Bandpass filters are used to effectively reduce strong signals outside the operating band. This reduces noise and in-band noise, in a receiver there is a much lower risk of producing unwanted signals in the mixer. This gives better overall reception.
On the transmit side, spurious emission signals are suppressed as well, reducing interference with the neighbouring stations. The 160m high-pass filter reduces all signals below 1700 kHz (medium and long wave band) which in turn reduces the load of strong broadcast stations on the receiver input and leads to better reception.
Bandpass filters are often used at contest stations, for example in Multi/Multi or Multi/2 setups. Built also smaller stations with one operator and two stations (SO2R) can benefit from good filters by reducing the interference between the two radios. Hunt for contest multipliers on one band while transmitting on another band!
The band-filters are constructed with high quality ceramic ATC capacitors, to reduce insertion loss. Also these capacitors allow a higher power handling of 1000 W PEP. The filters have PL sockets (SO-239) and are inserted by using a short coaxial cable right behind the amplifier and before the antenna. Impedance 50 Ω, size incl. PL sockets 125 x 58 x 58mm.
The Competition variants of the bandpass filter have significantly steeper skirts, i.e. much higher attenuation outside the pass band. This is necessary in situations where for example contest stations are located nearby.
The housing is waterproof according to IP66 standard. To prevent internal condensation, an air pressure valve has been installed in the housing. This valve keeps the air pressure inside the housing equal to the air pressure outside the housing.
This valve must not be removed or sealed.
Note: Never use an auto tuner with high rf power when using the band-pass filters. Only use low RF power to auto tune your VSWR, and switch your auto tuner to manual operation before using high power.