This 23cm interdigital bandpass filter was constructed using the available information found in the ARRL Handbook (Year 2005, chapter 12, Fig 12.41). It has an insertion loss of about 0.4dB and 110MHz bandwidth according to the article. 1mm sheet copper was used for the enclosure which was soldered together. The internal “fingers” were made out of aluminum rods. I changed the connectors to SMA and added screws for tuning just in case (the original plan had BNC connectors and no tuning screws). It will be used in the frontend of the 23cm transverter which is under construction.