Re: Topband: ZS6BKW(G5RV) on 160m?
The ZS6BKW is really a quite different antenna than a G5RV. On 40, 20, 18, 12 and 10 meters, the feedpoint is close enough to 50 ohms to present a good match when properly trimmed . The coax is matched so the length of the coax is not important and losses are low ON THESE BANDS. It actually is very similar to a G5RV. It just has some length adjustments. I guess one could argue that most antennas are similar, just with length adjustments. Take a 160 ft long wire, cut it up into 5 pieces, presto. A 5 element 20 meter beam... ;) Kevin _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
The ZS6BKW is really a quite different antenna than a G5RV. On 40, 20, 18, 12 and 10 meters, the feedpoint is close enough to 50 ohms to present a good match when properly trimmed . The coax is matched so the length of the coax is not important and losses are low ON THESE BANDS. It actually is very similar to a G5RV. It just has some length adjustments. To be fair, the original G5RV was designed as a 20 meter antenna prima rily and it works only after a fashion on the other bands (as G3OIT found) due to losses in the unmatched coax, for the most part. With the ZS6BKW here, I switch from the coax to ladder line back to the shack at the feedpoint as G3OIT does on the unmatched bands (80, 30 and 15) . On 160, I short the ladder at the feedpoint and feed it through a matching network against a radial system. The G5RV is actually pretty good on 80, 40, 20, and 12 meters. Here is how I used a G5RV on 160. It would work with the ZS6BKW. http://www.w8ji.com/g5rv_facts.htm I used my G5RV on 160 phased against a 100 foot tower as a two element vertical array. I worked JT1 and lots of other good DX from a suburban Atlanta lot, just outside the city. It was a good antenna for a location where I could really only have one tower and a few wires. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
On Thu,3/26/2015 2:12 PM, Mike Smith VE9AA wrote: This is great info. Hey, thanks guys,.As I read these comments, I am now wondering if there is a magic length of coax, that attaches to the 40’ of 450 ladder line that I could short right in/at the improvised vacation shack end, or just at the interface to the door/window/outside world, where I will be allowed to bring the coax in the (for lack of a better term), “cottage”….? Mike, Don't even think of trying to load that antenna on 160M as a flat wire fed with transmission line. It will be a really lousy antenna. What WILL work is tying both sides of the ladder line together and loading it as a semi-vertical long wire. The top wires will act as top loading. You need SOMETHING to act as a counterpoise. Study the 160M Power Point slides on my website. k9yc.com/publish.htm Then do the best you can with what you have at your vacation site. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
Marsh, Kevin, Jim, everyone This is great info. Hey, thanks guys,.As I read these comments, I am now wondering if there is a magic length of coax, that attaches to the 40’ of 450 ladder line that I could short right in/at the improvised vacation shack end, or just at the interface to the door/window/outside world, where I will be allowed to bring the coax in the (for lack of a better term), “cottage”….? It’s a long story, but I am thinking I am going to be limited to one antenna, and there may not be any more than one coax, and no going in and out the building in the wee hours of the morning. A restrictive scenario, but you’ll just have to trust me. So, if I could have, let’s say…..10’ of coax in the “shack”, then let’s just say for example, 40’ feet of coax and then the 40’ of ladder line, could I short the coax 10’ from the rig in the shack (and even add a coil ?), then if I wanted to get back on the other bands, simply unshort the 10’ run and put everything as normal? My goal would