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Outdoor Scanner Antenna
What could I expect from an outdoor Antenna? I have nothing to attach
an antenna to on my roof. I'm newbie at this, and was curious as to how hard it would be to install this http://www.radioshack.com/product/in...rs&tab=support Years ago my neighbor was a cb freak, and he had a freaking tall antenna on his roof. How would I get this up high enough? Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. |
When I lived in San Antonio, I had a Grove Scanner Beam up 25 ft. With it, I could easily pick up car to car transmissons over 150 miles away. Can you put up an antenna that high Yes, it is directional and you could mount a rotor on the pole.
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Outdoor Scanner Antenna
On 2005-10-28 11:30:45 -0700, Scott said:
What could I expect from an outdoor Antenna? I have nothing to attach an antenna to on my roof. I'm newbie at this, and was curious as to how hard it would be to install this http://www.radioshack.com/product/in...rs&tab=support Years ago my neighbor was a cb freak, and he had a freaking tall antenna on his roof. How would I get this up high enough? Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. Hi Scott The discone type antenna is probably the best antenna available for a scanner. Of course there are some other considerations to be aware of, specifically, what are your "bands of interest"? Would you also like to be able to receive transmissions from satellites, and/or other overhead aircraft? Are you interested in receiving signals from a great distance, or just local traffic? You're in luck, the Discone does all that! If you have a "vent pipe" on your roof, it would then only require a short section of mast to mount the Discone to, and then mount the mast to the vent pipe. This is exactly how I have mounted my discone, and it works very well. I have even used a Discone antenna inside with quite acceptable results. The advantage here is that only a very short cable is required. There are many types of Discone antennas available, and for different parts of the RF spectrum. AOR has one which is good form 75Mhz - 3Ghz, and it is less than three feet tall. Do a search for "DS3000". Hope this helps. Best regards george |
Outdoor Scanner Antenna
On Fri, 28 Oct 2005 16:26:20 -0700, George
wrote: Sounds like what I need then. Will the work with a handheld scanner? I have the Pro 95. I see that I need the discone Antenna, the vent pipe mount that i also saw at RS...What about wiring? I need cable and adapter plugs to get everything hooked up from the Antenna to my scanner. What type of Cable if I go with the outside setup? I'm also wondering what type of connectors I need to hook the antenna up to the pro 95 handheld. I basically just need to know exactly what type of cable and connectors I need to finish this job. I see so many connectors but dont know which ones I need :( Help!!! What else do i need? Remember I'm a newbie :) On 2005-10-28 11:30:45 -0700, Scott said: What could I expect from an outdoor Antenna? I have nothing to attach an antenna to on my roof. I'm newbie at this, and was curious as to how hard it would be to install this http://www.radioshack.com/product/in...rs&tab=support Years ago my neighbor was a cb freak, and he had a freaking tall antenna on his roof. How would I get this up high enough? Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. Hi Scott The discone type antenna is probably the best antenna available for a scanner. Of course there are some other considerations to be aware of, specifically, what are your "bands of interest"? Would you also like to be able to receive transmissions from satellites, and/or other overhead aircraft? Are you interested in receiving signals from a great distance, or just local traffic? You're in luck, the Discone does all that! If you have a "vent pipe" on your roof, it would then only require a short section of mast to mount the Discone to, and then mount the mast to the vent pipe. This is exactly how I have mounted my discone, and it works very well. I have even used a Discone antenna inside with quite acceptable results. The advantage here is that only a very short cable is required. There are many types of Discone antennas available, and for different parts of the RF spectrum. AOR has one which is good form 75Mhz - 3Ghz, and it is less than three feet tall. Do a search for "DS3000". Hope this helps. Best regards george |
Outdoor Scanner Antenna
Scott wrote in
