Picked up an R-10A, that's the 520-1500kc receiver from the ARC-12 series. It's in lovely condition and includes a neat 28V dynamotor. In contrast to ARC-5, I can find very little material on the ARC-12. I have a schematic (glad to have that, at least!), but that's all. Would be glad to get pointers to any info. 73, ian K3IMW