be to work some W1’s/W2’s/VE3’s and perhaps a G/EA, Carib? on 160m just for mults. I’d rather not carry too much gear with me, so if I could get it in the ballpark and let the Icom’s internal tuner handle a small mismatch, I’d be OK with that. I might even rethink the 2 gnd radials and tie into the cottage gnd, but whatever works. I’m not clear yet what the trip hazard ratio will be where I am at. Hope I was clear. Yes, it’s a strange scenario.hi hi, I even laugh, but I can’t really tell the whole story. One coax, one antenna-ZS6BKW, no going outside at night, no external remote tuners …all bands 10-160. Hm. If I had more flexibility, I’d string up an inverted L off my proposed 35’ fiberglass mast and run a 2nd coax, but for this particular place, I am constricted. I can build and test this before I leave, but I still have to find bare ground first. We still have many FEET of snow everywhere. Spring has not really sprung yet. Mike VE9AA Mike, Coreen Corey Keswick Ridge, NB From: kol...@rcn.com [mailto:kol...@rcn.com] Sent: March 26, 2015 2:33 AM To: Mike Smith VE9AA Cc: topband@contesting.com Subject: Re: Topband: ZS6BKW(G5RV) on 160m? Mike, this is exactly the antenna I use here at the home QTH. Mine is set up as a 92 ft flattop and 42 ft feeder, one end at 50 ft the other at 25 ft (that's what I had to work with). I have a switching box at the bottom that has three modes: a)the ladderline is connected directly to the coax running back from the box to the shack (with a bit of trimming this gives you tunerless operation on 40,20,18,12 and 10 meters. b)the ladderline is passed through to an extention random piece of ladderline to a tuner at the shack for 80,30 and 15 meters c)the feeder is shorted and fed to a coax connector to a dedicated external tuning unit for 160, then back into another connector where it goes back to the shack through the same piece of coax as the a) arrangement. I have out 30 radials, I know you can't do as many but one does what one can. This arrangement is one of the best modest all band antennas I have used, and it does fairly well on 160, I have worked over 100 countries with this, not awesome, but not too bad for a small station with a so-so operator. I use a K9AY for RX here. Just for a dumb comparison, it greatly outperforms a butternut (not that hard to do, LOL). I modeled this with a simple antenna modeling program (that I barely knew how to use) and the matching network it came up with got me in the ballpark. I wish I remember what figures I got... Best, Kevin K3OX _ From: Mike Smith VE9AA ve...@nbnet.nb.ca To: topband@contesting.com Sent: Wednesday, March 25, 2015 8:57:18 PM Subject: Topband: ZS6BKW(G5RV) on 160m? I might have a chance to operate from a portable location this summer for a contest or two but at the location they have no antennas, nor is there room for any huge vertical, inverted L, guys ropes etc. etc. and no permission to climb roofs, chimneys, or put a bolt in the building, nor touch the trees. All very restrictive. I might be able to erect a 35' freestanding fiberglass mast with a ZS6BKW. Maybe. The ZS6BKW is basically a 94' dipole with a 40' downlead of 450ohm ladeer line..which will be sloped slightly, as I don't see a way to get the peak above 35' Suffice to say, the best I MIGHT be able to do is sneak in this low ZS6BKW(G5RV) as an inv. vee to run 10m-80m but I am looking for a way to ALSO be on 160m to make a few dozen contacts in a contest or two. I am thinking the peak of the ZS6BKW (G5RV like antenna) would be at max 35'. For 160m, could I short the 2 leads of the 450ohm ladder line together where they meet the coax run and sneak out 2 x 65' (bent) ground radials and attach them to the braid side of the coax? (maybe I'll even make up a switchbox so I don't have to be running around in the dark a few times a night
Re: Topband: ZS6BKW(G5RV) on 160m?
