Radios seem to be locked on frequency

A couple of months ago our supplier of wireless kit didn’t have any 5.8GHz grid antennae. We ended up buying two 5.3GHz 27dBi grids from them and using these grids in a point to point link.

Site 1:
RB433AH, 2 x R52H one of which had the one 27dBi grid.

Site 2:
RB433AH, 3 x R52H one of which had the other 27dBi grid.

Both sites are high sites in a backbone. There’s a lot of noise at site 2. The aerials were designed to work from 5275MHz to 5375MHz. The only bit of clear airspace we could find at site 2 was 5200MHz - 5280 to 5380 is heavily congested. Site 1 is 6km from site 2 and has very little noise.

The link didn’t work properly from the beginning. The best link quality we ever got was around 30%.

Today I collected a pair of nice 30dBi grids, removed the old grids, scanned the frequency range around 5475 to 5725MHz that the aerials are cut for and found a clean frequency. The only problem is that the radios would not lock on the new frequency. I then tried other frequencies and had the same problem over and over again.

Eventually I got the radios to lock on - you guessed it - 5200MHz.

I’m now getting 45-50% throughput.

The aerials are all wrong for the frequency being used, but the radios won’t lock on anything other than 5200MHz.

Do these radios build up a memory?
Is there a way to reset them?

What can I do to get the radios to work on frequencies other than 5200MHz?

The RB433AH at site 2 has two other R52H radios that are also used for point to point links. One blasts out at 5500 MHz and the other blasts out at 5520MHz without any issues.

You may have far too much signal strength for this distance.
I have longer links running at full speed with smaller antennas.
Besides, consider replacing the R52H with R5H - it costs the same and works better.

What is the signal level at both sides?