The PKI 4250 Handheld Non-Linear Junction Detector is designed to detect various kinds of electronic devices containing semiconductor elements. Flooding of suspected areas or targets with spectrally pure microwave RF signals locate eavesdropping devices, microphone amplifiers, audio recorders etc. – both in switched-on and switched-off mode. Analysing both 2nd and 3rd harmonics returned and varying on the materials with the different metallic junctions and semiconductor junctions return, gives the operator a clear indication of the source of any reflected signal. Due to the use of different formats of modulation for fundamental signals there is a possibility not only to detect radio transmitting devices, but also to define their types by listening to them.

The PKI 4250 Handheld Non-Linear Junction Detector provides perfect characteristics for counter surveillance operations:
• Uses advanced technologies and materials, ergonomic design
• operates in hard-to-find places and under limited space conditions due to low antenna thickness not exceeding 18 mm
• both pulse and CW operation modes
• high detection capability (it is highly competitive to the best conventional NLJDs)
• listens to the envelope detector output as well as to the level of the received signal of the 2nd and 3rd harmonics via a built-in loudspeaker and wireless head phones
• automatic and manual modes of the probing signal power control
• easy-to-use, optionally used as an inspection tool
• light-weight and compact size