el bandido
TNAP-Images
Two things that could cause a 5G C band bandpass filter to quit working are animals and frequency shift. Having a cover for the feedhorn is real important for the bandpass filter. With a lnb, you have wasps and other insect types that like to make nests inside the feedhorn tube. With a bandpass filter, you have a nice, long cavity that would make a cozy place for insects to stay. Anything inside your bandpass filter such as insects will block the signal.
The bandpass filter will have tuning slugs. The frequency of the filter could change if these slugs moved or became loose. We have dro type lnbs that also have a tuning slug for the l.o. frequency. LNB's hardly ever give problems with the l.o. tuning slug moving, but it has happened. It is doubtful the tuning slugs on these bandpass filters will move, but it is possible.
Shown below is a side cover of a filter removed and showing the tuning slugs. It looks like one side of Rick's Alga filter is filled with epoxy to keep the slugs from moving. IMO, that is a cheap way of doing things if that is the case.

https://www.satellites.co.uk/forums/threads/which-c-band-lnb-5g.182040/page-3
The bandpass filter will have tuning slugs. The frequency of the filter could change if these slugs moved or became loose. We have dro type lnbs that also have a tuning slug for the l.o. frequency. LNB's hardly ever give problems with the l.o. tuning slug moving, but it has happened. It is doubtful the tuning slugs on these bandpass filters will move, but it is possible.
Shown below is a side cover of a filter removed and showing the tuning slugs. It looks like one side of Rick's Alga filter is filled with epoxy to keep the slugs from moving. IMO, that is a cheap way of doing things if that is the case.

https://www.satellites.co.uk/forums/threads/which-c-band-lnb-5g.182040/page-3