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Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
John Smith wrote:
his secret location in NV. 9041 Desert Lane Pahrump, NV 89048 http://maps.google.com |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
"Roy Lewallen" wrote in message treetonline... Here's why antenna efficiency is important for transmitting but not for HF receiving. First, the definition of efficiency: For a transmitting antenna, it's the fraction of the power applied which is radiated. The remainder is turned into heat. For receiving, it's the ratio of the power which is delivered to the receiver to the power which could be delivered to the receiver if the antenna had no loss. The efficiency of a given antenna is the same when transmitting and receiving. Sometimes people use "efficiency" to mean other things -- this is the meaning of the term in all antenna literature and texts. Consider this communications system: transmitter - antenna - propagation path - antenna - receiver - listener A receiver unavoidably adds noise to the received signal. So if no noise is injected in the propagation path, the signal/noise ratio is the ratio of the signal entering the receiver to the noise created by the receiver's input circuitry. This is generally the case at VHF and above. When receiver noise dominates, as above, increasing the receive antenna's efficiency increases the signal arriving at the receiver, so the signal/noise ratio improves. This allows you to hear the signal better. But it only works for VHF and above. HF is a different story. At HF, there's a lot of atmospheric noise (injected in the "propagation path" part of the system), and unless the receive antenna and receiver are exceptionally bad, the atmospheric noise is much greater than the noise created by the receiver. I mentioned a simple test in my last posting, to see whether this is the case -- just disconnect the antenna. If the noise level drops, atmospheric noise dominates. It's not hard to make a receiver that atmospheric noise will dominate with a 3 foot whip antenna at HF. So at HF where atmospheric noise dominates, the signal/noise ratio is the ratio of the signal entering the receiver to the atmospheric noise entering the receiver. Compare this to the situation described above for higher frequencies. Now let's see what happens when we improve the efficiency of an HF receiving antenna. Because both the signal and the dominant noise come from locations in front of (that is, on the transmit side of) the antenna, improving the efficiency of the antenna makes both the signal and noise greater in the same proportion when they arrive at the receiver. There's no improvement at all in the signal/noise ratio. The effect is the same as turning up the receiver volume control. The only way you can improve the signal/noise ratio is to somehow favor one over the other, such as by making the antenna directional. And an inefficient, directional antenna like a Beverage or small loop will nearly always enable you to hear better in some directions than an efficient, nondirectional antenna because directionality helps and inefficiency doesn't hurt. How about transmit antenna efficiency? The signal strength from the transmit antenna is proportional to the antenna's efficiency. (It also depends on other things, but I'm just talking about efficiency here.) So if the efficiency of the transmit antenna increases from, say, 33% to 66%, the power levels of the signals at the receive antenna and the receiver double, and there's no change to the received noise, on either HF or VHF and above. So improving the transmit antenna efficiency always improves the signal/noise ratio at the receiver, in this case by 3 dB. That's why you can hear bunches of HF stations with a very inefficient antenna, but they won't hear you if you try to transmit using that same antenna -- it's because the noise is injected into the system between you. And it's likely that you'll be able to hear stations just as well with the very inefficient antenna as with a much larger, efficient one. Roy Lewallen, W7EL Well said Roy, however, can you explain why this is not so at VHF and above? I would think that would have to do more with mode than with antenna/propagation. When I turn down the squelch on my vhf rx i get lots of noise. Let me know. TIA, B |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
Brian Oakley wrote:
Well said Roy, however, can you explain why this is not so at VHF and above? I would think that would have to do more with mode than with antenna/propagation. When I turn down the squelch on my vhf rx i get lots of noise. Let me know. TIA, B It's purely because of where the dominant noise comes from, more specifically whether it gets into the system before or after the antenna. Atmospheric noise gets greater as you go down in frequency. At VHF and above, it's less than receiver noise, so receiver noise dominates and masks whatever atmospheric noise there might be. At HF and below, it's usually greater than receiver noise, so atmospheric noise masks the receiver noise. Obviously there's no precise line, so somewhere typically near the upper end of HF either one might dominate, depending on conditions, antenna, and receiver. The noise you get from your VHF radio when you turn down the squelch is receiver noise. You can prove it by disconnecting the antenna and noticing that the noise doesn't change. Disconnect the antenna from an HF receiver and the noise will drop, because it's coming from the other side of the antenna. Roy Lewallen, W7EL |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
On Mon, 29 Dec 2008 20:32:58 -0800, Roy Lewallen
wrote: It's purely because of where the dominant noise comes from, more specifically whether it gets into the system before or after the antenna. Atmospheric noise gets greater as you go down in frequency. At VHF and above, it's less than receiver noise, so receiver noise dominates and masks whatever atmospheric noise there might be. At HF and below, it's usually greater than receiver noise, so atmospheric noise masks the receiver noise. Obviously there's no precise line, so somewhere typically near the upper end of HF either one might dominate, depending on conditions, antenna, and receiver. (...) Roy Lewallen, W7EL This might help: http://en.wikipedia.org/wiki/Atmospheric_noise If you extend the red line showing man made noise, at greater than about 30Mhz, the man made noise (ignition noise, motor noise, etc) predominates over atmospheric noise. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
5/8 WL Antennas ?