: What could I expect from an outdoor Antenna? I have nothing to attach an antenna to on my roof. I'm newbie at this, and was curious as to how hard it would be to install this http://www.radioshack.com/product/in...arch&cp=&produ ctId=2103160&kw=base+scanners&tab=support Years ago my neighbor was a cb freak, and he had a freaking tall antenna on his roof. How would I get this up high enough? Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. Well yes you do have things on your roof to attach an antenna to :-) You have 2" or 3" or 4" pipes sticking out the top of your roof, i.e. every home or apartment in the USA has them. If your buying that Radio**** antenna then you also need to pick up: http://www.radioshack.com/product/in...tId=2062040&cp and http://www.radioshack.com/product/in...ductId=2062033 &cp=&kw=antenna+mast&parentPage=search and you will need http://www.radioshack.com/product/in...tId=2103483&cp and last http://www.radioshack.com/search/ind...Id=&kw=278-120 And that will put you 5 feet in the air.. You can stop into Lowe's and pickup a 10 foot mast for $14.00 rather then use the 5 footer from Radio****.. -- kla1899 |
Outdoor Scanner Antenna
On Fri, 28 Oct 2005 14:30:45 -0400, Scott wrote:
What could I expect from an outdoor Antenna? strong signals will overload most scanners, and you will get stuff on frequencies you won't expect or want. might need a notch filter to go along with the antenna. --- Bob Anderson*Bitwisebob Eugene Oregon |
Outdoor Scanner Antenna
On Fri, 28 Oct 2005 14:30:45 -0400, Scott said in
rec.radio.scanner: Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. Four things you should be aware of: 1) A discone is a negative gain antenna - that is, it has less gain than a dipole, which is the standard by which 0 gain is measured. Since the signal it receives is so weak, the cable is VERY important - the lower the loss the better, even if it's a fairly short run. DON'T buy your cable from Radio Shack - they don't sell any low loss cable - only cable that's lowER loss than the regular cable. Go to this site http://www.timesmicrowave.com/cgi-bin/calculate.pl, plug in the highest frequency you're interested in (will you be listening to 850?), the cable type (try a few of the common ones - RG6, RG8, RG58) and the approximate length of cable, and you'll see how much signal the cable will lose. Look at the "efficiency". Subtract that from 100 and that's how much signal is being lost. Don't let anyone tell you that it only matters if you're transmitting. Do you see any "direction" choice there? The same amount of signal is lost in both directions. (Actually a little more is lost with a scanner because the scanner isn't a 50 ohm load to the cable.) Be prepared to spend at least 50 cents/foot for decent cable and up to $2/foot for good cable. Putting up a gainless antenna and lossy cable (like 100 feet of RG58 for 850 MHz - 96% of the signal is lost in the cable) is just a waste of time and money. You'll probably receive better with a rubber duck on the scanner. 2) Don't buy hype, buy an antenna. If a discone is designed properly, and very well made, it will cover a frequency range of 4:1. (Most real - not on paper - discones are more like 3:1.) The lowest frequency is that at which the radials are 1/4 wave long. So to receive VHF-lo well they have to be about 6 feet long. The highest frequency this antenna will be any good at will be about 120 MHz. The typical discone with 3 foot radials will cover from about 75-225 MHz. 25-1300 MHz is advertising copy, not measured performance. If anyone can get a discone (without a whip sticking up on top - just a pure discone - if you want whips, buy a Scantenna, or something like it) to cover a 50:1 frequency range (25-1300), you're going to hear him named a Nobel prize winner in physics. And science will have to be rethought. ANYTHING that's not an insulator will receive signals. The question is whether that thing, at the end of some reasonable length of affordable cable will receive any more signal than an antenna plugged right into the scanner. Why put up an antenna that gives you 6db gain over the antenna on the scanner and connect it with cable that gives you 9db loss? You just REDUCED the signal you're going to hear by 50% (3db). Sure the antenna has 6db gain over the one on the scanner - but it's not going to do you any good unless the cable loss is less than 6db. 3) Wherever you put the antenna, and no matter how high you put it, figure out where it will fall if the mount breaks away at the base. It should fall within the confines of your property - for a few of reasons. 1) You don't want a neighbor getting hurt if it falls. 