[TowerTalk] Homage to Ohmage

[Jim Brown]

On 10/21/2021 1:52 PM, KD7JYK DM09 wrote:
> When we had standards, it was 52.  Once standard became "nominal", it 
> was rounded down in print to cover sloppiness/ease in manufacturing.

More likely because Zo and VF of ALL transmission lines vary with 
frequency. It's predicted by the wave equations. Several years ago, I 
measured Zo, VF, and Attenuation vs frequency for all of the 
transmission line types used in the HF transmitting chokes in my 
Cookbook. Harbour Industries MIL-spec RG400, for example, is 52 ohms 
around 1.2 MHz, with VF just below 0.69; at 50 MHz, it's 50 ohms and 0.722.

Here's a tutorial I wrote for guys working in pro audio who thought 
(mistakenly) that long audio cables in performance venues ought to be 
viewed as transmission lines.

http://k9yc.com/TransLines-LowFreq.pdf

73, Jim K9YC