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On Thu, 16 Aug 2007 14:18:16 -0400, "Rick (W-A-one-R-K-T)"
wrote: "Probably works better than a dipole" isn't good enough to spend a big one on. As for being resonant and rotatable, that's not worth a thousand bucks (to me) either. Hi Rick, This is what I mean by meticulous (in any formulation): What "is" good enough? One could fill a book with what is wrong with a suggestion and we would be no nearer an answer. you are beginning to accumulate quite an antenna farm as it is. That would be true if I had actually put any of them up. So far I have two inverted vees, one dual-band NVIS dipole, and a 144/220/440 vertical. OK, I suppose that's another way of saying having four antennas covering up to 6 bands isn't enough - that is why we have our own newsgroup, because many share that feeling. I have more than one need. The general need is to be able to operate on a list of CAP and MARS frequencies from 2 to 24 MHz. That one doesn't need any gain or directivity, or any specific level of power (I routinely participate in CAP and MARS nets with my inverted vee and 5 watts out of my FT-817). I'm considering the T2FD only because then I can load all the needed frequencies into the radio and put it on scan, and if someone I need to talk to shows up on one of the channels I can pick up the mic and hope for the best. But I'm not about to spend $300 for one (sorry if that sounds like I'm "hedging away"... whatever that means...). You have a need, but you are not going to spend $300 to fill it. Again, you say what is wrong, but not what is right. Will you spend $299? This threatens to call this portion of the game 300 questions. So to practice the engineering form of Jeopardy: "in the form of a question respond to 'I might spend more than $150 but less than $300'?" (answer: "What is a binary search?" Thank you Don Pardo.) Spending aside, a lot of performance be can be built for less if you discount the value of your time (that is why they call it a hobby). The trouble I have here is that you don't want to spend money (neither would I), but then you ask about spendy items like the T2FD or SteppIR. Say What? I see the 2 to 24 MHz requirement trotted out, and strictly speaking it is exceedingly obvious you won't buy that solution on the open market for $300 or less (unless it is a bribe to a Government official that has the power to surplus gear). So it stands to reason you would have to build it. That can be done to the limitations you offer above (and probably exceeding the performance of the T2FD). Doubling the dimensions of: http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm would satisfy 3/4ths of your spectrum requirement and the ambitious amateur could erect it without too much care for precision or cost. If you were to come back to me with a negative reply ("it won't....") what is one to do? The more specialized need requires higher power and a rotatable, directional antenna, in the frequency range from something below 20 meters Tell me that you want to spend less than $300 for this and we can all have a chuckle. About the only thing that qualifies was described as having a Gaussian Array (no suggested retail price - and for good reason). I have been informed that I probably won't be able to participate with a wire antenna and 150 watts, so since it appears that's their story and they're stickin' to it, I'm looking for some alternatives that don't involve buying a whole separate antenna just for MARS. I hope you didn't hear that story here, it qualifies as fiction in the library. There are wire solutions that are steerable, and certainly power is not an issue (especially if you were going to pour it into a T2FD). You want to try again? Thanks, but I guess not. I'm doing my best already, to gather information and make a decision I can afford and will work reasonably efficiently for me. I'm sorry if you find my questions unclear or "hedging" or whatever but think I've been pretty clear on my questions up to now, and I've learned a lot from reading you guys. Your questions tend toward seeking validation: "Will X work for Y?" To which some responses offer "Um, yes, but why would you want to do that?" "Because I don't what Z." "OK, X for Y without Z can be found with model A." "Model A will do, but it doesn't give me B." "OK, X for Y without Z but with B." This can go on for a long time. The fact is I have more than one question (surprise!), each of which has been formulated meticulously enough, and each of which serves a different though related need. We are up to model XY(/Z)+B+specialC, then. This latest one is the simple and meticulously-crafted question that says, simply, "Can a 2-element beam work efficiently with only 0.07 wl spacing between elements?". The W8JK works quite well at 0.10 wl spacing between elements and has been around for more than 50 years. How much can squeezing it to 0.07 spacing hurt? The free version of EZNEC can answer that in less than a minute (none). If you build it wrong, then the answer is no, it cannot work efficiently. You can even buy one that won't work for the same reason - you as a builder of the package of bits and pieces that arrives UPS. In this world of free competition and lead painted toys for children, you can also buy one that won't work - irrespective of your construction talents. Being meticulous about "efficient" would have you expressing what loss is allowable. By inference to your tendency to select a T2FD (loss in the ballpark of at least 3dB), then yes (and with proper design and construction), 0.07 wl spacing between elements is efficient (even if it loses 1.8dB along the way in getting there). If 1.8dB is too much loss (another negative reaction), then you weren't very meticulous at all. On the other hand, it would serve you well to know that doing better would probably cost beaucoup bucks more than $300 (or even a grand). The related question, which I think is equally clear, was "Any of you guys have the SteppIR 2-element and if so, what do you think of it?". I can't think of a way to meticulously craft either of those questions that will yield a self-contained answer on its own. Thus this newsgroup has a benefit - at least from my habit of rhetorical excess. (a tip o' the hat to Myles for flowers.) Your one-question-at-a-time is easy to respond to and satisfactory in most respects, but when you combine the separate answers into this goal of a Grand Unification Theory of MARS/CAP operation, it is like watching someone on rubber crutches. I cringe, but laughing is one of those involuntary reflexes. 73's Richard Clark, KB7QHC |
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