The Telewave TWNC-1008-2 Notch Cavity Filter - 88-108 MHz - is dual 8” diameter, ¼-wave length notch cavity with an adjustable coupling loop. Notch cavities are typically used to eliminate a particular frequency, with very low loss outside the notch band. Telewave can also “tilt” the notch response to move a notch very close to a pass frequency without adversely affecting the pass response.
TWNC-1008-2 cavities cover 88-108 MHz, and can be tuned at 50 or 75 ohms upon request. All cavities are tuned to specified frequencies prior to shipping, and no further adjustments should be required. The positive locking mechanism allows for quick field re-tuning if frequency changes become necessary.
These cavities feature calibrated adjustable coupling, which can be easily changed to improve selectivity. This allows cavity response to be optimized for any operating environment. At densely populated sites, the TWNC-1008-2 dual cavity filter provides a deeper notch with minimum insertion loss. Multiple cavities can also provide a wider notch when required. Mounting rails are provided for all multiple-cavity filters.
Excellent frequency stability is achieved by the use of a specially machined compensator and Invar rod. The notch frequency is temperature stable from -30°C to +70°C. Telewave Ground Loop technology places the center conductor of each coupling loop at DC ground potential for lightning protection and noise reduction. Heavy duty materials are used throughout each cavity to insure high performance and long life. Cavity top plates are machined from ¼-inch aluminum, and are heliarc welded to the cavity body at the high current point for improved conductivity and strength. This allows Telewave cavities to handle up to 350 watts, depending on insertion loss. Rigid foam inserts support the tuner assembly allowing vertical or horizontal mounting. Similar metals and alodined aluminum help prevent galvanic corrosion. Silver plated tuners and beryllium copper finger stock provide non-corrosive low loss contact, and ensure reliable, long-term performance.