[G0HZU_JMR]

Yes, Rogers 3010 might be another option. Whatever alternatives are considered they ideally need to be available in the correct PCB thickness and I'm not sure what this is yet. It looks to be about 0.8mm which is about 0.03".

Taconic CER-10 is not the prettiest PCB material. It is a dull cardboard brown colour so not that pleasing on the eye. From memory, the original PCB material in the TR4172 IF1 module is a very glossy/glassy grey or off white colour. It looks expensive...

I had a go at guessing the dimensions of the inner IF1 LPF that sits between the square filter and the IF1 amplifier. See the image below where it is circled in red. I guessed it from the photos and used the outer dimensions of the IF1 enclosure to scale it. It looks like this filter is just under 50mm long. I tried drawing the PCB layout into Genesys and then used Sonnet to analyse the PCB layout. This was based on Taconic CER-10 material with a dielectric constant of 10 and a PCB thickness of 0.030".

The results below are surprisingly good. The simulation shows a LPF with a sharp cutoff at about 2050MHz. The passband ripple is very low so it could be that I've managed to get close to the response of the original design.