Consider another is user of
coax these days (though rapidly moving to Cat 5 and
ethernet) -
CCTV. A run of 60 odd metres that you are talking about is not a whole lot for a
CCTV run and they are using the same cables we are talking about here.
Now onto the side threads...
2km is easily doable on 14mm
Triax. The
triax multiplexing is well designed. As distance goes up and you start pushing your bandwidth (which by the way is up around 600 MHz for HD, NOTHING like the couple of MHz of composite), you in order lose
teleprompter, intercom, data,
return viewfinder. The core video is at the lowest frequencies. The other thing about
triax is that you are sending a not insubstantial amount of
power back to the camera to run it. The
CCU normally will up the
voltage as much as needed to keep the camera, up to about 190 volts. It will also
switch between AC and DC as needed. The double shielding helps keep up the bandwidth and RF rejection.
The fibre "
triax" cable ruinexplorer is talking about would be the
SMPTE spec hybrid fibre cable. 2 strands of single mode 9mic fibre and 4 copper wires for
power mostly. Good for 3km at least. MUCH MUCH harder to field repair than
triax.
Composite video behaves like a good analog signal should. It doesn't magically stop like digital, it just degrades.
I don't see what the issues is with mixing RG6 and RG59 unless there are propagation constant issues. They are both 75
ohm coaxes and you'll probably get more loss at the connectors than through cable mismatch. RG58 and RG8 are 50
ohm coaxes, I don't feel like going into the differences again - search it. the
impedance mismatch from 50 to 75 and back again will only be a dB at each
point but it also has the ability to produce reflections which can do nasty things to the
image. RG6 will have less loss than RG59 (There also tend to be different grades of 59 - from those with an actual braided
shield to those that have a marginal
bit of copper for shielding.) If you need a really long run of
coax you could step up to RG11, but I don't think it is needed for this.
There are also the newer grades of
coax - Belden and co make em. I know some of what I've wired in recent months has 4.5 GHz bandwidth. These are also an option and generally a smaller
coax than 59, but you'd have to check the specs for loss per length comparisons.
I would always favour the use of a single run of any cable from A - B especially if it is running anywhere close to the punters - less think for people to fiddle with and barrels will up the cable diameter and
play silly buggers with any mats that might be covering it.
I'm curious what Nick is talking about with making one's own Cat 5
adapter - are you talking about a proper
balun or just connecting 2 wires together?
DMX cabling =
AES cable = the actually look at what
impedance it's coming out as and keep it reasonably close to 110
ohm rather than anywhere between say 90 and 200 for an analog cable. Very acceptable to run analog on a digital grade cable, reverse may or may not work depending on how it's feeling.
Cat 5 - rugged stuff is all well and nice - use with
Ethercon (one will note however that
Ethercon are only rated to 1000 mating cycles). The beauty of Cat 5 is that you can leave it behind rather than spend the time pulling it out... Solid is best for this - better bandwidth and easier to
crimp than stranded. Now if Aviom would redesign their pods to take
Ethercon... Another story for another thread.
It's not designed for bearded computer boffins - it's designed to go in walls and stay there... Stranded is designed for patch leads.
Basically for
one off events, install solid core, terminate it at required length. If it ever gets back to the shop great, if not no great loss.
Wireless - Nick only touched onto it - are we talking consumer 2G4 units? Avoid like the plague. 2G4 is a fickle beast and attenuated nicely by bodies which won't be there in testing but will show up for the gig. Also affected by WiFi and Bluetooth potentially.
Oops, looks like this turned into a Shipesque post...