On 26/03/2015 21:12, Mike Smith VE9AA wrote: This is great info. Hey, thanks guys,.As I read these comments, I am now wondering if there is a magic length of coax, that attaches to the 40’ of 450 ladder line that I could short right in/at the improvised vacation shack end, or just at the interface to the door/window/outside world, where I will be allowed to bring the coax in the (for lack of a better term), “cottage”….? It’s a long story, but I am thinking I am going to be limited to one antenna, and there may not be any more than one coax, and no going in and out the building in the wee hours of the morning. A restrictive scenario, but you’ll just have to trust me. So, if I could have, let’s say…..10’ of coax in the “shack”, then let’s just say for example, 40’ feet of coax and then the 40’ of ladder line, could I short the coax 10’ from the rig in the shack (and even add a coil ?), then if I wanted to get back on the other bands, simply unshort the 10’ run and put everything as normal? My goal would be to work some W1’s/W2’s/VE3’s and perhaps a G/EA, Carib? on 160m just for mults. I’d rather not carry too much gear with me, so if I could get it in the ballpark and let the Icom’s internal tuner handle a small mismatch, I’d be OK with that. I might even rethink the 2 gnd radials and tie into the cottage gnd, but whatever works. I’m not clear yet what the trip hazard ratio will be where I am at. Hi Mike, I haven't quite got my head round what you're planning, but what I'm doing may give you some ideas... A G5RV is a compromise antenna. It's based round a doublet fed with ladderline, and a coaxial feed that sort-of matches it. It works, sort-of. I had one here. I wasn't impressed with the performance. I removed the coax, brought the ribbon feeder into the shack, and built a matching unit using a roller inductor, switched variable and fixed capacitors, and air-cored baluns. I tried a broadband ferrite balun, but it got very hot on some bands. The air ones don't even get warm. Getting rid of the G5RV coax improved performance significantly - I can get an indicated 1:1 match on all the HF bands on the input to the matching unit. I don't know how well it's performing overall since I don't have the measuring equipment, but it does well in pileups and I seem to be able to work stuff. It takes a while to retune when I change band, but I'm not in a hurry. I have all the settings written down. On 160, I strap the ribbon feeder and load the whole antenna as a T, tuned against ground. I live in a house built around 1490 and there are all kinds of restrictions on what I'm allowed to do, but nobody knows about the radial field that runs round the garden, across the lawn, etc - about half an inch below the surface. The antenna runs between three trees, with a telescopic pole hidden in the middle one to get the feedpoint above the treetop. I need to do some more experimenting with it on 160. I can work all of Europe and into Africa and Asia, but I'm definitely in the little pistol category on top band. I don't think there's a better solution given the restrictions of the listed property. Best of luck - hope maybe we will work on 160! Best 73, Keith G3OIT _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
Here is what I would do. First, build the proposed antenna, set it up at home with the coax connected directly to the ladder line at the bottom, the hot and ground each to one leg. Trim the ladder for lowest SWR on the low end of 40 meters (this should get 20,18,12 and 10 more or less right). Then see if your internal tuner will tune the antenna as it sits through the coax on 80, 30 and 15 meters. At this point, you will know if you have a viable all band antenna (unfortunately, most internal tuners are not wide rang e things). If you are good to here, put down your radials and reconfigure the feedpoint by shorting the ladder line at the bottom and connect that to the hot side of the coax and the radials to ground side. Now t ry to tune this arrangement with the internal tuner. If this doesn't work and you have a 4 to one balun around, you can put it between the output of the rig and the coax to the antenna and try to bring the load into the range of the internal tuner with that. It's worth a try... If you find a workable arrangement in test, b uild a remote switch box and ghost the 12 volts to key the remo te relay box through the Coax. You will need a small switch box at the shack end and a relay box at the antenna end, basically you need a simplified version of the Ameritron RCS-4 (schematic on Ameritron website) system. This will switch between 4 antennas through the coax without a control wire , but y ou only need 0 and +12 volts and one relay at the antenna, so all you need is a two position on-off toggle , the capacitor/choke/input- output connectors and 12 volt connection at the shack