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#21
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ml wrote:
i still ponder if i put power into a superconducting antenna if their is no resistance, and a given about of power would therefore 'stay' in the antanna longer ie no resistance and a sorta flywheel effect exists the fields would have to exist longer for fixed-given power , .. Using copper, the reflected current back at the feedpoint of a 1/2WL standing-wave antenna is in the ballpark of 90% of the forward current. Exactly how much improvement is possible? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#22
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Jim - NN7K wrote:
This discussion kinda reminds me of a tome I read (and once actually thought possible), from a CQ article by one "Dr. Shorza Gitchigoomie" (if i spelled that right), progonosticating on the magnicifiant effects of negative resistance! Did your read the one about DED's? (Dark Emitting Diodes) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#23
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Ah, c'mon. Reg says 7 dB isn't enough to worry about. "Kurt Sterba" said
that even 15 dB isn't. All the people who think that linears and beams help their signals are just imagining things. The real experts say so. You're not going to listen to the old wives, are you? Roy Lewallen, W7EL -- One of Reg's "Old Wives" Caveat Lector wrote: I would like to put a different spin on the 7dB statement below. Where the extra gain or power really comes into play is very weak signal DXing - not the pileups necessarily. Cases in point - my Dxing log has several contacts where using a linear got my signal far enough above the noise level for the DX station to understand me. True on phone or CW. In most of these cases, the DX was calling QRZ and no one was answering -- the DX station was so weak -- seems folks just gave up or maybe everyone worked them. Turning on the linear got me the contacts. Definitely Without Question - Worked an R1MV Malyj Vysotskij, HK0 Malpelo Is, VK9/M Mellish Reef, and VP8/G So Georgia by turning on the linear feeding a vertical multibander. I had this happen enough times to realize this to be the real benefit of adding a linear. And it sure can't hurt in a pileup either, if you know how to work a pileup. |
#24
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The fact that superconductors have zero resistance above DC isn't a
limitation of today's technology (although technology limitations cause current high-temperature superconductors to have resistivity greater than theoretically possible), but a fundamental property of the nature of superconductors. What I'm saying is that a "truly superconducting", "hypothetical perfect" superconductor has finite resistance at any frequeny above DC. Imagining a material that has zero resistivity at frequencies above DC requires imagining something other than a superconductor. Roy Lewallen, w7EL Dave Platt wrote: . . . Let's assume that you could find a superconductor which would be truly superconducting even at RF frequencies (which today's superconductors are not, I gather). So, you could cut the loss resistance of the antenna to precisely zero, in this hypothetical case. . . . Using the hypothetical perfect superconductor (which may be impossible) you might reduce this dipole resistance to zero. Great reduction in loss, right? . . . |
#25
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In article ,
Roy Lewallen wrote: The fact that superconductors have zero resistance above DC isn't a limitation of today's technology (although technology limitations cause current high-temperature superconductors to have resistivity greater than theoretically possible), but a fundamental property of the nature of superconductors. What I'm saying is that a "truly superconducting", "hypothetical perfect" superconductor has finite resistance at any frequeny above DC. Imagining a material that has zero resistivity at frequencies above DC requires imagining something other than a superconductor. Roy Lewallen, w7EL Dave Platt wrote: . . . Let's assume that you could find a superconductor which would be truly superconducting even at RF frequencies (which today's superconductors are not, I gather). So, you could cut the loss resistance of the antenna to precisely zero, in this hypothetical case. . . . Using the hypothetical perfect superconductor (which may be impossible) you might reduce this dipole resistance to zero. Great reduction in loss, right? . . . well seems everyone is 'strictly' (narrow) focused on the antenna's resistence loss, i mentined it as the starting point as that is first thing i think of when it goes critical... however one the resistance drops, other effects take place no? both in the material and in respect to other forces aside from just resistance, once it reaches near 0 and begins being a superconductor guess i won't know until i build it and mesure it i wanted to try 10m really but 2m might be easier to keep chilly(0) and i am looking foward to rig it i've got most of the stuff i think i need so far i'd also like to build a superconductie ocilator, i'd suspect that i could power it using a truly small ammount of power? |
#26
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Perhaps the cost/benefit ratio is not viable
because of the expense to keep the antenna cold ? On spacecraft missions to the outer plantes, the antenna were not supercooled but the space environment was very cold ! |
#27
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Hi Roy -- reminds me of the time I worked an S79 on 15M phone. Very weak but
the contact was made. I posted the S79 on the DX packet cluster. A local big gun came back at me with "Miniprop sez there is absolutely no propagation to the Seychelles". I replied Oh Gosh, I had better send the QSL card back when it gets here. The QSL did arrive. I decided to keep it. I have an old wife here -- don't listen to her either hi hi. -- Caveat Lector -- I'll take an S-unit increase every time. "Roy Lewallen" wrote in message ... Ah, c'mon. Reg says 7 dB isn't enough to worry about. "Kurt Sterba" said that even 15 dB isn't. All the people who think that linears and beams help their signals are just imagining things. The real experts say so. You're not going to listen to the old wives, are you? Roy Lewallen, W7EL -- One of Reg's "Old Wives" Caveat Lector wrote: I would like to put a different spin on the 7dB statement below. Where the extra gain or power really comes into play is very weak signal DXing - not the pileups necessarily. Cases in point - my Dxing log has several contacts where using a linear got my signal far enough above the noise level for the DX station to understand me. True on phone or CW. In most of these cases, the DX was calling QRZ and no one was answering -- the DX station was so weak -- seems folks just gave up or maybe everyone worked them. Turning on the linear got me the contacts. Definitely Without Question - Worked an R1MV Malyj Vysotskij, HK0 Malpelo Is, VK9/M Mellish Reef, and VP8/G So Georgia by turning on the linear feeding a vertical multibander. I had this happen enough times to realize this to be the real benefit of adding a linear. And it sure can't hurt in a pileup either, if you know how to work a pileup. |
#28
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Wefax_Dude wrote:
Perhaps the cost/benefit ratio is not viable because of the expense to keep the antenna cold ? It's certainly more economical to increase the transmitter's power output than to supercool a dipole. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#29
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Real world experience: If the bands up you might not be able to tell
the difference, when its down its the difference between no copy and Q-5 ****** It's a relative, not an absolute. 73 WG8Z Yet look at all the people who go to all the trouble of putting up a 3 element beam, then think that the 7 dB gain over a dipole actually makes their signal louder. Or get a 500 watt amplifier for their 100 watt rig. Silly fools! Old wives! Roy Lewallen, W7EL Greg Z to thine own sound be true WG8Z |
#30
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In article , Cecil Moore
wrote: ? It's certainly more economical to increase the transmitter's power output than to supercool a dipole. it think this statement is not totally correct, as if someone manages to build an antenna that serves some pourpose that achieves it's built p goal, then it's worth the expense for certain additionally... who knows maybe sombody might invent somthing that is more efficient or discover something like a benificial offshoot.. who knws what the cost will be one day to supercool a antenna, of which dipole is one of many kinds |
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