CT-125 Coax

[Guest england145]

Hey guys. just wondering what the max cable run is with ct125 without using an amp. also, same question with rg59, urm70 and rg11 please. got a test on wednesday n may need to no this info

[j.paul]

Hey guys. just wondering what the max cable run is with ct125 without using an amp. also, same question with rg59, urm70 and rg11 please. got a test on wednesday n may need to no this info

67076[/snapback]

URM70(RG59) - a short run cable with average acceptable runs of up to 305 m.

CT100(RG-6) - a medium run cable with average acceptable runs of up to 450 m.

CT125(RG-11) - a long distance cable with average acceptable runs of up to 900 m.

[Guest england145]

Thanks alot!

[Guest england145]

it is a eng grade test. was told i might need to know max cable runs n couldnt find any info on web :s

[camstop]

This is a "Tavcom training handy hint" from last years Visionlink book...

A camera's picture is generally measured by quality of picture vs noise received (signal to noise ratio) this is measured in decibels (dB). The further you send a picture along a cable run, the higher the picture loss and therefore the lower the dB figure becomes.

Whilst there is no strict written rule regarding the maximum distance cable can be run whilst still obtaining a usable picture, it is generally accepted that 250-300 metres on RG59 or URM70 is the maximum to ensure a good picture is still achieved. (It is worth noting that in many cases cable runs of much longer distances can also provide adequate results, but these are much less likely).

This is from the Norbain book...

A 6dB loss at 5MHz will give you acceptable results for a high resolution black and white or colour camera.

Typical losses on common cables...

RG59...... 2.2dB per 100 metres

URM70..... 2.3dB per 100 metres

RG11...... 1.2dB per 100 metres

CT125..... 1.1dB per 100 metres

CT167..... 0.8dB per 100 metres

On the assumption that your using the quoted (standard high quality)cables above, and i've seen low quality RG59 (2.6dB loss per 100 metres) for sale in the UK, you should archive the following...

RG59........ 273 metres = 6dB loss

URM70....... 260 metres = 6dB loss

RG11........ 500 metres = 6dB loss

CT125....... 545 metres = 6dB loss

CT167....... 750 metres = 6dB loss

Like everyone else i've had great pictures at longer than that on RG59 but that's the quoted distances.

Hope that helps

[Doktor Jon]

Only a couple of points to add;

Poor quality terminations and cable joints will all serve to attenuate the signal, and so may effectively reduce any theoretical maximum cable run.

Also, whilst maximum cable runs are generally taken to mean using a colour camera, the fact is that the Chrominance (colour ) signal will degrade well before the Luminance (monochrome) signal is severely affected.

In practice, if you used 250 - 300 metres of quality RG 59B/U as a theoretical maximum for video transmission, you could actually use a much greater run (perhaps 400 - 500 metres) if you are prepared to accept a significant softening in the contrast of transmitted monochrome signals.

Nowadays, whilst CT 100 type cable may be used on occasions, CT 125 or 167 would rarely if ever be considered in preference to other more suitable options.

[Guest england145]

Thanks for all your posts guys. much appreciated