end and a DPDT relay, choke/capacitor arrangement, one coax connector and a pair of banana jacks for the ladder line and a DPDT relay at the relay box end. The relay is set up with one side of the ladder line to each relay section and the deenergized side hooked up to the coax connector back to the shack directly and the energized contacts sending both sides of the ladder line to the center conductor of the connector. Mak e a ground connection on the relay box to hook your radials to. If you really wanted to get slick, you could add another relay and a small matching network (a coil and a capacitor) for 160 in the relay box (I assume you will only run 100 watts) if the internal tuner won't match on 160. Good luck. What you want to do won't be easy, but could be worth it if you can make it happen ! Best, Kevin - Original Message - From: Mike Smith VE9AA ve...@nbnet.nb.ca To: topband@contesting.com Sent: Thursday, March 26, 2015 5:12:11 PM Subject: Re: Topband: ZS6BKW(G5RV) on 160m? Marsh, Kevin, Jim, everyone This is great info. Hey, thanks guys,.As I read these comments, I am now wondering if there is a magic length of coax, that attaches to the 40’ of 450 ladder line that I could short right in/at the improvised vacation shack end, or just at the interface to the door/window/outside world, where I will be allowed to bring the coax in the (for lack of a better term), “cottage”….? It’s a long story, but I am thinking I am going to be limited to one antenna, and there may not be any more than one coax, and no going in and out the building in the wee hours of the morning. A restrictive scenario, but you’ll just have to trust me. So, if I could have, let’s say…..10’ of coax in the “shack”, then let’s just say for example, 40’ feet of coax and then the 40’ of ladder line, could I short the coax 10’ from the rig in the shack (and even add a coil ?), then if I wanted to get back on the other bands, simply unshort the 10’ run and put everything as normal? My goal would be to work some W1’s/W2’s/VE3’s and perhaps a G/EA, Carib? on 160m just for mults. I’d rather not carry too much gear with me, so if I could get it in the ballpark and let the Icom’s internal tuner handle a small mismatch, I’d be OK with that. I might even rethink the 2 gnd radials and tie into the cottage gnd, but whatever works. I’m not clear yet what the trip hazard ratio will be where I am at. Hope I was clear. Yes, it’s a strange scenario.hi hi, I even laugh, but I can’t really tell the whole story. One coax, one antenna-ZS6BKW, no going outside at night, no external remote tuners …all bands 10-160. Hm. If I had more flexibility, I’d string up an inverted L off my proposed 35’ fiberglass mast and run a 2nd coax, but for this particular place, I am constricted. I can build and test this before I leave, but I still have to find bare ground first. We still have many FEET of snow everywhere. Spring has not really sprung yet. Mike VE9AA Mike, Coreen Corey Keswick Ridge, NB From: kol...@rcn.com [mailto:kol...@rcn.com] Sent: March 26, 2015 2:33 AM To: Mike Smith VE9AA Cc: topband@contesting.com Subject: Re: Topband: ZS6BKW(G5RV) on 160m? Mike, this is exactly the antenna I use here at the home
Re: Topband: ZS6BKW(G5RV) on 160m?
The ZS6BKW is really a quite different antenna than a G5RV. On 40, 20, 18, 12 and 10 meters, the feedpoint is close enough to 50 ohms to present a good match when properly trimmed . The coax is matched so the length of the coax is not important and losses are low ON THESE BANDS. To be fair, the original G5RV was designed as a 20 meter antenna prima rily and it works only after a fashion on the other bands (as G3OIT found) due to losses in the unmatched coax, for the most part. With the ZS6BKW here, I switch from the coax to ladder line back to the shack at the feedpoint as G3OIT does on the unmatched bands (80, 30 and 15) . On 160, I short the ladder at the feedpoint and feed it through a matching network against a radial system. Best, Kevin K3OX - Original Message - From: Keith Jillings (G3OIT) g3oit.ke...@jillings.org.uk To: Mike Smith VE9AA ve...@nbnet.nb.ca, topband@contesting.com Sent: Thursday, March 26, 2015 6:51:49 PM Subject: Re: Topband: ZS6BKW(G5RV) on 160m? On 26/03/2015 21:12, Mike Smith VE9AA wrote: This is great info. Hey, thanks guys,.As I read these comments, I am now wondering if there is a magic length of coax, that attaches to the 40’ of 450 ladder line that I could short right in/at the improvised vacation shack end, or just at the interface to the door/window/outside world, where I will be allowed to bring the coax in the (for lack of a better term), “cottage”….? It’s a long story, but I am thinking I am going to be limited to one antenna, and there may not be any more than one coax, and no going in and out the building in the wee hours of the morning. A restrictive scenario, but