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Phone line as SW antenna
http://www.rdrop.com/users/billmc/phone_antenna is built around
a ".01uF capacitor", but what kind? Are big .01uF capacitors better than small ones etc.? Is .01uF critical or is there actually a range that is acceptable? Also the "RF connector" isn't clear. What are examples of this "radio frequency connector"? Perhaps just coax to alligator clip? Is the 50 ohm coax critical? How about a plain wire from the capacitor to the radio's telescoping antenna? Should the telescoping antenna still be extended, or retracted? How do we know if our phone line antenna is working properly? Should time signals on 5000, 10000 khz etc. jump out in perfect clarity? Certainly there must be a slight advantage between one of red and green vs. the other... or might we not even bother comparing, as they are certain to be the same? By the way, I found a .01uF capacitor that the capacitor numbers web pages don't seem to decode: 103K PE50. I can't figure out what the PE50 or PE5Q means. Lastly, the article has some spelling mistakes, e.g., lightening arrestors. |
Subject: Phone line as SW antenna
Probably *not* a Good Idea if the telephone line is employed in DSL service. Jonesy -- | Marvin L Jones | jonz | W3DHJ | OS/2 | Gunnison, Colorado | @ | Jonesy | linux __ | 7,703' -- 2,345m | config.com | DM68mn SK |
I used to do this by wrapping the curly-cord around my radio's rod antenna. Worked quite well. |
John Smith wrote:
**Don't let the phone people find out, they control the government.** I'm going senile. What movie was that? I remember a desert scene and the actor and a phone booth... mike |
Yea, had James Colburn in it.
Was a early spoof on James Bond, forgot the name of the movie too. The Phone Company won too. "m II" wrote in message news:F2hoc.862$RM.844@edtnps89... John Smith wrote: **Don't let the phone people find out, they control the government.** I'm going senile. What movie was that? I remember a desert scene and the actor and a phone booth... mike |
John Smith wrote:
Yea, had James Colburn in it. Was a early spoof on James Bond, forgot the name of the movie too. The Phone Company won too. That was enough..I found it.."The President's Analyst" James Coburn! It's been a while, so maybe there's hope for me yet. Thank you. |
"John Smith" wrote in message ... Yea, had James Colburn in it. Was a early spoof on James Bond, forgot the name of the movie too. The Phone Company won too. "The President's Analyst." http://www.imdb.com/title/tt0062153/ "PM" |
m II wrote:
John Smith wrote: Yea, had James Colburn in it. Was a early spoof on James Bond, forgot the name of the movie too. The Phone Company won too. That was enough..I found it.."The President's Analyst" James Coburn! It's been a while, so maybe there's hope for me yet. The "Flint" movies were also spoofs of James Bond with James Colburn. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
I got a good answer in mail:
"J" == Jerry writes: http://www.rdrop.com/users/billmc/phone_antenna is built around a ".01uF capacitor", but what kind? Are big .01uF capacitors better than small ones etc.? J It isn't the size but the voltage rating that matters. The point of the J capacitor is to protect the RF stage of your radio from the ringer signal of J the phone, which will be anywhere from 40 to 70 volts. Considering that J your radio may be sensitive to signals in the microvolt range, it isn't J surprising that 70 volts could be a radio killer. I'd use a cap of 200 volt J or more rating. There are a lot of different kinds of caps. A ceramic disk J would be appropriate and dirt cheap. Sure wish there would be that warning on that regular posting to rec.radio.info . Yes I emailed McFadden. Is .01uF critical or is there actually a range that is acceptable? J The point is to have it big enough to pass all the RF signals your J interested in, but not signals lower in frequency than you want. 0.01uf is J a standard value, but double or half that would be OK. Also the "RF connector" isn't clear. What are examples of this "radio frequency connector"? Perhaps just coax to alligator clip? J Just connect one end of the capacitor to the phone line and the other to J your radio. If your radio has a telescoping antenna, just clip it to that. Is the 50 ohm coax critical? How about a plain wire from the capacitor to the radio's telescoping antenna? Should the telescoping antenna still be extended, or retracted? J You're making this too complicated. Just connect the capacitor to the J antenna. Any wire will do. Considering that the