Dave wrote:
RHF wrote: Dave here is a Picture of a . . . 5/8 WL Ground Plane Antenna No it isn't. http://users.belgacom.net/hamradio/s...calantenna.htm "The "ringostar" based coil: Is made out of 26 cm of 2,5mm installation wire. Remove the isolation of the wire and tin with a soldering iron the entire wire. The coil is 1,2 turns and has a diameter of 5 cm. One side is connected to the antenna and the other side to the boom." . Note "Installation Instructions" of 5/8 wave vs 1/4 wave antennas. 1/4 wave verticals require a proper ground plane (radials or sheet metal) to approximate the other half of a center fed dipole. The 5/8 wave is already over a half-wave long; no plane required. The coax shield needs a ground, the antenna doesn't. http://www.diamondantenna.net/m285.html http://www.diamondantenna.net/hf6fx.html You can use the outer-braid of the coax, or a ground wire, as a counterpoise, as your text indicates ... but, for proper operation, at least in all my experience, a counterpoise IS necessary. However, as is common, people claim poor antennas are more than satisfactory, for them ... Regards, JS |
Antenna for shortwave reception
flashdrive wrote:
... Has anyone ever successfully reverse engineered the pre-amp of a Wellbrook loop? It might be possible to dissolve the encapsulating material (epoxy?) to reveal the PCB and componants. Otherwise a medical scanner (seriously) might reveal some useful information. My question would be, "Why go to the trouble?" Indeed, grab a DC - 1Ghz MMIC device (make sure you don't get an SMC component, unless you like soldering under a microscope), stick a proper filter for the freqs/bands in front of it, and feed its' input with a well designed loop ... if you need EXTREME gain, you can cascade a couple of MMICs. Regards, JS |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
Jeff Liebermann wrote:
This might help: http://en.wikipedia.org/wiki/Atmospheric_noise If you extend the red line showing man made noise, at greater than about 30Mhz, the man made noise (ignition noise, motor noise, etc) predominates over atmospheric noise. In my last couple of postings, I was lumping man-made and atmospheric noise together as "atmospheric noise". Both enter the system between the transmit and receive antenna, so improving the receive antenna efficiency won't help the ratio of signal to either atmospheric or man made noise. The referenced graph doesn't show receiver noise at all, which dominates at VHF and above. It can be useful, however, to distinguish between atmospheric noise and *local* man-made noise, since the latter can sometimes be reduced by using techniques such as feedline decoupling and using horizontally polarized antennas. Roy Lewallen, W7EL |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
In article
, Telamon wrote: In article , Dave wrote: John Smith wrote: However, in side-by-side comparisons on 10-6-2m antennas I have built, comparing a 5/8 against the 1/2 (construction methods/materials and matching components identical) ... the actual difference, in the real world, must be less than the width of a meter needle in the readings ... or, put simply, I no longer deal with the extra length required of the 5/8 ... your mileage may vary ... The advantage of a physical height (antenna length) between 180 and 215 degrees (see previous post regarding the magic number being around 195 degrees) is improved take-off angle and reduced skywave-groundwave interaction, not dramatic nearfield voltage increases. Regarding Mr. Smith's comments above my experience and others is the opposite. 5/8 is a much better performing antenna than a 1/2 wave for local VHF and UHF communications. Well worth the effort to build a 5/8 wave antenna over a 1/2 wave. The 5/8 had some kind of series load coil part way up the whip where the 1/2 wave match/compensation was done at the base so the whip was solid. Sorry I can't more specific then that as those experiments were many years ago. Mr. Smith is still lost in space. Here is an example of the 5/8 wavelength antenna I recall using in the center of the page. The one I used was permanent mount not magnetic though. The van roof it was installed on was the ground plane. http://www.new-tronics.com/main/html/mobile_vhf.html When this antenna was changed for a 1/2 wave a lot of coverage was lost. This was before cell phones so I had to start using pay phones a lot. -- Telamon Ventura, California |
5/8 WL Antennas ?
