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Filter to remove AM radio from telephone lines
I have a standard POTS line for a phone and if the extensions in the
basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Can I make a simple filter to get rid of this? What size capacitor would I use (in parallel with the phone I presume)? Would I need a coil? I have lots of coils I have cut out of old tv's etc, but the rating of the coil is usually not written on them, or at least not legible. It turns out that the phone company will provide a filter for free, but they charge for a half-hour service call, which is like 70 or 80 dollars these days. Remove NOPSAM to email me.. |
Filter to remove AM radio from telephone lines
"mm" wrote in message ... I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Can I make a simple filter to get rid of this? What size capacitor would I use (in parallel with the phone I presume)? Would I need a coil? I have lots of coils I have cut out of old tv's etc, but the rating of the coil is usually not written on them, or at least not legible. It turns out that the phone company will provide a filter for free, but they charge for a half-hour service call, which is like 70 or 80 dollars these days. Grab a ferrite clip around filter. http://www.evertek.com/viewpart.asp?auto=22360 |
Filter to remove AM radio from telephone lines
Have you tried using a DSL filter? They already come with male and
female phone connectors. They sell for about a dollar each at the electronics surplus stores in Silicon Valley, and usually less than $5 at regular retail stores (although I have seen them advertised for over $20). You may need one for each phone. |
Filter to remove AM radio from telephone lines
"Homer J Simpson" wrote in news:WqYYg.17305$P7.12287
@edtnps90: "mm" wrote in message ... I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Grab a ferrite clip around filter. http://www.evertek.com/viewpart.asp?auto=22360 Does anyone know whether a ferrite RFI filter like this (the kind that goes around a cable) also attenuates voltage spikes? Seems I recall that a typical spike lasts about a microsecond, so the fequencies involved would be a megahertz and above, so it seems like it might work. (Just thinking about adding them to my surge protectors.) |
Filter to remove AM radio from telephone lines
On 16 Oct 2006 20:58:09 -0700, "
wrote: Have you tried using a DSL filter? They already come with male and female phone connectors. They sell for about a dollar each at the electronics surplus stores in Silicon Valley, and usually less than $5 at regular retail stores (although I have seen them advertised for over $20). You may need one for each phone. I haven't tried one because this is the first I heard. I'll look for one. 90% of my phone calls are from my desk phone, so that ought to be enough. Strangely, I rarely hear the radio when the conversation starts, but if I talk for 30 or 60 minutes, it starts and gradually gets louder and louder until I can recognize what is said (and know what station.) Also it has stopped for a couple months for some reason. And then later for a few days. But when it restarted up again the second time, I thought I should look into curing this. Remove NOPSAM to email me.. |
Filter to remove AM radio from telephone lines
On Tue, 17 Oct 2006 03:51:18 GMT, "Homer J Simpson"
wrote: "mm" wrote in message .. . I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Can I make a simple filter to get rid of this? What size capacitor would I use (in parallel with the phone I presume)? Would I need a coil? I have lots of coils I have cut out of old tv's etc, but the rating of the coil is usually not written on them, or at least not legible. It turns out that the phone company will provide a filter for free, but they charge for a half-hour service call, which is like 70 or 80 dollars these days. Grab a ferrite clip around filter. http://www.evertek.com/viewpart.asp?auto=22360 I may see these at hamfests. The last one of the season is this Sunday. I'll look. Thanks to all. Remove NOPSAM to email me.. |
Filter to remove AM radio from telephone lines
mm wrote:
I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Contact the engineer at the station. They will help you. Note that it may be your phones, not the wire. Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM IL Voice: (07)-7424-1667 Fax ONLY: 972-2-648-1443 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ |
Filter to remove AM radio from telephone lines
