Back in the day, ABC Radio in Tramore used to transmit on 729 Khz. They abandoned this in late 83 / early 84 when the purchase of a new Gates unit was bought into operation on 1026 Khz. The Communicator was being fitted out at this time, very close by in New Ross, so it is possible the tx crystal became available for test purposes if nothing else. A transmission was alleged to have taken place whilst still moored in the ship yard before she sailed for the Thames Estuary. My guess is the frequency was never intended to be permanent but as Paul suggests, just used to prove the project was a viable concept.