Apollo 13 tracking question

OK, I'm slightly confused. A while back we had a thread in which it
was stated (I believe) that ground tracking of the CSM was done by the
comms system through active means on the CSM (i.e. the downlink
frequency was linked to the uplink freq. for Doppler, etc.)

So what was the reason for the termination of the urine dumps on 13
after the explosion? For some reason I was under the impression that
the ice crystals were affecting a ground based radar tracking system.

Or am I just misremembering again?

Thanks!

--
Jim
Grasping another opportunity to be wrong!