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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. |
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