John Smith wrote:
Dave wrote: RHF wrote: Dave here is a Picture of a . . . 5/8 WL Ground Plane Antenna No it isn't. http://users.belgacom.net/hamradio/s...calantenna.htm "The "ringostar" based coil: Is made out of 26 cm of 2,5mm installation wire. Remove the isolation of the wire and tin with a soldering iron the entire wire. The coil is 1,2 turns and has a diameter of 5 cm. One side is connected to the antenna and the other side to the boom." . Note "Installation Instructions" of 5/8 wave vs 1/4 wave antennas. 1/4 wave verticals require a proper ground plane (radials or sheet metal) to approximate the other half of a center fed dipole. The 5/8 wave is already over a half-wave long; no plane required. The coax shield needs a ground, the antenna doesn't. http://www.diamondantenna.net/m285.html http://www.diamondantenna.net/hf6fx.html You can use the outer-braid of the coax, or a ground wire, as a counterpoise, as your text indicates ... but, for proper operation, at least in all my experience, a counterpoise IS necessary. However, as is common, people claim poor antennas are more than satisfactory, for them ... Regards, JS A "counterpoise" is not a ground plane. We all would like to drill a hole in the middle of the roof, but sometimes we are forced to clamp to something. The 5/8 Wave works well on a clamp, at least as well as the 1/4 Wave in the middle of the roof. "...However, as is common, people claim poor antennas are more than satisfactory, for them ..." "Buckets of irony littered the lobby" |
Antenna for shortwave reception
John Smith wrote:
flashdrive wrote: ... Has anyone ever successfully reverse engineered the pre-amp of a Wellbrook loop? It might be possible to dissolve the encapsulating material (epoxy?) to reveal the PCB and componants. Otherwise a medical scanner (seriously) might reveal some useful information. My question would be, "Why go to the trouble?" Indeed, grab a DC - 1Ghz MMIC device (make sure you don't get an SMC component, unless you like soldering under a microscope), stick a proper filter for the freqs/bands in front of it, and feed its' input with a well designed loop ... if you need EXTREME gain, you can cascade a couple of MMICs. Regards, JS I do SMD rework occasionally, with MagEyes. You'd use a power amplifier for a pre-amp? |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
Telamon wrote:
In article , Telamon wrote: In article , Dave wrote: John Smith wrote: However, in side-by-side comparisons on 10-6-2m antennas I have built, comparing a 5/8 against the 1/2 (construction methods/materials and matching components identical) ... the actual difference, in the real world, must be less than the width of a meter needle in the readings ... or, put simply, I no longer deal with the extra length required of the 5/8 ... your mileage may vary ... The advantage of a physical height (antenna length) between 180 and 215 degrees (see previous post regarding the magic number being around 195 degrees) is improved take-off angle and reduced skywave-groundwave interaction, not dramatic nearfield voltage increases. Regarding Mr. Smith's comments above my experience and others is the opposite. 5/8 is a much better performing antenna than a 1/2 wave for local VHF and UHF communications. Well worth the effort to build a 5/8 wave antenna over a 1/2 wave. The 5/8 had some kind of series load coil part way up the whip where the 1/2 wave match/compensation was done at the base so the whip was solid. Sorry I can't more specific then that as those experiments were many years ago. Mr. Smith is still lost in space. Here is an example of the 5/8 wavelength antenna I recall using in the center of the page. The one I used was permanent mount not magnetic though. The van roof it was installed on was the ground plane. http://www.new-tronics.com/main/html/mobile_vhf.html When this antenna was changed for a 1/2 wave a lot of coverage was lost. This was before cell phones so I had to start using pay phones a lot. The one with the center coil is a collinear. It is 2 stacked verticals with a "delay" between. |
Transmitting with a "Beverage" Antenna and/or a Ferrite Rod Antenna
On Dec 29, 5:52*am, Dave wrote:
John Smith wrote: Now, let me give you a mechanical example, so those willing and/or able may grasp the concept, in fact, let me give you a couple: 1) The neighbors light is shining in my window(s), it is too bright too sleep--I place a thick blanket over the window--WAALAA, "masked" the problem! 2) The neighbors stereo is too loud. *I plug my ears, again, WAALAAA, problem fixed! 3) [add your own example here] telemundo is an argumentative idiot with a poor working knowledge of what discussions he engages in *... *:-( But then, if you don't possess the knowledge/experience to be able to realize this, no one can blame you for being fooled ... later. Regards, JS - Telemundo is a subsidiary of General Electric. - - Your analogies don't hold up. -*You cannot transmit with a Beveridge - and you cannot transmit with a ferrite loop. Dave -says- You cannot transmit with a Beveridge and Dave that is "Beverage" Antenna http://en.wikipedia.org/wiki/Beverage_antenna and sure you can Transmit with it. http://www.qsl.net/k2hq/bev.htm http://www.kkn.net/~n2nc/bev_arrays/ http://members.cox.net/kb1gw/bev-page.htm http://www.n0hr.com/hamradio/66/10/ham_radio0.htm http://www.seed-solutions.com/gregor...n/Beverage.htm -IF- You really wanted a Beverage Antenna for very Directional Transmitting : Single-point on a Single Frequency : You might try one at 1.5 WL or 3 WL Dave -says- you cannot transmit with a ferrite loop. Sure you can Dave and Ferrite Rod Transmitting http://www.st-andrews.ac.uk/~www_pa/...rt7/page5.html Antennas are just about every where you go . . . http://www.radio-electronics.com/inf...od_antenna.php -think- Low Power Very Directional Transmitting Antenna RFID Detection Exit Door Systems in many Retail Stores : Some/Many of these use Ferrite Rod Transmitting Antennas {Transponders}. http://www.elnamagnetics.com/library/rfant.pdf Dave even Arnie Coro "DXers Unlimited" [RHC] says it can be done ;-} http://www.radiohc.org/Distributions...s/01-1222.html "you can build a ferrite rod loop antenna" |
The Characteristically 50 Ohm Impedance Coax Cable is 'only' 50Ohms Nominal when . . .