2) You WILL be considered legally negligent if you mount it so that it can fall outside your property line. 3) Your insurance won't cover the judgment against you - you'll pay it all out of your pocket. But don't mount an antenna on your chimney. Aside from the fact that a chimney isn't made to withstand the torque produced when the wind hits the antenna, part of what goes up the flue is sulphur and, when it comes into contact with water (like from air with any humidity at all), it forms sulphuric acid. Do you really want your antenna bathed in that for months at a time every year? Add last, but by no means least, if you're going to put up an outside antenna, PLEASE put in a good grounding system, ground the mast to it and use a static discharge device on the cable. The ground system should tie ALL the grounds in the house to one point - telephone, electric, antenna. And a decent ground (not a good one, a decent one) is AT LEAST 4 10 foot ground rods spaced in a rectangle at least 10 feet on a side, with wire going from 1 to the next, but NOT forming a loop, with all your grounds connected at one point along that run - any one point, preferably near the middle. I'm not making this up - read the National Electric Code on grounding, or ask an electrician. This is important - people are killed every year by bad antenna installations. Not many - but if you're one of them, it doesn't matter how many there are. With all that in mind, this is a hobby, so enjoy it. |
Outdoor Scanner Antenna
On Sat, 29 Oct 2005 10:45:03 -0700, Bob Anderson
said in rec.radio.scanner: On Fri, 28 Oct 2005 14:30:45 -0400, Scott wrote: What could I expect from an outdoor Antenna? strong signals will overload most scanners, and you will get stuff on frequencies you won't expect or want. might need a notch filter to go along with the antenna. A lot of notch filters. FM Broadcast. A few to cover the TV broadcast spectrum. GRE receivers don't like big antennas - they overload easily. |
Outdoor Scanner Antenna
On Sat, 29 Oct 2005 07:43:52 -0400, Scott said in
rec.radio.scanner: Sounds like what I need then. Will the work with a handheld scanner? The antenna will work with anything. A GRE (Radio Shack) scanner will overload easily so, if there are any transmitters within a few miles of you, you probably don't want too much antenna. What about wiring? I need cable and adapter plugs to get everything hooked up from the Antenna to my scanner. What type of Cable if I go with the outside setup? Again - how long and what frequency? I'm also wondering what type of connectors I need to hook the antenna up to the pro 95 handheld. BNC for the scanner end. I'm not sure about that particular antenna, but I think it takes a PL-259 (278-205). Soldered. Even at 150 MHz, you don't want a non-solder connector. At 850 MHz, it's as good as 5 feet of cable missing between the antenna and scanner. Radio Shack doesn't list a solder-type BNC connector, so you might want to use another PL-259 (they come 2 to a pack at RS) and use an adapter (278-120) to go to the scanner. |
Outdoor Scanner Antenna
"Al Klein" wrote in message Four things you should be aware of: 1) A discone is a negative gain antenna - that is, it has less gain than a dipole, which is the standard by which 0 gain is measured. ------------------------------------------------------------------------------- Name 1 "scanner" antenna that does have gain? Not an amatuer antenna a "scanner" antenna. NONE, have any gain. If you want to use a amateur antenna as in a dual band, fine. But its going to operate in negative gain territory outside of its design limits also. Not many people want to listen to just 2 areas of the spectrum, i.e. 146Mhz and or 440Mhz. With trunking a fact of life nowdays most people want to listen anywhere from 100 to 900Mhz. There are only 2 antennas that work well all the way thru that area, one is the discone and the other is the Austin Ferret. With the Ferret running at 225$ most people dont want to spend that much. Since the signal it receives is so weak, the cable is VERY important - the lower the loss the better, even if it's a fairly short run. DON'T buy your cable from Radio Shack - they don't sell any low loss cable - only cable that's lowER loss than the regular cable. Go to this site http://www.timesmicrowave.com/cgi-bin/calculate.pl, plug in the highest frequency you're interested in (will you be listening to 850?), the cable type (try a few of the common ones - RG6, RG8, RG58) and the approximate length of cable, and you'll see how much signal the cable will lose. Look at the "efficiency". Subtract that from 100 and that's how much signal is being lost. -------------------------------------------------------------------------- Actually a nice link, very informative and agree with it totally. I use Quad Shielded RG 6 with only about a 25' run. Im good up to about 1 Gig. Not much above that to listen to anyway. Be prepared to spend at least 50 cents/foot for decent cable and up to $2/foot for good cable. Putting up a gainless antenna and lossy cable (like 100 feet of RG58 for 850 MHz - 96% of the signal is lost in the cable) is just a waste of time and money. You'll probably receive better with a rubber duck on the scanner. 