On Tue,11/24/2015 5:56 PM, Tom W8JI wrote:
Factually, the little bumps or even big bumps on VHF are meaningless
for active problems on lower frequencies. They might predict a
future issue, but on 160 meters even crushing a cable flat for five
feet would be meaningless for receive loss unless the center actually
contacted the shield.
Factually, that is not good analysis. One can use any measurement tool
in multiple ways. If, for example, one is searching for tiny holes the
outer diectric that are letting in water, we must look at the higher
frequencies to see that level of detail. We're not looking for SWR or
loss, we're looking for some sort of mechanical defect that degrades the
cable.
On Tue,11/24/2015 5:56 PM, Tom W8JI wrote:
If I wanted to find the reason for high signal loss on 160, the last
thing I would ever do is look at the system on 150 MHz or even 30
MHz. I would first look at the system down around where the problem
is, or as close as I could to that frequency.
That's because you don't understand FFT analysis. I'm not looking for
the loss, I'm looking for the CAUSE of the loss, and I want to get
within a few inches of it. You CANNOT do that with a low frequency test
signal -- the system does not have sufficient resolution.
73, Jim K9YC
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