mm wrote: I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Easiest is to find a DSL line filter. They're just the right specs for killing AM band signals. Plug it in series with the loudest phone. If you can't get one of those, try a 0.01uF to 0.05uF capacitor, across the red and green wires. You may need one at EACH phone jack. Way back when I used to live in the shadow of a 50KW AM station, it took a pair of capacitors across the phone line, with 2.5mH chokes in series, to eliminate the background chatter. But you can probably get by with less than that. |
Filter to remove AM radio from telephone lines
mm wrote:
I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Can I make a simple filter to get rid of this? What size capacitor would I use (in parallel with the phone I presume)? Unless that radio station is very close to you, the problem is likely caused by a corroded connection. You can filter it out, but if you can find the connection and clean it you'll solve it too. One problem with this is that the problem may exist internally in one of the phones. But you can track that down easily by unplugging phones. This happens all the time with music equipment. Poor connections on cables start tuning local radio stations. All you really need to make an old fashion crystal radio is a diode. Corroded connections can do a fine job at this. Then the capacitance and inductance in the rest of the amplifier functions as the tuning stage. |
Filter to remove AM radio from telephone lines
In article .com,
Ancient_Hacker wrote: In 1975 when I moved my bussiness to a building a quarter mile from an AM station we could hear it on the phone. The phone co. sent out people two times and put various filters on the line all to no avail. Finally on the third visit an old timer who looked about to retire came in, put a small mylar type cap across the ear end terminals in the handset. No more problem, not ever on other extensions when they were put in. Chuck P. |
Filter to remove AM radio from telephone lines
MOP CAP wrote: In article .com, Ancient_Hacker wrote: In 1975 when I moved my bussiness to a building a quarter mile from an AM station we could hear it on the phone. The phone co. sent out people two times and put various filters on the line all to no avail. Finally on the third visit an old timer who looked about to retire came in, put a small mylar type cap across the ear end terminals in the handset. No more problem, not ever on other extensions when they were put in. This was a standard fix back then. I also probably saw it in one of the ARRL handbooks. That was the first thing I was going to say. Ferrite filters on the phone lines, handsets, power cords, should help. I would put an MOV across the phone line at the service entrance. Actually one on each line to ground. Good power surge suppressors have inductors and caps after the MOV's to filter RF and the spikes caused when MOV's are in action. greg |
Filter to remove AM radio from telephone lines
"Jim Land" wrote in message . 3.44... Does anyone know whether a ferrite RFI filter like this (the kind that goes around a cable) also attenuates voltage spikes? Bound to. Even plain wire will do that and the filter will do it more. |
Filter to remove AM radio from telephone lines
Ancient_Hacker wrote: mm wrote: I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Easiest is to find a DSL line filter. They're just the right specs for killing AM band signals. Plug it in series with the loudest phone. If you can't get one of those, try a 0.01uF to 0.05uF capacitor, across the red and green wires. You may need one at EACH phone jack. Way back when I used to live in the shadow of a 50KW AM station, it took a pair of capacitors across the phone line, with 2.5mH chokes in series, to eliminate the background chatter. But you can probably get by with less than that. I lived one street over from a 27.5kW (ERP) FM radio station in suburban Cleveland in the early 1970s; I could see the station's tower from my third-floor bedroom window at night. The signal didn't get into the telephones in the house where I was living at the time, but I was hearing the station darn nearly everyplace else--on my TV sets on channel 6, between local stations on an FM/stereo radio (cheap offshore brand), even in an Ampex Micro 88 cassette tape recorder my dad had. I didn't know much about this type of interference in those days, much less how to deal with it, but I lived in that suburb only three years, so I didn't have to tolerate the problem very long. I now live in a small town located about five miles from a 1kW AM station. The station's signal doesn't get into my telephones or anything else electronic in my apartment (except my AM radios, of course), but during the day I can hear the station at two points on the AM radio dial--1460 kHz (the station's fundamental frequency) and 560 kHz, 0.9 MHz (900 kHz) away. The problem is still there at night, but less noticeable as the station reduces power to 1kW after sundown. I didn't realize that line filters such as are used on telephone lines carrying DSL Internet service (to prevent the DSL signals from interfering with regular telephone usage) could also be used to filter out AM broadcast interference. You learn something new every day, I guess, which is one reason I read these forum posts all the time (they arrive each day in my inbox in digest format). Every now and then I can hear another cordless phone when I am using my own SBC 900-MHz phone, and I even get interference at times, not very often, that sounds like crossed wires on my corded phone as well. I guess that's one drawback of living in an apartment building; the fact that all devices (radios, televisions, cordless telephones, etc.) certified to comply with Part 15 regulations must accept any and all interference they may receive is annoying at times as well, but that's life in the 21st century, like it or not. 73 (best of regards), Jeff Strieble, WB8NHV (email addy not shown to deter spammers) Fairport Harbor, Ohio USA |
Filter to remove AM radio from telephone lines
Homer J Simpson wrote: Grab a ferrite clip around filter. Those clip-around filters are really good at high-frequencies, but at the AM band they're kinda negligible impedance. You need something in the millihenry range, not the low microhenries. |
Filter to remove AM radio from telephone lines
"Ancient_Hacker" wrote in message ups.com... Those clip-around filters are really good at high-frequencies, but at the AM band they're kinda negligible impedance. You need something in the millihenry range, not the low microhenries. Buy an audio or power transformer, strip it down and re assemble around the power line? |
Filter to remove AM radio from telephone lines
mm wrote:
I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Can I make a simple filter to get rid of this? What size capacitor would I use (in parallel with the phone I presume)? Would I need a coil? I have lots of coils I have cut out of old tv's etc, but the rating of the coil is usually not written on them, or at least not legible. It turns out that the phone company will provide a filter for free, but they charge for a half-hour service call, which is like 70 or 80 dollars these days. Remove NOPSAM to email me.. Are there any unused wires in the phone cables? Try grounding them. For instance,when they ran the phone wiring here,they used CAT-5..We had two phone lines at the time (one mostly used for a dial-up connection),so there 4 unused wires in the CAT-5 cables..I went out to the phone box,and connected the unused wires to the earth ground connection. It killed the bit of cross-talk we had and some of the noise,and the dial-up modem would connect at a faster speed. I even went as far as to connect the extra grounded wires to the unused contacts in the phone jacks at a couple spots,to use the "extra" pair of wires (yellow and black) in the (long) phone cord runs to act as a quasi-shield also.But that trick only works with 4 conductor phone cords,not the cheaper 2 conductor ones. |
Filter to remove AM radio from telephone lines
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Filter to remove AM radio from telephone lines
On Thu, 19 Oct 2006 02:02:45 -0700, PhattyMo
wrote: mm wrote: I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Are there any unused wires in the phone cables? Try grounding them. This seemed like a really good and easy idea also, and I was going to do it, but as the other post says, I found the problem when I had to replace the phone that caused the problem, after it broke. Thanks. For instance,when they ran the phone wiring here,they used CAT-5..We had two phone lines at the time (one mostly used for a dial-up connection),so there 4 unused wires in the CAT-5 cables..I went out to the phone box,and connected the unused wires to the earth ground connection. It killed the bit of cross-talk we had and some of the noise,and the dial-up modem would connect at a faster speed. I even went as far as to connect the extra grounded wires to the unused contacts in the phone jacks at a couple spots,to use the "extra" pair of wires (yellow and black) in the (long) phone cord runs to act as a quasi-shield also.But that trick only works with 4 conductor phone cords,not the cheaper 2 conductor ones. If you are inclined to email me for some reason, remove NOPSAM :-) |
Filter to remove AM radio from telephone lines
On 17 Oct 2006 03:22:51 -0700, "Ancient_Hacker"