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 Ventura, California 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 |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
On Dec 29, 1:35*pm, John Smith wrote:
RHF wrote: ... JS, Good Antenna Building Concept : You Can't Talk To Them -unless- You Can First Hear Them. ~ RHF *. Well, I'd like an antenna like this one (see URL, below.) *He comes into my location in the low valley of CA like a door buster, from his secret location in NV. Jumping the high Sierra Mountains in a single leap! *grin - http://www.smeter.net/w6obb/antenna-farm.php - - Regards, - JS JS - Yeah some people have the money to Do-It-Up right. ~ RHF |
5/8 WL Antennas ?
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 ... Generally, a ground-plane is not referred to as counterpoise, but it certainly IS one; it "balances" an unbalanced antenna by providing the mechanics where the counterpart of the wave may be mirrored. And, although every ground-plane IS a counterpoise, not every counterpoise need be a ground plane ... again, DUH! Regards, JS |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
Dave wrote:
... http://www.new-tronics.com/main/html/mobile_vhf.html When this antenna was changed for a 1/2 wave a lot of coverage was lost. This was before cell phones so I had to start using pay phones a lot. The one with the center coil is a collinear. It is 2 stacked verticals with a "delay" between. If I remember correctly, from running comparisons thought antenna prediction softwares, 1.5db is about the most "gain" which can, theoretically, be had between a 1/2 and a 5/8; and, not even "all that gain" (i.e., max 1.5db) is gained in such a narrow point or swath of pattern so as to account for "a lot of coverage lost." And, rarely, if ever, is the theoretically reached, in my humble experience. Something is obviously wrong with that whole statement ... perhaps a "chit poor" 1/2 is being compared to a reasonable performing 5/8? Regards, JS |
Antenna for shortwave reception
Dave wrote:
... I do SMD rework occasionally, with MagEyes. You'd use a power amplifier for a pre-amp? For some? ABSOLUTELY! Like, is the loop completely shielded? How efficient of a loop are we speaking of? Etc. But in all cases, yeah, I would provide for much more amplification factor than I will ever need, why not? I mean, do I really need the 454 with blower in my "toy car?" Regards, JS |
Antenna for shortwave reception
John Smith wrote:
Dave wrote: ... I do SMD rework occasionally, with MagEyes. You'd use a power amplifier for a pre-amp? For some? ABSOLUTELY! Like, is the loop completely shielded? How efficient of a loop are we speaking of? Etc. But in all cases, yeah, I would provide for much more amplification factor than I will ever need, why not? I mean, do I really need the 454 with blower in my "toy car?" Regards, JS And, certainly, I am assuming, you are using "power amplifier" in correct context, when dealing with low power devices--as opposed to the 5kw POWER AMPLIFIER behind, and NOT in front of, my rig? Regards, JS |
W6OBB Art Bell's 5-Acre Antenna Farm in Pahrump, Nevada
On Dec 29, 7:18*pm, Dave wrote:
John Smith wrote: - - his secret - - location in NV. - 9041 Desert Lane - Pahrump, NV 89048 - - http://maps.google.com |
5/8 WL Antennas ?
