Band-pass filters (BPF)
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UKW Praktika offers band-pass coaxial λ / 4 resonator – filters, for installation between the FM transmitter output and the antenna input.
Their designation is to secure the 108 ÷ 136 MHz frequency range protection, as this frequency range is used by the Air Traffic Management for aeronautics and communications.
These filters are aimed at suppressing the eventual spurious products generated by the transmitter, such as intermodulation, combinational and harmonic frequencies.
FM Transmitters, factory-supplied with such band-pass filters, are not available at the market, that is why they are necessary to be installed additionally.
UKW Praktika produces 2 types of BP resonator-filters - with screw and telescopic adjustment, which are approved by the Communications Regulation Commission (CRC).
UKW Praktika offers 2 models of each type of filters- up to 300 W and up to 1000 W. It is recommended to install two- or three- resonator filters in order to achieve higher technical parameters.
The Communications Regulation Commission uses filters, made by UKW Praktika, mainly for its measuring purposes, which is an attestation for their high quality. |
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Max output power
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up to 300 W |
up to 1000 W |
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Resonators (number)
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1 |
1 |
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Construction type
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screw adjustment / telescopic adj. | screw adjustment / telescopic adj. |
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Frequency range (FR)
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87.5 MHz – 108 MHz | 87.5 MHz – 108 MHz |
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Attenuation in the FR
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- 0.5 dB | - 0.3 dB |
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Frequency range (-3 dB)
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500 KHz | 400 KHz |
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Attenuation (Fo±10MHz)
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< -25 dB ( for 1 resonator) < - 40 dB (for 2 resonators) < - 60 dB (for 3 resonators) |
< -28 dB ( for 1 resonator) < - 45 dB (for 2 resonators) < - 65 dB (for 3 resonators) |
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SWR (at the input)
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< 1.15 | < 1.1 |
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Connector type
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50 Ω | 50 Ω |
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Operating temp.range
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from - 5 ˚ to + 45 ˚ | from - 5 ˚ to + 45 ˚ |