2) Don't buy hype, buy an antenna. If a discone is designed properly, and very well made, it will cover a frequency range of 4:1. (Most real - not on paper - discones are more like 3:1.) The lowest frequency is that at which the radials are 1/4 wave long. So to receive VHF-lo well they have to be about 6 feet long. The highest frequency this antenna will be any good at will be about 120 MHz. ------------------------------------------------------------------------------ Actually a good discone is closer to a 10: 1 ratio. Most, without the vertical stinger are good from 100-1000Mhz. I have transmitted on mine on 52, 144, 440, and 904Mhz with anywhere from excellent to good results. ( mine does have the stinger) Actually mine works very well in the 900Mhz area in general, better than any other scanner antennas I have used, and I have had them all up at one time or another. Scantenna, Scan King 1500, various Antenna Specialist scanner antennas and most of them were almost deaf in that range. The typical discone with 3 foot radials will cover from about 75-225 MHz. -------------------------------------------------------------------------- The math for a discone is totally different than the math for a dipole. They just dont work the same way. 3) Wherever you put the antenna, and no matter how high you put it, figure out where it will fall if the mount breaks away at the base. It should fall within the confines of your property - for a few of reasons. Agreed Add last, but by no means least, if you're going to put up an outside antenna, PLEASE put in a good grounding system, ground the mast to it and use a static discharge device on the cable. The ground system should tie ALL the grounds in the house to one point - telephone, electric, antenna. And a decent ground (not a good one, a decent one) is AT LEAST 4 10 foot ground rods spaced in a rectangle at least 10 feet on a side, with wire going from 1 to the next, but NOT forming a loop, with all your grounds connected at one point along that run - any one point, preferably near the middle. --------------------------------------------------------------------------- You're getting carried away here again with the grounding thing. Nobody, and I mean nobody puts a grd system in as you describe here. It simply isnt needed. I'm not making this up - read the National Electric Code on grounding, or ask an electrician. This is important - people are killed every year by bad antenna installations. Not many - but if you're one of them, it doesn't matter how many there are. -------------------------------------------------------------------------------- The people that do get killed are the idiots that put up a mast and an antenna 10' from a power line, and when it goes down and lands on a power line bad things happen. Rule No. 1, do not put ANY antenna even remotely close to ANY power line and you wont have any problems. |
Outdoor Scanner Antenna
Hi Scott
There are many types of Discone antennas available depending on what frequency range your interested in receiving. Cable is a very important consideration and often overlooked. When I purchased the Icom AH-7000 Discone antenna, about twelve years ago, a fifty foot section of their so called "low loss" cable was included, and terminated with "N" connectors at both ends. Personally I wouldn't even give that included cable away to someone I didn't know, as it is pretty poor quality. When this particular Discone was installed, the cable I selected was Belden 9913. This cable has a 9 1/2 AWG solid center conductor, a solid spiral teflon tube continuously running around the center conductor which is enclosed in a air dielectric teflon tube bonded with copper foil on the outside and that is covered with a braided copper shield and covered with a soft PVC water-proof jacket. There is an "N" connector with the center pin specifically made for this exact cable. Since this cable is not as flexible as some installations may require, "Cable Experts" has a "9913" equivalent cable which is a little more flexible, it's "CXP1318" and is available in various lengths terminated with either an "N" or "PL-259" connector. Believe it or not, the difference in this cable compared to the cable included with the Discone was significant. This test was made with the Icom AH-7000 Discone using equal lengths of both cables, fifty feet, and both cables were terminated with type "N" connectors. Using my Icom IC-970H multi-mode transceiver, I observed