Really Freaky

Post by **knoxville** » 04 Jan 2006, 13:21

Hi, I was searching throught the air band on my Yaesu VR 120D, I came across the frequency 134.000 MhZ AM. I heard some talking and it was going on constantly. Figured it wasn't anything to do with aircraft, as I went upstairs it became clearer. It almost sounded like TV transmission. So I checked the Analogue channels but nothing, no match. Just to be sure I checked cable....I came across Sky News and it matched!!!!!
How is this possible?????? I have NTL Cable, as I go near the box the signal becomes clearer. How is Sky News, getting to my scanner in the airband range AM??????
Also, the NTL box is downstairs and I got a clear signal upstairs!?!?

Very confused Knoxville

Post by kc » 04 Jan 2006, 16:02

What were your neighbours watching ?.
I would guess that what you were picking up was their TV & that if your TV was not on then the cable was giving you a stronger signal via inductance, our bedroom mirror picks up my signals a treat when I place the receiver next to it.

Post by **knoxville** » 04 Jan 2006, 16:28

No, but the thing is, Sky News you can only get on NTL, Sky or Freeview and they are all digital

And I get better reception when im near the cable box. Where the computer is, we have another NTL cable for the internet, and I get ok signal here.

What do you think this is?

Post by kc » 04 Jan 2006, 16:50

The signals in these cables are there just waiting for someone to turn the receiver on & it sounds probable that what you are receiving is what is escaping the cable shielding.
Each cable has a loss factor & it sounds like you are picking that up on 134 megs.

Post by **Guzzy** » 04 Jan 2006, 21:12

Analogue wireless speakers somewhere nearby maybe?

Post by **mycbworld** » 17 May 2006, 12:39

This could have been an i.f. signal leaking from a cable/sat set top box after conversion to analogue for feeding to the tv. Trying a multi standard pocket lcd tv i bought, tuning through the vhf low band i found my sky box, flicking to the epg proved this.
next time, with the scanner by the box, try changing channels on your cable box, it might prove my theory.

Simon

Andrew · Post by **Andrew** » 17 May 2006, 23:33

I used to get Living (now Living tv) on 166.000. It wasn't there, it was just harmonics courtesy of the cable system in the house. I also used to get MTV on 91 mHz, almost ripping through Radio 3.

Post by **Panteneman** » 29 Aug 2006, 22:26

Andrew wrote:I used to get Living (now Living tv) on 166.000. It wasn't there, it was just harmonics courtesy of the cable system in the house. I also used to get MTV on 91 mHz, almost ripping through Radio 3.

Hey guys,

I just HAD to add my imput about this, regarding interferance to radio equipment.

Recently, I made an important discovery...

Setup: Icom R71E, Palstar AA30 Active Antenna Box connnected to a G5Rv Jr in "Vee" configuration just under the roof of the house. Yupiteru MVT7100 scanner running on a Commtel "mini" discone on a Moonraker scanner pre-amp. President George multimode (used purely to recieve connected to the G5RV due to no suitable antenna and used static mobile with a Mag Mounted Tornado Stinger antenna nearly 6ft long).

The scanner would stop on various random channels, sometimes on UK FM 27/81 channels inputted into the scanner, Marine Band or Aircraft, preset frequency for BBC OB links etc. And, the Icom would come up with a "Wdddbrrrrrrrrrrrrrrrrrrrrrrrrr" sound every few hundred khz, varying in strength depending on the band. It also affected the President George multimode on 27.005mhz

This was far more bearable vs. the Realistic DX394 (which was all signal amplification, no noise reduction so RFI was worse also because of plastic casing, as opposed to the shielding of the Icom's metal casing) due to PBT and Notch Filter adjustments, and the BHI NES 10-2 extension speaker (really SUPERHCHARGED the RX by the way). The Icom is an entirely different league.

I systematically went through the house, testing various appliances for RFI (Cooker, DVD, Fridge, ANYTHING with a mains socket) and upon unplugging ONE item, it VANISHED

Want to know the culprit??

SONY VTX-760U - The Sky Digibox

It appears that this Sky Digibox appears to give out CHRONIC RFI. Over at my girlfriends gaff (who has a Sagem Digibox) it doesn't cause it hassle when using the scanner (I take it with me as its programmed with stuff over a 40 mile radius, various frequencies).

I remember Analog Sky Boxes (intergrated receivers with built in Videocrypt decoders) and standalone Videocrypt decoders of years gone by used to hassle a Panasonic shortwave we owned, and Panasonic RF 3100 on a 100ft approx end fed long wire with home brew ATU.

So NOTHING, not even the PC and the ADSL router, or the Sony Bravia TV downstairs hassles the radio gear but the innocuous Digibox does.

I have put a small RFI choke on the mains, and it has dampened its RFI. I shall look further into it and try a larger one or maybe get another Sky Box....

Just thought I'd share it with you guys and girls out there

Post by **Andy** » 30 Aug 2006, 09:33

Interesting, Panteneman. When we signed up for Sky digital a few years ago, I was dreading it. I imagined that my listening would be ruined by loud video hash and digital noises. After all, you'd imagine that all that fast processing of a high-speed digital video stream would produce a racket, wouldn't you? But there was nothing! If I hold a MW/SW radio right next to the box, all I get is a gentle 'sshshshshsh'.
Same with our new-ish 26" LCD WS telly - hardly a sound!
It's just a shame that next door's ols CRT telly obliterates everything......

Post by **Panteneman** » 31 Aug 2006, 19:32

Dunno mate, might just have a rouge Sky Box that pours out RFI from all of its electronic orifices. I suspect bad shielding lurking somewhere within

What I find particularly ironic is that you can't tell your neighbour off for their crap tele pouring out RFI and affecting your Ham Radio/CB/Listening Post gear, yet THEY can send the Seven Horsemen Of The Apocalyse onto YOU for a little bit of TVI from your Ham Radio/CB rigs messing up their Coronation Street, made worse from the fact they are using crappy cabling on their system or a Poundland Special set top TV antenna !!!

I mean, my next door neighbour has a TV antenna below the roof which is 10 foot away from the centre of my G5RV in the garden. Good job I don't transmit from it.

This country may have got it's act together re. RF Shielding from electronics equipment - but it's not a patch on the US FCC strict guidelines. You could get a good kicking for having a PC (or similar offending item) that could pour out RFI and mess someones radio/TV up over there, I am lead to believe...

Post by **THE_SNAIL** » 11 Jan 2007, 19:22

this reminds me of when i was a kid.i had an 27mhz remote contol car,the single button type to make it reverse.i was into electronics and radios.i put the arial from the car onto the arial of a fm tranny radio and i got CB chat comming from the tranny and every time some one spoke the cars wheels would turn but as soon as i removed the tranny the wheels would stop and the normal radio would be on.we didnt have any fm breakers close by.when i went to collage and told them they said i was talking out of may backside,but i had 6 members of my family watching this.