![]() That inform user can be transmit (LED green ON) or not (LED red ON). Q1 and Q3 is used to control Green and Red external LED. The LM385-2.5V is soldering for VREF ADC converter. One for the ATU and another for the remote control. Here is the equivalent circuit to calculate the attenuator if you want to change the gain.Īnother dedicated printed circuit has been specially designed to facilitate assembly of the Arduino nano. Indeed AD8307 can be measure power lower than 17dbm (50mW). You need to insert -14 dB attenuator between coupler and AD8307. This avoids the use of diodes and one can measure small powers. RF transformer is made with 3 T50-2 side by side and 25 turns (0.6mm wire) If is necessary add some decoupling capacitor on 5V power like the scheme of the MCP23008 IO expander with 5V power supply connected to relay cardĪ dedicated printed circuit has been specially designed to facilitate assembly of the coupler You must add 2 wires to powering 5V to the relays card. #define pcfCRAdr 0x20 //address i2c PCF8574T #define pcfLRAdr 0x38 //address i2c PCF8574AT This expander is easy to use, cheaper, but be careful to the I☬ address #define mcpCRAdr 0x21 Home made expander (distance between J1 and J2 change according to relay models) ![]() #define mcpLRAdr 0x20 //adresse i2c mcp23008 If you want to use another I☬ address, change line in source code here Inductors relays card: J19 2-3 position, address 0x20Ĭapacitors relays card: J19 1-2 position, address 0x21 Take care of J19 jumper position setting the I☬ address. Balun 4/1 on T200-2 and LZHZ inverterĪn OM made with MCP23008 or manufactured modules like PCF8574 expanderġ2V power supply is plugged to both J21 terminal blocks, 5V power supply comes with the I☬ bus. If ATU being used at low power, capacitors voltage is not critical.ĭirectly soldering inductors and capacitors on relay cards, placing the two cards in front of each other, making connections with wires. You can use other toroid models and calculate them with Mini Tore Calculator from DL5SWB for example. Values of inductors and turns depending of toroid for QRP: Values of inductors and turns depending of toroid for QRO: To prevent HF return, you need to weld capacitor on each transistor One is used to switch eight inductors and another to switch eight capacitors (another relay module is high/low impedance switcher and symmetric / asymmetric inverter) QRO tores QRP tores Those relays are enabled at 0 logic Level.ĥV input is used for the optocoupler and led Don’t forget to add capacitors ! They can be found on online merchant sites. They are optocoupled insulated and have screw terminal blocks, reducing cost and assembly time. The trick was to use eight 12V relays manufactured modules for Arduino. Prototyping an ATU is not easy nor cost efficient with spare parts. The L matching network is a classical design in amateur radio. Pcb available mail me : and his RS485 remote CTRL Boards interconnection PCB available in january 2017 Simple protocol between ATU and remote control.Ajustable trigger power (lower than 1W).Balun integrated symmetric and asymmetric output.In addition it can be installed outdoors and controlled remotely by an rs485 link It will not be necessary to spend more than 70$ for an ATU of 100W. For several months I have been thinking about a way to make one around an Arduino and using economic cards. Most of the time the L match circuit is used. However the atu is composed essentially of relays commanding inductors and capacitors. ![]() Generally Automatic Atu are very expensive. Going ham on Ham Rad… dans Raspberry Pi for HAM Radi…
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