Strange Vertical - need help
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That is an untuned vertical. You need an antenna tuner for most bands (the
Zero5 website tells you this). If your new K3 is equipped with the autotuner, you'll be fine. Phil - AD5X ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Strange Vertical - need help
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In reply to this post by KC6CNN
The Zero-Five web site specifies 100 feet of feedline and a "wide range antenna tuner" for that antenna. The SWR readings you report are about what I would expect for an untuned antenna of its type. The Zero-Five GP40-10 is essentially a 20 meter half wave (26 feet vertical, 8.25 feet horizontal) fed 25% from one end ... a classic OCF design. The claims of operation on 40 (and 30 meters) bother me since the antenna is far too short for effective 40 meter operation. I suspect the feedline is part of the antenna on 40 meters. Since the antenna manufacturer specifies a minimum feedline length of 100 feet, they're obviously using the feedline to moderate the native feed impedance so the tuner can handle it. 73, ... Joe, W4TV On 3/11/2012 11:48 AM, KC6CNN wrote: > I installed a vertical with ground radial kit up 20 feet. > The antenna mast and negative sheild connector is grounded to a ground rod. > The antenna covers 10 to 40 meters. > I can tune 10 meters fine, and fourty meters fine, but 12,15,17,20,and 30 > will not tune and SWR are high. > here are the SWR reading taken on AM running 25 watts. > > 10 meter > > 2804550 is 2 to 1 SWR > > 2882000 is 1.5 to 1 SWR > > > 12 meter > > 2490000 is 3 to 1 SWR > > 24990 is 3 to 1 SWR > > > 15 meter > > 2103900 is 4 to 1 SWR > > top porting is 3 to 1 SWR > > > 17 meter > > 1809000 is 3 to 1 SWR > > 1817000 is 2 to 1 SWR > > > 20 meter > > 1402800 is 2 to 1 SWR > > 1430000 is 2 to 1 SWR > > > 30 meter > > 1010500 is 4 to 1 SWR > > 1014000 is 4 to 1 SWR > > > 40 meter > > 7026 is 2 to 1 SWR > > 7290 is 1.5 to 1 SWR > > Any help or suggestions would be greatly appreciated. I will be receiving my > K3 on Tuesday and am trying to get this antenna sorted out before then. > Oh yea the rig I'm using right now is a Kenwood 570, the Coax is LMR400 with > a 100' run. the Antenna is a ZeroFive GP10-40. > > Thank you > Gerald Manthey > KC6CNN > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/Strange-Vertical-need-help-tp7363205p7363205.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Strange Vertical - need help
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Correct. They're using the 100 feet of coax to add enough loss to swamp out the native feed impedance. Note that they specify it as a minimum length, not some particular length that might provide some kind of transformation. If you use enough coax with enough loss you can get almost a perfect 50 ohm match at the transmitter with an open circuit on the far end. It becomes just a long dummy load. KC6CNN could improve his match by simply exchanging the low loss LMR400 for RG-8X. ;) But he wouldn't get any more power to the antenna. 73, Dave AB7E On 3/11/2012 10:06 AM, Joe Subich, W4TV wrote: > The Zero-Five web site specifies 100 feet of feedline and a "wide range > antenna tuner" for that antenna. The SWR readings you report are about > what I would expect for an untuned antenna of its type. > > The Zero-Five GP40-10 is essentially a 20 meter half wave (26 feet > vertical, 8.25 feet horizontal) fed 25% from one end ... a classic > OCF design. The claims of operation on 40 (and 30 meters) bother me > since the antenna is far too short for effective 40 meter operation. > I suspect the feedline is part of the antenna on 40 meters. > > Since the antenna manufacturer specifies a minimum feedline length > of 100 feet, they're obviously