delay setting for external filter on 900 ap setup

How do we determine what the seting is if we add a cavity to a 900 ap?
What happens if nothing is entered? Does it affect the max distance setting on the ap by throwing the value off?
We put a txrx filter on a site with paging at 929 and cellular a 894 on the same tower and it seemed to help the re-registering problem with the sm’s 1-2 miles away.

Not Sure I know the answer but am having the same kind of Re-Reg problem. Have a 900 AP and some of the SMs re-Reg like crazy and some are rock solid all the SMs are in the Same small subdiv. and are no more than 2 mile from the tower and in some cases less than a block apart. Some work fine some don’t. What kind of filter did you install? How much did it help?

we bought a txrx filter pretuned to 906 with a 10 meg pass window and notch at 929. It helped with the re-register problem. We are co-located on a tower at 220ft with two other paging transmitters at 929. Our uplink times to the ap increased with the filter. It was about $300

you might also look at they make a tower top amp which is bi directional and includes a cavity filter built in for 900-928. You can use heliax up the tower and keep your ap in the shack where you can fix it easily. It also uses power over coax.