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Stacking Winegard HD-6065P antennas
gregz wrote:
Jerry Stuckle wrote: On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? :) The reason big speaker systems work in large places is efficiency gain using multiple arrays, must be in phase. As I was saying, it's a known fact, which I have measured. You can actually get near 10 dB gain using several speakers. It's why horn loudspeakers have gain, better impedance matching to air. I once believed two in phase speakers provided 3 dB increase also. I then read a speaker project by the now famous diAppolito configuration designer in Speaker Builder magazine 80's ?. I can try to find a reference. Greg I found a reference by a well known author designer. The other tricky added to the equation, is using one channel amplifier, and getting twice the power with lowered Z. It still works for two separate amps. DiAppolito and linkwitz, two biggies of speaker systems... http://www.linkwitzlab.com/faq.htm#Q21 Greg |
Stacking Winegard HD-6065P antennas
In message , Sal
writes "Jeff Liebermann" wrote in message .. . On Mon, 6 Jan 2014 06:28:11 +0000 (UTC), gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Nope. Power is by the square of the voltage: P = V^2 / R If you double the voltage, you get 4 times the power. A 1.414 times increase in voltage will produce twice the power. I tried to convert the antenna model of the HD-6066P antenna from the AO .ant format to .nec using 4NEC2 and failed. The plan was to model the stacked arrangement and see what happens: http://www.ham-radio.com/k6sti/hd6065p.htm The .ant file imported without error, the wire tables and images look correct, but the pattern is more like a point source than a gain antenna. I'll look at it later to see where I screwed up, but it would be nice if someone would look at the problem. I just set up an experiment. I connected my roof antenna to my signal level meter and read the signal strength of my Channel 10. It was 10 dBmV, the unit typically used for TV signal strength work. Next, I connected the same roof antenna to the inport port of one of a pair of passive splitters connected back-to-back with equal short lengths of the same 75-ohm cable. Finally, I connected the output port of this network to the signal level meter and observed a signal that was approximately 1.25 dBmV less. (A quarter of a dBmV is about as close as I can reliably read; individual whole number marks are only a few mm apart.) Thus, I conclude that the 1 dB nominal loss for a passive splitter -- either combining or splitting -- is confirmed. Combining two identical suignals does get you something more than one, alone. RELATED: When I used identical twin UHF antennas side-by-side, separated by a free-space half-wave distance to cancel interference from one side, it worked nicely and showed about the same loss figures as above. That is, my reading for two antennas combined was about 2 dBmV higher than for either of the twin antennas alone, thus reflecting the 1dB loss in the combiner. Combining antennas can be an uncertain business because the phase relationships change with wavelength; the arrangement that strengthens one channel may weaken another channel if the respective signals come from different directions and/or the cable lengths are not matched. It's a matter of reinforcement or cancellation, depending on phase relationships. You missed out step #2, which was to measure the output level of the splitter alone. Using your figures, this would have shown a signal loss of 3.625dB (3dB power split loss and 0.625dB of circuit loss). When you then added the combiner, you would have 3dB power split loss and 0.625dB of circuit loss, followed by 3db power combine gain and 0.625dB of circuit loss - so as you measured, a total loss of only 1.25dB. Despite working in the cable TV industry for 43 years, for some reason this is an experiment I don't recall ever performing! -- Ian |
Stacking Winegard HD-6065P antennas
On 1/7/2014 11:17 PM, gregz wrote:
Jerry Stuckle wrote: On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? :) The reason big speaker systems work in large places is efficiency gain using multiple arrays, must be in phase. As I was saying, it's a known fact, which I have measured. You can actually get near 10 dB gain using several speakers. It's why horn loudspeakers have gain, better impedance matching to air. I once believed two in phase speakers provided 3 dB increase also. I then read a speaker project by the now famous diAppolito configuration designer in Speaker Builder magazine 80's ?. I can try to find a reference. Greg We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
On 1/7/2014 10:55 PM, Sal wrote:
"Jeff Liebermann" wrote in message ... On Mon, 6 Jan 2014 06:28:11 +0000 (UTC), gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Nope. Power is by the square of the voltage: P = V^2 / R If you double the voltage, you get 4 times the power. A 1.414 times increase in voltage will produce twice the power. I tried to convert the antenna model of the HD-6066P antenna from the AO .ant format to .nec using 4NEC2 and failed. The plan was to model the stacked arrangement and see what happens: http://www.ham-radio.com/k6sti/hd6065p.htm The .ant file imported without error, the wire tables and images look correct, but the pattern is more like a point source than a gain antenna. I'll look at it later to see where I screwed up, but it would be nice if someone would look at the problem. I just set up an experiment. I connected my roof antenna to my signal level meter and read the signal strength of my Channel 10. It was 10 dBmV, the unit typically used for TV signal strength work. Next, I connected the same roof antenna to the inport port of one of a pair of passive splitters connected back-to-back with equal short lengths of the same 75-ohm cable. Finally, I connected the output port of this network to the signal level meter and observed a signal that was approximately 1.25 dBmV less. (A quarter of a dBmV is about as close as I can reliably read; individual whole number marks are only a few mm apart.) Thus, I conclude that the 1 dB nominal loss for a passive splitter -- either combining or splitting -- is confirmed. Combining two identical suignals does get you something more than one, alone. RELATED: When I used identical twin UHF antennas side-by-side, separated by a free-space half-wave distance to cancel interference from one side, it worked nicely and showed about the same loss figures as above. That is, my reading for two antennas combined was about 2 dBmV higher than for either of the twin antennas alone, thus reflecting the 1dB loss in the combiner. Combining antennas can be an uncertain business because the phase relationships change with wavelength; the arrangement that strengthens one channel may weaken another channel if the respective signals come from different directions and/or the cable lengths are not matched. It's a matter of reinforcement or cancellation, depending on phase relationships. "Sal" (KD6VKW) In addition to the splitter losses, you have coax and connector loss. Coax loss probably isn't too bad, but unless you use a high quality crimping tool, connector loss can easily approach 0.25 to 0.5 db. Even with a high quality crimping tool, you can get around 0.1 db per connector. There is also the possibility of a slight phase difference of the signals coming out of the combiner, which would also affect the output (splitters/combiners aren't perfect, either). But I wouldn't think this would show up at such low frequencies unless you have lab-grade test equipment (microwave frequencies and above are a different story). -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
