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Picking up HAM or CB talk over PC speakers

By circusboy01
Jan 1, 2011
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  1. jobeard

    jobeard TS Ambassador Posts: 13,474   +329

    we're still interested - - what's your current status?
     
  2. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    Things are kind of on hold. I've been feeling under the weather ( COPD ) was out of town for a couple days. I'v got to get on it though. their on it now every 2 or 3 days.
    I just have to measure the chord so I'll know what size chokes to send for..will get them on and tell you if they worked or not. Thanks for checking back. CB
     
  3. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    Hello to all. I'm making progress honest.
    iv'e been looking at ferrite chokes on line. I'm confused. Should I get one for High Freq.0r Low Freq? Both my cords ( TV and PC.) are11/2" circumference and 3/8" diameter.How do I know which size to buy using their measurerments like 0.4 o. 0.3 0.32 0.40 ? When I get the correct ones I'm not going to put them on until I hear the ham/cber's again. That way I will know if they work instead of wondering if they just stopped broadcasting. CB
     
  4. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    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 !!
     
  5. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12



    O.K. So I'm looking for a 27MHZ--28MHZ 11 Meter Wavelength choke 0.35 to 0.4 in size. Right? Thanks
    I'll try to order a couple before the days over. CB wont be ordering on line 2 $1.95 chokes would cost me almost $10.00 shipping and handling .
    Forget that. I'm going to Radio Shack.( as soon as I can find a ride )
     
  6. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    Went to Radio Shack today. Told them I need acoupleFerrell chokes for 27 to 28 mgh.Because I was having problems with Ham Or CB operators.The guy knew just what I needed.Sold me a couple Snap-on Ferrite Data Line filters. DID NOT work on the TV Not sure about the PC . I've got 3 ways to turn up my volume On screen,on the keyboard,and the speaker system control. I turned them all up full blast and I could barely hear them when I held a speaker up to my ear.
    So I need to know.Is it all or nothing with these chokes? Can they make the talk so low trhat you can barely hear it? Or do they stop the sound 100%?
    Is there a chance that their broadcasting on a new frequency,that comes through load and clear on my TV. But can Barely be heard on my PC
    Got them from Radio Shack because on line shipping and handling was so high.
    these things cost Over 10 bucks for the two of them. I should have ordered them on line. That way I know I would have gotten the right ones. CB


    Watched a vidio today saying that a good e-mail should ontl be about three sentences long. Guess I need to work on that . Huh?:rolleyes:
     
  7. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    So that's fixed the breakthrough on the Pc. The TV is probably picking up the CB signals through your Tv's antenna. I don't know the frequencies of TV signals in the USA, but in UK it's 400 to 800 MHz (approx), for analogue signals. In that case, you would need a high pass filter, to block RF below (say) 100MHz, but passing everything above that. A more tricky way, is to build a 'notch' filter, to take out everything around 26-30MHz. You would need to have some electronic skills, and you could buy everything in Radio Shack. It might be possible to buy one ready made. (The real culprit here is the guy transmitting the CB signals, he should have a $10 low-pass filter in the antenna coax, then none of these problems would be happening.) It is mush easier to block problems at source.
    I will do some searching......
     
  8. jobeard

    jobeard TS Ambassador Posts: 13,474   +329

    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.
     
  9. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    CB signals getting into TV reception

    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.
     
  10. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12




    I am going to go out to check for tall antennas. Also big rig trucks that are parked near by. when you say 3 pole you mean a grounded plug right? I use a surge protector with 6 grounded outlets which is plugged into a 3 hole grounded outlet in the wall.
    So I should go out and look at my dish and see if there are any loing bare wires. Right? Thanks CB
     
  11. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12



    The notch filter you show in the link. I'm a dummy. Does it hooks up to my Tv inside the house Out side on the Dish, Or some where on the CB guys equipment?

    Your link is to a store in England. I'm guessing I can find one here inthe US
     
     
  12. jobeard

    jobeard TS Ambassador Posts: 13,474   +329

    you can use a high-pass filter on that cable/antenna lead which will give low impedance to
    the CB band and thus shunt it to ground, while allowing all signals above the cutoff to pass uninhibited. The curciut looks like this

    Code:
      capacitor in series
    (in)-----| | ----+------(out)
                     |
                    /
                    \       inductor to ground
                    /
                    \
                    |
    (common) -------+---------(out)
    
    A hi-pass for CB should be a stock item at Radio Shack
     
  13. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    (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!
     

    Attached Files:

  14. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    You guys are doing all the work,and I'm just setting at my computer,piling on question after question..I apologize for that. But I have one more.
    I can't find a 27mhd notch filter for sale here in the US . I looked at just 27mhd filters The only thing I found were things that looked like they were meant to be used on the CB equipment itself. Nothing I could use on my end. Any ideas on where and what to search for?
     
  15. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    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.
     

    Attached Files:

  16. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    Had a brainstorm right after reading this post. I'm going to go to or call a place that sells cb equipment to cbers they might have what I need CB
     
  17. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    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.
     
  18. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    Thank you for the info on what to ask for.I was just going to call them up and say.
    "I'm getting CB voices on my TV speakers. Do you have anything to make them go away? In which case they probably would have sold me a 27 MHz low pass filter
    This way I can at least sound like I know what I'm talking about.:approve:
    That link you gave me is that a UK store or a US store? If it's UK I didn't know you had Direct TV over there Thanks again Oh yea Thanks also for build my own instructions.
     
  19. mike1959

    mike1959 TS Addict Posts: 1,122   +22

    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.
     

    Attached Files:

  20. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12


    Your dish looks to be the same size as the two main satellite dish providers here.
    Direct TV and Dish Network.Not too many years back.Our dishes were huge,about 5 to 6 feet across..

    We may get more channels over here. But I'll bet yours are more quality channels.
    Where we have an abundance of crap on ours.
    Thanks again for all the info. Now all I have to do is remember to call the CB store before they close for the Day CB
     
  21. Tedster

    Tedster Techspot old timer..... Posts: 10,074   +13

    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.
     
  22. circusboy01

    circusboy01 TS Enthusiast Topic Starter Posts: 882   +12

    As far as I know all the satellite companies have all gone to the small dishes.I know people were always having problems with the big dishes The smaller ones used now days are a lot more dependable CB
     
  23. Tedster

    Tedster Techspot old timer..... Posts: 10,074   +13

    considering c-band has been around since the early 60s and everything is pretty much digital now, I doubt they have much use except for experimentation.
     
  24. exeuropean

    exeuropean TS Rookie

    One more option: Locate CB operator. If he is unwilling to do anything, cut the antenna support wires during a storm
     
  25. captaincranky

    captaincranky TechSpot Addict Posts: 10,986   +957

    Isn't this thread overdue for the padlock? Locking it seems preferable to pulling the prank posts, such as the one I just received via Email.
     


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