Tuning bandpas filter with thin film dielectric glued on top, what is that material?

[Terminator3]

Long time ago i saw amateur website, where band pass filter tuned a little down in frequency by adding thin film of yellow color above the filter. I tried using pcb dielectric and plastic film from advertisement, but it is difficult to glue. So any suggestions on that material?

 

[edf]

Long time ago i saw amateur website, where band pass filter tuned a little down in frequency by adding thin film of yellow color above the filter. I tried using pcb dielectric and plastic film from advertisement, but it is difficult to glue. So any suggestions on that material?

The thin yellow film was most likely Kapton take.

 

[Terminator3]

Thank you! It is what i am looking for!

 

[biff44]

yeah but kapton tape is not very high dielectric constant. A small piece of ceramic, rtv-ed in the corners, may work better.

also, depending on the filter type, u might get by with adding solder, or even short lengths of wire, to the resonator ends. A solder blob, with its fringing capacitance to ground, will tune a resonator lower in frequency.