Automatic Band decoder

This is the VK5TM’s design populated for easy implementation.

The main purpose of this circuit is to provide automatic band switching capabilities for LPF to any radio rig. The main principle is RF detection during tuning and use the PIC as a frequency counter and switch. All my tests and experimentation was performed with TINYSA , a NANOVNA or a SARK100 on the high level RF input.

The final implementation i am using the Low level input with a ferrite core . i wrap few turn on the core to achieve a RF sample to the PIC (You need to test according the core you are using)

I have included the following features:

-PTT circuit

-High level RF input (You can tap directly on your low power input from 1 to 5w)

-Low level RF input (a simple tiny antenna is sufficient or few turns on a ferrite core)

-A switch in order to switch the RF level input . I am using a 2P switch with a middle neutral position to cancel any RF input.

https://www.vk5tm.com/homebrew/freq_switch/freq_switch.php

I am using this design with my 30w Mosfet and 300w LDMOS amplifiers. So far this system is working quit well