[time-nuts] Galvanic decoupling of GPS antenna
jimlux at earthlink.net
Fri Jun 18 17:46:48 UTC 2010
Robert Benward wrote:
> Rated for 1400V from CENTER conductor to shield, not shield to the
> outside. If you choose to use RG-58 with 250V on the shield then you
> will need to put the entire cable inside conduit. It is not acceptable
> to have any type of exposed mounting.
Yeah... I've been looking for the jacket rating... As a practical
matter, I've used solid dielectric RG-58 (both A and C flavors) to carry
10kVrms AC (neon sign transformer type voltages). Usually, you don't
get breakdown between center/shield.
However, considering that ordinary PVC insulated hookup wire is rated at
300V, I suspect it's ok.
Obviously, we're talking a transient here.. if you're floating the
shield at 200V above surrounding objects/ground, a better solution is
Interestingly, looking at MIL-C-17 (which covers coax)
There are several requirements for RG-58 (MIL-C-17-28)
Spark test: 5000V rms +10%/-0%
Voltage Withstanding: 5000Vrms +10%/-0%
Corona extinction voltage 1900Vrms minimum
Then, looking at the test procedures in Sec 4.8 of MIL-C-17G
Spark test (4.8.3) A test voltage at a frequency...shall be applied
between the outermost braid or shield and the outer surface of the jacket.
Voltage withstanding (4.8.4) (a) For coaxial cables. The test voltage
shall be applied between the inner and the outer conductor, with the
outer conductor grounded.
Overall.. MIL-C-17 is a great reference on how to test coax (or to ask
your coax supplier about how they test...)
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