[TowerTalk] 600 Ohm Line

[Jim Brown]

>Pretty much the same here. 600 ohm balanced pair to the house. 

What is coming into the house on a 600 ohm balanced pair?  An RF transmission 
line I would believe. A telco line or audio line I would not. The military surplus field 
telephone transmission line being discussed in conjunction with the Beverage thread 
on the Top Band reflector was cited as being 150 ohms, and someone confirmed 
that with measurements. 

I'm a fairly old guy, and I have never seen a transmission line having a Zo much 
greater than about 150 ohms that wasn't some form of either ladder line or open wire 
line. Virtually all cable used for telco and audio has a Zo on the order of 50-100 
ohms.  Doing the arithmetic for Zo and cable construction shows that it's pretty 
difficult to get a Zo greater than about 200 ohms using anything but open wire line.  A 
careful study of a cable catalog (Belden, for example) will confirm this. 

73,

Jim Brown  K9YC