Jerry Stuckle wrote:
On 1/7/2014 11:17 PM, gregz wrote: Jerry Stuckle wrote: On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? :) The reason big speaker systems work in large places is efficiency gain using multiple arrays, must be in phase. As I was saying, it's a known fact, which I have measured. You can actually get near 10 dB gain using several speakers. It's why horn loudspeakers have gain, better impedance matching to air. I once believed two in phase speakers provided 3 dB increase also. I then read a speaker project by the now famous diAppolito configuration designer in Speaker Builder magazine 80's ?. I can try to find a reference. Greg We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg |
Stacking Winegard HD-6065P antennas
On 1/8/2014 10:22 PM, gregz wrote:
Jerry Stuckle wrote: On 1/7/2014 11:17 PM, gregz wrote: Jerry Stuckle wrote: On 1/7/2014 2:29 AM, gregz wrote: Jeff Liebermann wrote: On Mon, 06 Jan 2014 23:23:56 -0500, Jerry Stuckle wrote: On 1/6/2014 11:04 PM, Jeff Liebermann wrote: On Tue, 7 Jan 2014 03:19:54 +0000 (UTC), gregz wrote: Jerry Stuckle wrote: On 1/6/2014 1:28 AM, gregz wrote: wrote: "only 3 db", but that's twice the signal. I have mine stacked 12 feet, but I believe Winegard says either 8 or 10 feet. Mine work swell. +:^] I got mine just after they were discontinued in 2005/6. Had to email a number of suppliers until I found the second one. I bet there are some still in storage somewhere, email different places that sell Winegard, you may still find one. John K9RZZ Twice the signal means twice the voltage, for me. Greg Twice the voltage is a 6 db gain. Twice the power is a 3db gain. Exactly. If I got 1 microvolt, 2 microvolts will be twice the signal. Greg Sorta. If you got 1 microvolt, 2 microvolts will be twice the signal voltage but only 1.414 times the signal power. That's why we have units of measure to avoid such ambiguities. Just to be difficult, working with antennas, the "signal" is the field strength measured in dBuV/M. If you define what you're measuring and specify your units of measure, you wouldn't be having such problems. You've got it backwards, Jeff. Twice the voltage is 4 times the power. 1.414 times the voltage would be twice the power. Very embarrassing. Temporary loss of IQ from working on my broken car with a cold or flu this afternoon. It should be: If you got 1 microvolt, 2 microvolts will be twice the signal voltage but 4 times the signal power. Thanks for the correction (grumble)... Maybe if I go to sleep early, when I wake up tomorrow, this didn't happen. I have not really been specifying units. I was just going over the situation in my mind, and I straightened out in rf terms. I got this going out terminology. IF, in audio, I got two speakers transmitting equal energy, with two amps or channels, and I receive that totally in phase, I got twice the signal or 6 dB power increase. I've measured it. It's true. Same thing would happen with two antennas with two transmitters. Two antennas, one transmitter, with one splitter would only give 3 dB power increase at the receiver. I'm just thinking out loud. I had to ease my mind. I think I'm ok now. Almost bedtime. Greg No, two in-phase speakers provide 3db increase, not 6db. If you could double the signal and get 4x the power you could make gazillions! Of course, you'd be creating energy out of nothing, but who cares about the laws of physics? :) The reason big speaker systems work in large places is efficiency gain using multiple arrays, must be in phase. As I was saying, it's a known fact, which I have measured. You can actually get near 10 dB gain using several speakers. It's why horn loudspeakers have gain, better impedance matching to air. I once believed two in phase speakers provided 3 dB increase also. I then read a speaker project by the now famous diAppolito configuration designer in Speaker Builder magazine 80's ?. I can try to find a reference. Greg We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. |
Stacking Winegard HD-6065P antennas
On 1/9/2014 10:53 AM, boomer wrote:
We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) I would hate to have you as my neighbor. I would have to call the police on you. |
Stacking Winegard HD-6065P antennas
On 1/9/2014 11:53 AM, boomer wrote:
We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. OK, so instead of putting out 100W to one eight-ohm speaker, you're putting out 100W to two eight ohm speakers. So you have a 3db gain, assuming the speakers are in phase. It is no different than feeding two eight-ohm speakers from separate 100W amplifiers, and the results are the same. -- ================== Remove the "x" from my email address Jerry Stuckle JDS Computer Training Corp. ================== |
Stacking Winegard HD-6065P antennas
On 1/9/2014 11:06 AM, Jerry Stuckle wrote:
On 1/9/2014 11:53 AM, boomer wrote: We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. OK, so instead of putting out 100W to one eight-ohm speaker, you're putting out 100W to two eight ohm speakers. So you have a 3db gain, assuming the speakers are in phase. It is no different than feeding two eight-ohm speakers from separate 100W amplifiers, and the results are the same. exactly |
Stacking Winegard HD-6065P antennas
On 1/9/2014 11:00 AM, John S wrote:
On 1/9/2014 10:53 AM, boomer wrote: We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) I would hate to have you as my neighbor. I would have to call the police on you. We live in the North country close to the border. Our home, as are all, is heavily insulated. I run the music loud as I want without bothering the neighbours. The high wattage rating per channel is mostly just for the incredibly low terminal impedance. This makes for very good fidelity on high power low frequency. It is called inertial dampening. You have to run large diameter wire to keep this all working. I have the speakers hooked up with #10 wire. I checked performance of the speakers for this type wire by running one speaker with #16 lamp cord which I had been using and the other one hooked up with #10. I then switched to mono on the preamp. Using the balance control clearly showed a very noticeable improvement. I was told to use large dia wire to keep the resistance very low. I first thought this was really over-kill but by experiment I found that my advisor was correct. The impedance from the amp and wiring should be in the very low milliohms to prevent inertial overshoot. Purple Haze definitely sounded better :-) PS some have actually used #00 wire to their speakers. Without experimenting myself I feel by guessing that this is over-kill. I could be wrong, I was before. |
Stacking Winegard HD-6065P antennas
In message , boomer
writes We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. If I understand things correctly, I don't think that many audio amplifiers have an output impedance as high as 4 ohms. It's generally a fraction of an ohm. However, an amplifier will be designed to deliver a given power into a given load with a specified maximum distortion. -- Ian |
Stacking Winegard HD-6065P antennas
On 1/9/2014 2:37 PM, Ian Jackson wrote:
