RF issues / fixed / sort of

[Matt_7800]

So I bought a 7800 (my first one) of ebay and an old vcr and tried to hook them up to a modern TV. The picture quality was not great, so I tried using my 2600 junior in the same setup and it looked just as bad.

 

So I moved the 7800 to another room and hooked it directly up to an older tv and the picture was even worse. It was then I remembered that my computer used to interfere with the junior and free to air tv so I switched my computer off.

 

WOW!, crystal clear picture, no static, as good as I could ask for.

 

So, my question is, can I do something to the 7800 to insulate it from the effects of other RF sources?.

 

 

[Matt_7800]

LOL and this!.

 

 

[+DrVenkman]

You can try using a thicker, insulated RF cable and also, or alternately, buy a ferrite bead “choke” to clamp around the RF cable to try to reduce interference. In my life experience the help provided by these measures is noticeable but not perfect. The best solution is to AV mod the system. 

[ChildOfCv]

Fabricate a shield for the computer ?

 

Well, it sounds like that's what really needs to happen, though probably not practical.

[+Stephen Moss]

20 hours ago, Matt_7800 said:

So, my question is, can I do something to the 7800 to insulate it from the effects of other RF sources?.

If the 7800 has a shield and you are certain that it and the RF modulator shield have a good connection to 0V then there is not really anything more you can do to it. Are you certain the issue is withthe 7800 and not the TV?.

 

As you appear to have identified the the PC as the source of the interference the simplest solution is to turn the PC off, or even putting it to sleep may help if you don't what a total shut down.

If the PC is modern the there should be regulation to ensure it does not radiate out enough interference to affect other devices, however as it does appear to be the source try moving the the TV and console as far from the PC as possible to reduce the amount of interference that is picked up.

 

If the interference is being radiated then the aforementioned ferrite on the RF cable can help if the interference is being picked up by the RF cable, but not if being pick up by the 7800 is already embedded in the video signal prior to it entering the RF modulator. If it is radiated then you may also want to consider placing ferrites on the power leads as close to the console/TV as possible, in case it is coming in on the power rails. 

 

Most TV's I have seen are not generally shielded except around the RF receiver, consequently if the radiated interference is being pickup by the TV somewhere after the receiver there is little you can do beyond moving it as far away as possible or placing it in a big screened box.

 

If the interference is being transmitted down the power lines then plugging them all into filtered mains outlets may help to prevent its propagation to other devices through the mains wiring.