From: wa2ise@netcom.com (Robert Casey) COAX TABLE Got out the Belden & Pasternack catalogs. Far as I know, the RG numbers look random. Probably assigned by a clerk in the Pentagon during WW2. Below is a short table of the various coaxes and the more important characteristics. # impedence attenuation per 100' velocity max voltage RMSkv @ 50MHz @ 1GHz RG6U 75 1.5 dB 11 dB 78% (foam) 0.6kv RG8U 52 1.2 9 66 (polyethlene) 5kv RG8U 50 1.1 78 (foam) 0.6 RG8X 50 13.5 2.5 RG11U 75 1.3 9 66 (poly) 5 RG11U 75 1.0 78 (foam) 0.6 RG55B/U 53.5 16.5 1.9 RG58U 53 3.1 20 66 (poly) 1.9kv RG58U 50 3.2 78 (foam) 0.2kv RG59U 73 2.4 11.5 66 (poly) 2.3 RG62U 93 1.9 8.5 84 (air & poly) 0.7kv RG59U 75 2.1 78 (foam) 0.3kv RG71U 93 1.9 8.5 84 (air & poly) 0.7 RG108A/U 78 26.2 1.0 RG122U 50 4.5 29.2 66 (poly) 1.9 RG140U 75 13 2.3 RG141U 50 2.1 13 69 (teflon) 1.9 RG142U 50 2.7 13 69 " 1.9 RG178U 50 10.5 45 69 " 1.0 RG179U 75 8.5 25 69 " 1.2 RG180U 95 4.6 16.5 69 " 1.5 RG187U 75 8.5 25 69 " 1.2 RG188U 50 9.6 30 69 " 1.2 RG196U 50 10.5 45 69 " 1.2 RG303U 50 2.1 13 69 " 1.9 RG302U 75 13 2.3 RG316U 50 9.4 30 69 " 1.2 RG393U 50 7.5 5 RG400U 50 13 1.9 RG401U 50 7.5 (semi rigid) 3 RG402U 50 13 " 2.5 RG405U 50 22 " 2 RG174U 50 6.6 31 66 (poly) 1.5 RG210U 93 3.1 0.75 RG213U 50 1.6 9 66 " 5 RG214U 50 1.6 9 66 " 5 RG217U 50 5.8 7 RG218U 50 3.8 11Kv RG219U 50 3.8 11 RG223U 50 3.1 16.5 66 " 1.9 RG225U 50 7.5 5 RG9U 51 1.6 66 " 5 ethernet 50 1.2 78 (foam) 0.6 22B/U 95 twisted pair 2.1 66 (poly) ? twin lead 300 0.8 <-worse when wet! 80 (poly) ? 8281 75 9.2 2.9 9913 50 4.5 0.6 9914 50 6 0.6 8218 75 20 0.6 these are all the RG#'s I found. The attenuation curves generally follow a straight line when drawn on log-log graph paper. The slope is such that a coax with 2dB at 50Mhz will be 0.8 at 10Mhz. Most coaxes have about the same slope. So, one need only look at the same freq when comparing attenuations when selecting which coax you're gonna use from under the shack table (not strictly true, but close enough for "goverment" work! :-) ). Voltage ratings: note that foam dielectric cannot take as much voltage as solid dielectric. 73 de WA2ISE