Enter up to four transmit frequencies. The tool computes harmonics
(2nd through 5th, configurable), 3rd-order intermod products
(2F1±F2 for every pair), and flags any that land in US amateur
bands.
All math runs in your browser. Nothing is stored.
Transmit frequencies
MHz
MHz
MHz
MHz
Computed products
Enter at least one frequency above.
Trace a birdie
Hearing an unexpected carrier on a quiet band? Type the
frequency, your location, and a search radius. We'll scan
every licensed FM / AM / TV transmitter nearby for any
harmonic (2H to 5H) or 3rd-order intermod (2Fi±Fj) that lands
within ±10 kHz of your target, then rank by likelihood
(high power + close + low order = more likely culprit).
MHz
km
"Ham band hit" means the product frequency lands inside an
FCC-allocated amateur sub-band (160 m through 23 cm in this
calculator). Same-band IMD predicts in-band interference;
harmonics landing in higher bands predict spurious emissions
you'd want to filter. Not modeled: signal bandwidth, modulation
effects, RX front-end overload, antenna directivity.