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MatchBoxes Do They Work ? -aka- Improve Your Effective RadiatedPower ?
RHF wrote:
... JS, Oh Well I Give Up You Have Worn Me Down: You Clearly Don't Have The Answer To The Ultimate Question. hint "42" ~ RHF . -ps- Telamon could must likely 'clue-you-in' provided that you were only willing to listen, think and learn. . LOL ... Regards, JS |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
"Telamon" wrote in message ... In article , "RP" wrote: "Telamon" wrote in message ... In article , John Smith wrote: Dave wrote: ... A tuner at the antenna is a much better setup. You are doing things right. Most HAM's don't. When Mr. Smith imagines doing this he does it wrong. He's right, too. My sloper is resonant but I still use a tuner to protect the transceiver. I was going to use the Remote Autotuner but don't need it. I get a decent match even on 160. Actually, Telemundo is just the same old idiot, pulling the same old tricks and attempting to appear as a guru to those possessing even less knowledge than himself ... That's our boy Telamon! I'm not your boy Mr. Anonymous open news server user. You're the newsgroup hobo, bum, etc. Hanging around, pretending you are some authority on something. You're the newsgroup tramp. |
5/8 WL Antennas ?
"Telamon" wrote in message ... In article , John Smith wrote: Dave wrote: ... A "counterpoise" is not a ground plane. ... "Buckets of irony littered the lobby" Oh no, here we go again with more magical/mystical antenna physics and supernatural powers ... SNIP No, for that we all defer to you anonymous Mr. Assembly-wizard. Telamon is just too much! The newgroup Jester! |
The Difference Between : Telaturd and real newsgroup users...
"Telamon" wrote in message ... In article , "RP" wrote: "Telamon" wrote in message ... In article , John Smith wrote: RHF wrote: [stuff] RHF, I have no bone to pick with you, don't fall victim to trolls here which just wish to "stir up chit", to mask their ignorance ... SNIP Now that is funny. One Trolling idiot posting a response to another trolling idiot "don't fall victim to the Trolls". And the hobo of s.r.sw Teleamon, the biggest troll here....is telling other trolls how to act! Hillarious! You are just a two bit anonymous posting moron that does not contribute to the news group in any meaningful way. None care what you post. Yet you keep reading and responding to all these posts that you claim not to care about. Hillarious is right! You keep reading these people that you say contribute nothing. Hillarious again! Some people contribute to the newsgroup simply by pointing out what a turd you are....making sure others don't step in you. -- Telamon Ventura, California |
The Characteristically 50 Ohm Impedance Coax Cable is 'only' 50 Ohms Nominal when . . .
In article ,
"Hangman" wrote: "Telamon" wrote in message ... In article , RHF wrote: On Dec 29, 12:37 pm, Telamon wrote: In article , RHF wrote: On Dec 28, 8:36 pm, Telamon wrote: In article , John Smith wrote: SNIP I never even commented on where the placement of the matchbox would be, and, as everyone knows, anywhere along the line you can place it. The best place would be between the coax (feedline) and the antenna- Right. That's because you are to stupid to understand a concept until someone rubes your nose in it. This would not even occur to you until someone else brought it up. -that is, taking for granted that the match from your rig to the feedline is perfect. SNIP You are really worried about the match of 50 ohm coax to your radios 50 ohm output? Now that's funny. IIRC - The Characteristically 50 Ohm Impedance Coax Cable is 'only' 50 Ohms nominal . . . Until you attach something to it. SNIP Nope. The cable itself has a characteristic impedance of some design value. The spacing and size of the conductors along with the dielectric constant of the insulator between them dictates the impedance of the coax. You are confusing the characteristic impedance of the coax with its ability to be an effective transmission line. The coax only behaves as an effective transmission line when both ends of it are terminated at its characteristic impedance. Telamon, OK -restatement- The "Measured" {by You} 50 Ohm Impedance Coax Cable is 'only' 50 Ohms nominal* * Until you attach something to it. -IF- You then attach a Transmitters Output that is a Nominal 50 Ohms to one end of the Coax Cable and then the 'other' end will still "Measure*" about 50 Ohms. * This is what the Antenna will see. However -if- You attach an Unknown "Z" Antenna and Ground to one end of the Coax Cable; then the 'other' end may "Measure*" near or far from 50 Ohms. * This is what the Transmitter will see. Unknown "Z" Antenna = Random Wire Antenna as always . . . i may be 'w-r-o-n-g' - iane ~ RHF You are just confusing a few things. You need to understand that at RF all parts of a circuit are not "seen" by the RF energy "at the same time." The energy has to propagate through the circuit. This is different