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In article U060d.158329$Fg5.72937@attbi_s53, "Jeff" oldog@(nospam)
mchsi.com says... This is what you want. Will blow away about any other omni antenna out there. Light years ahead of a discone. http://users.cis.net/kingpop/Scanner/Scantenna.htm BDK ------------------------------------------------------------------------------- Not quite light years ahead of a discone. Last year I put up a discone on one side of my house and a ST 2 on the other side, fed them both with RG 6U double shielded. Had them feeding a Yaesu VR 5000 alternately. The discone was the one that had the vertical element on top. On 30-50 I could tell no difference between the 2. But I could use the discone on 6 meter fm with a 1.9-1 swr. on 148-170 they appeared to be the same. On some freqs the ST 2 was a tad, and I mean a tad better. ON other signals in VHF (i.e.144mhz ssb amateur) the discone picked up distant ssb chatter while the ST 2 picked up nothing. On the discone I can use on 2 mtr. fm with almost a flat swr. On 440-470 they apeared to be the same for all intent. Although I can use the discone on 440 fm with a 1.5-1 or so swr. On the 470-512 area there is nothing to listen to around here so thats a wash. But on 800-912mhz the discone worked quite well and is somewhat resonant there, while the ST 2 seemed to be about deaf in this area. If you live in an area that gets freezing rain and wind, even the new improved ST 2 will not last. Its too fragile. I have never had a discone come down. After my tests I took down the ST 2 and sold it, and still have up the discone. There is no substitute for being resonant at various points on a freq plot. The ST 2 basically fakes the radio as far as impededance with the 300 ohm transformer. It hardly blows the discone out of the water, like I hear so often. Advertising hype. Jeff I havent seen the heavier duty one in person, so I can't say for sure how strong it is, but a discone really truly blows as an antenna. A ringo ranger 2 works pretty well, better than any of the discones I have had on most freqs. I wonder if the Yaesu was hearing better on the discone because it was desensitizing. I had one here for a while, and it was a disaster, intermod and hash all over, and so I sold it to a friend who lives 20 miles from any really big town. Works good out there.. Right now I have two Scantennas in the attic, along with a discone and a home brew ground plane cut for 161 Mhz (trains), The discone is in the "sweet spot" in the attic (it was there first), and until I bought the first Scantenna, I thought it was ok. I even replaced the original coax on the discone with 9913 and it was a tiny bit better on 800, but wasn't anywhere else. I have the discone connected to my BC9000, as it's better on that antenna, since it seems most prone to losing it's cool due to a nearby TV station's huge signal. The Pro 2005 and 2006 on the scantennas will both easily beat the 9000 in every way but scan speed, on any antenna. If I had my choice as one single antenna to use, I would probably pick the home built ground plane (I can build one that will last forever), with the ringo a close second. The scantenna's next only due to it's fragility. I may build a HD one myself one of these days.. As far as impedance goes, it's pretty meaingless for receivers, loss is much more of a problem. I need to find a climber to change the coax on my ringo, and put up another discone as a backup to it, for 2M/440. I don't want to get ripped off for 300 bucks like I did 10 years ago, 25 of it was for coming over the border into my town. That 150 yards cost 4 times as much as the ground plane I made the day before cost me! BDK |
"BDK" wrote in message ------------------------------------------------------------------------------- If I had my choice as one single antenna to use, I would probably pick the home built ground plane (I can build one that will last forever), with the ringo a close second. The scantenna's next only due to it's fragility. I may build a HD one myself one of these days.. As far as impedance goes, it's pretty meaingless for receivers, loss is much more of a problem. I need to find a climber to change the coax on my ringo, and put up another discone as a backup to it, for 2M/440. I don't want to get ripped off for 300 bucks like I did 10 years ago, 25 of it was for coming over the border into my town. That 150 yards cost 4 times as much as the ground plane I made the day before cost me! ------------------------------------------------------------------------------- I suggest you go back and study some rf transmission basics. Impedance is important on recieve if you want to get maximum signal transfer. In an impedance matched circuit you will get maximum flow of rf, than in a non resonant circuit. This applies to recieve as well as transmit. Why do you think they use that little 1.95$ 300ohm to 50ohm transformer on the scantenna? It isnt there for looks. And no my VR 5k wasnt suffering from intermod or overload, had an AM filter, an FM filter, and a paging freq. filter on it and it works quite well. If you build your own ground plane, I bet you will make the elements to come out to 1/4 wave on the freq. you want it to work best on wont you? Why? because a 1/4 wave is a 52 ohm load at the resonant frequency. Thats what a discone does, it happens to be a 1/4 wave on a lot of different frequencies, thats why you can xmit on it. Scantennas work, just not well enough for me to have one up and with the 1st freezing rain and wind that comes along it ends up bent up like a pretzel. The only band where it outperformed the discone was in the 152-155 band where the LEO's use in different counties. Jeff |
