Coax Internet Cable: If I have to build one, what am I looking for exactly?

Interesting. As I stated I used a consumer device and all I was hoping for was a close measurement of RFI. The fact that my friend in a different city had RF on his coax line and router indicates interference is finding an entry point somewhere, somehow. With all the RFI around us, some cables have the potential to act like an antenna and I've never seen evidence that coax is capable of this. 

I live in a city rowhome in an old neighborhood where some houses aren't even grounded. Now we have FIOS, new transformers on the block, but my electrician tells me these homes with old wiring can be polluting the mains for each neighbor. I'm giving you some background on the level of noise possible in our mains. I'm only guessing that being in a large city there's some way RFI is entering the cable feed.

Answer to 1. is the Jade ™  FX-Ag Pure Silver Audiophile F-type RJ6 Coaxial Cable.

I took a look and the Jade FX-Ag is a very expensive cable.  It is also listed as using a very small 25 awg conductor, which means that the F-Connector is not a true F-Connector but an adapter that I would assume has a 18awg pin.

For much less money, I would look at the DH Labs D-750 which are available with F-Type connectors.   The cable is also a true RG6 design that uses an 18awg solid-core silver-plated copper conductor.

On true F-Type RG6 cables, the conductor itself is the actual pin that is inserted into the COAX socket.  The "F-Type" connector is just the ground shield and a "screw-on" assembly that holds the cable onto the connection.

On true F-Type RG6 cables, the conductor itself is the actual pin that is inserted into the COAX socket. The "F-Type" connector is just the ground shield and a "screw-on" assembly that holds the cable onto the connection.

The coax cable ground shield is also the current return path back to the source.

That’s why a loose and or corroded F connector connection will have an effect on the signal.

Example: Power flow in a coaxial cable

Note the signal does not flow in either the center conductor or the shield conductor but rather through the space, dielectric, between the two conductors. The signal travels in one direction >>>> from the source to the load in the form of an electromagnetic wave

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Thanks everyone. I went with @jea48 's cable recommendation in the first message: PHAT SATELLITE's solid copper core quad shielded. It was very affordable. In the future, I may play around with pricer cables here, but for now, I'm just eliminating bottlenecks. 

My purpose of looking into internet coax cables in the first place was because I wanted to hide the modem behind the furniture where it couldn't been seen. I made a simple isolation platform composed of a nice looking wood cutting board and some isolation feet by Hudson HiFi. Living room looks just a little nicer without the blinking black box visible (see my profile pic). 

Unfortunately, I can't tell whether the tweaks to the system sounds any different because I let my Qobuz sub go thinking Spotify HiFi would have been out by now. Because the tunes are all lossy, I can't say how meaningful the tweaks have been. 

One thought on streaming from the cloud: it seems plausible that having an internet coax cable with at least a solid copper core and some shielding would make a difference for A/V equipment. But I haven't heard any talk about this from digital HiFi reviewers/influencers. Just like having a dedicated power line is something more and more people are recommending, wiring the house with a coax cable containing a solid copper core could become gospel one day for good digital hygiene.