about SEVEN S units in signal strength at 432Mhz. That's right, SEVEN! I now have a twenty two foot section of "Andrews Heliax" hardline cable connected to a "KB6KQ 432Mhz loop antenna". Realizing I'm getting off topic here, the point I'm attempting to make is the CABLE is a VERY important issue! May I suggest that before you finalize your anticipated antenna installation, do some testing with antenna placement, you may find that it may not be necessary to have it mounted outside in the weather. I'm located right on the beach and routinely need to remove, clean and replace my Discone every few months due to corrosion. This next week I'll be purchasing the AOR DS3000A Discone antenna. This will be mounted inside with only a six foot section of CXP1318 cable and dedicated to the Uniden BC796D I purchased just last week. Believe it or not, it is my very first "scanner". You may even have an area in the attic which will accommodate your installation. I say this because when you start installing antennas outside, sometimes your neighbors suddenly become interested in what your doing. Something else you may want to consider. My nearest neighbor is probably less than a mile away, so I do not worry about this and have various antennas mounted outside only because their also used for transmitting as well. If you do not plan on using your Discone for transmitting you may get away with it mounted inside. Above all, use good cable and if possible, keep cable lengths to a minimum! Best regards george On 2005-10-29 12:12:53 -0700, Al Klein said: On Fri, 28 Oct 2005 14:30:45 -0400, Scott said in rec.radio.scanner: Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. Four things you should be aware of: 1) A discone is a negative gain antenna - that is, it has less gain than a dipole, which is the standard by which 0 gain is measured. Since the signal it receives is so weak, the cable is VERY important - the lower the loss the better, even if it's a fairly short run. DON'T buy your cable from Radio Shack - they don't sell any low loss cable - only cable that's lowER loss than the regular cable. Go to this site http://www.timesmicrowave.com/cgi-bin/calculate.pl, plug in the highest frequency you're interested in (will you be listening to 850?), the cable type (try a few of the common ones - RG6, RG8, RG58) and the approximate length of cable, and you'll see how much signal the cable will lose. Look at the "efficiency". Subtract that from 100 and that's how much signal is being lost. Don't let anyone tell you that it only matters if you're transmitting. Do you see any "direction" choice there? The same amount of signal is lost in both directions. (Actually a little more is lost with a scanner because the scanner isn't a 50 ohm load to the cable.) Be prepared to spend at least 50 cents/foot for decent cable and up to $2/foot for good cable. Putting up a gainless antenna and lossy cable (like 100 feet of RG58 for 850 MHz - 96% of the signal is lost in the cable) is just a waste of time and money. You'll probably receive better with a rubber duck on the scanner. 2) Don't buy hype, buy an antenna. If a discone is designed properly, and very well made, it will cover a frequency range of 4:1. (Most real - not on paper - discones are more like 3:1.) The lowest frequency is that at which the radials are 1/4 wave long. So to receive VHF-lo well they have to be about 6 feet long. The highest frequency this antenna will be any good at will be about 120 MHz. The typical discone with 3 foot radials will cover from about 75-225 MHz. 25-1300 MHz is advertising copy, not measured performance. If anyone can get a discone (without a whip sticking up on top - just a pure discone - if you want whips, buy a Scantenna, or something like it) to cover a 50:1 frequency range (25-1300), you're going to hear him named a Nobel prize winner in physics. And science will have to be rethought. ANYTHING that's not an insulator will receive signals. The question is whether that thing, at the end of some reasonable length of affordable cable will receive any more signal than an antenna plugged right into the scanner. Why put up an antenna that gives you 6db gain over the antenna on the scanner and connect it with cable that gives you 9db loss? You just REDUCED the signal you're going to hear by 50% (3db). Sure the antenna has 6db gain over the one on the scanner - but it's not going to do you any good unless the cable loss is less than 6db. 3) Wherever you put the antenna, and no matter how high you put it, figure out where it will fall if the mount breaks away at the base. It should fall within the confines of your property - for a few of reasons. 1) You don't want a neighbor getting hurt if it falls. 