[Elecraft] Tracking Local QRN

[Dale Kretzer]

    I recently uncovered a surprising source of in-house r.f. interference on 40 meters, hindering reception on my beloved K2/100. I had already eliminated such sources as defective touchlamp units, and replaced wall-mounted dimmer switches that are infamous for the static they generate. That left me still contending with a wide, noisy signal about every 10kc across the entire 40 meter band, including 7045 where Kevin conducts the Sunday ECN sessions.
    I grabbed my handy KX1 and a loose coil of wire, clipping it to the antenna input and using it as a direction-finding loop. In no time at all, it led me right to the source of the signal .... our home security system! An oscillator used in the device was radiating strong harmonics throughout the house on all the wires running to the door and window sensors. Talk about a curtain antenna!
    In this case, the cure is expensive because the central monitoring unit is having to be replaced. It was not type-approved by the FCC. The new system is guaranteed not to be a spurious generator on the ham bands.
    I'd never thought of the KX1, or any of the little Elecraft rigs, as an rf interference "sniffer," but they work ideally for that purpose. A properly designed, handheld loop antenna might be required in tougher cases, but give anything handy a try and see what surprises you uncover.
    Happy hunting.
    Dale -K6PJV
    Sacramento, CA.