you’ll just have to trust me. So, if I could have, let’s say…..10’ of coax in the “shack”, then let’s just say for example, 40’ feet of coax and then the 40’ of ladder line, could I short the coax 10’ from the rig in the shack (and even add a coil ?), then if I wanted to get back on the other bands, simply unshort the 10’ run and put everything as normal? My goal would be to work some W1’s/W2’s/VE3’s and perhaps a G/EA, Carib? on 160m just for mults. I’d rather not carry too much gear with me, so if I could get it in the ballpark and let the Icom’s internal tuner handle a small mismatch, I’d be OK with that. I might even rethink the 2 gnd radials and tie into the cottage gnd, but whatever works. I’m not clear yet what the trip hazard ratio will be where I am at. Hi Mike, I haven't quite got my head round what you're planning, but what I'm doing may give you some ideas... A G5RV is a compromise antenna. It's based round a doublet fed with ladderline, and a coaxial feed that sort-of matches it. It works, sort-of. I had one here. I wasn't impressed with the performance. I removed the coax, brought the ribbon feeder into the shack, and built a matching unit using a roller inductor, switched variable and fixed capacitors, and air-cored baluns. I tried a broadband ferrite balun, but it got very hot on some bands. The air ones don't even get warm. Getting rid of the G5RV coax improved performance significantly - I can get an indicated 1:1 match on all the HF bands on the input to the matching unit. I don't know how well it's performing overall since I don't have the measuring equipment, but it does well in pileups and I seem to be able to work stuff. It takes a while to retune when I change band, but I'm not in a hurry. I have all the settings written down. On 160, I strap the ribbon feeder and load the whole antenna as a T, tuned against ground. I live in a house built around 1490 and there are all kinds of restrictions on what I'm allowed to do, but nobody knows about the radial field that runs round the garden, across the lawn, etc - about half an inch below the surface. The antenna runs between three trees, with a telescopic pole hidden in the middle one to get the feedpoint above the treetop. I need to do some more experimenting with it on 160. I can work all of Europe and into Africa and Asia, but I'm definitely in the little pistol category on top band. I don't think there's a better solution given the restrictions of the listed property. Best of luck - hope maybe we will work on 160! Best 73, Keith G3OIT _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
I am not sure how a 40' tall vertical with 94' of top loading, models in NEC, but it seems like it might be close-ish(?) to resonating on 160m. (will I be in the ballpark?) What kind of matching will I need if any? Mike, I modeled a 40' vertical with 92' of top loading on 1.825MZ using EZNEC+ 5.0.66. EZNEC+ 5 uses NEC-2. NEC-2 does not like connections to ground with Real/High Accuracy ground. So I modeled two (2) 65' radials at 6 inches above Real/High Accuracy ground. The pattern looks very good with a deep overhead null. As for feeding the antenna, 40' of vertical and 92 ft of top loading is too short for 160M. The calculated feedpoint impedance is 16.22 - J 365.6 ohms. You can add a series inductor and use a 1:2 balun (50 ohm source to 25 ohm load) and get the SWR to about 1.5:1. The actual feedpoint impedance will almost surely be different than calculated. Before you order/wind a balun and wind an inductor, it might be a good idea to build the antenna and measure the actual feedpoint impedance. Then you will know for sure what you need to match. I would not count on an internal ATU to do the job. I hope this helps at least some. 73, Marsh, KA5M From: Mike Smith VE9AA ve...@nbnet.nb.ca To: topband@contesting.com Sent: Wednesday, March 25, 2015 8:57:18 PM Subject: Topband: ZS6BKW(G5RV) on 160m? I might have a chance to operate from a portable location this summer for a contest or two but at the location they have no antennas, nor is there room for any huge vertical, inverted L, guys ropes etc. etc. and no permission to climb roofs, chimneys, or put a bolt in the building, nor touch the trees. All very restrictive. I might be able to erect a 35' freestanding fiberglass mast with a ZS6BKW. Maybe. The ZS6BKW is basically a 94' dipole with a 40' downlead of 450ohm ladeer line..which will be sloped slightly, as I don't see a way to get the peak above 35' Suffice to say, the best I MIGHT be able to do is sneak in this low ZS6BKW(G5RV) as an inv. vee to run 10m-80m but I am looking for a way to ALSO be on 160m to make a few dozen contacts in a contest or two. I am thinking the peak of the ZS6BKW (G5RV like antenna) would be at max 35'. For 160m, could I short the 2 leads of the 450ohm ladder line together where they meet the coax run and sneak out 2 x 65' (bent) ground radials and attach them to the braid side of the coax? (maybe I'll even make up a switchbox so I don't have to be running around in the dark a few times a night reconfiguring bare wires in an unfamiliar location.) I've read 3830 contest reports where folks have done this type of thing, but of all the antennas I have ever had (many!