tag:blogger.com,1999:blog-5480750694693825336.post3421583506121629628..comments2024-03-21T00:59:58.137-07:00Comments on G0KYA's Amateur Radio Blog: The EFHW - an efficient monoband end-fed half wave for 10m, 20m or any other HF bandSteve Nicholshttp://www.blogger.com/profile/03564402221894277279noreply@blogger.comBlogger22125tag:blogger.com,1999:blog-5480750694693825336.post-71041795641744007692016-04-01T10:30:17.323-07:002016-04-01T10:30:17.323-07:00have a look at my qrz page regarding an all band 7...have a look at my qrz page regarding an all band 7 mtr roach pole vertical.works for me dave g0ayd.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-60241836959103265002016-03-19T11:40:47.365-07:002016-03-19T11:40:47.365-07:00No I haven't. I quite favour PD7MAA's one-...No I haven't. I quite favour PD7MAA's one-stop tuning box. That's something I want to play with. See https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://pa-11019.blogspot.com/2012/04/149-transformer-for-endfed-antennas-35.html&ved=0ahUKEwjb047dss3LAhVCnA4KHQCvDUEQFggbMAA&usg=AFQjCNEJ84rcvW_axkF_jgaoVCQyjigQdQ&sig2=MRGAIOYswNyHPW6mW0lK8ASteve Nicholshttps://www.blogger.com/profile/03564402221894277279noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-43632384555766884502016-03-19T06:16:27.943-07:002016-03-19T06:16:27.943-07:00Hi Steve
Been looking at this design for multiband...Hi Steve<br />Been looking at this design for multibanding! Now think having an Fixed inductor & switched coax caps (RG174) will allow this with dedicated 1/2W trapped verts for 20/15, 17/10 & inductively loaded 40m.(Connect when want to operate on that band, ie one match box 3 separate selected wires Wonder if you tried this? <br />73s <br />Chris G4LDSAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-22282490449486275772015-11-28T23:22:57.890-08:002015-11-28T23:22:57.890-08:00Thanks Steve, replicated your design and it works ...Thanks Steve, replicated your design and it works fine :-) Now working on a 30/20/17/15m version using the Sotabeams 100W traps. It all fits (just!) on the 10m Sotapole and will use your universal matching unit described above. I'll let you know how I get on.<br />73<br />Geoff ZL3GAGeoff ZL3GAhttps://www.blogger.com/profile/09194987419816323417noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-6255802648067094182015-11-23T01:50:39.656-08:002015-11-23T01:50:39.656-08:00Hi,
I used 40mm white PVC pipe - the stuff you fi...Hi,<br /><br />I used 40mm white PVC pipe - the stuff you find in hardware stores for home plumbing.<br /><br />Steve G0KYASteve Nicholshttps://www.blogger.com/profile/03564402221894277279noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-64204828001417686862015-11-22T20:03:19.289-08:002015-11-22T20:03:19.289-08:00Hi Steve, nice blog! For the 20/17/15m trapped ver...Hi Steve, nice blog! For the 20/17/15m trapped version, what diameter former did you use for the traps? I'm building one on a 10m SOTA pole for my next trip to Vanuatu. <br />Thanks and 73<br />Geoff ZL3GA/YJ0GAGeoff ZL3GAhttps://www.blogger.com/profile/09194987419816323417noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-69339233014668955762014-11-24T01:18:02.252-08:002014-11-24T01:18:02.252-08:00Hi, there isn't really a downside to having a ...Hi, there isn't really a downside to having a shorter capacitor. it may mean you have a turn too many on the secondary. I wouldn't worry about it - just enjoy it. I think Didier is right. A lot of information has come up since I wrote the original feature. I have some type 43 toroids now and will try them out next spring. I did notice that a 4:1 balun made with a T200-2 worked well at 20m, but it fell off as you went up and down from that. The red T200 seems to work OK on the 20m -10m EFHWs