In message , boomer writes We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. If I understand things correctly, I don't think that many audio amplifiers have an output impedance as high as 4 ohms. It's generally a fraction of an ohm. However, an amplifier will be designed to deliver a given power into a given load with a specified maximum distortion. That too is my understanding. I believe that connecting a 4 or 2 ohm speaker to an amplifier rated at 8 ohms would likely cause distortion. For those still following this thread here is a simple explanation of inertial dampening. http://www.crownaudio.com/media/pdf/...ing_factor.pdf The output impedance of the Crown 810 is rated at less than 10 milliohms. This is an important specification when you are wanting to hear very little distortion. There of course other important factors including Frequency Response, Phase Response, Signal-to-Noise Ratio, Total Harmonic Distortion (THD), Intermodulation Distortion (IMD), Damping Factor, Slew Rate, Output Power, and Crosstalk. And of course then there is the whole science of speakers. Amplifier design is much easier to understand. I cannot really get my head around all the factors that come into play designing speakers. It is complicated enough to almost appear to be magic to me. |
Stacking Winegard HD-6065P antennas
boomer wrote:
On 1/9/2014 11:00 AM, John S wrote: On 1/9/2014 10:53 AM, boomer wrote: We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) I would hate to have you as my neighbor. I would have to call the police on you. We live in the North country close to the border. Our home, as are all, is heavily insulated. I run the music loud as I want without bothering the neighbours. The high wattage rating per channel is mostly just for the incredibly low terminal impedance. This makes for very good fidelity on high power low frequency. It is called inertial dampening. You have to run large diameter wire to keep this all working. I have the speakers hooked up with #10 wire. I checked performance of the speakers for this type wire by running one speaker with #16 lamp cord which I had been using and the other one hooked up with #10. I then switched to mono on the preamp. Using the balance control clearly showed a very noticeable improvement. I was told to use large dia wire to keep the resistance very low. I first thought this was really over-kill but by experiment I found that my advisor was correct. The impedance from the amp and wiring should be in the very low milliohms to prevent inertial overshoot. Purple Haze definitely sounded better :-) PS some have actually used #00 wire to their speakers. Without experimenting myself I feel by guessing that this is over-kill. I could be wrong, I was before. Yo only get so much damping with small wire. Most of it is determined by the driver box design, driver, and resistance in the coil. What you gain most is a more even driving Z to cover changes in speaker Z throughout the response range. Greg |
Stacking Winegard HD-6065P antennas
Jerry Stuckle wrote:
On 1/9/2014 11:53 AM, boomer wrote: We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. OK, so instead of putting out 100W to one eight-ohm speaker, you're putting out 100W to two eight ohm speakers. So you have a 3db gain, assuming the speakers are in phase. It is no different than feeding two eight-ohm speakers from separate 100W amplifiers, and the results are the same. Don't try to design a speaker using parallel midrange units. Your speaker will fail due to the midrange gain. Greg |
Stacking Winegard HD-6065P antennas
boomer wrote:
We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) What, horns produce magical gain. Greg So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. |
Stacking Winegard HD-6065P antennas
boomer wrote:
On 1/9/2014 2:37 PM, Ian Jackson wrote: In message , boomer writes We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. If I understand things correctly, I don't think that many audio amplifiers have an output impedance as high as 4 ohms. It's generally a fraction of an ohm. However, an amplifier will be designed to deliver a given power into a given load with a specified maximum distortion. That too is my understanding. I believe that connecting a 4 or 2 ohm speaker to an amplifier rated at 8 ohms would likely cause distortion. For those still following this thread here is a simple explanation of inertial dampening. http://www.crownaudio.com/media/pdf/...ing_factor.pdf The output impedance of the Crown 810 is rated at less than 10 milliohms. This is an important specification when you are wanting to hear very little distortion. There of course other important factors including Frequency Response, Phase Response, Signal-to-Noise Ratio, Total Harmonic Distortion (THD), Intermodulation Distortion (IMD), Damping Factor, Slew Rate, Output Power, and Crosstalk. And of course then there is the whole science of speakers. Amplifier design is much easier to understand. I cannot really get my head around all the factors that come into play designing speakers. It is complicated enough to almost appear to be magic to me. You would get more distortion with lower z, but it would be mostly depend on the volume level. Kept low, distortion would be minimal. Here is another post about damping. It even includes getting gain from two drivers. It's old, been there, done that..... http://zekfrivolous.com/sub/usenet/pierce/damp.txt Greg |
Stacking Winegard HD-6065P antennas
gregz wrote:
boomer wrote: On 1/9/2014 2:37 PM, Ian Jackson wrote: In message , boomer writes We aren't talking multiple arrays in large places. Of course multiple speakers will provide more gain than one speaker. And horn speakers get their "gain" by directing more energy in one direction; there is a loss of signal in other directions. It has nothing to do with "impedance matching to the air" (there is no such thing). The laws of physics say it is impossible to create energy out of nothing, which is what you would be doing if you quadrupled the power (6db gain) by placing two speakers in phase. If you "measured" this, you need a new meter. I would love to tear apart your "reference". Non believer in facts. If you don't believe you should do tests, like me. I'll skip the horn for now.. If you can't believe two speakers will move TWICE the air doubling intensity, I don't know what else to say, except test yourself. Greg I have (I was an EE major). You can't create energy from nothing. The laws of physics don't allow it. And I currently have a business which deals with home entertainment systems. At MOST, two speakers in phase can move twice the air. No more, and in reality, because of inefficiencies, it will be less. I hate to question the law of conservation of energy at all, but I must say that there could be more energy delivered from two 8 ohm speakers in parallel than a single speaker powered by the same amplifier. Many amplifiers have 4 ohm outputs. So, you see the possibility. You would be delivering the same energy to both speakers as was delivered to one. Of course for those who believe in magical energy production, no reasoning will help. I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) So, matching output impedance of amplifier to speaker will result in maximum energy transfer and using the most efficient speakers will result in of course more acoustic energy produced. All we are talking about here is not wasting energy in poor efficiency systems. If I understand things correctly, I don't think that many audio amplifiers have an output impedance as high as 4 ohms. It's generally a fraction of an ohm. However, an amplifier will be designed to deliver a given power into a given load with a specified maximum distortion. That too is