• Description

This board provides automatic band switching capabilities for LPF and antenna switches for any
radio rig and amp. The main principle is to count the RF frequency during tuning and use the STM32G CPU
as a frequency counter and switch.

Device works like this:

1. Wait for PTT (GND active) to be activated
2. Once PTT activated, wait for RF to appear
3. Measure incoming RF, AMPL LED lights on a successful measurement
(return to the beginning on any error)
4. Set the output according to measured frequency
5. LPF relay activation 10ms time delay
6. Set output PTT (AMPL, GND active)
7. Wait for PTT to be released
8. Go back to waiting for PTT

Board band plan is

1.8-2.0 MHz               B1
3.5-4.0 MHz               B2
5.33-5.41 MHz           B3
7.0-7.2 MHz               B3
10.10-10.15 MHz       B4
14.00-14.35 MHz       B4
18.068-18.168 MHz   B5
21.0-21.45 MHz         B5
24.89-24.99 MHz       B6
28.0-29.7 MHz           B6
50.0-54.0 MHz           B7
69.0-70.5                    B8

There is B* are board outputs, OPEN DRAIN, GND active

 

•     TECHNICAL SPECIFICATION

Power supply +7-15V, 50mA max
Input RF impedance – >=1 kΩ, can be connected directly to 50 Ohm output
Maximum input frequency – 100 MHz
RF Sensitivity – 3V RMS, it is 0.2W RF power at 50 Ohm load

Maximum RF input – 25V RMS, it is 12.5W RF power at 50 Ohm load

Nominal RF input - 10V RMS, it is 2W RF power at 50 Ohm load

Number of 50V/100mA outputs – 8

Board sizes 60×50 mm