Bill, I'm using the RG-8 from the old Holden TAG antenna. It's from the same reel of vintage coax that your 200 feet came from. Hmmm...Jay and I looked at that 200 foot-plus coax up at Deerfield, and the shield looked a little skimpy. Does it look OK to you? BTW - my big 137 kHz loop measures 53 +j1060 at 507 kHz. It's very close to a quarter wave in perimeter. JA