my understanding. I believe that connecting a 4 or 2 ohm speaker to an amplifier rated at 8 ohms would likely cause distortion. For those still following this thread here is a simple explanation of inertial dampening. http://www.crownaudio.com/media/pdf/...ing_factor.pdf The output impedance of the Crown 810 is rated at less than 10 milliohms. This is an important specification when you are wanting to hear very little distortion. There of course other important factors including Frequency Response, Phase Response, Signal-to-Noise Ratio, Total Harmonic Distortion (THD), Intermodulation Distortion (IMD), Damping Factor, Slew Rate, Output Power, and Crosstalk. And of course then there is the whole science of speakers. Amplifier design is much easier to understand. I cannot really get my head around all the factors that come into play designing speakers. It is complicated enough to almost appear to be magic to me. You would get more distortion with lower z, but it would be mostly depend on the volume level. Kept low, distortion would be minimal. Here is another post about damping. It even includes getting gain from two drivers. It's old, been there, done that..... http://zekfrivolous.com/sub/usenet/pierce/damp.txt Greg For interest, the other part".... http://zekfrivolous.com/sub/usenet/pierce/damp2.txt Greg |
Stacking Winegard HD-6065P antennas
"boomer" wrote in message news:_fDzu.213384$4q1.203346@en-nntp- PS some have actually used #00 wire to their speakers. Without experimenting myself I feel by guessing that this is over-kill. I could be wrong, I was before. While going from # 20 or so speaker wire to # 10 is often helpful, I doubt going much larger is going to help unless you have a very long run. Lots of things are over sold to te audio people. Best one I know of is some special oxygen free teflon wire ( or something like that) that replaces the line cord to the wall outlet for over $ 100. Even if it actually did something, that extra 50 or so feet of regular wire back to the breaker box and other wire to the main power feed would make it worthless. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Stacking Winegard HD-6065P antennas
"Ian Jackson" wrote in message You missed out step #2, which was to measure the output level of the splitter alone. Using your figures, this would have shown a signal loss of 3.625dB (3dB power split loss and 0.625dB of circuit loss). When you then added the combiner, you would have 3dB power split loss and 0.625dB of circuit loss, followed by 3db power combine gain and 0.625dB of circuit loss - so as you measured, a total loss of only 1.25dB. Despite working in the cable TV industry for 43 years, for some reason this is an experiment I don't recall ever performing! Thanks Ian, Earlier in this thread, I saw what I thought to be an error in some postings .... about losses in excess of 3dB in the combiner and a conclusion that stacking results in less signal, which shouldn't be the case. My little experiment was meant to demonstrate a signal increase from combining in-phase signals in a passive device. Put another way, I wanted to show that a 3dB loss is not inherently present in both directions. You are correct that I did not make the measurement of the output level of the splitter alone, since it has been made and documented on many occasions. A real lab experiment would have measured that and the cable losses, too. (My 35 year-old Jerrold 747 was within easy reach and "close enough.") It was my intent to show, when two equal signals (presumptive on my part that the two outputs of a splitter are equal) are combined, that the result is the addition of the two, minus ohmic and coupling losses, which I think I did show. "Sal" |
Stacking Winegard HD-6065P antennas
"Jerry Stuckle" wrote in message ... snip In addition to the splitter losses, you have coax and connector loss. Coax loss probably isn't too bad, but unless you use a high quality crimping tool, connector loss can easily approach 0.25 to 0.5 db. Even with a high quality crimping tool, you can get around 0.1 db per connector. There is also the possibility of a slight phase difference of the signals coming out of the combiner, which would also affect the output (splitters/combiners aren't perfect, either). But I wouldn't think this would show up at such low frequencies unless you have lab-grade test equipment (microwave frequencies and above are a different story). All correct. As I said to Ian, I wanted to show I could create two matching signals then add them and the passive splitter/combiner output would be greater than either input, alone. Accuracy within a dB or so was sufficient to make the point. I wouldn't go to a professional meeting with the demonstration rig I used last night. Another experiment I ran (back around 1975) was to take 100 feet of cable and measure the loss, then repeat the measurement using a different 100 feet made from ten different pieces. Yup, the loss was about 3 dB more, indicative of an average 0.3 dB loss per joint, neatly within the range you specified. "Sal" |
Stacking Winegard HD-6065P antennas
"Jerry Stuckle" wrote in message ... OK, so instead of putting out 100W to one eight-ohm speaker, you're putting out 100W to two eight ohm speakers. So you have a 3db gain, assuming the speakers are in phase. It is no different than feeding two eight-ohm speakers from separate 100W amplifiers, and the results are the same. Discussion of audio amplifier power in home systems always prompts me to relate this: I worked for a guy who was formerly a projectionist at Radio City Music Hall in New York. He told me the sound system used amplifiers rated at 70 watts per channel. That's a 6,000-seat theater. He worked there a long time ago, so this not a claim of what they use today. Use for perspective only, please. "Sal" |
Stacking Winegard HD-6065P antennas
"Sal" salmonella@food poisoning.org wrote:
"Jerry Stuckle" wrote in message ... OK, so instead of putting out 100W to one eight-ohm speaker, you're putting out 100W to two eight ohm speakers. So you have a 3db gain, assuming the speakers are in phase. It is no different than feeding two eight-ohm speakers from separate 100W amplifiers, and the results are the same. Discussion of audio amplifier power in home systems always prompts me to relate this: I worked for a guy who was formerly a projectionist at Radio City Music Hall in New York. He told me the sound system used amplifiers rated at 70 watts per channel. That's a 6,000-seat theater. He worked there a long time ago, so this not a claim of what they use today. Use for perspective only, please. "Sal" Some of the early amps were smaller. I remember a discussion about a movie coming in that suggested higher power. Those speakers were typically at least 100 times more power efficient than average home speakers, or 10 dB spl. Many were altec a7's. Greg |
Stacking Winegard HD-6065P antennas
On 1/9/2014 11:21 PM, Ralph Mowery wrote:
"boomer" wrote in message news:_fDzu.213384$4q1.203346@en-nntp- PS some have actually used #00 wire to their speakers. Without experimenting myself I feel by guessing that this is over-kill. I could be wrong, I was before. While going from # 20 or so speaker wire to # 10 is often helpful, I doubt going much larger is going to help unless you have a very long run. Lots of things are over sold to te audio people. Best one I know of is some special oxygen free teflon wire ( or something like that) that replaces the line cord to the wall outlet for over $ 100. Even if it actually did something, that extra 50 or so feet of regular wire back to the breaker box and other wire to the main power feed would make it worthless. Definitely! A lot of audio people want the best sound, but are unfamiliar with the technical aspects. This leaves them ripe for greedy salespeople. I remember going into circuit City a few years ago. All I needed was a few feet of speaker wire. The salesman tried to sell me a 50' spool of 16 gauge wire for about $50. I asked him why it was so expensive - he replied "Because it's (brand name here)". I then asked him what was so special about Monster. His only response was "It's (brand name here)!". I went down the street to Radio Shack and got something similar for under $10. That was 15 or more years ago, and it's still working fine. If you want to sell me something that's 5x the price of the competition, you need to be ready to tell me WHY it's 5x the price. And just saying it's because it's a certain brand doesn't work. -- ================== Remove the "x" from my email address Jerry Stuckle JDS Computer Training Corp. ================== |
Stacking Winegard HD-6065P antennas
On 1/10/2014 12:45 AM, Sal wrote:
"Jerry Stuckle" wrote in message ... OK, so instead of putting out 100W to one eight-ohm speaker, you're putting out 100W to two eight ohm speakers. So you have a 3db gain, assuming the speakers are in phase. It is no different than feeding two eight-ohm speakers from separate 100W amplifiers, and the results are the same. Discussion of audio amplifier power in home systems always prompts me to relate this: I worked for a guy who was formerly a projectionist at Radio City Music Hall in New York. He told me the sound system used amplifiers rated at 70 watts per channel. That's a 6,000-seat theater. He worked there a long time ago, so this not a claim of what they use today. Use for perspective only, please. "Sal" Yes, this is where speaker efficiency comes into play. Due to the need for stiffer cones, larger voice coils, etc., higher-power speakers are generally less efficient than lower power ones. So 10W into a 10W-rated speaker will provide a higher SPL than that same 10W into a 100W speaker. And, of course, speaker placement is also critical, especially in larger venues. You can cover a large area with not a lot of power if the system is designed properly. -- ================== Remove the "x" from my email address Jerry Stuckle JDS Computer Training Corp. ================== |
Stacking Winegard HD-6065P antennas
On 1/9/2014 11:06 PM, gregz wrote:
boomer wrote: snip I personally have a Crown 810 powering a couple of AR SRT380s. The amplifier has 4 ohm outputs and the speakers are 4 ohms. There is nothing to be done to increase sound power except buy more efficient folded horn types. I have neither the space nor money to do so. However, at 420 watts rms per channel as it is now, I really don't require more power. Jimmy Hendrix sounds just fine to me. :-) What, horns produce magical gain. They don't have gain, but some speakers are more efficient, so you have less loss. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
In a circa 1970s issue of Stereo Review there was a cartoon showing the
Front Window of a Stereo Dealers. There was a sign advertising an OLD FOLKS SPECIAL -- a speaker with a frequency response of 500Hz to 5KHz. A caption stated 'Why Pay Good Money For Sound You Can No Longer Hear?' Incidentally, if you Google Wickipedia there are a number of articles on 'speaker damping factor'. In those days I didn't know much math or physics, so I just used line cord to hook up the speakers. They sounded great to me! Those were also the days when if you turned up (or down) the Bass and Treble controls you were in danger of being poo-pooed by your audiophile friends! Irv VE6BP -- Political correctness is a doctrine, fostered by a delusional, illogical minority, and rapidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a piece of **** by the clean end. "Jerry Stuckle" wrote in message ... On 1/9/2014 11:21 PM, Ralph Mowery wrote: "boomer" wrote in message news:_fDzu.213384$4q1.203346@en-nntp- PS some have actually used #00 wire to their speakers. Without experimenting myself I feel by guessing that this is over-kill. I could be wrong, I was before. While going from # 20 or so speaker wire to # 10 is often helpful, I doubt going much larger is going to help unless you have a very long run. Lots of things are over sold to te audio people. Best one I know of is some special oxygen free teflon wire ( or something like that) that replaces the line cord to the wall outlet for over $ 100. Even if it actually did something, that extra 50 or so feet of regular wire back to the breaker box and other wire to the main power feed would make it worthless. Definitely! A lot of audio people want the best sound, but are unfamiliar with the technical aspects. This leaves them ripe for greedy salespeople. I remember going into circuit City a few years ago. All I needed was a few feet of speaker wire. The salesman tried to sell me a 50' spool of 16 gauge wire for about $50. I asked him why it was so expensive - he replied "Because it's (brand name here)". I then asked him what was so special about Monster. His only response was "It's (brand name here)!". I went down the street to Radio Shack and got something similar for under $10. That was 15 or more years ago, and it's still working fine. If you want to sell me something that's 5x the price of the competition, you need to be ready to tell me WHY it's 5x the price. And just saying it's because it's a certain brand doesn't work. -- ================== Remove the "x" from my email address Jerry Stuckle JDS Computer Training Corp. ================== |
Stacking Winegard HD-6065P antennas
"Jerry Stuckle" wrote in message ... If you want to sell me something that's 5x the price of the competition, you need to be ready to tell me WHY it's 5x the price. And just saying it's because it's a certain brand doesn't work. Had he told people the wire was teflon coated so the electrons flowed beter and the copper was oxygen free so the electrons would not be degraded, he could have sold it.. From what I have been seeing the TV people are about the same, Selling high dollar hdmi cable or special high defination antennas with the same snake oil pitch. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Stacking Winegard HD-6065P antennas
"Sal" salmonella@food poisoning.org wrote in message ... Discussion of audio amplifier power in home systems always prompts me to relate this: I worked for a guy who was formerly a projectionist at Radio City Music Hall in New York. He told me the sound system used amplifiers rated at 70 watts per channel. That's a 6,000-seat theater. He worked there a long time ago, so this not a claim of what they use today. Use for perspective only, please. I wonder if that was 'real watts' instead of inflated watts. I have seen some wall wart computer speakers rated at 50 watts or so. Open them up and inside the speaker may have 3 watts on the lable. Same as with the listed gain of antennas for hams and especially the CB. One antenna of modern times had a gain listed of several times more than it should. Claimed to be the gain from one of the computer programs. It may have been,but they were adding in a lot of ground gain and certain take off angles. Not sure where they were getting the gain numbers from,but he old CC 11 element 2 meter beams had a number that was way too high if you compaired it on the air with another antenna. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Stacking Winegard HD-6065P antennas
