The Telewave TWNC-1508-1 Notch Cavity Filter - 148-174 MHz - is a 8” diameter, ¼-wave length notch cavity with an adjustable coupling loop. Notch cavities are often used together with Pass or Pass/Reject cavities 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-1508 cavities cover 148-174 MHz. 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 also feature calibrated adjustable coupling, which can be easily changed to improve selectivity. This allows cavity response to be optimized for any operating environment. 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 ensure 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.