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Bird - The RF Experts

15-88-12, 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
500 kHz
1 MHz
2 MHz
10 MHz
Attenuation vs Pass to Notch
50 dB @ 500 kHz
70 dB @ 1 MHz
86 dB @ 2 MHz
96 dB @ 10 MHz
Power Rating
300 W
Impedance Ω
1.25:1 max.
Cavity Length - Electrical
Temperature Range
-30 to +60 °C
Cavity Diameter
Number of Cavities
Cavity Height
13" w/ tuning rod extended, 19" max.
Shipping Weight
18 lbs.