wrote: mm wrote: I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Easiest is to find a DSL line filter. They're just the right specs for killing AM band signals. Plug it in series with the loudest phone. I was definitely going to do this. I talked to a phone company guy who said that rather than get one from him, and pay for a half hour phone company labor, I could get one at Radio Shack! :) But they wanted 15 dollars. That's still sounds like real money to me. Especially if I might end up needing more than one. And after all, this is a repair newsgroup, which to me always means replacing or adding the smallest part which will do the job. If you can't get one of those, try a 0.01uF to 0.05uF capacitor, So this was my first choice. Thanks, and thanks especially for being the only one to address my specific question, which was, What size capacitor would I use. Even though the problem is solved at this time in this place, I'm going to get one or two of these out of my stock of miscellaneous parts, or maybe just buy a few from Mouser. across the red and green wires. You may need one at EACH phone jack. Does it matter if they are polarized or not? Way back when I used to live in the shadow of a 50KW AM station, it took a pair of capacitors across the phone line, with 2.5mH chokes in series, to eliminate the background chatter. But you can probably get by with less than that. Still I appreciate the suggested value for later, more serious cases that may arise. Thanks. If you are inclined to email me for some reason, remove NOPSAM :-) |
Filter to remove AM radio from telephone lines
mm wrote:
On 17 Oct 2006 03:22:51 -0700, "Ancient_Hacker" wrote: mm wrote: I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Easiest is to find a DSL line filter. They're just the right specs for killing AM band signals. Plug it in series with the loudest phone. I was definitely going to do this. I talked to a phone company guy who said that rather than get one from him, and pay for a half hour phone company labor, I could get one at Radio Shack! :) But they wanted 15 dollars. That's still sounds like real money to me. Especially if I might end up needing more than one. ALL Electronics sells DSL filters for around $3 apiece. Jerry |
Filter to remove AM radio from telephone lines
On Sat, 16 Dec 2006 21:13:12 GMT, Jerry Peters
wrote: mm wrote: On 17 Oct 2006 03:22:51 -0700, "Ancient_Hacker" wrote: mm wrote: I have a standard POTS line for a phone and if the extensions in the basement and main bedroom are plugged in, the phones in the kitchen and office play WBAL AM radio, 1090. Easiest is to find a DSL line filter. They're just the right specs for killing AM band signals. Plug it in series with the loudest phone. I was definitely going to do this. I talked to a phone company guy who said that rather than get one from him, and pay for a half hour phone company labor, I could get one at Radio Shack! :) But they wanted 15 dollars. That's still sounds like real money to me. Especially if I might end up needing more than one. ALL Electronics sells DSL filters for around $3 apiece. Thanks. I just noticed your post. I'm going to get one or two. Jerry If you are inclined to email me for some reason, remove NOPSAM :-) |
Filter to remove AM radio from telephone lines
mm wrote:
ALL Electronics sells DSL filters for around $3 apiece. Thanks. I just noticed your post. I'm going to get one or two. Jerry From my experience: The 'pigtail' type filters are only two wire connections for a single phone line. If you use the other two wires, like a 2 line phone, they don't work on that extra line I've seen two types of pigtail filters: both cost around 10 to 12 1) simple single cap across the line - don't work well 2) common mode choke and cap - work very well the choke looks like one of those 1/4 inch 600 ohm audio transformers, actually has laminated core in it Sometimes radio stations change their beam pattern to satisfy FCC requirements. Depending on the time of day, you may see different influences from that AM station. Like dusk, 6pm or so. In Aptos, California near the 10KW AM radio station, the Station's Engineer kindly supplied the excellent pigtail line filters to nearby residents, who asked for them, at no charge, as a 'public relations courtesy' You mentioned that the effect gets worse with time OFF HOOK. Very interesting, because ON HOOK you have high voltage and ON HOOK there is lower voltage. Perhaps there is corrosion that is detecting the AM signal. Even using pigtails, keep in mind that *if* your lines are unbalanced, the audio can get into them because the protection block is nonlinear and detects AM. Once the audio is on your lines, it cannot be blocked at any phone, because it is now legitimate audio. - Robert - |
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