Topband: Cable shields

[Tom W8JI]

> Tom, I don't doubt that you performed the cable TI measurement correctly
> but I have seen folks take data that is actually the TI of the test 
> fixture
> and not the cables under test.
>
> What TI impedance did you measure?

I can't actually measure it Dave. I have a spare port on my test fixture 
that is identical to the sample port. When I swap my voltmeter over to that 
port and run 1 amp of RF current on the tested cable, it won't lock on the 
signal. When I swap the cable to the spare sample port, and put the meter on 
the original port, it won't lock. My meter locks at 0.2 mV, and I'm 
measuring levels up around 30-40 mV, so I have maybe 30-40 dB of headroom 
for fixture leakage and common mode.

It isn't UHF, it's 160 meters. Groundplanes and shields can be pretty good. 
:-)

73 Tom