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1. Re: Topband: Bird Meter (score: 1): Author: "Mauri" <i4jmy@iol.it>; Date: Mon, 26 Sep 2005 10:46:01 +0200; Bird 43 is a useful instrument, and I agree with your points about directional coupler meters advantages. Sensors, diodes or thermocouples (bolometers) have instead pros and cons. It remains the fact; /archives//html/Topband/2005-09/msg00090.html (9,534 bytes)
2. Re: Topband: Bird Meter (score: 1): Author: "Mauri" <i4jmy@iol.it>; Date: Fri, 23 Sep 2005 18:10:15 +0200; Just as I told and You confirmed, the real power is not directly measured by a bird wattmeter when load isn't 50 Ohms. The real power (when a reflected power is existing) is only obtainable by subtr; /archives//html/Topband/2005-09/msg00080.html (8,933 bytes)
3. Re: Topband: Efficiently Matching Low-Impedance Antennas to 50ohms (score: 1): Author: "Mauri" <i4jmy@iol.it>; Date: Thu, 22 Sep 2005 17:07:18 +0200; Assuming the ammeter is based on a thermocouple, your measurement has sense, even if the impedance is other than 50 Ohms and reactive. The same doesn'apply to bird wattmeter, which doesn't measure p; /archives//html/Topband/2005-09/msg00068.html (8,101 bytes)
4. Re:Topband: Tophat? Does it have to be at the top? (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Mon, 7 Jun 2004 18:01:22 +0200; If the hat has the purpose of substantially loading a short element in the most efficient possible way, then it has to be at the top of the element. If the hat has instead the purpose of loading an e; /archives//html/Topband/2004-06/msg00016.html (8,041 bytes)
5. Re: Topband: Inverted-L Summary (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Sat, 17 Jan 2004 22:53:10 +0100; 10 pieces in parallel, each one 3.3ft long, will better approximate a capacitor than a 33ft long single run of coaxial cable, at least at 2Mhz. All shields togheter, one side, all inners togheter the; /archives//html/Topband/2004-01/msg00160.html (8,180 bytes)
6. Re:Topband: Col-atch-co 160/80 meter antenna (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Sat, 10 Jan 2004 21:11:03 +0100; The Col-atch-co antenna is 42' tall. On 80m it's purely a capacitively top loaded vertical with a wire hat. Efficiency will be the highest possible for that height, and, of course, function of the us; /archives//html/Topband/2004-01/msg00117.html (8,830 bytes)
7. Re:Topband: 2 Wire Beverage Feedpoint Matching (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Fri, 9 Jan 2004 16:47:16 +0100; It?s a good advice if RF transformers for this application are wound as multifilar windings, interleaving wires, each winding covering all the available core space, side to side with the others. If f; /archives//html/Topband/2004-01/msg00102.html (9,282 bytes)
8. Re: Topband: Apparent Multiple Resonances on a single antenna (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Wed, 7 Jan 2004 15:10:46 +0100; Beeing Bills? antenna shortened, resonances will not appear on odd harmonics, neither on even ones. With linear elements (not shortened) resonances actually occur also on even harmonics. There, anywa; /archives//html/Topband/2004-01/msg00080.html (8,849 bytes)
9. Re: Topband: 160m int L (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Tue, 6 Jan 2004 17:50:10 +0100; Sinisa, also I don?t like L unsymmetry, but what do you mean for an inverted T? Upper of the loading horizontal wires, the horizontal section of the inverted T, currents are low and radiated energy i; /archives//html/Topband/2004-01/msg00063.html (8,271 bytes)
10. RE: Topband: 160m int L (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Tue, 6 Jan 2004 17:22:22 +0100; That antenna is basically an upside down GP with two radials, and it works fine if the radials are quite high above the ground, and if the vertical section is ¼ WL. Opposite to an inverted L t; /archives//html/Topband/2004-01/msg00062.html (8,635 bytes)
11. Re:Topband: 160m int L (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Tue, 6 Jan 2004 17:01:43 +0100; Inverted L does not necessarily need a cap (a reactance) to work and to be properly matched. It may be matched with a capacitor with when its feed-point is looking reactive (inductively), as well as; /archives//html/Topband/2004-01/msg00061.html (8,833 bytes)
12. Re: Topband: Balun Discussions (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Thu, 1 Jan 2004 18:32:34 +0100; Hi Tom, the procedure of parking choke resonances out of bands can't be used in a 2-30 MHz continuous coverage unit, and I don't like to have chokes like that in my own amplifiers. When plate choke w; /archives//html/Topband/2004-01/msg00014.html (9,953 bytes)
13. Re: Topband: Balun Discussions (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Thu, 1 Jan 2004 15:02:43 +0100; A plate choke must ?resonate? well above the operating frequency when installed and connected to the amplifier circuits. Choke anomalies of such kind are easily visibile tracking for PI return loss,; /archives//html/Topband/2004-01/msg00011.html (9,248 bytes)
14. Re: Topband: Balun Discussions (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Wed, 31 Dec 2003 23:09:50 +0100; Nobody told that beyond the resonance the choke impedance goes further increasing, of course it doesn't because of inductor self capacitance. Disregarding self capacitance, which is a parasitic effec; /archives//html/Topband/2003-12/msg00340.html (8,427 bytes)
15. Re:Topband: To Balun or not to Balun that is the question. (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Wed, 31 Dec 2003 15:31:38 +0100; Unless a small reduction of RF energy fixed the problem, for example lowering the voltage just under a semiconductor threshold, hardly those 6 turns works like an effective choke at 7 Mhz. Only chanc; /archives//html/Topband/2003-12/msg00330.html (8,892 bytes)
16. Re: Topband: To Balun or not to Balun that is the question. (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Wed, 31 Dec 2003 15:13:27 +0100; Like this "sounds" much better. A reasonable number of turns for the band in use and a larger diameter winding. Note that each time the number of turns is doubled, the reactance is multiplied by a ra; /archives//html/Topband/2003-12/msg00327.html (8,606 bytes)
17. Re:Topband: To Balun or not to Balun that is the question. (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Wed, 31 Dec 2003 01:55:50 +0100; By the way, depending the diameter of the coil, line lenght, and coil position, I'm afraid those 6 turns are not enough to have a good choke on 20m. Expecially in cases where a choke is not on a curr; /archives//html/Topband/2003-12/msg00312.html (7,838 bytes)
18. Re:Topband: Receiving Loops (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Mon, 29 Dec 2003 00:21:41 +0100; Kevin, think about detuning your 160m transmitting antenna when receiving, this is the first step. Then, if the problem is still clearance, you can try with a simple loop antenna in the following way; /archives//html/Topband/2003-12/msg00248.html (8,300 bytes)
19. Re:Fw: Topband: DX window? (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Sun, 28 Dec 2003 18:40:35 +0100; Be realistic Josep, contest rules are issued by the contest organizer/s but sooner or later they turn to express the will of entrants, i mean the majority of them, unless already they do. Those ?rule; /archives//html/Topband/2003-12/msg00238.html (9,733 bytes)
20. Re:Topband: TOPBAND : Antenna reception 160/80 ? (score: 1): Author: "i4jmy@iol.it" <i4jmy@iol.it>; Date: Fri, 26 Dec 2003 00:03:58 +0100; Didier, a one WL beverage is not a bad antenna at all, moreover You might try phasing two of them for 80m. About 160m, I'd suggest a 4 square receiving array. If You understand italian language take; /archives//html/Topband/2003-12/msg00218.html (7,823 bytes)

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