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#1
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Hi, all.
I'm about to become a General class licensee, and I'm trying to work out a HF antenna plan for my new apartment. I have a small balcony on the top (4th) floor, which is good, but unfortunately there's a roof overhanging it and is 8' over the balcony floor and juts 4' out over the balcony edge, so a tall vertical is out of the question. What about a 'vertical' that is angled about 45 deg. down from vertical? Will that be good for phone DXing on any HF band? Also, sadly, the balcony is all metal and so is the top of the roof. What about some kind of loop? Thanks! ~swooz |
#2
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![]() "Swoozie Pellegrino" wrote in message ... Hi, all. I'm about to become a General class licensee, and I'm trying to work out a HF antenna plan for my new apartment. I have a small balcony on the top (4th) floor, which is good, but unfortunately there's a roof overhanging it and is 8' over the balcony floor and juts 4' out over the balcony edge, so a tall vertical is out of the question. What about a 'vertical' that is angled about 45 deg. down from vertical? Will that be good for phone DXing on any HF band? Also, sadly, the balcony is all metal and so is the top of the roof. What about some kind of loop? Thanks! ~swooz Try the Half Sloper if you could. It is quarter wave wire suspended between balcony and run at about 45 deg down to a tree or whatever. There is a good chance you will end up with 50 ohm impedance and can be fed directly with a coax, shield connected to metal railing or door frame and center wire to the antenna. Trim to frequency. Had one like that from the 9th floor at the hotel in Bahamas, worked very well. 73 Yuri, K3BU.us |
#3
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On Feb 12, 8:05*am, "Yuri Blanarovich" wrote:
"Swoozie Pellegrino" wrote in message ... Hi, all. I'm about to become a General class licensee, and I'm trying to work out a HF antenna plan for my new apartment. I have a small balcony on the top (4th) floor, which is good, but unfortunately there's a roof overhanging it and is 8' over the balcony floor and juts 4' out over the balcony edge, so a tall vertical is out of the question. What about a 'vertical' that is angled about 45 deg. down from vertical? *Will that be good for phone DXing on any HF band? Also, sadly, the balcony is all metal and so is the top of the roof. What about some kind of loop? Thanks! ~swooz Try the Half Sloper if you could. It is quarter wave wire suspended between balcony and run at about 45 deg down to a tree or whatever. There is a good chance you will end up with 50 ohm impedance and can be fed directly with a coax, shield connected to metal railing or door frame and center wire to the antenna. Trim to frequency. Had one like that from the 9th floor at the hotel in Bahamas, worked very well. 73 *Yuri, K3BU.us- Hide quoted text - - Show quoted text - Thanks, Yuri. Unfortunately, there's no good tree or pole to attach to below. There *is* a parking garage about 400 feet straight across from me though! LOL, would be a really long wire. I may try the dangling wire that Rick described earlier in this thread. I'll just have to figure out what fraction of 20m and 40m wavelengths that will work best with that and cut the wire(s) accordingly. I have about 50' of height to work with. Or maybe a MFJ-1622 clamped to the railing? http://www.eham.net/reviews/detail/2035 Thanks, ~swooz |
#4
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On Feb 12, 8:05*am, "Yuri Blanarovich" wrote:
"Swoozie Pellegrino" wrote in message ... Hi, all. I'm about to become a General class licensee, and I'm trying to work out a HF antenna plan for my new apartment. I have a small balcony on the top (4th) floor, which is good, but unfortunately there's a roof overhanging it and is 8' over the balcony floor and juts 4' out over the balcony edge, so a tall vertical is out of the question. What about a 'vertical' that is angled about 45 deg. down from vertical? *Will that be good for phone DXing on any HF band? Also, sadly, the balcony is all metal and so is the top of the roof. What about some kind of loop? Thanks! ~swooz Try the Half Sloper if you could. It is quarter wave wire suspended between balcony and run at about 45 deg down to a tree or whatever. There is a good chance you will end up with 50 ohm impedance and can be fed directly with a coax, shield connected to metal railing or door frame and center wire to the antenna. Trim to frequency. Had one like that from the 9th floor at the hotel in Bahamas, worked very well. 73 *Yuri, K3BU.us- Hide quoted text - - Show quoted text - I think that I'm going to start with this idea, since I have a radio coming in the mail and would like to do the simplest and cheapest up front to get the radio tested out. I have a few questions: 1. After I wire up the antenna & coax as described above, can I do my trimming to frequency by using only the radio's SWR meter, or do I need an external tuner at the wire? 2. This radio can output 100W on HF. Can't this setup with a 10m length of 26-gauge magnet wire handle this? 3. I may need to run up to 30' of coax. What type should I buy? Thanks for all the help! ~swooz |