In article kUq0d.22548$D%.9053@attbi_s51, "Jeff" oldog@(nospam)
mchsi.com says... "BDK" wrote in message ------------------------------------------------------------------------------- If I had my choice as one single antenna to use, I would probably pick the home built ground plane (I can build one that will last forever), with the ringo a close second. The scantenna's next only due to it's fragility. I may build a HD one myself one of these days.. As far as impedance goes, it's pretty meaingless for receivers, loss is much more of a problem. I need to find a climber to change the coax on my ringo, and put up another discone as a backup to it, for 2M/440. I don't want to get ripped off for 300 bucks like I did 10 years ago, 25 of it was for coming over the border into my town. That 150 yards cost 4 times as much as the ground plane I made the day before cost me! ------------------------------------------------------------------------------- I suggest you go back and study some rf transmission basics. Impedance is important on recieve if you want to get maximum signal transfer. In an impedance matched circuit you will get maximum flow of rf, than in a non resonant circuit. This applies to recieve as well as transmit. Why do you think they use that little 1.95$ 300ohm to 50ohm transformer on the scantenna? It isnt there for looks. And no my VR 5k wasnt suffering from intermod or overload, had an AM filter, an FM filter, and a paging freq. filter on it and it works quite well. If you build your own ground plane, I bet you will make the elements to come out to 1/4 wave on the freq. you want it to work best on wont you? Why? because a 1/4 wave is a 52 ohm load at the resonant frequency. Thats what a discone does, it happens to be a 1/4 wave on a lot of different frequencies, thats why you can xmit on it. Scantennas work, just not well enough for me to have one up and with the 1st freezing rain and wind that comes along it ends up bent up like a pretzel. The only band where it outperformed the discone was in the 152-155 band where the LEO's use in different counties. Jeff LOL, whatever you say...calm down. If I had to throw all those filters on the Yaesu, I would have just bought an ICOM R8500 in the first place and it would have made life easier, or kept my 7100, since I didn't need another SW receiver. You do realize that a scanner doesn't want 50/52 ohms at most of it's freq coverage, dont you? It's kind of hit and miss at best. I know what the transformer is for. I'm just posting that in my almost 40 years of VHF and up monitoring, the scantenna, fragile as it was/is (I don't have a HD version to check out)is vastly, not just a little bit superior to a discone. Let them buy discones if they want!! I don't own Channel Master, or whoever makes it these days... BDK |
BDK wrote:
A ground plane made with an SO-239 connector and some coat hangers will blow a discone away. A total waste of money, unless you want it as a back up antenna to transmit on.... I guess I've have different experiences than you. Is it possible that there is a strong signal source close to you that was desensing your receiver when using the discone and you've created a "high pass" filter with your tuned 1/4 wave? -D -- "One ought, every day at least, to hear a little song, read a good poem, see a fine picture, and, if it were possible, to speak a few reasonable words." - Johann Wolfgang von Goethe |
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"BDK" wrote in message
... A ground plane made with an SO-239 connector and some coat hangers will blow a discone away. A total waste of money, unless you want it as a back up antenna to transmit on.... BDK A ground plane antenna, though, will limit the useful range of frequencies, won't it? I agree that it could outperform a discone at (and around) its resonant frequency, but for wideband scanning purposes, how could it outperform an antenna better optimized for wideband use like a discone? Like Donald K, I have had very good experiences with a discone. It even worked well for HF listening with compact wideband receivers that overload easily with wire antennas. On the other hand, if one needs a band-specific antenna, a ground plane would be easier and certainly cheaper. |
"Donald K" wrote in message
... Mac Tabak wrote: I know a few have suggested discones....but they are really for horizontalradiation, you need vertical polarisation for police. Try a 1/2 wave dipole, easy to make. Um, discone *is* vertical. Page 7-29 ARRL Antenna Book, 20th Ed. -- "One ought, every day at least, to hear a little song, read a good poem, see a fine picture, and, if it were possible, to speak a few reasonable words." - Johann Wolfgang von Goethe Yep, I sense a little bit of confusion entering the eqation here. The Discone is vertically polarised, whereas typically a dipole is horizontally polarised - particularly on the lower frequencies. For example on 80m (3.5 MHz), a dipole would typically be around 20 metres in length, which is not the easiest antenna to string upright, so most poeple will put them up horizontally. On the VHF and UHF bands, a dipole can be setup for either vertical or horizontal polarisation and as stated a couple of postings above, they are pretty easy to construct. Matt |
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