On Dec 29, 8:05*am, RHF wrote:
On Dec 29, 5:42*am, Dave wrote: Telamon wrote: In article , *Dave wrote: John Smith wrote: However, in side-by-side comparisons on 10-6-2m antennas I have built, comparing a 5/8 against the 1/2 (construction methods/materials and matching components identical) ... the actual difference, in the real world, must be less than the width of a meter needle in the readings ... or, put simply, I no longer deal with the extra length required of the 5/8 ... your mileage may vary ... The advantage of a physical height (antenna length) *between 180 and 215 degrees (see previous post regarding the magic number being around 195 degrees) is improved take-off angle and reduced skywave-groundwave interaction, not dramatic nearfield voltage increases. Regarding Mr. Smith's comments above my experience and others is the opposite. 5/8 is a much better performing antenna than a 1/2 wave for local VHF and UHF communications. Well worth the effort to build a 5/8 wave antenna over a 1/2 wave. The 5/8 had some kind of series load coil part way up the whip where the 1/2 wave match/compensation was done at the base so the whip was solid. Sorry I can't more specific then that as those experiments were many years ago. Mr. Smith is still lost in space. - 5/8 wavelength antennas do not require a ground plane, do they? Dave here is a Picture of a . . . 5/8 WL Ground Plane Antennahttp://home.att.net/~wizardoz/cbmw/Images/antenna2.gifhttp://users.belgacom.net/hamradio/schemas/50mc58golf.gifhttp://users.belgacom.net/hamradio/schemas/on6muvhf58verticalantenna.htm *. CBers use 5/8 WL Ground Plane Antennas very often.http://cgi.ebay.com/_W0QQitemZ260334577278 * Elevated Vertical Element * Load Matching Device * Ground Plane Radialshttp://www.pacificaerials.co.nz/antInfo/antennaTypes.htm#3 *. FWIW the 5/8 WL* does go 'mobile' as a Vertical "CB" Antenna but it uses the Car's body as the Ground Plane.http://www.firestik.com/Catalog/FS2-FS5.htm * They do require Tuning {Matching} for Transmithttp://www.firestik.com/Tech_Docs/TUNABLE.htmhttp://www.firestik.com/Catalog/FS2-FS5.htm *. Some where I remember a 5/8 WL Vertical Element on top of a 5/8 WL Vertical Mast {Grounded} as being a very good Antenna : Mono-Pole ? Collinear ? http://www.signalengineering.com/ultimate/verts.jpg : ]========"---------------- : :Ground Level ~ RHF |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
"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! |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
You ridiculous fool. You are the most complete brain dead example of a sub-human which has ever been presented to me ... You dumb twit. We don't care about transmitting. We don't...? Receiving is EQUALLY as important as the transmitting element in the above. Again you dumb twit, we don't care about transmitting. We don't...? Yeah, very sad of you to keep plonking and then continue to read me. I thought this was your trick? What a goofball. Takes one to know one. |
The Difference Between : Shortwave Radio Listener (SWL) -and- Amateur Radio Operators (Hams)
"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! |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur RadioAntennas
RP wrote:
You ridiculous fool. You are the most complete brain dead example of a sub-human which has ever been presented to me ... You dumb twit. We don't care about transmitting. We don't...? Receiving is EQUALLY as important as the transmitting element in the above. Again you dumb twit, we don't care about transmitting. We don't...? Yeah, very sad of you to keep plonking and then continue to read me. I thought this was your trick? What a goofball. Takes one to know one. Hey, telemundo is a great man, in his own mind, leave him alone ... humor here is sparse, he provides for a needed demand ... :-) Regards, JS |
The Difference Between : Shortwave Radio Listener (SWL) -and-Amateur Radio Operators (Hams)
RP wrote:
... And the hobo of s.r.sw Teleamon, the biggest troll here....is telling other trolls how to act! Hillarious! Hmmm, I can see how you are mistaken; but, brother you are mistaken. telemundo would not even amount to a pimple of a decent trolls hoary old butt ... indeed, I can't imagine the lifeform he could make a pimple on .... grin But then, you know, he already knows that ... :-( Regards, JS |
5/8 WL Antennas ?
RHF wrote:
... Some where I remember a 5/8 WL Vertical Element on top of a 5/8 WL Vertical Mast {Grounded} as being a very good Antenna : Mono-Pole ? Collinear ? http://www.signalengineering.com/ultimate/verts.jpg : ]========"---------------- : :Ground Level ~ RHF . . I don't know if I interpret that, correctly, or not ... however, I think a 5/8 is a FINE performer ... I only complain when having to add the extra length to a 15m - 20m and longer! Indeed, a 1/2 becomes impossible, and quickly--but then, you already know that ... At 6m and below (talking meter length), no problem! Regards, JS |
Transmitting with a "Beverage" Antenna and/or a Ferrite Rod Antenna
RHF wrote:
Dave even Arnie Coro "DXers Unlimited" [RHC] says it can be done ;-} http://www.radiohc.org/Distributions...s/01-1222.html "you can build a ferrite rod loop antenna" . all things are 'possible' : especially for the man who does not know that he can not do it ~ RHF Arnie Coro also recommends the T2FD. |
The Characteristically 50 Ohm Impedance Coax Cable is 'only'50 Ohms Nominal when . . .