On 1/10/2014 10:55 AM, Ralph Mowery wrote:
"Jerry Stuckle" wrote in message ... If you want to sell me something that's 5x the price of the competition, you need to be ready to tell me WHY it's 5x the price. And just saying it's because it's a certain brand doesn't work. Had he told people the wire was teflon coated so the electrons flowed beter and the copper was oxygen free so the electrons would not be degraded, he could have sold it.. From what I have been seeing the TV people are about the same, Selling high dollar hdmi cable or special high defination antennas with the same snake oil pitch. Yup, I know what you mean. There are some major differences between different HDMI cables; they'll all work pretty well at five feet, but many of the cheaper brands (and a bunch of what you see on TV) won't work at 50 feet (the maximum for the spec). For some, even 15 feet is problematical. Best is to buy from a reputable high-end dealer, especially if it's a local store and not a chain. They know their stuff. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
On Thu, 9 Jan 2014 21:08:11 -0800, "Sal" salmonella@food
poisoning.org wrote: Another experiment I ran (back around 1975) was to take 100 feet of cable and measure the loss, then repeat the measurement using a different 100 feet made from ten different pieces. Yup, the loss was about 3 dB more, indicative of an average 0.3 dB loss per joint, neatly within the range you specified. 0.3dB per connector at what frequency? This is more fun: http://802.11junk.com/jeffl/antennas/connector-loss/index.html Just take every connector that you can find, put them in series, and measure the loss. In this case, it was done at 2.4Ghz and 450MHz. End to end loss at 2.4GHz was 2dB for about 25 adapters or about 0.08dB per adapter. At 250MHz, the loss was about 0.2dB or 0.008dB per adapter. I've done similar demonstrations using two wattmeters at the local radio club meeting. The results are typically that the adapter string has the same loss as an equivalent length of small coax cable. I had a surplus of BNC T connectors, so a strung about 50 of them in series and obtained similar results. Bottom line: Connectors and adapters aren't as evil as the data sheets and literature suggest. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Stacking Winegard HD-6065P antennas
On 1/10/2014 11:03 AM, Ralph Mowery wrote:
"Sal" salmonella@food poisoning.org wrote in message ... Discussion of audio amplifier power in home systems always prompts me to relate this: I worked for a guy who was formerly a projectionist at Radio City Music Hall in New York. He told me the sound system used amplifiers rated at 70 watts per channel. That's a 6,000-seat theater. He worked there a long time ago, so this not a claim of what they use today. Use for perspective only, please. I wonder if that was 'real watts' instead of inflated watts. I have seen some wall wart computer speakers rated at 50 watts or so. Open them up and inside the speaker may have 3 watts on the lable. Same as with the listed gain of antennas for hams and especially the CB. One antenna of modern times had a gain listed of several times more than it should. Claimed to be the gain from one of the computer programs. It may have been,but they were adding in a lot of ground gain and certain take off angles. Not sure where they were getting the gain numbers from,but he old CC 11 element 2 meter beams had a number that was way too high if you compaired it on the air with another antenna. If it was a long time ago, I suspect it was "real watts". Manufacturers didn't really start inflating the wattage until the 70's or so. Nowadays, a "100W" amplifier is probably more like 20 "real" watts. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
In message , Jeff Liebermann
writes On Thu, 9 Jan 2014 21:08:11 -0800, "Sal" salmonella@food poisoning.org wrote: Another experiment I ran (back around 1975) was to take 100 feet of cable and measure the loss, then repeat the measurement using a different 100 feet made from ten different pieces. Yup, the loss was about 3 dB more, indicative of an average 0.3 dB loss per joint, neatly within the range you specified. 0.3dB per connector at what frequency? This is more fun: http://802.11junk.com/jeffl/antennas/connector-loss/index.html Just take every connector that you can find, put them in series, and measure the loss. In this case, it was done at 2.4Ghz and 450MHz. End to end loss at 2.4GHz was 2dB for about 25 adapters or about 0.08dB per adapter. At 250MHz, the loss was about 0.2dB or 0.008dB per adapter. I've done similar demonstrations using two wattmeters at the local radio club meeting. The results are typically that the adapter string has the same loss as an equivalent length of small coax cable. I had a surplus of BNC T connectors, so a strung about 50 of them in series and obtained similar results. Bottom line: Connectors and adapters aren't as evil as the data sheets and literature suggest. I've always assumed that the loss measured through connectors and adapters was mainly (a) because they have unavoidable length (ie not a lot), and (b) because the impedance match through them is less than perfect (ie not a lot). The ohmic contact resistance may also be a tiny tad higher than the same length of coax (even less). -- Ian |
Stacking Winegard HD-6065P antennas
"Ralph Mowery" wrote in message m... "Sal" salmonella@food poisoning.org wrote in message ... Discussion of audio amplifier power in home systems always prompts me to relate this: I worked for a guy who was formerly a projectionist at Radio City Music Hall in New York. He told me the sound system used amplifiers rated at 70 watts per channel. That's a 6,000-seat theater. He worked there a long time ago, so this not a claim of what they use today. Use for perspective only, please. I wonder if that was 'real watts' instead of inflated watts. I have seen some wall wart computer speakers rated at 50 watts or so. Open them up and inside the speaker may have 3 watts on the lable. Same as with the listed gain of antennas for hams and especially the CB. One antenna of modern times had a gain listed of several times more than it should. Claimed to be the gain from one of the computer programs. It may have been,but they were adding in a lot of ground gain and certain take off angles. Not sure where they were getting the gain numbers from,but he old CC 11 element 2 meter beams had a number that was way too high if you compaired it on the air with another antenna. Hard to know, Ralph. Some years ago, I was the repairman for my son's high school music group, a show choir that traveled with a serious suite of electronics. One evening, I changed a bad tweeter in a big roll-around speaker system and tested it before I put it in my van. I clipped leads on the speaker terminals and plugged into the headphone jack on a small boombox -- powered by four D-cells. When I began to crank it up on the patio, my lovely wife came roaring out and demanded that I turn it down. "Do you know what time it is?" Well, yes, I did know, but that wasn't exactly her point. Clearly, four D-cells provide more than enough sound power to upset a whole neighborhood and she felt the need to heighten my concern. ;-) "Sal" |
Stacking Winegard HD-6065P antennas
On 1/10/2014 7:01 PM, Ian Jackson wrote:
