Air band BPF from DD Amtek

Hello,

After posting an article about a cheap BPF for Air band from China, I received few emails asking if I knew of a better filter.

This filter is equipped with BNC connectors and is available for around €20.

Band pass filter for the VHF Air Band prevents overloading of the receiver by interfering signals outside the air-band.

Pass band 112 – 140 MHz

RX only

Insertion loss within passband: 2 dB typ.

Rejection of the range 0 – 100 MHz: min. 40 dB (typ)

Rejection of signals above 155 MHz: min. 40 dB (typ)

Input/output connector: BNC

Input/output impedance: 50 Ohm

Size: 33 × 71 × 18 mm

Weight approx.: 35 g

Here is what you can expect from this unit in reality. Be note that attenuation is lower for about 0.5dB due to connected coaxial test cables and all used adapters as it was not compensated in this case.

Compared to the measured data on the VNA screen, the actual insertion loss within the passband is only 2.1-2.1dB due to non-compensated added test cables and adapters. I did not reach -40dB up to 100MHz or above the 152MHz but in overall, this filter works very well together with my LNA and Diamond vertical antenna on the roof.