using the feedline to moderate the > native feed impedance so the tuner can handle it. > > 73, > > ... Joe, W4TV > > > On 3/11/2012 11:48 AM, KC6CNN wrote: >> I installed a vertical with ground radial kit up 20 feet. >> The antenna mast and negative sheild connector is grounded to a ground rod. >> The antenna covers 10 to 40 meters. >> I can tune 10 meters fine, and fourty meters fine, but 12,15,17,20,and 30 >> will not tune and SWR are high. >> here are the SWR reading taken on AM running 25 watts. >> >> 10 meter >> >> 2804550 is 2 to 1 SWR >> >> 2882000 is 1.5 to 1 SWR >> >> >> 12 meter >> >> 2490000 is 3 to 1 SWR >> >> 24990 is 3 to 1 SWR >> >> >> 15 meter >> >> 2103900 is 4 to 1 SWR >> >> top porting is 3 to 1 SWR >> >> >> 17 meter >> >> 1809000 is 3 to 1 SWR >> >> 1817000 is 2 to 1 SWR >> >> >> 20 meter >> >> 1402800 is 2 to 1 SWR >> >> 1430000 is 2 to 1 SWR >> >> >> 30 meter >> >> 1010500 is 4 to 1 SWR >> >> 1014000 is 4 to 1 SWR >> >> >> 40 meter >> >> 7026 is 2 to 1 SWR >> >> 7290 is 1.5 to 1 SWR >> >> Any help or suggestions would be greatly appreciated. I will be receiving my >> K3 on Tuesday and am trying to get this antenna sorted out before then. >> Oh yea the rig I'm using right now is a Kenwood 570, the Coax is LMR400 with >> a 100' run. the Antenna is a ZeroFive GP10-40. >> >> Thank you >> Gerald Manthey >> KC6CNN >> >> >> -- >> View this message in context: http://elecraft.365791.n2.nabble.com/Strange-Vertical-need-help-tp7363205p7363205.html >> Sent from the Elecraft mailing list archive at Nabble.com. >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by KC6CNN
Gerald,
The specs for the GP10-40 call for use of the transceiver's ATU (Antenna Tuning Unit). If you have an ATU in your K3 you should have no problem with it providing a proper match to the transmitter with the SWR measurements that you mention in your note. They quote using a 100 foot long run which you have. They also imply in the specs that if a shorter line (75 ft) is used, a wider range tuner would be needed. Do you have an ATU in your K3? If so, make sure that it is not in BYPASS mode (Hold the ATU button to change it) then tap the ATU TUNE button and it should easily make the K3 happy with the load that it sees. If you don't have the internal K3 ATU, then you will either need to install one or use an external antenna tuner to provide the proper match for the K3. 73, Rich - K1HTV = = = -----Original Message----- From: KC6CNN [mailto:[hidden email]] Sent: Sunday, March 11, 2012 11:48 AM To: [hidden email] Subject: [Elecraft] Strange Vertical - need help I installed a vertical with ground radial kit up 20 feet. The antenna mast and negative sheild connector is grounded to a ground rod. The antenna covers 10 to 40 meters. I can tune 10 meters fine, and fourty meters fine, but 12,15,17,20,and 30 will not tune and SWR are high. here are the SWR reading taken on AM running 25 watts. 10 meter 2804550 is 2 to 1 SWR 2882000 is 1.5 to 1 SWR 12 meter 2490000 is 3 to 1 SWR 24990 is 3 to 1 SWR 15 meter 2103900 is 4 to 1 SWR top porting is 3 to 1 SWR 17 meter 1809000 is 3 to 1 SWR 1817000 is 2 to 1 SWR 20 meter 1402800 is 2 to 1 SWR 1430000 is 2 to 1 SWR 30 meter 1010500 is 4 to 1 SWR 1014000 is 4 to 1 SWR 40 meter 7026 is 2 to 1 SWR 7290 is 1.5 to 1 SWR Any help or suggestions would be greatly appreciated. I will be receiving my K3 on Tuesday and am trying to get this antenna sorted out before then. Oh yea the rig I'm using right now is a Kenwood 570, the Coax is LMR400 with a 100' run. the Antenna is a ZeroFive GP10-40. Thank you Gerald Manthey KC6CNN -- View this message in context: http://elecraft.365791.n2.nabble.com/Strange-Vertical-need-help-tp7363205p736320 5.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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