F800 outputing RF interference through bad cable on HD-SDI 2 output at DVinfo.net

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Old June 27th, 2012, 01:57 AM   #1
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F800 outputing RF interference through bad cable on HD-SDI 2 output

I had a problem recently with my F800 creating interference with radio mics. The source of the issue was tracked down to a faulty BNC cable attached to HD-SDI 2 output and a Small HD DP6 monitor.

The tech that helped solve the problem was a SNG engineer, not a camera tech, but he said that he was surprised that RF even got to the HD-SDI output.

Has anyone had a similar issue?
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Old June 27th, 2012, 04:43 AM   #2
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Re: F800 outputing RF interference through bad cable on HD-SDI 2 output

Any digital signal can create RF interference. HDSDi operates at high radio frequencies and contains lots of digital data which creates harmonics way up the radio spectrum. Any RF engineer would know this. That's why screen cables are used, to contain the signal and to prevent leakage.
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Old July 1st, 2012, 10:34 PM   #3
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Re: F800 outputing RF interference through bad cable on HD-SDI 2 output

Thank you Alister.

The reason the Tech questioned the RF to the HD-SDI connector was because of the level of the interference. The first reaction of the Tech seeing the RF levels being outputted was "you should sell your camera to the Americans to jam the Russia satellites"

So my question probably should have been - Has anyone had any issue with RF interference on radio mics caused by excessive RF generated by the camera.

Surely spectrum blocking RF output from the camera must not be normal?
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Old July 2nd, 2012, 12:53 AM   #4
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Re: F800 outputing RF interference through bad cable on HD-SDI 2 output

If a co - ax cable carrying the UHF frequencies that SDI uses turns up faulty, with either a termination impedence problem or something else, the results can be quite spectacular.

It can blast noise across a huge frequency spectrum.

As you have already said, the Tech found the cable faulty, so there's your culprit.

I've seen very low powered "channel shifters" used to move UHF TV to VHF frequencies blast equipment up to 200 metres away if a connection went phut, and they did, with monotonous regularity.

(I was installing the above into hospital TV systems which had been wired and equipped for VHF TV, so all the new UHF channels had to be "shifted" to spare VHF channels, else re - equip the entire place with new UHF equipment - was never going to happen.)

I've even had a mast head UHF TV aerial amp "go balistic" and take out FM reception for any neighbour within 100 metres.

Slippery stuff, electrickery.


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