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Total 18 documents matching your query.

1. [TowerTalk] EFHW core (score: 1): Author: "Tom Osborne Sr." <w7why1@gmail.com>; Date: Mon, 21 Sep 2020 15:44:50 -0700; Hi All Today I put together an EFHW antenna for 40-10. In checking it out, the SWR was good and all looked like it was going to work. Made one contact with it, running around 500 watts, and the core; /archives//html/Towertalk/2020-09/msg00200.html (7,293 bytes)
2. Re: [TowerTalk] EFHW core (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Mon, 21 Sep 2020 15:48:50 -0700; How can an antenna be a "half wave" on 40 thru 10 meters all at the same time? Rick N6RK Today I put together an EFHW antenna for 40-10. In checking it out, the SWR was good and all looked like it wa; /archives//html/Towertalk/2020-09/msg00201.html (7,665 bytes)
3. Re: [TowerTalk] EFHW core (score: 1): Author: K9MA <k9ma@sdellington.us>; Date: Mon, 21 Sep 2020 18:27:55 -0500; It's a multiple of a half wave on all those bands, which means the feedpoint impedance is very high, typically 2,000 to 5,000 Ohms. A good transformer with a turns ratio of about 8:1 should get it wi; /archives//html/Towertalk/2020-09/msg00202.html (9,907 bytes)
4. Re: [TowerTalk] EFHW core (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Mon, 21 Sep 2020 17:49:32 -0700; "all"? If it were about 65 feet long, it could be a half wave on 40 CW, and a full wave on 20 low phone, 1.5 wl on 15 high phone and 2 wavelengths on 10 FM. (The resonant frequency increases by a fac; /archives//html/Towertalk/2020-09/msg00203.html (7,795 bytes)
5. Re: [TowerTalk] EFHW core (score: 1): Author: K9MA <k9ma@sdellington.us>; Date: Mon, 21 Sep 2020 21:58:19 -0500; "all"? If it were about 65 feet long, it could be a half wave on 40 CW, and a full wave on 20 low phone, 1.5 wl on 15 high phone and 2 wavelengths on 10 FM. (The resonant frequency increases by a fac; /archives//html/Towertalk/2020-09/msg00204.html (9,897 bytes)
6. Re: [TowerTalk] EFHW core (score: 1): Author: Ignacy Misztal <ignacy.misztal@gmail.com>; Date: Mon, 21 Sep 2020 20:11:55 -0400; It s hard to be smart here without tons of experimentation. Danny Horvat of myantennas.com seems to have done it. First he selected cores that do not heat much yet require few turns. Second he found; /archives//html/Towertalk/2020-09/msg00205.html (12,049 bytes)
7. Re: [TowerTalk] EFHW core (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Tue, 22 Sep 2020 10:04:36 -0700; Huh? How about studying the fundamentals? The ARRL Handbook and ARRL Antenna Book are great places to do that. NEC modeling is a great learning tool for antennas, and SimSmith is great for studying t; /archives//html/Towertalk/2020-09/msg00206.html (8,753 bytes)
8. Re: [TowerTalk] EFHW core (score: 1): Author: jimlux <jimlux@earthlink.net>; Date: Tue, 22 Sep 2020 10:09:44 -0700; Huh? How about studying the fundamentals? The ARRL Handbook and ARRL Antenna Book are great places to do that. NEC modeling is a great learning tool for antennas, and SimSmith is great for studying t; /archives//html/Towertalk/2020-09/msg00207.html (9,031 bytes)
9. [TowerTalk] EFHW Core (score: 1): Author: Wilson Lamb <infomet@embarqmail.com>; Date: Tue, 22 Sep 2020 14:06:14 -0400 (EDT); It's incredible how much trouble we'll go to to "make something work" while avoiding the simple. Yes, I can see the charm, if you must have coax to get out of the house to the antenna. I've used end; /archives//html/Towertalk/2020-09/msg00208.html (8,185 bytes)
10. [TowerTalk] EFHW core (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Tue, 29 Sep 2020 07:51:20 -0700; <Huh? How about studying the fundamentals? The ARRL Handbook and ARRL <Antenna Book are great places to do that. NEC modeling is a great <learning tool for antennas, and SimSmith is great for studyin; /archives//html/Towertalk/2020-09/msg00252.html (8,864 bytes)
11. Re: [TowerTalk] EFHW core (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Tue, 29 Sep 2020 10:07:32 -0700; If that's true, I'll bet it wasn't the result of an infinite number of monkeys and typewriters, but the rather the result of serious understanding of how antennas and networks work, combined with som; /archives//html/Towertalk/2020-09/msg00259.html (9,262 bytes)
12. Re: [TowerTalk] EFHW core (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Tue, 29 Sep 2020 10:39:40 -0700; That EFHW ant that Danny Horvat makes is pretty damned good. Covers 8 bands, 75-40-30-20-17-15-12-10 No tuner required. Uses 3 big cores. Good for 2 kw icas. Unique design. https://myantennas.com/wp; /archives//html/Towertalk/2020-09/msg00261.html (9,824 bytes)
13. Re: [TowerTalk] EFHW core (score: 1): Author: K9MA <k9ma@sdellington.us>; Date: Tue, 29 Sep 2020 13:15:54 -0500; I went through a similar exercise with a 40 m EFHW for 40 and 20. It is true that the full wave resonance is not exactly twice the full wave one. I designed and built a small QRP tuner specifically; /archives//html/Towertalk/2020-09/msg00263.html (10,824 bytes)
14. Re: [TowerTalk] EFHW core (score: 1): Author: "Tom Osborne Sr." <w7why1@gmail.com>; Date: Tue, 29 Sep 2020 11:35:26 -0700; I put up an EFHW and it worked. I just don't know how we ever put up antennas back in 'the day' before modeling. I worked 260 countries with a Gotham quad tribander. You know - the one with aluminum; /archives//html/Towertalk/2020-09/msg00264.html (10,865 bytes)
15. Re: [TowerTalk] EFHW core (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Tue, 29 Sep 2020 13:26:01 -0700; I just don't know how we ever put up antennas back in 'the day' before modeling. I worked 260 countries with a Gotham quad tribander. You know - Tom W7WHY When I put up my EFHW 35 years ago, I built; /archives//html/Towertalk/2020-09/msg00266.html (9,564 bytes)
16. [TowerTalk] EFHW core (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Wed, 30 Sep 2020 09:00:51 -0700; <If that's true, I'll bet it wasn't the result of an infinite number of <monkeys and typewriters, but the rather the result of serious <understanding of how antennas and networks work, combined with; /archives//html/Towertalk/2020-09/msg00270.html (9,251 bytes)
17. Re: [TowerTalk] EFHW core (score: 1): Author: Jim Brown <jim@audiosystemsgroup.com>; Date: Wed, 30 Sep 2020 10:36:05 -0700; that cover 160-10m, with 8-12 K of RS..and RS > XS ? No Z bumps either. Ingenious staggered core design. And no, you wont blow em up with 4 kw. The obvious question is, "is the winding on the ferrite; /archives//html/Towertalk/2020-09/msg00271.html (8,984 bytes)
18. Re: [TowerTalk] EFHW core (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Wed, 30 Sep 2020 11:36:20 -0700; AFAIK, the answer in this case (choke or xfmr) is: none of the above. Only an autotransformer (or a transformer connected as an autotransformer) could possibly work, utilizing the coax shield as a co; /archives//html/Towertalk/2020-09/msg00272.html (10,270 bytes)

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