Hi, I had a usb tv-tuner stick, which I thoughtfully managed to break the connector off of . Instead of just bodging a new one on, I decided to try and relocate it inside a duplo brick. In doing this, I usefully broke a ~60pf cap, although it seems to work fine with a 100pf cap (It was inline between the center pin of the coax cable and the circuitry.) However, my problem is that it only works when the socket is soldered really, really close to the board. What I have at the moment: almost works, I can watch really badly distorted tv, but nowhere near good enough quality. I assume I need to shield something, but I really don't know what. If anyone has any idea, please help.
yes the whole lot def needs to be shielded. the shielding should be trapped onto the antenna socket sheath. a proper steel box should do it - maybe find one of those galvanised steel boxes that are sunk into walls to hold light switches / mains sockets / etc. (just a thought though!) I would think the 60pf cap is to block all signals below a certain frequency, so in putting the 100pf cap in, you might be letting other signals into the circuit (don't quote me on this)
If those are from steel then they are rather old, nowadays they are all made of plastic, (metal and mains power don't mix to good) If you have those in steel you probally also have steel pipes (wich carry the wiring) and also no earth wires.
foil/aluminium flashing tape should do the job nicely, you can get it from a local DIY store. Just remember not to let any of the circuits touch the tape.
Galvanised steel back boxes for sunk-in-plaster sockets and switches are still very common here, they're strong and very heat-resistant. The cables come in through rubber grommets, there's a screw connection for the earth wire and the touchable switch or socket mounting screws are automatically earthed, so safety is well covered. Plastic back boxes are more used for dry-lining (plasterboard) applications AFAIK. A bit ugly for this job, though, and no lid. A metal sweet or tobacco tin would be better.
Here only plastic ones are used (i'm an electrician) The only steel ones you find here are really old ones with steel pipes and the old color codes for the wiring. I have to agree that an metal one would look ugly.
Unfortunately, the problems I had encountered seemed to be due to the tracks on the pcb having broken when the stick was bent. I can only get it to work when held at a certain angle, which I think is irrepareable. I might try this again with a new stick from ebuyer.
