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Bird - The RF Experts

15-88-12-DM, 890-960 MHz, Vari-Notch Cavity Filter
The Vari-Notch® design passes a relatively narrow band of frequencies and rejects (notches out) a relatively wide frequency band. Equivalent to a combination series-tuned and parallel-tuned circuit, this filter has a greater notch depth than the Series- Notch® design. The notch depth is adjustable but varies with passband insertion loss (0.3dB or 0.6dB typical) and the difference between pass and notch frequencies. Vari-Notch® is ideal for moderately close to wide separations (400 KHz and greater) in UHF applications.

  • Various Low-Loss High-Rejection Models to choose from.
  • All Loop Plate/connector assemblies are silver-or Alballoy®-plated for low IM.
  • Welded cavity construction and silver-plated tunable probe and loops give superior pass and reject characteristics.

Cascading Filters
All cavity types mentioned above may be cascaded to achieve an arithmetic sum of individual filter attenuation. Up to 6 dB of additional attenuation can be achieved when the proper length of cable is used to interconnect the cavities. (This additional 6 dB does not occur in the filter passband but only at frequencies where moderate to high attenuation occurs.) A TX RX system specialist can assist you in ordering the proper length of interconnecting cable for your frequencies.

Cavity Filters
product specifications:
Item No
Item Name
890-960 MHz, Vari-Notch Cavity Filter
Frequency Range
890-960 MHz
Minimum Separation - Pass to Notch
400 KHz
Frequency Separation
400 kHz
500 kHz
600 kHz
1 MHz
Attenuation vs Pass to Notch
39 dB @ 400 kHz
45 dB @ 500 kHz
50 dB @ 600 kHz
60 dB @ 1 MHz
Power Rating
250 W (400 kHz and 500 kHz)
400 W (600 kHz and 1 MHz)
Impedance Ω
1.25:1 max.
Cavity Length - Electrical
Temperature Range
-30 to +60 °C
Cavity Diameter
Number of Cavities
Cavity Height
17.5" w/ tuning rod extended, 23" max.
Shipping Weight
17 lbs.