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 Ventura, California 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. That depends on the length of the transmission line. |
W6OBB Art Bell's 5-Acre Antenna Farm in Pahrump, Nevada
RHF wrote:
On Dec 29, 7:18 pm, Dave wrote: John Smith wrote: - - his secret - - location in NV. - 9041 Desert Lane - Pahrump, NV 89048 - - http://maps.google.com . Art Bell, W6OBB, Pahrump, Nevada http://www.smeter.net/pahrump/art-bell.php http://en.wikipedia.org/wiki/Pahrump,_Nevada . Art Bell's 5-Acre Antenna Farm http://www.smeter.net/w6obb/antenna-farm.php SAT IMAGE = http://tinyurl.com/828s5d . The Art Bell W6OBB Loop Antenna Slide Show http://patriciaray.net/movie1.html QRZ : Art Bell [W6OBB] Pahrump, Nevada http://www.qrz.com/callsign.html?callsign=W6OBB . . KNYE-FM 95.1 MHz in Pahrump, Nevada http://www.knye.com/ http://en.wikipedia.org/wiki/KNYE http://www.rayjanko.com/area_51/21.htm http://www.radio-locator.com/cgi-bin...sr=Y&call=KNYE * From the The Kingdom of [K]NYE . . . http://www.kingdomofnye.com/ http://www.co.nye.nv.us/ http://en.wikipedia.org/wiki/Nye_County,_Nevada . KNYE-FM 95.1 MHz Transmitter Location : 36° 11' 52" N -by- 116° 02' 08" W http://maps.google.com/maps?f=q&hl=e...(KNYE-FM)&om=1 . http://www.fccinfo.com/MapIt5.php?la...&Button=Map+It |
5/8 WL Antennas ?
RHF wrote:
On Dec 29, 8:05 am, RHF wrote: On Dec 29, 5:42 am, Dave wrote: Telamon wrote: In article , Dave wrote: John Smith wrote: However, in side-by-side comparisons on 10-6-2m antennas I have built, comparing a 5/8 against the 1/2 (construction methods/materials and matching components identical) ... the actual difference, in the real world, must be less than the width of a meter needle in the readings ... or, put simply, I no longer deal with the extra length required of the 5/8 ... your mileage may vary ... The advantage of a physical height (antenna length) between 180 and 215 degrees (see previous post regarding the magic number being around 195 degrees) is improved take-off angle and reduced skywave-groundwave interaction, not dramatic nearfield voltage increases. Regarding Mr. Smith's comments above my experience and others is the opposite. 5/8 is a much better performing antenna than a 1/2 wave for local VHF and UHF communications. Well worth the effort to build a 5/8 wave antenna over a 1/2 wave. The 5/8 had some kind of series load coil part way up the whip where the 1/2 wave match/compensation was done at the base so the whip was solid. Sorry I can't more specific then that as those experiments were many years ago. Mr. Smith is still lost in space. - 5/8 wavelength antennas do not require a ground plane, do they? Dave here is a Picture of a . . . 5/8 WL Ground Plane Antennahttp://home.att.net/~wizardoz/cbmw/Images/antenna2.gifhttp://users.belgacom.net/hamradio/schemas/50mc58golf.gifhttp://users.belgacom.net/hamradio/schemas/on6muvhf58verticalantenna.htm . CBers use 5/8 WL Ground Plane Antennas very often.http://cgi.ebay.com/_W0QQitemZ260334577278 * Elevated Vertical Element * Load Matching Device * Ground Plane Radialshttp://www.pacificaerials.co.nz/antInfo/antennaTypes.htm#3 . FWIW the 5/8 WL* does go 'mobile' as a Vertical "CB" Antenna but it uses the Car's body as the Ground Plane.http://www.firestik.com/Catalog/FS2-FS5.htm * They do require Tuning {Matching} for Transmithttp://www.firestik.com/Tech_Docs/TUNABLE.htmhttp://www.firestik.com/Catalog/FS2-FS5.htm . Some where I remember a 5/8 WL Vertical Element on top of a 5/8 WL Vertical Mast {Grounded} as being a very good Antenna : Mono-Pole ? Collinear ? http://www.signalengineering.com/ultimate/verts.jpg : ]========"---------------- : :Ground Level ~ RHF . . Except for the lowly 1/4 Wave Marconi, most antennas work better up in the air. |
MatchBoxes Do They Work ? -aka- Improve Your Effective Radiated Power?
On Dec 29, 1:44*pm, John Smith wrote:
RHF wrote: [...] - Anyway you cut it ... a matchbox never will improve - the performance of a poor antenna, JS, So you are saying that I have an Antenna and Transceiver and can hear 5 Radio Operators in a Net on a Frequency; but only 2 of them can hear me. I then put a MatchBox in-line between my Antenna and Transceiver and Adjust-It; and can still hear all 5 Radio Operators on a Frequency and now all 5 of them can hear me. To Me That Is Very Real Improved Performance from My Antenna and Transceiver that is a direct result of using the MatchBox between them. ~ RHF |
Antenna for shortwave reception
"Telamon" wrote in message ... In article , Dave wrote: John Smith wrote: Dave wrote: John Smith wrote: I said NO such thing, indeed, I stated the EXACT opposite, it allows maximum power transfer to the antenna, however, the losses in the POOR antenna are now increased due to the losses in the matchbox--as heat. And, no problems which exist in the POOR antenna have been rectified, they are just masked ... That is vastly oversimplified. Absolutely, and at some point I must trust the reader has the resources to extrapolate; otherwise, all postings would soon turn in to the length, depth and completeness of a college textbook ... For example, an antenna is a two lane road, running in both directions(T/R), the same parameters which allow it to be the best choice for transmitting, also are in action when that same antenna "plucks" its' signals from the ether ... something I have pointed out in multiple ways, multiple times ... The average person must hear, read, study the same material six times before "learning" it. And, an instructor once pointed out to me, not all people respond to the same method, personality, mode-of-presentation as another or others ... so, he pointed out the importance of gathering data from multiple sources until the "epiphany" is realized ... You're the guy from Lost in Space! You are to kind Dave. The lost in Space Dr. Smith fooled some of the people some of the time where our Smith fools none of the people none of the time. And who does the Telanut think he is fooling? |
MatchBoxes Do They Work ? -aka- Improve Your Effective RadiatedPower ?
