RG-59

[agentgates]

Hello Everyone,

I just bought a 100m reel of RG-59 cables marked as "mini" (⌀4mm), that I was going to use for CCTV. Unfortunately the external diameter is smaller than what my BNC plugs could accept (⌀5.35mm).

What would be the best solution:
1. Buying some BNC crimp connectors for ⌀4mm coax and use the RG-59 for the video?
2. Buying a larger diameter coax for the BNC crimp connectors and keep the RG-59 for a later project: the audio signal from the cameras? Is the RG-59 good for this type of audio application?

Many thanks in advance.

 

[leadbelly]

If it were me I would just buy a used reel of RG-6. At least they are common locally; a homeowner or tradesperson buys a whole reel, uses it for their project, and sells the remaining quantity for a big discount.

 

[duncan2]

A somebody having 3 large satellite dishes with reception to Europe and elsewhere and expensive 3 input satellite box I use F connectors .


RG6 is the standard ( low cost ) coax but as I have a long run I use expensive very low loss -double shielded coax.


I also have special BNC plugs with internal screwing so you insert the cable and turn the coax to grip the outer edge of the cable so it is less than 5.35mm which is the same diameter as F connectors and yes 4mm would fit through the hole.

 

[MarcelvdG]

Assuming the CCTV signal is old-fashioned composite video (frequencies up to 5 MHz) and the cables are not longer than 40 m, I expect RG-59 to work fine for both video and audio.

 

[agentgates]

Assuming the CCTV signal is old-fashioned composite video (frequencies up to 5 MHz) and the cables are not longer than 40 m, I expect RG-59 to work fine for both video and audio.

Thanks for the advice. The CCTV uses 1080p AHD or TVI (depends on the camera). I doubt 5MHz would cover that. The audio will be a separate cable.

 

[Mark Tillotson]

I think you'll find its copper-clad steel, suitable for UHF and above, not so good for baseband.

 

[MarcelvdG]

RG-59 is far too lossy at UHF and above, unless the cable is very short.

 

[agentgates]

Thanks for the help, guys. I think I will buy the proper cable for the video signal and I'll use the RG-59 for the audio.

 

[Speedskater]

Note that some RG-6 and RG-59 coax cables are optimized for UHF and CCTV frequencies, while other RG-6 & RG-59 cables are optimized for low frequencies and are suitable for audio interconnects.

 

[MarcelvdG]

Maybe I'm overlooking something, but as long as you don't care about the minuscule amount of extra distortion that you could get due to the iron core, I can't think of anything that would make a 75 ohm coaxial cable unsuitable for microphone or line level audio.

 

[Mark Tillotson]

RG-59 is far too lossy at UHF and above, unless the cable is very short.

Mini coax is for inside a unit, not antenna feeds.

 

[Speedskater]

Only RG-59 cables that are optimized for UHF and CCTV frequencies have Copper Clad Steel (CCS) center conductors and they are not lossy at UHF frequencies.

 

[duncan2]

RG_59.pdf


Not a cable I would even consider for use with my satellite systems.


Notice the much less loss of the expensive braid+foil which I use which after 30 years of satellite involvement is well worth paying the extra for especially in bad weather where not only dish size makes a difference but the amount of loss in a long cable .


Please be aware I am NOT talking of a 20 feet run of cable for a normal entertainment set up but a longer run to pick up weaker satellite signals.


Its not just the signal strength that counts a lot but the QUALITY of that digital signal.
Good signal /bad quality= NO signal.


Coaxial Cable Specifications Cables Chart - RF Cafe

 

[MarcelvdG]

That makes sense because of the effect of the cable losses on the noise figure/noise temperature. The IF of a satellite television receiver is usually in the hundreds of megahertz range, where RG-59 is rather lossy. The cable losses have thermal noise associated with them at the cable temperature and they aggravate the effect of the noise of the satellite receiver (I mean the IF part), while the noise temperature of the antenna is very low because it is in radiation contact with outer space. That is, depending on the gain of the LNB and the noise figure of the receiver, you probably won't need much cable loss to substantially reduce the signal to noise ratio.

Friis formulas for noise - Wikipedia

I don't think any of this relates to a baseband CCTV installation, though.

 

[MarcelvdG]

Only RG-59 cables that are optimized for UHF and CCTV frequencies have Copper Clad Steel (CCS) center conductors and they are not lossy at UHF frequencies.

29.5 dB for 100 m at 400 MHz according to https://www.farnell.com/datasheets/84294.pdf , so at 400 MHz, you lose almost half the signal power in every 10 metres. Like Mark wrote, fine for short connections, not for long cables.

 

[Speedskater]

A few Belden RG-59/U Type coax cables with stranded copper center conductors and good UHF response:
8241F, 9659, 9259, 89259 & 82589

 

[MarcelvdG]

I looked up the first one: nominally 6.6 dB/100 ft at 400 MHz, so 21.65 dB/100 m, the power halves every 13.9 metres. It's indeed a bit better than the cable I looked up, but I still wouldn't use it for long cables at UHF. See https://catalog.belden.com/techdata/EN/8241F_techdata.pdf

 

[Speedskater]

From a recent Blue Jeans Cable page:

we have recently added Belden's newest 12G cables -- 4855R, 4505R, 4694R, and 4794R. Apart from the jacket lettering, externally these cables look just like the 6G versions, but internally they've been re-engineered for 12G. This has meant going to silver-plated copper center conductors, for improved attenuation; bonded foil, for tighter control of impedance; and reconfigured shield braids to prevent the shield from creating return loss issues.

Cable Technical Specs:

Belden 4694R (RG-6 sized, up to 12G, riser-rated)
Belden 4794R (RG-7 sized, up to 12G, riser-rated)
Belden 4505R (RG-59 sized, up to 12G, riser-rated)
Belden 4855R (mini-59 sized, up to 12G, riser-rated)

Links to spec sheets at:
SDI Cables at Blue Jeans Cable