As a surplus article I bought 2011 relatively cheap an old mechanical filter. It is a Collins F455-21Y with the Collins part number 526-9337-00. An internet search revealed that the filter was installed in the Collins amateur receiver line 75S-x (in the Collins receiver 75S-1 from 1958 - 1962 as FL2 part). The middle frequency is 455 kHz and the 6 dB bandwidth is 2.1 kHz.
Mechanical filters are very interesting components. In principle the filter is a mechanically resonant device which receives electrical energy, converts it into
mechanical vibration, filters out unwanted frequencies, then converts the mechanical vibration back into electrical energy at the output. The conversion is based on the fact that an electrical signal is sent through a coil which contains a magnetostrictive material as the core, the electrical oscillation will be converted into a mechanical oscillation and or vice versa. A proper termination of the filter is essential.
A quick and easy measurement showed that the filter is functional and a nice project for the component I will surely find ...
 filter box |
 F455-21Y filter |
 Mounting angle |
 Filter data |
 Filter curve |
 Quick measure |
 Measurement |
 Functionality |