however. Martin G8JNJ has done a lot of work on toroids - see www.g8jnj.netSteve Nicholshttps://www.blogger.com/profile/03564402221894277279noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-60196600553560465072014-11-23T14:28:23.983-08:002014-11-23T14:28:23.983-08:00Hallo, build one for 10meter and it seems to work ...Hallo, build one for 10meter and it seems to work fine. But <br />I had to snip away much of the coax Capacitor (12 windings on T200-2), its only about 3cm long with best swr about 28.500. The swr looks good through the whole band. whats is the downside of a much shorter coax cap? it seems to work anyway. Best TimTimnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-62119283210012476862014-07-11T08:19:39.283-07:002014-07-11T08:19:39.283-07:00Hello , with all antennas , the material of the to...Hello , with all antennas , the material of the toroïd is very important . Note that the T200-2 has not a large bandwith , and is good chiefly for frequencies over 10 MHZ or more .<br />But the 43 or 61 matérial has a larger bandwith , and I think they would be better <br />Didier F4DME France Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-70027533325496493852013-04-17T14:24:02.061-07:002013-04-17T14:24:02.061-07:00Sounds like it is using the feedline as part of th...Sounds like it is using the feedline as part of the radiating system. This can happen if it is not earthed or the coax doesn't run alomg the ground (so it doesn't couple to earth). I would add 2-4 radials to the earthing point. Try 1-1.5m wire each radial, probably 1.4m best if using PVC coated wire. That might tame it.<br /><br />Steve G0KYA Steve Nicholshttps://www.blogger.com/profile/03564402221894277279noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-88706760134181550032013-04-17T13:37:09.122-07:002013-04-17T13:37:09.122-07:00Today I put up a 6m. band vertical efhw antenna. E...Today I put up a 6m. band vertical efhw antenna. Element is 4mm2 wire and it's hold by a 3m. fishing rod. Coil is wound on T-200-6 (yellow), 10 turns. Capacitor is made on RG58 and it's about 1cm. long! I made a 7 turns RF choke of RG213 but not radials (how long should they be?)<br />Antenna is tuned to about 51MHz, being SWR 1.3 on band edges.I noticed the antenna is detuned about 500kHz when RG213 feed line is connected (why?) No TX testing because need a transverter or new rig.<br /><br />73s Isaac Diaz EA8BNP <br />Isaac EA8BNPnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-45262554818909912992012-10-25T02:04:52.248-07:002012-10-25T02:04:52.248-07:00Excellent news - there are still some people who s...Excellent news - there are still some people who say it can't work! I do advocate adding a ground stake, four simple radials and a choke about 20ft back down the coax now. <br /><br />A lot of development work and practical experience has shown that this will get rid of any RF problems and prevent feedback when operating multiple stations for special events etc. <br /><br />If you are on your own, or just running QRP, as long as the coax runs along the ground RF doesn't appear to be a problem.<br /><br />Steve G0KYASteve Nicholshttps://www.blogger.com/profile/03564402221894277279noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-68647382998868656382012-10-12T11:44:00.231-07:002012-10-12T11:44:00.231-07:00Put one together for 15 meters today. T-200 has 14...Put one together for 15 meters today. T-200 has 14 turns and 2 turn primary. Air variable at about 15Pf. Signals about 1 to 2 S points better than my Hustler HF-5-V and seems to get out better. SWR about 1.2:1, which is no problem.Ron G3TAGnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-38506948438034148012012-10-02T10:58:09.942-07:002012-10-02T10:58:09.942-07:00nice blog...
