gt1541b@BBN.COM> (01/11/90)
I posted some time ago about my DX440 radio and hooking up an external antenna with some 58/u cable, and I wanted to know if I should worry about impedance matching. I still have this question. Can it damage the radio and reception if I don't -- I'm getting nervous with all these people talking about the Sony 2010 problems with static and antennas. Boris Laffkin 25 metre jockey
Boris Laffkin <@RUTGERS.EDU:gt1541b@prism> (02/20/90)
Okay, everybody keeps talking about all these active and passive antenna kits. What I'm looking for is a book that simply describes how to build and tune them. I already have tons of wire and such, but would simply like some antenna equations out of a book to put them together properly. Preferably this would be a "how-to" book, and not just some EE theory text. I know some EE's here at Tech, and even they are shaky on hooking up active antennas to my DX440. Boris Laffkin Quantum Mechanic @ the Sub-Atomic Garage
Barry Ornitz <@CS.ROCHESTER.EDU:ornitz@kodak> (02/21/90)
In article <6177@hydra.gatech.EDU> gt1541b@prism.gatech.EDU (Boris Laffkin) writes: >Okay, everybody keeps talking about all these active and passive >antenna kits. What I'm looking for is a book that simply describes >how to build and tune them. I already have tons of wire and such, >but would simply like some antenna equations out of a book >to put them together properly. Preferably this would be a >"how-to" book, and not just some EE theory text. Get a copy of the ARRL Antenna Book published by the American Radio Relay League in Newington, CT. Cost is around $20. This book is an excellent introduction to antennas and is quite practical. If you want to get into antenna theory, it is there too. You will find everything from simple wire antennas to large arrays in this book; also you can get good information on materials of construction, rotators, etc. in this book. Most of the designs are for the amateur radio bands but you should be able to scale them to whatever you need in frequency. You might even get interested in getting a ham license (Heh, Heh - ulterior motive in my posting!). Several things need to be remembered in antenna design for receiving: 1. A dollar spent on an antenna will probably do more than $100 on a better receiver in terms of sensitivity - or...you want to hear the weak ones? put up a good outdoor antenna. 2. Receivers can tolerate far, far more impedance mismatch than transmitters before their performance is seriously degraded. This means that just about any hunk of wire put up outdoors will perform well - probably better than most active antennas. 3. Antenna tuners for receiving may or may not be of benefit. If your receiver overloads from a local broadcast band station, the tuner might provide enough front-end selectivity to help; the problem is actually with the poor overload characteristics of the receiver. Vacuum tube radios are better than solid-state radios in this regard. My R-390A is nearly impossible to overload! A high-pass filter will also knock out BCB overload. If you want to try a tuner, the ARRL Antenna Book has designs. Remember for receiving- only applications, high-voltage capacitors are not needed. See also 2 above. Tuners are rarely needed for impedance matching of receivers. 4. Tinker. Antennas are fun. Just remember to be careful near power lines. Also disconnect and ground the antenna when not in use to avoid lightning zap. Good luck in your experiments. Happy listening. 73, Barry ----------------- | ___ ________ | Dr. Barry L. Ornitz WA4VZQ | | / / | | UUCP: ....rutgers!rochester!kodak!ornitz | | / / | | Eastman Kodak Company | |< < K O D A K| | Eastman Chemical Company Research Laboratories | | \ \ | | P. O. Box 1972, Building 167B | |__\ \________| | Kingsport, TN 37662 615/229-4904 | | INTERNET: ornitz@kodak.kodak.com -----------------
Brian Daly <dalyb@godzilla.bitnet> (02/23/90)
In article <6177@hydra.gatech.EDU>, gt1541b@prism.gatech.EDU (Boris Laffkin) writes: > Okay, everybody keeps talking about all these active and passive > antenna kits. What I'm looking for is a book that simply describes > how to build and tune them. I already have tons of wire and such, > but would simply like some antenna equations out of a book > to put them together properly. Preferably this would be a > "how-to" book, and not just some EE theory text. > > I know some EE's here at Tech, and even they are shaky on > hooking up active antennas to my DX440. > I'd suggest you try some of the ARRL publications: ARRL Handbook ARRL Antenna Book There are also other ARRL publications that go into antenna construction. See the latest issue of QST magazine -- there is usually an order form in each issue. -- Brian K. Daly WB7OML @ AG Communication Systems, Phoenix, Arizona UUCP: {...!ames!ncar!noao!asuvax | uunet!zardoz!hrc | att}!gtephx!dalyb Phone: (602) 582-7644 FAX: (602) 582-7111 ~
Ken Greer <@BBN.COM:kgreer@mcnc.org.uucp> (02/26/90)
In article <48d1778a.1423f@godzilla.UUCP> dalyb@godzilla.UUCP (Brian Daly) writes: +In article <6177@hydra.gatech.EDU>, gt1541b@prism.gatech.EDU (Boris Laffkin) writes: ++ Okay, everybody keeps talking about all these active and passive ++ antenna kits. What I'm looking for is a book that simply describes ++ how to build and tune them. + + ARRL Handbook + ARRL Antenna Book I would suggest that you check in your local public library before spending any money on them, not that they are not good books in their own right. Or, also try any nearby university engineering library. Kim Greer klg@orion.mc.duke.edu