# Online calculators

## Pi-matching network calculator:

The calculator is designed to calculate a Pi-matching circuit of a transmitter power amplifier. It is assumed that the idle Q-factor of * C1* and

*is much higher than that of the*

**C2***. It is true for most capacitors. Increasing the loaded Q-factor of the Pi-circuit*

**L***, increases harmonic suppression and condensers capacitance (important for high-power electron tubes), but reduces efficiency.*

**Q**_{p}For the output Pi-network of the amplifier:`R1 ≈ Ea / (2.1 • Ia)`

(where** Ea** is a constant voltage and

**is a direct current of the anode), or**

`Ia`

`R1 ≈ (0.9Ea) 2 / 2P`

(where

**is the input power of the matching circuit).**

`P`

In case of input Pi-matching circuit for the power amplifier with a common grid `R2 ≈ 1 / S`

(where ** S** is the gain slope of the electron tube).

To estimate the design requirements for the circuit parts, effective currents in the coil and in the capacitors are calculated. For capacitors, peak voltage and reactive power are also calculated. The peek voltage can increase 2..3 times (depending on the antenna SWR) compared with the exact matching case.

###### Pi-matching network calculator

Original calculator by DL2KQ is the prototype of this calculator.

The calculator has been developed by DL2KQ collaborating with UA3DA UA3SDE and other.