Mauricio Beraldo PY4MAB
Brazil
py4...nice blog...<br /><br />Mauricio Beraldo PY4MAB<br />Brazil <br /><br />py4mab@amsat.org PY4MABhttps://www.blogger.com/profile/08005959111243229957noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-88241342089839934542012-05-03T22:59:44.993-07:002012-05-03T22:59:44.993-07:00If you are seeing a 1:1 match and 50Ohms I wouldn&...If you are seeing a 1:1 match and 50Ohms I wouldn't worry about any residual reactance - it will work fine. The usual way to remove it is to add series inductance/capacitance depending on whether the reactance is capacitive/inductive. By all means try. but it might be easier to leave it!Steve Nicholshttps://www.blogger.com/profile/03564402221894277279noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-37105444249821158412012-05-03T11:18:41.512-07:002012-05-03T11:18:41.512-07:00I built this antena for 10 meters using air wound ...I built this antena for 10 meters using air wound inductors and toroids. Your toroid design resulted in improved tuning to the desired frequency. I used an air variable capacitor instead of coax. At SWR of 1.1, 50 ohm impedance, I still had some reactance. How do I tune this reactance to zero.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-46834912411926882992012-02-11T00:55:34.185-08:002012-02-11T00:55:34.185-08:00The End Fed Half Wave antenna described is a very ...The End Fed Half Wave antenna described is a very good choice for those operators who have limited space and require an effective radiator.<br />I have built a number of these on different bands and found the design extremely repeatable.<br />Results are encouraging but tuning them up can get a bit fiddley.<br />My solution to this is to use a small beehive capacitor in place of the coax capacitor and to date have expeineced on problems with 100 watts input.<br />The Beehive does give the opportunity to try to tune the antenna without the cutting back of the coax then finding that you need to move the tapping point!<br />The Antenna should by rights have the name of The G0KYA.<br />A lot of good work with this antenna was carried out by Steve and by rights he should get all the credit.What you get is a cracking low angle radiator of low impact design, easy to put up and most importantly replicable.<br />Thank you Steve. Chris G7HXWAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-29294544969468171732010-12-13T13:36:46.656-08:002010-12-13T13:36:46.656-08:00great post very useful 73 to you great blog matt m...great post very useful 73 to you great blog matt m6cebmatt m6cebhttp://www.m6ceb.co.uk/index.php/amateur-radio/puxing-px-888-reviewnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-80176451273014690692010-11-28T16:15:46.968-08:002010-11-28T16:15:46.968-08:00I have tried this type of antenna using a coil wou...I have tried this type of antenna using a coil wound on a PVC white pipe form.<br />The resonant frequency at the center of the band is found with a variable air spaced capacitor... Then I measure the capacitance required to resonate the LC circuit and replace it with a length of coax cable ¨capacitor¨...<br />On 20 meters I like to add at least three 1/8 of a wavelength radials to act as a counterpoise...<br />Last but not least, it is ALWAYS a good idea to include a coil made of coaxial cable to act as an RF choke to prevent ¨antenna currents¨ from flowing on the outside of the coaxial cable shield.<br />BTW, the antenna works well also when installed as a sloper... something I had to do out of necessity, and proved to work quite well...<br />73 and DX<br />Arnie Coro <br />CO2KKArnie Coro CO2KKhttp://dxersunlimited.blogspot.comnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-68408447349110695292010-11-22T09:14:00.998-08:002010-11-22T09:14:00.998-08:00Yes, the RG58 is left open at one end - I just cov...Yes, the RG58 is left open at one end - I just cover it with PVC tape. You then snip it to tune. If you can't get a match less than 1:1.5 try spreading the turns out, removing a turn or adding a turn to the primary.<br /><br />Steve G0KYAAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-70326848036537668902010-11-20T06:31:37.495-08:002010-11-20T06:31:37.495-08:00Hi Steve,
I have passed your link onto a pal of m...Hi Steve,<br /><br />I have passed your link onto a pal of mine from our local radio club as he is building this antenna.<br /><br />The end-fed design is popular with a few of use round here due to it's very ease of feeding.<br /><br />73 Paul.Paul M0PCZhttps://www.blogger.com/profile/15826957754325181436noreply@blogger.comtag:blogger.com,1999:blog-5480750694693825336.post-76164131666260917532010-11-18T07:55:53.309-08:002010-11-18T07:55:53.309-08:00Hi Steve,
I am working QRP on 20 with an "ori...Hi Steve,<br />I am working QRP on 20 with an "original" 1/2 wave end fed Zepp. It's working FB with open feeders. It's quite difficult and expensive nowadays to buy that stuff, and TV-ribbon is no where to find anymore.<br /><br />So I was planning to build a AA5TB design half wave with a polyvaricon. But your solution with a short piece of coax sounds better and cheaper I think.<br />But do you use for the tuning coax just a piece of RG-58 with one side unconnected, thus leaving the other side complete open ?? and tuning by snipping a small piece at the time?<br />I want to experiment with a T50- or T68-2 core.<br /><br />Regards, Wally PA3BTTWallyhttps://www.blogger.com/profile/06885503515355454099noreply@blogger.com