This simple series-resonant filter/trap is tuned to 2680 KHz, which is twice the 1340 KHz operating frequency of the station.  The photo shows a filter/trap on a bench being readied for service.  Note the wire that connects between the right end of the coil to about 1/3rd of the way in.  That wire shorts the end of the coil to get just the right inductance to resonate the circuit at 2680 KHz in this case. 

Here is a view of the filter/trap being tested using a Delta OIB-3 RF Operating Impedance Bridge and a Delta RG-4 Receiver-Generator on a service bench.  When installed at the client station, the circuit was connected at a 50-ohm point near the main/auxiliary transmitter switch.

Actual component values are determined by the station's operating frequency, t harmonic frequency that needs to be attenuated and power level.

The stories go on and on.  Stop in again sometime.  I'll leave the soldering iron on for you. 
Mark W. Persons   ham W0MH