Several years ago, I did a friend a favor by providing guidance about
suppressing RFI to the HF installation on her sailboat. As you might
guess, I gave her a bunch of ferrite cores. In appreciation, she gave me
a short length (turned out to be 28 ft) of a so-called "Marine Grade"
coax with an Ankor brand. It had laid on a shelf outside the shack until
I picked it up a few days ago, put a connector on one end, hooked it up
to my VNWA, did a TDR sweep, made 5 MHz to 100 MHz shorted and open
impedance sweeps, and fed them to ZPlots to compute Zo, VF, and
attenuation.
Results were unimpressive, but unsurprising given a physical examination
of the cable. It's labeled RG213, has a flimsy outer jacket that is
easily nicked, a tinned copper braid that's also easily nicked, and what
appears to be a stranded copper-clad steel center! Loss was 0.77dB/100
ft at 10 MHz, VF was 0.669. The outer jacket came to me nicked in one
place (a slice about 0.5 in long), and there was obvious staining from
corrosion of shield that lay beneath it.
The Ankor website describes their RG213 as having a "premium tinned
copper center conductor as well as a tinned copper outer braid for
corrosion resistance and easy soldering. It features signal loss ratios
of up to 50 percent less than other coaxial cables. 96 percent braid
provides best signal strength and least interference with UV inhibited
white jacket for longest life." The website contains no specs.
In fact, loss is significantly greater than ordinary good quality RG8
and RG213 from companies like Belden, Times, and Davis RF, and physical
properties are significantly worse. Amazon sells a 100 ft length for
$95. And they'll sell you Shakespeare-branded gold PL259-knockoffs for
$12.87 EACH! A gold plated barrel (also a knock-off) will set you back
$11.74. Compare with great coax like Buryflex with AWG 9.5 stranded
copper shield, foil plus tinned copper braid shield, and really nice
UV-resistant PE jacket. 100 ft costs you $0.89/ft.
This marine stuff is on the level of the ultra-expensive but useless
stuff sold to high-futility folks!
73, Jim K9YC
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