#5
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Swoozie Pellegrino wrote:
On Feb 12, 8:05 am, "Yuri Blanarovich" wrote: Try the Half Sloper if you could. It is quarter wave wire suspended between balcony and run at about 45 deg down to a tree or whatever. There is a good chance you will end up with 50 ohm impedance and can be fed directly with a coax, shield connected to metal railing or door frame and center wire to the antenna. Trim to frequency. Had one like that from the 9th floor at the hotel in Bahamas, worked very well. 73 Yuri, K3BU.us- Hide quoted text - - Show quoted text - I think that I'm going to start with this idea, since I have a radio coming in the mail and would like to do the simplest and cheapest up front to get the radio tested out. I have a few questions: 1. After I wire up the antenna & coax as described above, can I do my trimming to frequency by using only the radio's SWR meter, or do I need an external tuner at the wire? 2. This radio can output 100W on HF. Can't this setup with a 10m length of 26-gauge magnet wire handle this? 3. I may need to run up to 30' of coax. What type should I buy? Thanks for all the help! ~swooz One thing you should realize about the half sloper is that it's only half an antenna. The outside of the coax, in your case, is the other half of the antenna. If you put one amp into the "antenna" wire, one amp will flow down the outside of the coax. So don't be surprised if you find strange effects in your shack, such as electronic keyers which keep sending, push-to-talk buttons that turn on the transmitter but don't turn it off, RF burns from the microphone, and an SWR that changes when you move the feedline around or change its length. You might get lucky and not see these effects if the length of coax to the antenna and from the rig to the ground is favorable, or you might not. You'll also need to take care to keep the feedline as far away as possible from power or telephone wiring because it's radiating just like the "antenna" part of the actual antenna. For those reasons it wouldn't be my choice for an indoor antenna, but apparently Yuri has gotten lucky and had success with it, and so might you, too. I'm sure you'll get some other suggestions from people with a lot of experience. 26 gauge magnet wire is fine for most indoor antennas (about anything except an electrically small loop). RG-58 is fine for the coax, up to a few hundred watts, if the SWR is fairly low. If the SWR is fairly high (say, above 3:1) and you're running 100 watts, you might want to use RG-59 or RG-58x instead. Have fun! Roy Lewallen, W7EL |
#6
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![]() "Roy Lewallen" wrote in message ... Swoozie Pellegrino wrote: On Feb 12, 8:05 am, "Yuri Blanarovich" wrote: Try the Half Sloper if you could. It is quarter wave wire suspended between balcony and run at about 45 deg down to a tree or whatever. There is a good chance you will end up with 50 ohm impedance and can be fed directly with a coax, shield connected to metal railing or door frame and center wire to the antenna. Trim to frequency. Had one like that from the 9th floor at the hotel in Bahamas, worked very well. 73 Yuri, K3BU.us- Hide quoted text - - Show quoted text - I think that I'm going to start with this idea, since I have a radio coming in the mail and would like to do the simplest and cheapest up front to get the radio tested out. I have a few questions: 1. After I wire up the antenna & coax as described above, can I do my trimming to frequency by using only the radio's SWR meter, or do I need an external tuner at the wire? 2. This radio can output 100W on HF. Can't this setup with a 10m length of 26-gauge magnet wire handle this? 3. I may need to run up to 30' of coax. What type should I buy? Thanks for all the help! ~swooz One thing you should realize about the half sloper is that it's only half an antenna. The outside of the coax, in your case, is the other