In message , Jeff Liebermann writes On Thu, 9 Jan 2014 21:08:11 -0800, "Sal" salmonella@food poisoning.org wrote: Another experiment I ran (back around 1975) was to take 100 feet of cable and measure the loss, then repeat the measurement using a different 100 feet made from ten different pieces. Yup, the loss was about 3 dB more, indicative of an average 0.3 dB loss per joint, neatly within the range you specified. 0.3dB per connector at what frequency? This is more fun: http://802.11junk.com/jeffl/antennas/connector-loss/index.html Just take every connector that you can find, put them in series, and measure the loss. In this case, it was done at 2.4Ghz and 450MHz. End to end loss at 2.4GHz was 2dB for about 25 adapters or about 0.08dB per adapter. At 250MHz, the loss was about 0.2dB or 0.008dB per adapter. I've done similar demonstrations using two wattmeters at the local radio club meeting. The results are typically that the adapter string has the same loss as an equivalent length of small coax cable. I had a surplus of BNC T connectors, so a strung about 50 of them in series and obtained similar results. Bottom line: Connectors and adapters aren't as evil as the data sheets and literature suggest. I've always assumed that the loss measured through connectors and adapters was mainly (a) because they have unavoidable length (ie not a lot), and (b) because the impedance match through them is less than perfect (ie not a lot). The ohmic contact resistance may also be a tiny tad higher than the same length of coax (even less). The main loss in a connector is due to the impedance bump at the connector. This can be easily seen on a TDR (Time Domain Reflectometry) display. Some connectors are better than others; for instance, the older F connectors which are crimped down with a ring are the worst. Next is the connector where the crimp is a hex crimp - it doesn't give a consistent impedance around the connector. The best (and the ones we use) compress the entire base of the connector evenly, creating a smooth crimp. The end of the coax is evenly covered by the connector. The other problem is the technician installing the connectors. I've seen great ones, and not-so-great ones. There are a lot of chances for going wrong - for instance, it's easy to screw up the braid when trying to insert a crimp-on connector under the outer jacket and shield. And soldering connectors (i.e. PL-259 and N) is almost sure to give you a huge bump (and loss) because it's almost impossible to solder the shield without melting the inner insulator to some point. It may not short out, but that doesn't mean you don't have loss there. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Stacking Winegard HD-6065P antennas
On Sat, 11 Jan 2014 00:01:57 +0000, Ian Jackson
wrote: In message , Jeff Liebermann writes On Thu, 9 Jan 2014 21:08:11 -0800, "Sal" salmonella@food poisoning.org wrote: Another experiment I ran (back around 1975) was to take 100 feet of cable and measure the loss, then repeat the measurement using a different 100 feet made from ten different pieces. Yup, the loss was about 3 dB more, indicative of an average 0.3 dB loss per joint, neatly within the range you specified. 0.3dB per connector at what frequency? This is more fun: http://802.11junk.com/jeffl/antennas/connector-loss/index.html Just take every connector that you can find, put them in series, and measure the loss. In this case, it was done at 2.4Ghz and 450MHz. End to end loss at 2.4GHz was 2dB for about 25 adapters or about 0.08dB per adapter. At 250MHz, the loss was about 0.2dB or 0.008dB per Oops. That should be 450 Mhz, not 250 MHz. adapter. I've done similar demonstrations using two wattmeters at the local radio club meeting. The results are typically that the adapter string has the same loss as an equivalent length of small coax cable. I had a surplus of BNC T connectors, so a strung about 50 of them in series and obtained similar results. Bottom line: Connectors and adapters aren't as evil as the data sheets and literature suggest. I've always assumed that the loss measured through connectors and adapters was mainly (a) because they have unavoidable length (ie not a lot), and (b) because the impedance match through them is less than perfect (ie not a lot). As I misunderstand it, below about 1GHz, most of the loss is ohmic, which are the surface and contact resistance of the connections and conductors. Above 1GHz, the dielectric losses begin to become significant. Extra points of dissimilar metals and bad construction. Except for the PL-259/SO-239 and phono connectors, most of the connectors are fairly close to 50 ohms. The ohmic contact resistance may also be a tiny tad higher than the same length of coax (even less). Yep. It's more than a tiny tad higher. For example, at 2.4 GHz, LMR240 has an attenuation of 12.6 dB/100ft. Each coax adapter is maybe an inch long, resulting in: 12.6 dB/100ft = 0.126 dB/ft = 0.01 dB/inch which is 8 times less than the 0.08dB/adapter that the measurements show. However, there's plenty of room for measurement error here. I suspect that if quality connectors were used, such as SMA, the numbers could come out closer to a similar wire gauge coax cable. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Stacking Winegard HD-6065P antennas
"Jeff Liebermann" wrote in message ... On Thu, 9 Jan 2014 21:08:11 -0800, "Sal" salmonella@food poisoning.org wrote: Another experiment I ran (back around 1975) was to take 100 feet of cable and measure the loss, then repeat the measurement using a different 100 feet made from ten different pieces. Yup, the loss was about 3 dB more, indicative of an average 0.3 dB loss per joint, neatly within the range you specified. 0.3dB per connector at what frequency? This is more fun: http://802.11junk.com/jeffl/antennas/connector-loss/index.html Just take every connector that you can find, put them in series, and measure the loss. In this case, it was done at 2.4Ghz and 450MHz. End to end loss at 2.4GHz was 2dB for about 25 adapters or about 0.08dB per adapter. At 250MHz, the loss was about 0.2dB or 0.008dB per adapter. I've done similar demonstrations using two wattmeters at the local radio club meeting. The results are typically that the adapter string has the same loss as an equivalent length of small coax cable. I had a surplus of BNC T connectors, so a strung about 50 of them in series and obtained similar results. Bottom line: Connectors and adapters aren't as evil as the data sheets and literature suggest. I agree. To answer your question, my test generator output was Channel 3, so my measurements were done about 61 MHz. I used all F-connectors, too, not exactly a precision connector. The reason I did the experiment [on USS Oriskany (CV-34), by the way] was because my prior duties as an Electronic Warfare Tech exposed me to a persistent rumor: Connectors cause a 3dB loss. I knew that it was nonsense but I had never taken the time to conclusively disprove it before I moved to the TV shop. Related: I'm in a local group that's experimenting with mesh networking (http://www.broadband-hamnet.org/). My first antenna connection required a stack of four adapters, so last week I bought eight different adapters. I should need only one. My big concern is not signal loss but the possibility of snapping something plastic with a stupid long stack of connectors on the back of a router. "Sal" |
Stacking Winegard HD-6065P antennas
On Fri, 10 Jan 2014 19:36:59 -0500, Jerry Stuckle
