I use a Shure PSM 600 wireless monitoring system with my band and have run into the problem several times where when travelling there will be TV interference on the two selectable frequencies on the P6R, rendering it pretty much useless. Is it possible to purchase a crystal (or crystals) for additional frequencies for these units from you, rather then purchasing an entirely new unit?
The PSM600 can be changed to new frequencies by Shure Service. However, once new crystals are installed, the entire system must be realigned (readjusted) to the new crystals. It is not feasible to exchange crystals in the field due to the critical realignment process.
For your needs, it appears the PSM700 system is a better choice as it has 32 selectable frequencies, not just two.