_) I have never EVER tried this shorting of the ladder line or coax and feeding what is a G5RV as a T-Top vertical. with a couple of radials. I am not sure how a 40' tall vertical with 94' of toploading, models in NEC, but it seems like it might be close-ish(?) to resonating on 160m. (will I be in the ballpark?) What kind of matching will I need if any? I could maybe even add more coax or ladder line to the vertical section when on 160m, however it will also have to be sloped/bent and on or very near the ground (probably not good, eh?) I'll be using a modern transceiver with internal ATU. I am not looking to run pileups on 160m.(where I am going is not rare, just a nice summer place)..I just want to pick up a few 160m mults in a contest or two. Ideas? Remember, I am very restricted. Gotta have the ZS6BKW for my antenna.and I may not be permitted to have more than 1 coax run out to the antenna. I doubt adding a couple extra 65' legs is possible either. (no square footage for that. Thanks Mike VE9AA Mike, Coreen Corey Keswick Ridge, NB _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
On Thu,3/26/2015 7:56 AM, Marsh Stewart wrote: I modeled a 40' vertical with 92' of top loading on 1.825MZ using EZNEC+ 5.0.66. EZNEC+ 5 uses NEC-2. NEC-2 does not like connections to ground with Real/High Accuracy ground. So I modeled two (2) 65' radials at 6 inches above Real/High Accuracy ground. The pattern looks very good with a deep overhead null. The major shortcoming of this antenna is not the shape of the pattern or the match to the rig, it is the fact that it's not very tall and the radial/counterpoise system is limited. It's not a lot different from what I had in Chicago. It sort of worked, but not great. BUT -- Mike is in VE9, so even barefoot, he might even work some EU if conditions are good. BTW -- to model this antenna in NEC, I'd forget about modeling the radials and instead add 10-15 ohms in series with a connection to Mini-NEC ground. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: ZS6BKW(G5RV) on 160m?
I might have a chance to operate from a portable location this summer for a contest or two but at the location they have no antennas, nor is there room for any huge vertical, inverted L, guys ropes etc. etc. and no permission to climb roofs, chimneys, or put a bolt in the building, nor touch the trees. All very restrictive. I might be able to erect a 35' freestanding fiberglass mast with a ZS6BKW. Maybe. The ZS6BKW is basically a 94' dipole with a 40' downlead of 450ohm ladeer line..which will be sloped slightly, as I don't see a way to get the peak above 35' Suffice to say, the best I MIGHT be able to do is sneak in this low ZS6BKW(G5RV) as an inv. vee to run 10m-80m but I am looking for a way to ALSO be on 160m to make a few dozen contacts in a contest or two. I am thinking the peak of the ZS6BKW (G5RV like antenna) would be at max 35'. For 160m, could I short the 2 leads of the 450ohm ladder line together where they meet the coax run and sneak out 2 x 65' (bent) ground radials and attach them to the braid side of the coax? (maybe I'll even make up a switchbox so I don't have to be running around in the dark a few times a night reconfiguring bare wires in an unfamiliar location.) I've read 3830 contest reports where folks have done this type of thing, but of all the antennas I have ever had (many!_) I have never EVER tried this shorting of the ladder line or coax and feeding what is a G5RV as a T-Top vertical. with a couple of radials. I am not sure how a 40' tall vertical with 94' of toploading, models in NEC, but it seems like it might be close-ish(?) to resonating on 160m. (will I be in the ballpark?) What kind of matching will I need if any? I could maybe even add more coax or ladder line to the vertical section when on 160m, however it will also have to be sloped/bent and on or very near the ground (probably not good, eh?) I'll be using a modern transceiver with internal ATU. I am not looking to run pileups on 160m.(where I am going is not rare, just a nice summer place)..I just want to pick up a few 160m mults in a contest or two. Ideas? Remember, I am very restricted. Gotta have the ZS6BKW for my antenna.and I may not be permitted to have more than 1 coax run out to the antenna. I doubt adding a couple extra 65' legs is possible either. (no square footage for that. Thanks Mike VE9AA Mike, Coreen Corey Keswick Ridge, NB _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ZS6BKW(G5RV) on 160m?