2) You WILL be considered legally negligent if you mount it so that it can fall outside your property line. 3) Your insurance won't cover the judgment against you - you'll pay it all out of your pocket. But don't mount an antenna on your chimney. Aside from the fact that a chimney isn't made to withstand the torque produced when the wind hits the antenna, part of what goes up the flue is sulphur and, when it comes into contact with water (like from air with any humidity at all), it forms sulphuric acid. Do you really want your antenna bathed in that for months at a time every year? Add last, but by no means least, if you're going to put up an outside antenna, PLEASE put in a good grounding system, ground the mast to it and use a static discharge device on the cable. The ground system should tie ALL the grounds in the house to one point - telephone, electric, antenna. And a decent ground (not a good one, a decent one) is AT LEAST 4 10 foot ground rods spaced in a rectangle at least 10 feet on a side, with wire going from 1 to the next, but NOT forming a loop, with all your grounds connected at one point along that run - any one point, preferably near the middle. I'm not making this up - read the National Electric Code on grounding, or ask an electrician. This is important - people are killed every year by bad antenna installations. Not many - but if you're one of them, it doesn't matter how many there are. With all that in mind, this is a hobby, so enjoy it. |
Outdoor Scanner Antenna
On Fri, 28 Oct 2005 14:30:45 -0400, Scott wrote:
What could I expect from an outdoor Antenna? I have nothing to attach an antenna to on my roof. I'm newbie at this, and was curious as to how hard it would be to install this Just use a 1/4 wave VHF whip (unity gain on VHF, 1/2 wave gain on UHF) and some decent quality RG6X quad shield satellite cable. Put the whole thing on a short mast on your roof, use an "F to PL259" adapter on the antenna end, and an "F to BNC" adapter on the scanner end inside. Should give you PLENTY of improved performance over a duck. Discones are very low gain and wide band. They also bring in a LOT of unwanted interference with intermod/etc. You'll do fine with a VHF 1/4 wave as a base station antenna for scanner use. The impedence mis-match of the cable won't make a whole lot of difference to the scanner. |
Outdoor Scanner Antenna
On Sun, 30 Oct 2005 15:27:34 GMT, "Jeff"
said in rec.radio.scanner: "Al Klein" wrote in message Four things you should be aware of: 1) A discone is a negative gain antenna - that is, it has less gain than a dipole, which is the standard by which 0 gain is measured. Name 1 "scanner" antenna that does have gain? Not an amatuer antenna a "scanner" antenna. Since we never covered "scanner antenna" in antenna theory, define what you mean. Dipoles (or ground planes) have, by definition, 0dbd gain. A discone has negative gain, vis-a-vis a dipole. With trunking a fact of life nowdays most people want to listen anywhere from 100 to 900Mhz. There are only 2 antennas that work well all the way thru that area, one is the discone The discone operates, at best, over a 4:1 frequency range, not exactly VHF-hi to 850. Actually a nice link, very informative and agree with it totally. I use Quad Shielded RG 6 with only about a 25' run. Im good up to about 1 Gig. Not much above that to listen to anyway. I'll go along with 2.3db loss being ok, but what is quad shielding buying you with an unshielded scanner? Actually a good discone is closer to a 10: 1 ratio. When are they awarding you your Nobel prize? Most antenna engineers will quote you 3:1 for real world antennas. Some claim that they can actually achieve 4:1, but I suspect the machining costs would make the antenna unaffordable. Most, without the vertical stinger are good from 100-1000Mhz. I have transmitted on mine on 52, 144, 440, and 904Mhz with anywhere from excellent to good results. I can do the same thing with my R7, but that doesn't make the antenna an antenna at those frequencies. Conductors don't accumulate signal, they radiate it. The math for a discone is totally different than the math for a dipole. They just dont work the same way. Yep - the rule of thumb is that the lowest frequency is that at which the radials are 1/4 wave and the highest frequency is 3 times that for a good design that's been well implemented. You're getting carried away here again with the grounding thing. Nobody, and I mean nobody puts a grd system in as you describe here. No one you know - okay. Many people I know have and do. It simply isnt needed. Not unless you want a good ground. I'm not talking about not having the mic bite you, I'm talking about not living in a hole in the ground after the pole