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#1
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GeorgeF wrote in
ink.net: redrum wrote: Which is better? is scantenna really omnidirectional? is it built for a better reception on the most used frequencies or is really multiband? who sells the better implementation of discone? I have three scantennas and they work much much better than any discone I've yet to own. In the last 5 years I have thrown away 2 discones (even the Diamond $100+) because they didn't come close to what the AntennaWarehouse ScanTennas could do. Most of my listening is 225-400 MHz however have compaired them on many other freqs as well. I got my ScanTennas from http://www.antennawarehouse.com/Scanner/Scantenna.htm (AntennaWarehouse). Free shipping and speedy delivery. George - Daytona Beach, FL http://www.MilAirComms.com I got one of those and am not overly impressed with it. My discone consistantly pulls in stronger signals than the scantenna in just about every range. The only variables are 1) Discone is about 5 ft higher up 2) Discone uses a better feed belden 9913 3) Discone uses an N connecter vs. BNC for scantenna. Perhaps those three combined are enough to give the discone an edge in an of itself, but I doubt much of one. Not much UHF mil around my area unfortunatly, but I can pull in a wx station at an AFB about 40 miles away with the discone, and the scantenna doesn't. Just my observations. |
#2
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On Thu, 06 Jan 2005 04:42:00 GMT, "T-bone" wrote:
I got one of those and am not overly impressed with it. My discone consistantly pulls in stronger signals than the scantenna in just about every range. The only variables are 1) Discone is about 5 ft higher up 2) Discone uses a better feed belden 9913 3) Discone uses an N connecter vs. BNC for scantenna. Perhaps those three combined are enough to give the discone an edge in an of itself, but I doubt much of one. Not much UHF mil around my area unfortunatly, but I can pull in a wx station at an AFB about 40 miles away with the discone, and the scantenna doesn't. Just my observations. I cannot speak to the relative performance of a discone vs. the Scantenna because I've never used a Scantenna. I can, however, attest to the fact that a quality feedline is *extremely* important at UHF frequencies. Look at a list of specifications for different types of coaxial cable, paying particular attention to the specified signal loss (in decibels) per hundred feet of cable. At HF the loss even in plain old RG-58U is negligible, at UHF, it's astronomical by comparison. RG-8U is better, but still falls on its face at UHF. The extra five feet of height, well, most people would be surprised how much of a difference just five feet of elevation can make in your reception, especially at higher frequencies. While I've never used a Scantenna, I used a discone for some time for monitoring UHF milcomms here in the area near Niagara Falls, New York. In addition to a USAFR airlift wing and an ANG air refueling wing based at Niagara Falls, I also sit between a couple of air refueling tracks and am kind of on the flight path followed by aircraft based in the eastern US on CORONET EAST missions. The discone allowed me to log plenty of good catches, outperforming by far one of RadioShack's multi-band ground planes in that respect. One thing I did notice, though - the RS ground plane flat-out smoked the discone on the 30-50 MHz low VHF band, as demonstrated to me by years of monitoring fire department DX down there. John Kasupski, Tonawanda, New York Amateur Radio (KC2HMZ), SWL/Scanner Monitoring (KNY2VS) Member of ARES/RACES, ARATS, WUN, ARRL http://www.qsl.net/kc2fng E-Mails Ignored, Please Post Replies In This Newsgroup |
#3
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John Kasupski wrote in
: On Thu, 06 Jan 2005 04:42:00 GMT, "T-bone" wrote: I got one of those and am not overly impressed with it. My discone consistantly pulls in stronger signals than the scantenna in just about every range. The only variables are 1) Discone is about 5 ft higher up 2) Discone uses a better feed belden 9913 3) Discone uses an N connecter vs. BNC for scantenna. Perhaps those three combined are enough to give the discone an edge in an of itself, but I doubt much of one. Not much UHF mil around my area unfortunatly, but I can pull in a wx station at an AFB about 40 miles away with the discone, and the scantenna doesn't. Just my observations. I cannot speak to the relative performance of a discone vs. the Scantenna because I've never used a Scantenna. I can, however, attest to the fact that a quality feedline is *extremely* important at UHF frequencies. Look at a list of specifications for different types of coaxial cable, paying particular attention to the specified signal loss (in decibels) per hundred feet of cable. At HF the loss even in plain old RG-58U is negligible, at UHF, it's astronomical by comparison. RG-8U is better, but still falls on its face at UHF. The extra five feet of height, well, most people would be surprised how much of a difference just five feet of elevation can make in your reception, especially at higher frequencies. While I've never used a Scantenna, I used a discone for some time for monitoring UHF milcomms here in the area near Niagara Falls, New York. In addition to a USAFR airlift wing and an ANG air refueling wing based at Niagara Falls, I also sit between a couple of air refueling tracks and am kind of on the flight path followed by aircraft based in the eastern US on CORONET EAST missions. The discone allowed me to log plenty of good catches, outperforming by far one of RadioShack's multi-band ground planes in that respect. Granted, they are all factors, which is why I listed them, but I doubt if its enough to make a difference other than in sensitive test equipment. The coax used on the scantenna is the highest grade RS sells, isonly about a 30 ft run, and has in fact been exposed to the elements a couple years less than my 9913. If the scantenna was really the superior signal gatherer, it should more than make up for these variables. Which isn't to say that the scantenna might not be superior for someone else. Obviously, they get the job done for George, and I'm sure hes a more sophisticated monitor than myself, as you likely are too. One thing I did notice, though - the RS ground plane flat-out smoked the discone on the 30-50 MHz low VHF band, as demonstrated to me by years of monitoring fire department DX down there. Do you have a vertical element on your discone ? This tends to improve discone low band reception sometimes dramatically. I know the RS discone I use didn't come with one, but a little rubber cap on top came off, and lo and behold theres a threaded stud in there, juat waiting for an old CB antenna or some such to be screwed on. Why this element doesn't come with the package, and why they don't even mention it in the literature I don't know. |