Mike, this is exactly the antenna I use here at the home QTH. Mine is set up as a 92 ft flattop and 42 ft feeder , one end at 50 ft the other at 25 ft (that's what I had to work with). I have a switching box at the bottom that has three modes: a)the ladderline is connected directly to the coax running back from the box to the shack (with a bit of trimming this gives you tunerless operation on 40,20,18,12 and 10 meters. b)the ladderline is passed through to an extention random piece of ladderline to a tuner at the shack for 80,30 and 15 meters c)the feeder is shorted and fed to a coax connector to a dedicated external tuning unit for 160, then back into another connector where it goes back to the shack through the same piece of coax as the a) arrangement. I have out 30 radials, I know you can't do as many but one does what one can. This arrangement is one of the best modest all band antennas I have used, and it does fairly well on 160, I have worked over 100 countries with this, not awesome, but not to o bad for a small station with a so-so operator. I use a K9AY for RX here. Just for a dumb comparison, it greatly outperforms a butternut (not that hard to do, LOL). I modeled this with a simple antenna modeling program (that I barely knew how to use) and the matching network it came up with got me in the ballpark. I wish I remember what figures I got... Best, Kevin K3OX - Original Message - From: Mike Smith VE9AA ve...@nbnet.nb.ca To: topband@contesting.com Sent: Wednesday, March 25, 2015 8:57:18 PM Subject: Topband: ZS6BKW(G5RV) on 160m? I might have a chance to operate from a portable location this summer for a contest or two but at the location they have no antennas, nor is there room for any huge vertical, inverted L, guys ropes etc. etc. and no permission to climb roofs, chimneys, or put a bolt in the building, nor touch the trees. All very restrictive. I might be able to erect a 35' freestanding fiberglass mast with a ZS6BKW. Maybe. The ZS6BKW is basically a 94' dipole with a 40' downlead of 450ohm ladeer line..which will be sloped slightly, as I don't see a way to get the peak above 35' Suffice to say, the best I MIGHT be able to do is sneak in this low ZS6BKW(G5RV) as an inv. vee to run 10m-80m but I am looking for a way to ALSO be on 160m to make a few dozen contacts in a contest or two. I am thinking the peak of the ZS6BKW (G5RV like antenna) would be at max 35'. For 160m, could I short the 2 leads of the 450ohm ladder line together where they meet the coax run and sneak out 2 x 65' (bent) ground radials and attach them to the braid side of the coax? (maybe I'll even make up a switchbox so I don't have to be running around in the dark a few times a night reconfiguring bare wires in an unfamiliar location.) I've read 3830 contest reports where folks have done this type of thing, but of all the antennas I have ever had (many!_) I have never EVER tried this shorting of the ladder line or coax and feeding what is a G5RV as a T-Top vertical. with a couple of radials. I am not sure how a 40' tall vertical with 94' of toploading, models in NEC, but it seems like it might be close-ish(?) to resonating on 160m. (will I be in the ballpark?) What kind of matching will I need if any? I could maybe even add more coax or ladder line to the vertical section when on 160m, however it will also have to be sloped/bent and on or very near the ground (probably not good, eh?) I'll be using a modern transceiver with internal ATU. I am not looking to run pileups on 160m.(where I am going is not rare, just a nice summer place)..I just want to pick up a few 160m mults in a contest or two. Ideas? Remember, I am very restricted. Gotta have the ZS6BKW for my antenna.and I may not be permitted to have more than 1 coax run out to the antenna. I doubt adding a couple extra 65' legs is possible either. (no square footage for that. Thanks Mike VE9AA Mike, Coreen Corey Keswick Ridge, NB _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
