list of RST codes
Coordinate calculator - Find your latitude and longitude by entering your maidenhead square.
Grid square calculator - Find your maidenhead square by entering your latitude and longitude
Distance calculator - Find the distance between two Maidenhead squares
Unit converter - Convert between units
Location - Find your location
Dipole antenna - Calculate the optimal lengths of a dipole antenna for a given frequency
Vertical antenna - Calculate the optimal lengths of a vertical antenna for a given frequency
Cubical quad antenna - Calculate the optimal lengths of a cubical quad antenna for a given frequency
Inverted Vee antenna - Calculate the optimal lengths of an inverted vee antenna for a given frequency
Ground plane antenna - Calculate the optimal lengths of a ground plane antenna for a given frequency
J pole antenna - Calculate the optimal lengths of a J pole antenna for a given frequency
VSWR - Convert between VSWR, Refection coefficient, return loss and mismatch loss
Three element Yagi antenna - Calculate the optimal lengths of a three-element Yagi antenna for a given frequency
Seven-element Yagi antenna - Calculate the optimal lengths of a seven element Yagi antenna for a given frequency
Wavelength frequency converter - Convert between wavelength and frequency
Air core inductor - Calculate the inductance or lengths of an air core inductor
Low pass filter - Calculate the units of an RC or RL LPF circuit
High pass filter - Calculate the units of an RC or RL HPF circuit
Ohm's law - Convert between voltage, current, resistance and power by entering two
Reactance - Calculate the reactance of a capacitor or inductor
Decibel calculator - Convert between decibel values or calculate dB by entering the power or voltage
Voltage divider - Calculate the output voltage or resistance of one resistor
Resistor Color codes - Find the resistance of a resistor by entering the colors of the bands
Resistors in parallel - Calculate the resistance of resistors in parallel
Resistors in series - Calculate the resistance of resistors in series
Capacitors in parallel - Calculate the capacitance of capacitors in parallel
Capacitors in series - Calculate the capacitance of capacitors in series
Coaxial cable - Calculate the properties of a coaxial cable
Morse code
CW abbreviations
NATO phonetic alphabet

You can upgrade to the Pro version to remove all ads and get the following features:

Half wave coax balun - Calculate the optimal length of a half wave coax balun for a given frequency
Narrowband balun - Calculate the inductance and capacitance of a narrowband balun
Small magnetic loop - Calculate the optimal lengths of a small magnetic loop for a given frequency
Full wave loop antenna - Calculate the optimal lengths of a full wave loop antenna for a given frequency
ERP and EIRP - Calculate and convert ERP and EIRP
RMS voltage - Calculate the RMS voltage
Pi attenuator - Calculate the values of the resistors by entering the attenuation and impedance
T attenuator - Calculate the values of the resistors by entering the attenuation and impedance
Inductors in series - Calculate the inductance of inductors in series
Inductors in parallel - Calculate the inductance of inductors in parallel
Doppler shift - Calculate the Doppler shift

Step 1. Download Amateur Radio Toolkit Mod (Unlocked) APK file on HappyMod.com.
Step 2. Once it's downloaded, open Downloads, tap on the APK file, and tap Yes when prompted.
Step 3.Amateur Radio Toolkit Mod (Unlocked) APK will begin installing on your device. Simple.

Step 1. Download HappyMod APK file on HappyMod.com.
Step 2. Once it's downloaded, open Downloads, tap on the APK file, and tap Yes when prompted.
Step 3.Search Amateur Radio Toolkit Mod, click Download.
Step 4: You can download 100% working mods on HappyMod with one click.