On Dec 31, 6:13*am, Dave wrote:
RHF wrote: On Dec 29, 1:44 pm, John Smith wrote: RHF wrote: [...] - Anyway you cut it ... a matchbox never will improve - the performance of a poor antenna, JS, So you are saying that I have an Antenna and Transceiver and can hear 5 Radio Operators in a Net on a Frequency; but only 2 of them can hear me. I then put a MatchBox in-line between my Antenna and Transceiver and Adjust-It; and can still hear all 5 Radio Operators on a Frequency and now all 5 of them can hear me. To Me That Is Very Real Improved Performance from My Antenna and Transceiver that is a direct result of using the MatchBox between them. ~ RHF *. - It doesn't make the antenna any better. ? More Signal Out is Not Any Better ? -*It improves the system performance by reducing - the reflected mismatch at the generator end of - the transmission line. So - All the 'reflected mismatch' is now trapped, wasted, consumed as a Power Loss in the MatchBox ? Or - Just may be does some of the 'reflected mismatch' now get Radiated as Signal Output in the Antenna ? |
W6OBB Art Bell's 5-Acre Antenna Farm in Pahrump, Nevada
In article ,
John Smith wrote: RHF wrote: On Dec 29, 7:18 pm, Dave wrote: John Smith wrote: - - his secret - - location in NV. - 9041 Desert Lane - Pahrump, NV 89048 - - http://maps.google.com . Art Bell, W6OBB, Pahrump, Nevada http://www.smeter.net/pahrump/art-bell.php http://en.wikipedia.org/wiki/Pahrump,_Nevada . Art Bell's 5-Acre Antenna Farm http://www.smeter.net/w6obb/antenna-farm.php SAT IMAGE = http://tinyurl.com/828s5d . The Art Bell W6OBB Loop Antenna Slide Show http://patriciaray.net/movie1.html QRZ : Art Bell [W6OBB] Pahrump, Nevada http://www.qrz.com/callsign.html?callsign=W6OBB . . KNYE-FM 95.1 MHz in Pahrump, Nevada http://www.knye.com/ http://en.wikipedia.org/wiki/KNYE http://www.rayjanko.com/area_51/21.htm http://www.radio-locator.com/cgi-bin...sr=Y&call=KNYE * From the The Kingdom of [K]NYE . . . http://www.kingdomofnye.com/ http://www.co.nye.nv.us/ http://en.wikipedia.org/wiki/Nye_County,_Nevada . KNYE-FM 95.1 MHz Transmitter Location : 36° 11' 52" N -by- 116° 02' 08" W http://maps.google.com/maps?f=q&hl=e...(KNYE-FM)&om=1 . Oh yeah, that IS the dirty culprit, and if you know where to turn, in the 80m band, you just might hear him! lol Regards, JS IF he isn't at his wife's ancestral home in the Philippines.... |
W6OBB Art Bell's 5-Acre Antenna Farm in Pahrump, Nevada
You wrote: In article , John Smith wrote: RHF wrote: On Dec 29, 7:18 pm, Dave wrote: John Smith wrote: - - his secret - - location in NV. - 9041 Desert Lane - Pahrump, NV 89048 - - http://maps.google.com . Art Bell, W6OBB, Pahrump, Nevada http://www.smeter.net/pahrump/art-bell.php http://en.wikipedia.org/wiki/Pahrump,_Nevada . Art Bell's 5-Acre Antenna Farm http://www.smeter.net/w6obb/antenna-farm.php SAT IMAGE = http://tinyurl.com/828s5d . The Art Bell W6OBB Loop Antenna Slide Show http://patriciaray.net/movie1.html QRZ : Art Bell [W6OBB] Pahrump, Nevada http://www.qrz.com/callsign.html?callsign=W6OBB . . KNYE-FM 95.1 MHz in Pahrump, Nevada http://www.knye.com/ http://en.wikipedia.org/wiki/KNYE http://www.rayjanko.com/area_51/21.htm http://www.radio-locator.com/cgi-bin...sr=Y&call=KNYE * From the The Kingdom of [K]NYE . . . http://www.kingdomofnye.com/ http://www.co.nye.nv.us/ http://en.wikipedia.org/wiki/Nye_County,_Nevada . KNYE-FM 95.1 MHz Transmitter Location : 36° 11' 52" N -by- 116° 02' 08" W http://maps.google.com/maps?f=q&hl=e...(KNYE-FM)&om=1 . Oh yeah, that IS the dirty culprit, and if you know where to turn, in the 80m band, you just might hear him! lol Regards, JS IF he isn't at his wife's ancestral home in the Philippines.... That's where Cousin Burr is at. Probably sleeping off the 2009 festivities at this point in time...! |
Antenna for shortwave reception
In article ,
