[TowerTalk] Station interference Stubs

[Jim Brown]

On 2/12/2013 5:24 PM, ai2n at twcny.rr.com wrote:
> I have some Belden 8213 (RG-11, fairly low loss 75 ohm).  Could this coax be used for stubs in a 50 ohm system?

Yes, BUT -- one of the points I tried make in the tutorial on coax and 
stubs is that the higher velocity factor makes the stub longer, which 
cancels out the lower loss of the coax.

8213 is VERY good coax though.  I use it to feed my high 80/40 fan 
dipoles (at 110 ft).  And I used SimSmith and NEC to decide whether to 
use 8213 or a low loss 50 ohm coax. Part of that equation is height -- 
the impedance of most antennas vary with height, as well as the length 
of the line -- since any dipole is mismatched at some frequencies, we 
can choose the line impedance and its length to provide a good match.

73, Jim K9YC