I'm ex-Army Signal Corps (1874-1987.) On the modern battlefield EMP is a real concern and the radios were hardened. This would included solid-state as well as the Korean War tube type radios we had. 73, Craig Clark, K1QX RADIOWARE AND RADIO BOOKSTORE PO BOX 209 RINDGE NH 03461 603 899 6957 WWW.RADIO-WARE.COM