pig on the pole in front of your house suffers a direct strike. I'm not making this up - read the National Electric Code on grounding, or ask an electrician. This is important - people are killed every year by bad antenna installations. Not many - but if you're one of them, it doesn't matter how many there are. The people that do get killed are the idiots that put up a mast and an antenna 10' from a power line, and when it goes down and lands on a power line bad things happen. I'm talking about those killed by lightning. You don't run a ground system to blow breakers on a 440 line that are located a few miles, and a few transformations, from the ground. Rule No. 1, do not put ANY antenna even remotely close to ANY power line and you wont have any problems. Until the clouds gather. I hope you sleep well when someone actually takes your advice and it results in his death. *N*E*V*E*R* take *A*N*Y* chances with lightning. 50 million volts can't be "handled" by anything man can do when it has tens of thousands of amps available behind it. |
Outdoor Scanner Antenna
On Sun, 30 Oct 2005 14:30:00 -0800, Limited Viability
said in rec.radio.scanner: Just use a 1/4 wave VHF whip (unity gain on VHF, 1/2 wave gain on UHF) Minor point - 1/4 wavelength at 150 MHz is 3/4 wavelength at 450 MHz. Discones are very low gain and wide band. They also bring in a LOT of unwanted interference with intermod/etc. Being broadband, they bring in signals that may cause intermod, but that can't "bring in intermod". You'll do fine with a VHF 1/4 wave as a base station antenna for scanner use. Better than with a discone, but not for more than 2 bands - 150 and 450 - or 1 band of his choice. The impedence mis-match of the cable won't make a whole lot of difference to the scanner. It won't make any difference to the scanner - the load doesn't care about impedance mismatch. |
Outdoor Scanner Antenna
On Mon, 31 Oct 2005 05:57:39 -0500, Al Klein
wrote: On Sun, 30 Oct 2005 15:27:34 GMT, "Jeff" said in rec.radio.scanner: "Al Klein" wrote in message Four things you should be aware of: 1) A discone is a negative gain antenna - that is, it has less gain than a dipole, which is the standard by which 0 gain is measured. Name 1 "scanner" antenna that does have gain? Not an amatuer antenna a "scanner" antenna. Since we never covered "scanner antenna" in antenna theory, define what you mean. Dipoles (or ground planes) have, by definition, 0dbd gain. Incorrect, gain is normally quoted over an Isotropic radiator, which a Dipole is NOT. However relative to an isotropic radiatior, and Discone is a zero gain antenna. The attraction of the Discone is from the low VSWR over vast frequency range. A very high VSWR can turn a high gain antenna into a losing proposition because of feedline losses. A discone has negative gain, vis-a-vis a dipole. T |
Outdoor Scanner Antenna
On Mon, 31 Oct 2005 17:26:18 -0700, matt weber
said in rec.radio.scanner: On Mon, 31 Oct 2005 05:57:39 -0500, Al Klein wrote: Dipoles (or ground planes) have, by definition, 0dbd gain. Incorrect, gain is normally quoted over an Isotropic radiator, which a Dipole is NOT. Normally advertising hype is quoted in dbi, while honest antenna gain is quoted in dbd. So is engineering gain. |
Outdoor Scanner Antenna
One thing you could do is attach a 5-foot mast to your chimney with the
chimney mount kit from Radio Shack. It's easy to mount the discone to that mast. If you can figure a way to get the feed line into your house (through a gable vent, for example), you could expect to get great results as compared to a handheld or desktop antenna. I installed the 19-foot telescopic mast to my deck with a fixture that allows it to be tilted down (all hardware from Radio Shack). Since I was into ham radio at that time, it allowed me to install different antennas to try out. The deck is elevated, so I can get the antenna up about 25 feet from ground level without ever having to climb on the roof or installing guy wires. The first antenna I used was the RS discone, which worked very well. - Doug "Scott" wrote in message ... What could I expect from an outdoor Antenna? I have nothing to attach an antenna to on my roof. I'm newbie at this, and was curious as to how hard it would be to install this http://www.radioshack.com/product/in...rs&tab=support Years ago my neighbor was a cb freak, and he had a freaking tall antenna on his roof. How would I get this up high enough? Could someone really help a newbie out on what i would need to buy to get this antenna just right for scanning. I'm not afraid to do anything, but seriously just don't know what all I need, and what i should expect from this type of setup. |
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