#4
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T-bone wrote:
GeorgeF wrote in ink.net: redrum wrote: Which is better? is scantenna really omnidirectional? is it built for a better reception on the most used frequencies or is really multiband? who sells the better implementation of discone? I have three scantennas and they work much much better than any discone I've yet to own. In the last 5 years I have thrown away 2 discones (even the Diamond $100+) because they didn't come close to what the AntennaWarehouse ScanTennas could do. Most of my listening is 225-400 MHz however have compaired them on many other freqs as well. I got my ScanTennas from http://www.antennawarehouse.com/Scanner/Scantenna.htm (AntennaWarehouse). Free shipping and speedy delivery. George - Daytona Beach, FL http://www.MilAirComms.com I got one of those and am not overly impressed with it. My discone consistantly pulls in stronger signals than the scantenna in just about every range. The only variables are 1) Discone is about 5 ft higher up 2) Discone uses a better feed belden 9913 3) Discone uses an N connecter vs. BNC for scantenna. You are compairing apples and oranges here. First your 5' higher on the discone is going to be a little improvement. But the HUGH HUGH HUGH difference is the coax! 9913 is much better than the RG6 which comes with the ScanTenna. I don't use the RG6 that comes, I replace it with either 9913 or LMR-400. But that alone your going to see a major improvement on your ScanTenna in the UHF range. N .vs. BNC, not much there..... George - Daytona Beach, FL http://www.MilAirComms.com |
#5
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![]() "GeorgeF" wrote in message nk.net... You are compairing apples and oranges here. First your 5' higher on the discone is going to be a little improvement. But the HUGH HUGH HUGH difference is the coax! 9913 is much better than the RG6 which comes with the ScanTenna. I don't use the RG6 that comes, I replace it with either 9913 or LMR-400. But that alone your going to see a major improvement on your ScanTenna in the UHF range. ---------------------------------------------------------------------------------------- I dont think he's comparing apples to oranges at all. First off when it comes to VHF or UHF, 5' more height is nothing. Second of all there is no HUGE,, HUGE difference in db's of attenuation between RG 6 and 9913. The "average" db of attenuation for 9913 per 100' from 1mhz to 1ghz is 2.17 db. The "average" atenuation for RG 6 per 100' from 1mhz. to 1ghz is 3.2 db. The average difference between the 2 is 1.03 db, wouldnt even be noticeable. And those specs. are for a 100' run. I believe he said his run was more like 30'. I use quad shielded RG 6 all the time and it works great, not to mention its much easier to work with than the thick, stiff 9913, or LMR 400. Jeff |
#6
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GeorgeF wrote in
nk.net: T-bone wrote: GeorgeF wrote in ink.net: redrum wrote: Which is better? is scantenna really omnidirectional? is it built for a better reception on the most used frequencies or is really multiband? who sells the better implementation of discone? I have three scantennas and they work much much better than any discone I've yet to own. In the last 5 years I have thrown away 2 discones (even the Diamond $100+) because they didn't come close to what the AntennaWarehouse ScanTennas could do. Most of my listening is 225-400 MHz however have compaired them on many other freqs as well. I got my ScanTennas from http://www.antennawarehouse.com/Scanner/Scantenna.htm (AntennaWarehouse). Free shipping and speedy delivery. George - Daytona Beach, FL http://www.MilAirComms.com I got one of those and am not overly impressed with it. My discone consistantly pulls in stronger signals than the scantenna in just about every range. The only variables are 1) Discone is about 5 ft higher up 2) Discone uses a better feed belden 9913 3) Discone uses an N connecter vs. BNC for scantenna. You are compairing apples and oranges here. First your 5' higher on the discone is going to be a little improvement. Very little, granted. I've already pointed out that fact twice already. But the HUGH HUGH HUGH difference is the coax! 9913 is much better than the RG6 which comes with the ScanTenna. I don't use the RG6 that comes, I replace it with either 9913 or LMR-400. But that alone your going to see a major improvement on your ScanTenna in the UHF range. Never said I used RG6. RG8x is what I use for the scantenna feed. I have no problem deferring to your judgement, more or less. You are obviously more up to date than me on both equipment and methods. I think its generally accepted that the discone is a great all around monitoring antenna, but is really a jack of all trades, and master of none. Ideally, one would want to have a discone, along with one or more other antennas optimized for specific bands. Thats what I had in mind with my setup, and so far it hasn't worked out, but I must admit I haven't put a whole lot of effort into examining this apparent problem. I just don't think that discones should be dismissed as pure junk. Within their limits, I've found them to be fine general all around signal recievers, which is what their purpose is. |
#7
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T-bone wrote:
I just don't think that discones should be dismissed as pure junk. Within their limits, I've found them to be fine general all around signal recievers, which is what their purpose is. Agreed! You are absolutely right. George has been shilling Scantennas for Antenna Warehouse for several years now. He belittles whatever else anyone my recommend and refuses to acknowledge that another product may suffice for another's purposes. His shamelessly partisan promotion gets old after awhile. -- Milepost 11.7 - UPRR Jeff City Sub - N 38°34'53", W 90°22'32", 680' "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm" |
#8
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![]() "Dan Morisseau" wrote in message ... T-bone wrote: I just don't think that discones should be dismissed as pure junk. Within their limits, I've found them to be fine general all around signal recievers, which is what their purpose is. Agreed! You are absolutely right. George has been shilling Scantennas for Antenna Warehouse for several years now. He belittles whatever else anyone my recommend and refuses to acknowledge that another product may suffice for another's purposes. His shamelessly partisan promotion gets old after awhile. A discone is going to exhibit no gain, in fact probably less than unity gain, when compared to an isotropic, but you can essentially call a discone a 0 dB gain antenna across its entire bandwidth of operation. Using an oversimplification, the lower frequency of the discone will be largely determined by cone and disc element lengths (about 0.25 and 0.17 respectively), the upper frequency by the gap between the two. Although a discone will probably only exhibit an ideal response across about a 3 to 1 range (well short of this gap limitation). A dipole will exhibit a slight gain over the same source (isotropic), about 2.7 dB in the real world, across its bandwidth. However, the dipole will be much more narrow banded. The dipole has a single resonant frequency, determined mostly by physical size. It is easy to use transmit bandwidth to define 'peak' operation. Transmit bandwidth is defined as the band between the two frequencies at which the SWR on the feedline has risen to stated values, it being assumed the SWR at the band center has previously been adjusted by some means to be 1:1. However, receive bandwidth can also be defined. Receiving bandwidth is defined as the band between the two frequencies at which receiver input power has fallen to 1/2 the level at the band center. It is described as the 3dB bandwidth. For a Zo-matched receiver, 3dB bandwidth is 2*Fc/Q where Fc is the center frequency and Q is the intrinsic Q of the antenna. Remember this Q and look at where it is in the formula. For receive antenna purposes a lower Q will mean a broader bandwidth. The Scantenna is a modified multiple dipole antenna, on the quoted website it calls it a '15 element clustered dipole design'. The elements that splay out from the main element are there to broaden the bandwidth. The short elements on the mounting boom are to cover the higher frequencies. Without having tried the antenna myself, but having more than a little bit of professional experience with RF, I can make a pretty good stab at what I would expect the antenna to do in use. The longest length is about 101 inches. This is going to put the lowest usable frequency around 50 MHz. Guestimating the length of the other elements from this 101 number it looks like they have selected lengths that fall near certain bands, probably the 'major' scanner bands. So that the antenna will probably function quite well in those frequency areas. If you stay in those bands you will probably get better performance with the scantenna than you will with the discone. However, outside those narrow bands the discone will probably perform better. One thing to note. At the higher frequencies the Scantenna seems to use short boom mounted dipoles. These WILL display a directionality based on the relationship of the received signal directions to the main set of elements. In other words, it will look 'down' the boom better than to the side. At those higher bands the Scantenna will probably display a better performance ONLY when the transmitting station is along this direction. Other than that the discone will probably appear to perform better on average. So, depending on your primary scan activities, the discone will probably be the less limited choice. But, if the Scantenna fits your specific application it may exhibit a slight performance edge, within its band limitations. All just a guess on my part, but defendable. For most things I would opt for a well designed and built discone myself. C |
#9
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![]() "Colic" wrote in message news:lZxDd.79015$k25.9878@attbi_s53... All just a guess on my part, but defendable. For most things I would opt for a well designed and built discone myself. If your receiver had a front end with good dynamic range the discone might be ok. Most scanners do not have particularly good dynamic range. The discone will be fairly efficient in the FM broadcast band and also on some TV channels. That may overload the scanner and result in poor performance all around. It depends on how close the broadcast transmitters are to your receiving antenna. A five foot height difference can be significant if it allows the antenna to clear nearby obstructions. For most purposes a good grade of RG/6 like Belden 9116 performs well enough that changing to 9113 will not result in a significant improvement. Quad shield RG/6 has the same loss as ordinary RG/6 according to the Belden catalog. |
#10
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Has anyone had experience with both of these antennas.The 20-014 is the big
ground plane that was discontinued 5-6 years ago, it has several verticals (three I think) and I think the radials are 14 or 15 ft wide, looks more like a CB ground plane than a scanner antenna. I'm trying to decide which one I want to go up with. If memory serves me right MT gave the 20-014 a great write up. Rob Mills |
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