Just had this donated by a guy at work, turns on ok, TX/RX no problem until you've been TXing for 2-3 minutes then radio goes silent on am/fm/ssb. No RX or TX, turn the radio off, leave for 10 minutes, turn back on and radio works fine again. You can listen to the radio without TXing for about 15 minutes before the fault appears again. Seems like something is warming up or possibly overheating. Anyone any ideas about this intermitant fault?