With you set up you have a direct circuit tie from the Receiver to the Ignition Module via the TM1000. You ought to put a UHF scope on that circuit. You would be surprised what is on that circuit. The choke may take out the common mode currents. But depending on the material of the choke and the number of turns through it, various RF signals still made it down my circuit. I tried it several ways. That is why I went to HH's optical RPM coupler. It is made to plug into the ignition module's RPM port. It totally isolates the Receiver and Tm 1000 from the ignition module.