If you are regarding grounded grid tube amplifiers:
Input Section: Consist of a RC parallel where
1- The capacitance is normally specified in the tube data sheet (Cgk).
2- The catode's resistence is about 20 Ohms for RF triodes.
Use the impedance data above to calculate the matching network. As the Q of the catode impedance is relatively low, it is easy to get a broad impedance matching.
3- Now you mount the matching network in the physical socket of the tube.
For tuning the input matching proceed as foolows:
1- Place the tube in the socket
2- Connect a 20ohms resistor between catode and ground, with a very small leads (or use a short and wide cooper foil).
3- Apply filament to the tube (only filamente te plate voltage should be off).
4- Connect a swepper generator to the input of the matching circuit so that the return loss curve can be measured.
5- Tune the matching circuit, tweking the components to get a return loss between 18 e 20dB across the band of interest.
6- When done take the 20 ohms resistor out. You are ready to begin working in the output stage. What is subject for the next chapter.
I hope this can help somebody!!
NandoPG