phone wire may be miles J long, whether or not you extend the telescoping antenna is probably J irrelevant. How do we know if our phone line antenna is working properly? Should time signals on 5000, 10000 khz etc. jump out in perfect clarity? J HF signals are rarely perfectly clear, no matter what the antenna. You J ought to hear more than you do with the telescoping antenna alone. Certainly there must be a slight advantage between one of red and green vs. the other... or might we not even bother comparing, as they are certain to be the same? J If you have 4-wire phone, one of them will be ground, and that one certainly J will NOT work. The others are probably equal as antennas. Just try them J all. By the way, I found a .01uF capacitor that the capacitor numbers web pages don't seem to decode: 103K PE50. I can't figure out what the PE50 or PE5Q means. J Probably means 50 volts. Not enough. The first time the phone rings will J damange this capacitor. A 1000-volt 0.01uF cap is only a quarter or so a J Radio Shack. Far from stores, I wonder if the necessary high voltage capacitor could be found in my pile of broken radios. I suppose I would look for meaty cylindrical types rather than pill shaped types. OK, will look. |
Best way to do this is to use telephone quad (station)\
wire between the telco demarc and the rj-11telephone block. Phone pair will be the White, White/Blue or Red/Green pairs. You can then use any of the unused wires in the cable as the antenna lead. Radio signals will be common mode on the cables, and will capacitively couple to the adjacent pairs. No need for a direct capacitive coupling to the hot phone pair. Pete "Dan Jacobson" wrote in message ... http://www.rdrop.com/users/billmc/phone_antenna is built around a ".01uF capacitor", but what kind? Are big .01uF capacitors better than small ones etc.? |
McFadden responds! Hope he can integrate some of this into that
periodic posting. To: Dan Jacobson From: Bill McFadden http://www.rdrop.com/users/billmc/phone_antenna is built around a ".01uF capacitor", but what kind? Are big .01uF capacitors better than small ones etc.? It doesn't matter much, but a ceramic capacitor is probably going to be the best (and cheapest). A voltage rating 250V or higher would be good since the ringing voltage on a phone line is around 90 V RMS. Is .01uF critical or is there actually a range that is acceptable? The value isn't critical. Anything within a factor of 3 (.0033uf to .033 uF) should be okay. Also the "RF connector" isn't clear. What are examples of this "radio frequency connector"? The RF connector is whatever kind of plug fits the antenna input on your receiver. Perhaps just coax to alligator clip? That's how I made the first one. It was one clip lead from the phone line to the capacitor, and another clip lead from the capacitor to the whip antenna. Worked okay. Is the 50 ohm coax critical? How about a plain wire from the capacitor to the radio's telescoping antenna? Should the telescoping antenna still be extended, or retracted? You only need coax if you're feeding the coax antenna input on the receiver. You can use the whip antenna, which doesn't matter whether it's up or down. If you get a lot of interference from nearby broadcast stations, you'll need to use coax and one of the filters in the article. 50 ohm coax isn't critical. 75 ohm coax (TV coax) is often cheaper and better shielded. How do we know if our phone line antenna is working properly? Should time signals on 5000, 10000 khz etc. jump out in perfect clarity? You should get stronger signals than you would with the whip antenna alone. If the signal level drops when you disconnect it, then it's working. Certainly there must be a slight advantage between one of red and green vs. the other... or might we not even bother comparing, as they are certain to be the same? I didn't notice any difference, but it was easy to try both. By the way, I found a .01uF capacitor that the capacitor numbers web pages don't seem to decode: 103K PE50. I can't figure out what the PE50 or PE5Q means. 50 is probably the voltage rating (50V). PE may refer to the dielectric material, but I don't recognize it. Lastly, the article has some spelling mistakes, e.g., lightening arrestors. Fixed. |
Years ago before they started burying all the phone drops and cabling the
overhead wires, I connected my BC-348 to the phone withe a 0.005-uF disc ceramic capacitor. It gave me a VERY long wire, probabaly miles of long wire. Worked quite well. I haven't tried it since. 73 de Jack, K9CUN |
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