Dave wrote: John Smith wrote: flashdrive wrote: ... Has anyone ever successfully reverse engineered the pre-amp of a Wellbrook loop? It might be possible to dissolve the encapsulating material (epoxy?) to reveal the PCB and componants. Otherwise a medical scanner (seriously) might reveal some useful information. My question would be, "Why go to the trouble?" Indeed, grab a DC - 1Ghz MMIC device (make sure you don't get an SMC component, unless you like soldering under a microscope), stick a proper filter for the freqs/bands in front of it, and feed its' input with a well designed loop ... if you need EXTREME gain, you can cascade a couple of MMICs. Regards, JS I do SMD rework occasionally, with MagEyes. You'd use a power amplifier for a pre-amp? SMD is best for RF but small through lead components on a PCB should be OK for HF work. Depending on SMD size of the components I use 4X to 10X magnification. I agree with Smith, design your own stuff besides how well things work depends as much on how circuits are physically built or laid out. The encapsulate is for weather protection not for defeating copying. -- Telamon Ventura, California |
Shortwave Radio Listener (SWL) Antennas -versus- Amateur Radio Antennas
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. -- Telamon Ventura, California |
MatchBoxes Do They Work ? -aka- Improve Your Effective RadiatedPower ?
RHF wrote:
On Dec 29, 1:44 pm, John Smith wrote: RHF wrote: [...] - Anyway you cut it ... a matchbox never will improve - the performance of a poor antenna, JS, So you are saying that I have an Antenna and Transceiver and can hear 5 Radio Operators in a Net on a Frequency; but only 2 of them can hear me. I then put a MatchBox in-line between my Antenna and Transceiver and Adjust-It; and can still hear all 5 Radio Operators on a Frequency and now all 5 of them can hear me. To Me That Is Very Real Improved Performance from My Antenna and Transceiver that is a direct result of using the MatchBox between them. ~ RHF . increase the capture area of a poor antenna, etc. It will MASK that antennas' short-comings ... same as sweeping dirt under a rug (notice, another mechanical analogy to the above.) Regards, JS I guess, any possibly way it can be explained to you, will fail ... If you introduce an inductance to resonate the antenna, you introduce a loss, if you introduce a capacitance, the same ... LC or PI networks, commonly used in matchboxes, have notable losses. I have a 60ft longwire, mounted ~40 ft. in the air. Since it is only physically resonate on but a couple/few freqs, and, since I am not employing some form of matching on the antenna, and since the antenna does not, naturally, present a correct impedance to my feedline/rig, some form of lossy matching must be tolerated ... since the matchbox is located at my receiver, whatever feedlines I choose will also become a part of the "antenna." The ideal placement for a matchbox would be at the antenna, as everyone is and has been aware of for a long time, or should have been aware. As I stated, continue to state, and have no other choice than to state when worried about being correct--no matchbox will ever improve the performance of a poor antenna--all it can do is allow you to get maximum benefit of that poor performance. You have separate components, affects/effects, terms, etc. all confused and lumped together. Antenna design, capture area, etc. effect antenna efficiency--the impedance that/those designs/constructions entail, and the method of matching (transforming) that impedance to one acceptable, is another "thing", all-together. Regards, JS |
MatchBoxes Do They Work ? -aka- Improve Your Effective RadiatedPower ?
RHF wrote:
... - It doesn't make the antenna any better. ? More Signal Out is Not Any Better ? - It improves the system performance by reducing - the reflected mismatch at the generator end of - the transmission line. So - All the 'reflected mismatch' is now trapped, wasted, consumed as a Power Loss in the MatchBox ? Or - Just may be does some of the 'reflected mismatch' now get Radiated as Signal Output in the Antenna ? . Yep, the matchbox introduces more loss, no matching network which I am aware of is truly lossless. Heat is the only way I know of to "lose" the signal. If your rig had the correct input impedance to negate the use of a matchbox, you would suffer none of this loss ... the antenna would then deliver all the signal it was capable of to the rig. Regards, JS |
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