D
we're still interested - - what's your current status?
Hi. The CB frequency you are trying to 'choke' is 27MHz-28MHz (11meters wavelength). It's known as Short wave or HF.
Choose the choke from it's coverage in the spec sheet.
The mains cord in UK is 1/4" (0.25"). Extension gang plugs use a thicker lead, of around 3/8" so choosing a 0.35" or 0.4" choke would be fine. It does not have to fit the cord tightly. They work because the high frequency signals (CB) see the ferrite material as a high impedance, and cannot get past, but the mains AC is very low freq, (50-60 hz) or audio (300 hz -3khz) and sees the ferrite as a low impedance and passes with no trouble. (It's a low pass filter). I bought 2 DAB radios during '10, both had a separate mains transformer for a 6 or 9 volt dc output to the radio, and both had a ferrite choke already on the lead.
The only way you will know is to buy a couple. I really hope they work after all this !!
the USA UHF band was at 54mhz and above, but that has been vacated for newer services
and we're now all digital, not analog.
Again, if you are getting interference, especially over the air, then you have a neighbor that is the culprit - - go looking for those antennas.
IMO, you ought to verify you have grounded 3pole A/C outlets and all your equipment is
properly grounded.
Long unshielded wires (eg mic, speakers, a/v component cables) all act like antennas and
even though not associated with the RF circuits, they create magnetic pathways into your system.
In the UK we are just going over to all digital tv reception, area by area, ours is 31 March. Then the high power (100KW) analogue transmissions will be turned off, and the low power (25KW) digital signals will be turned up to 175KW.
If Tv coax sheild isn't at true ground (floating) it could be a problem, but I think if a CB transmitter is near enough, it will breakthrough anyway. I did some searching, and found this notch filter, that just 'takes out' CB frequencies, 26-28MHz (11meters wavelength), and it goes into the antenna downlead.
http://cgi.ebay.co.uk/AKD-Notch-Filter-Stop-TVI-Interference-CB-27MHz-/370450407646
I know this make, it's UK based but I bet someone sells them or similar in USA. A combination of this in the antenna downlead, plus a broadband ferrite choke on the mains AC, would be my approach to this problem.
capacitor in series
(in)-----| | ----+------(out)
|
/
\ inductor to ground
/
\
|
(common) -------+---------(out)
(Circusboy01) A 'notch' filter to take out the 27MHz frequencies (Citizen's band) goes in the TV antenna coax, probably best right at the back of the TV, or if you have a set-top box for digital, right at the back of that, where the coax plugs in.
So the order will be, starting at the Dish;
Dish-- coax downlead-- notch filter-- digital set-top box-- TV.
(About the data line filters you bought, not so sure what they are, most chokes like this are to go on the power supply cords, or just possible they are for networks for pc's. Anywhere you have long lengths of cable, you are going to pick up radio signals. If the cable has a grounded 'outer' braid, it should be fairly good at rejecting RF, but wires such as Ethernet CAT 5 types, have no shield, so they are just like an antenna, and do what antennas do.)
From what I can tell, your main problems are in breakthrough to TV, and the 27 MHz 'notch' filter is the way to go.
* Have attached a couple of pictures to show the Altec lansing speakers I use. This is as I bought them. The choke is by 'TDK' and you can see the part number. Hope this helps.
(jobeard) The idea of a 'high-pass' filter will work too, but I thought TV in USA was on 50MHz (Band 2) and it would be too close to 27 MHz to use a high-pass filter.
That's why I suggest a 27MHz 'notch', it's more likely to do the trick.
Also good effort at the circuit diagram, not easy to draw inductors in text!
I can't find a 27MHz notch filter either. I've been on the Radio Shack site but nothing found so far. The CB low pass filters in a metal box, about 2" x 3" with a socket at each end, are for the transmitter aerial. Not much use to you. It's what the CB guy's should have in their trucks/cars, then you wouldn't have this problem.
The good news is that you can make your own filter. If you can make up plugs and fit sockets to the end of coax, you can make a 1/4 wave open stub filter which would work well. I will have a go at a drawing, and attach it.
Still think you should be able to get an inline filter somewhere. The best ones were made by AKD, but that was bought out by Garex, UK I think.
Yes they might have what you want, but don't let them sell you a 27MHz low pass filter. If the CBers all had them in their cables, you wouldn't be in this situation, but they don't- obviously. You need an inline 27MHz 'notch' filter for Satellite TV downlead.
I spent some time looking for an answer, and found a 'pro' looking company that might be able to give you some answers.
www.solidsignal.com
The drawing I did will work to 'notch' out 27MHz, if you get no other answers, the only downside is the cost, 4 TV plugs/sockets, 1 Tee connector , & 2 meters Satellite coax. Plus you need to hide 1.8 meters of coax along the floor or behind something. But very effective in use. If you make it, the open end of the 1.8 meter section is not connected or soldered to anything. Just cut it clean across the coax.
The 'Solidsignal' site is USA based, I don't know if they could help you, but they might have contacts that we don't. If you can get a 'notch' filter to take out 27 MHz, plus the ferrite chokes on the mains AC cords, you should be clear of interference to PC and TV.
In UK we have about 50% roof top Yagi antennas, with analogue signals to give five channels. But that's all being switched off over the country last year and this, being replaced by 'Freeview', that's 52 channels, through the roof top yagi antenna. The other option is 'Freesat', which is 52 channels of 576i 'old style' tv, plus the new HD channels at 1080p, only 4 HD at this time, via dish. 'Sky' tv is a big satellite supplier here, for phone/BB 'net/TV packages. I do all my own mods, cables, & have 2 different dishes, Humax HD box, Pace box etc, plus 48 element Yagi in roof. Almost no-one here uses cable TV, it never 'caught on'. Have attached a photo of a popular type of TV dish as supplied by SKY.
the huge dishes you were referring to a few years back are called C-band antenna dishes. They are still used by some countries. Most of the satellites in north America are now shut off or have malfunctioned or have been bought out by other companies for other purposes. I am not sure if any American satellite companies still use C-band for television broadcast.