The following information is supplied to our customers in the event they have a technician do a realignment of the WEPIX 2000-B in the future.

The correct way to align the RF stage is to adjust the trimmer capacitors next to each coil so that the birdy marker from the sweep generator is in the valley between the 2 peaks of each output coil. The input coil of the next stage will then look like the scope image on the right.

Start with the coil after the red antenna coil as there is no gain at the antenna coil and it tunes broadly due to the low impedance and tight coupling required for low noise. Do not tune the capacitor near the red coil as it will affect the noise figure.

As you can see the input coil of the next stage "sucks out" the energy of preceeding coil. This amount of  "suck out" is determined by the  coupling between the coils and is fixed. It determines the coupling loss and the  selectivity of the circuit.

Use a one turn wire loop about 3/8" dia, on a 50 Ohm detector probe and place it near the cold end of the each coil to see it on a scope. Use a minimum amount of signal strength at the antenna input or you will saturate the stages and get clipping. If you don't see a valley on each output coil you are clipping.

   
            output of 1st stage                            input of 2nd stage
                             The same is applies for the next stage