So what ever I use these receivers for, I must use single conversion crystals. Is this right?

I wonder if they are low or high band. I was hoping to us channel 30 and 46. I think both of these channels are high band. I have been doing some research on the single and dual conversion and I understand it more now. I need to know about this high band/low band thing now. Maybe some one can help me determine if the receivers are high or low band. Thanks for all the help!