Field Strength Meter using MOSFET BF 900

Field Strength Meter is very useful tools for HAM Radio and hobbyist for measuring Power output of Antenna transmitter, such CB Radio, 80 meter transceiver and etc.
For the RF circuit, it is need special soldering and connection between component and grounding also must in good condition, for avoiding wild capacitance. 

For Field strength meter , should be sensitive, that's why we are using RF Mosfet BF900 . The strengthening arrange by Potensio resistor P1, and SW2 switch is selector for choose stride frequency of antenna that want to calibration.

S1 : 480 kHz ... 2.4 MHz (L1)
S2 : 24 kHz...... 12 MHz (L2) , and
S3 : 12 kHz...... 40 MHz (L3)

How to soldering RF Board  and Good Grounding in RF circuit :

Avoiding long wire component on soldering, the short of the leg of component more goods. Avoiding small grounding, 70% of RF board should be grounding, and if there was coil and oscillator, should be covered by aluminium or separated from other active component, so the frequency not change.