from DC where the whole circuit "is seen" by the energy source at once. I'm sure that at DC you are familiar with adding up resistor networks or loads into a total load resistance where you can figure out what the total current would be if you applied a certain voltage. This is also know as a lump sum circuit. At RF since it takes time for the energy to propagate through parts of the circuit so they are not seen at the same time and you have to use vector math that has magnitude and phase components, instead of just magnitude, to describe the current that results from an applied voltage. Now with this vector math representing the circuit impedance as opposed to just magnitude resistance you can make transformations similar to an equivalent DC total load resistance for RF current calculations but you have to keep in mind that these are time or phase dependent. A complication of this is some of the energy can even go backward depending on the circuit so these time dependent voltages and currents need to be summed as vectors with magnitude and phase, which represent a voltage or current at a spot in the circuit. The practical upshot of this is that RF paths like coax have to be viewed as transmission lines where the RF energy only "sees" a part of the coax at any one moment in time and after a short period of time the energy "sees" the next part of the coax and so on until it reaches the end. With this understanding it is the "environment" of the coax that causes it to represent an "impedance" or how it reacts to the RF energy as a complex resistance to its flow. This reactive environment is created by the size, spacing, and DC resistance of the two conductors along with the dielectric value of the insulator between them. Now with that said you can still make the R total type of RF impedance calculation with a resistor or a reactive load on the far end of a coax cable as a total transformed circuit impedance value but it does not change in any way the intrinsic impedance of the coax itself, which is fully dependent on its physical construction. Now, if you are still with me, the coax will only function properly as a transmission line when the source impedance at one end and the load impedance at the other end are the same value. In this state all the RF energy is internal to the coax and if the load or source impedance is not the same currents start to flow on the outside of the coax so it will not shield properly. All the energy will not even enter the coax at the source end and energy will be reflected at the load end creating standing waves of energy on the coax, which is the sum of the forward and reverse waves at any one point. Where these waves sum the voltages can be many times higher than the source causing excessive heating or even breakdown of the dielectric at that point or arcing at the connectors. Under these conditions the coax specifications will not be met. The coax will not meet its isolation, insertion loss, or VSWR specifications even though there is nothing wrong with it. Ole Telamonkey sure is one smart dude. Wow! Did it make any sense to you goofball or just sound like gobbledegook? -- Telamon Ventura, California |
The Characteristically 50 Ohm Impedance Coax Cable is 'only'50...
Telamon has some sense.
Thank You, Pasadena,California for the 2009 New Years Day Parade.Job Well Done. cuhulin |
The Characteristically 50 Ohm Impedance Coax Cable is 'only'50...
Brenda Ann is cuter though.
cuhulin |
Antenna for shortwave reception
flashdrive wrote:
... This one looks like a good candidate. The data sheet gives a suggested schematic on page-3. All it needs is the input filter for the MW/HF range. Not sure about the input/output impedance of that circuit though. http://www.minicircuits.com/pdfs/GALI-74+.pdf How about this: http://cgi.ebay.com/Sirenza-SGA-4586...3286.m20.l1116 (take care with line wrapping of the URL, above) 10 for $10.00 plus $2.50 USD -- comes to $1.25 a piece, and provides for a fatal error in construction/use. They are a bit small, sharpen your soldering iron, but should be easily "do-able." Regards, JS |
Antenna for shortwave reception
John Smith wrote:
... How about this: http://cgi.ebay.com/Sirenza-SGA-4586...3286.m20.l1116 (take care with line wrapping of the URL, above) 10 for $10.00 plus $2.50 USD -- comes to $1.25 a piece, and provides for a fatal error in construction/use. They are a bit small, sharpen your soldering iron, but should be easily "do-able." Regards, JS Soldering the device(s) would be similar to this: http://www.youtube.com/watch?v=kAADF...eature=related Regards, JS |
Antenna for shortwave reception
Dave wrote:
... The IMD is way worse than the Minicircuits device Telemon referenced. Telemondo is plonked, here ... :-) And, would be similar to the device I referenced: http://www.sirenza.com/documents/pro..._Datasheet.pdf There is a diagram, on the above sheet, which shows it mounted on an evaluation board ... Regards, JS |
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