Re: V5 Rcv cuts out
If the relay passes only small signals and nothing else, then it must have some kind of contact maintenance current -- even high quality ones need this.
Here is a service bulletin for one of their transceivers needed adding on because they forgot to do this: https://www.qsl.net/wb4kdi/Kenwood/TS-430S/Service%20Bulletins/asb0902.html The bulletin has info on both cleaning the contacts and then setting up the circuit.
The Icom IC-730 also needed a circuit added on for the pre-amp relay which went out too because it switched only small signal and had no maintenace current.
I'm sure such a circuit could be added on to the ubitx if desired.