Chris Scott & Associates -

AM band Notch filter - Tunable 535 to 1705 kHz

The AM problem solver   Ordering page
low loss or classic filter. The most popular unit is the COMBINED version which has an additional BNC output.  Knob style may vary.

The AM Notch filter is designed to aid emission measurement of AM broadcast stations using a spectrum analyzer or other calibrated receiver.  Accurate measurement of harmonic or spurious levels can be made in the presence of strong fundamental or interfering signals with a spectrum analyzer. Optimal Q makes this possible with negligible insertion loss at harmonic frequencies. 


Other applications include various reception enhancement arrangements where single frequency rejection is desired. One popular use at AM radio stations is to allow AM band EAS reception in the presence of another very strong rf field created by the co-located tower. 

Nominal response at one megahertz is shown below.  The low-loss function is designed to not only prevent spectrum analyzer non-linearities when measuring harmonic frequencies, but  to also be used for NRSC bandwidth measurements, displaying energy below the 70 or 80 db on-screen limit of some spectrum analyzers.  The low-loss mode (output 1) has negligible attenuation at  + - 75 kHz and beyond. 

The Deep Notch (output 2) provides the maximum attenuation. Both the deep notch and the low-loss functions are in the same unit for flexibility.  NRSC bandwidth testing use is covered in more detail in the page:  Breaking the 80 dB barrier. Hundreds of these are currently in use from Asia to Europe; many users email us with kind words. We also offer other related high-pass and low-pass filters here.

Actual two-port measurement at 1000 kHz.

Deep Notch (500 kHz span)

 Low-loss (200 kHz span)

  • Frequency range: .535 - 1.705 MHz
  • impedance: 50 ohms
  • Connectors: BNC
  • Maximum VSWR @ 2F notch: 1.3:1
  • Maximum attenuation @ 2F notch: see measurements
  • Maximum operating level: +30 dBm
  • Minimum Notch depth: see measurements
  • Insertion loss at AM harmonic frequencies: < 1 dB
  • Construction: cast aluminum.
  • Documentation: User guide


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Partial listing of clients and customers

Knob style may vary. Specifications and pricing subject to change
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