50 MHz Band pass Filter BPF uses high Q coils and capacitors with Q more than 4000. Low loss of the filter is achieved with careful design and adjustment.

Intended to be used with linear amplifiers 8877, GS35, GS31, 2xGI7B and with other tubes up to 1.5 kW output.

Although this filter is intended to be used as a transmitting filter, its design also allows it to be used as a receiving filter. It can be used before Wide Band LNA with PGA-103+ to protect sensitive device from strong out-of-band signals. 

Low Insertion loss filter is excellent to be placed before any LNA to protect the receiver from HF transmitters in DX expeditions or in multi-multi environment. This BPF will suppress any harmonic on 100 MHz, 150 MHz and more, and it will protect it from HF stations.

 

 

The recorded data on the assembled filter with HP8753ES full 2-port calibrated are presented below.

Measured Return Loss – S11 (CH 1) and Insertion Loss – S21 (CH 2). Characteristics of 50 MHz Bandpass filter for up to 1500 W transmitter.

 

Achieved results on build Band-pass Filter (Attenuation)

HF Band 1.8 MHz 3.5 MHz 7 MHz 14 MHz 21 MHz 28 MHz – 75 dB – 73 dB – 70 dB – 53 dB – 44 dB – 32 dB

Bandwidth: 50 – 51 MHz 50 MHz 50.11 MHz 50.25 MHz 50.5 MHz 51 MHz – 0.11 dB – 0.1 dB – 0.1 dB – 0.1 dB – 0.11 dB

FM attenuation 88 MHz  98 MHz  100 MHz 104 MHz 108 MHz – 39 dB – 49 dB – 46 dB – 44 dB – 43 dB

144 MHz / 432 MHz Band Attenuation 144 MHz 146 MHz 430 MHz 440 MHz – 45 dB – 45 dB – 69 dB  – 70 dB

These excellent results were achieved by careful selection of components and design of the filter. Band Pass filter will eliminate any harmonic emission from your linear amplifier.