half of the antenna. If you put one amp into the "antenna" wire, one amp will flow down the outside of the coax. So don't be surprised if you find strange effects in your shack, such as electronic keyers which keep sending, push-to-talk buttons that turn on the transmitter but don't turn it off, RF burns from the microphone, and an SWR that changes when you move the feedline around or change its length. Not as bad as foreseen. What the HalfSloper is - vertical or ground plane antenna turned on the side/angle and the pattern then formed between the antenna and the ground reflection. It is beneficial to connect as much "iron" as possible as a ground plane - guardrail, door frame flushing. The RF is then formed between the radiator wire and the "ground plane" with little getting behind it. Just to underline that sloping wire goes away from the building, not anywhere inside. You can use SWR meter on ic706 to find where the wire resonates and trim it to frquency. It should be close to 50 ohms, you should not need a tuner. I was expecting my setup to have lower impedance than 50 ohms and had coil ready, to be inserted between the guardrail and the wire and then finding the tap for 50 ohms on the coil, few turns up from the ground connection. But it turned out to be perect 50 ohms and wire length was original vertical wire from my baloon vertical working against 4 elevated radials on 160m. You might get lucky and not see these effects if the length of coax to the antenna and from the rig to the ground is favorable, or you might not. You'll also need to take care to keep the feedline as far away as possible from power or telephone wiring because it's radiating just like the "antenna" part of the actual antenna. I had no problem with RF, coax was about 8 feet between balcony and rig and computer next to it. In case of longer coax and to be safe, you could wind few turns of coax in a coil at the feed point to form the choke. For those reasons it wouldn't be my choice for an indoor antenna, but apparently Yuri has gotten lucky and had success with it, and so might you, too. I'm sure you'll get some other suggestions from people with a lot of experience. It is outdoor antenna with pattern being formed between the radiator wire and metal mess of the building, RF stays outside with reasonable amount of "iron" and wiring in the building. 26 gauge magnet wire is fine for most indoor antennas (about anything except an electrically small loop). RG-58 is fine for the coax, up to a few hundred watts, if the SWR is fairly low. If the SWR is fairly high (say, above 3:1) and you're running 100 watts, you might want to use RG-59 or RG-58x instead. Have fun! Roy Lewallen, W7EL I would use 50 ohm coax, RG 58 variety should be OK. 26 gauge wire should fine. 73 and GL Yuri, K3BU.us |
#7
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On Sun, 17 Feb 2008 13:44:05 -0800 (PST), Swoozie Pellegrino
wrote: Try the Half Sloper if you could. It is quarter wave wire suspended between balcony and run at about 45 deg down to a tree or whatever. There is a good chance you will end up with 50 ohm impedance and can be fed directly with a coax, shield connected to metal railing or door frame and center wire to the antenna. Trim to frequency. 1. After I wire up the antenna & coax as described above, can I do my trimming to frequency by using only the radio's SWR meter, or do I need an external tuner at the wire? Cut the wire long, and trim by small increments. If you are still trimming well after it is obviously shorter than a quarter wave, further trimming might find resonance, but you could be bucking up against unknowns (this is not likely to be big problem however). 2. This radio can output 100W on HF. Can't this setup with a 10m length of 26-gauge magnet wire handle this? And more. 3. I may need to run up to 30' of coax. What type should I buy? Common radio shack stuff will work fine. You can spend more, certainly, but if your antenna is tuned, no one will be able to tell the difference at the far end between hardline and RG156 (you won't find that at RS, probably, but there is a lot of RG8X). However, it you can put up one wire for one band (no tuner? THAT is odd) you can as easily put up three, four or five as a fan sloper (or dipole, or monopole...) and not have to worry about SWR for one band or several. It takes only slightly more construction ingenuity and effort, but perhaps it may be too much visual exposure that draws the unwanted eye (which, I suppose, is why you are using magnet wire in the first place). 73's Richard Clark, KB7QHC |
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