wrote: The main loss in a connector is due to the impedance bump at the connector. This can be easily seen on a TDR (Time Domain Reflectometry) display. Rubbish. Let's pretend that I mix in a 75 ohm coax connector into a 50 ohm system. Depending on the location of this "impedance bump", the VSWR is no more than 1.5:1 which is generally considered marginal. That's 0.18dB of mismatch loss. http://www.microwaves101.com/encyclopedia/calvswr.cfm If you're doing satellite or microwave DX work, then 0.18dB might be important. However, for most other applications, it's a trivial amount. You might be amused to know that most of my rooftop antennas are fed with 75 ohm coax and that my favored antenna designs are also 75 ohm. There are various reasons, but the main one is that coax cable losses are less at 75 ohms, than at 50 ohms. 50 ohms can handle more power, but 75 ohms has less loss. http://www.belden.com/blog/broadcastav/50-Ohms-The-Forgotten-Impedance.cfm The only problems I have with 75 ohms is finding the proper connectors and dealing with the pads needed to make my 50 ohm test equipment look like 75 ohms. (Actually the real reason is that the 75 ohm stuff is mostly CATV surplus, which tends to be really cheap). Mo http://www.qsl.net/n9zia/wireless/75_ohm_hardline.html Some connectors are better than others; for instance, the older F connectors which are crimped down with a ring are the worst. Next is the connector where the crimp is a hex crimp - it doesn't give a consistent impedance around the connector. I rip those out wherever I find them, even if they're on the ends of commercially crimped cables (usually RG-59/u which is another nightmare). However, the loss mechanism with the old CATV coax and associated crappy crimp connectors was radiation, not mismatch loss. The ground connections would fall apart, turning the coax shield into an impressive antenna. The best (and the ones we use) compress the entire base of the connector evenly, creating a smooth crimp. The end of the coax is evenly covered by the connector. I've had problems with some of those push-on connectors. I also don't want to stock a zillion different connector variations from different vendors. So, I've standardized on the "red" univeral T&B SNS1P6U RG-6/u connectors: www.ebay.com/sch/i.html?_nkw=SNS1P6U The other problem is the technician installing the connectors. I've seen great ones, and not-so-great ones. There are a lot of chances for going wrong - for instance, it's easy to screw up the braid when trying to insert a crimp-on connector under the outer jacket and shield. And soldering connectors (i.e. PL-259 and N) is almost sure to give you a huge bump (and loss) because it's almost impossible to solder the shield without melting the inner insulator to some point. It may not short out, but that doesn't mean you don't have loss there. Actually, it's not the crimp job that kills the connection. It's the stripping of the coax that causes the most problems. I use various rotary contrivances that have razor blades to make the cuts at the correct spacing. Those work well initially, but after about 50 connectors, the blades become dull and useless. Of course, nobody has spare blades or knows how to adjust them. They either continue to use a dull razor or steal my new stripper. Oops... dinner... gone. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Stacking Winegard HD-6065P antennas
"Jeff Liebermann" wrote in message ... On Fri, 10 Jan 2014 19:36:59 -0500, Jerry Stuckle Actually, it's not the crimp job that kills the connection. It's the stripping of the coax that causes the most problems. I use various rotary contrivances that have razor blades to make the cuts at the correct spacing. Those work well initially, but after about 50 connectors, the blades become dull and useless. Of course, nobody has spare blades or knows how to adjust them. They either continue to use a dull razor or steal my new stripper. I don't know the quality of the cutters you use, but I have bought several from China off ebay for about $ 2 each including shipping. For the very few connectors I do, they work. At that price, you could order a lot of them and not worry about the replacement blades. Just like the disposiable razors. They seem identical to the ones that sell in stores for $ 10 to $ 15 . --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Stacking Winegard HD-6065P antennas
On 1/10/2014 9:06 PM, Jeff Liebermann wrote:
On Fri, 10 Jan 2014 19:36:59 -0500, Jerry Stuckle wrote: The main loss in a connector is due to the impedance bump at the connector. This can be easily seen on a TDR (Time Domain Reflectometry) display. Rubbish. Let's pretend that I mix in a 75 ohm coax connector into a 50 ohm system. Depending on the location of this "impedance bump", the VSWR is no more than 1.5:1 which is generally considered marginal. That's 0.18dB of mismatch loss. http://www.microwaves101.com/encyclopedia/calvswr.cfm If you're doing satellite or microwave DX work, then 0.18dB might be important. However, for most other applications, it's a trivial amount. That's theoretical. Reality is much different. Have you ever worked with a TDR? It's one of the tools we use regularly (and an expensive one, also). You might be amused to know that most of my rooftop antennas are fed with 75 ohm coax and that my favored antenna designs are also 75 ohm. There are various reasons, but the main one is that coax cable losses are less at 75 ohms, than at 50 ohms. 50 ohms can handle more power, but 75 ohms has less loss. http://www.belden.com/blog/broadcastav/50-Ohms-The-Forgotten-Impedance.cfm The only problems I have with 75 ohms is finding the proper connectors and dealing with the pads needed to make my 50 ohm test equipment look like 75 ohms. (Actually the real reason is that the 75 ohm stuff is mostly CATV surplus, which tends to be really cheap). So? Dipoles aren't 50 ohm antennas. They're typically closer to 75 ohm. As for handling more power - rubbish. The current in 75 ohm coax is lower than that in 50 ohm coax, for the same power rating. Proper connectors are no problem when you can buy from commercial distributors. But we don't typically sell them individually. Mo http://www.qsl.net/n9zia/wireless/75_ohm_hardline.html Some connectors are better than others; for instance, the older F connectors which are crimped down with a ring are the worst. Next is the connector where the crimp is a hex crimp - it doesn't give a consistent impedance around the connector. I rip those out wherever I find them, even if they're on the ends of commercially crimped cables (usually RG-59/u which is another nightmare). However, the loss mechanism with the old CATV coax and associated crappy crimp connectors was radiation, not mismatch loss. The ground connections would fall apart, turning the coax shield into an impressive antenna. We use RG-59 where appropriate, like from an outlet to the set top box. But our in-wall coax runs are all RG-6 quad-shielded. But we're also doing less and less coax and more and more Category cable nowadays. The best (and the ones we use) compress the entire base of the connector evenly, creating a smooth crimp. The end of the coax is evenly covered by the connector. I've had problems with some of those push-on connectors. I also don't want to stock a zillion different connector variations from different vendors. So, I've standardized on the "red" univeral T&B SNS1P6U RG-6/u connectors: www.ebay.com/sch/i.html?_nkw=SNS1P6U They're OK for the hobbyist, but I don't know of any professionals who use them. In fact, checking our main wholesalers, they aren't even available through them (but other Beldon products are). The other problem is the technician installing the connectors. I've seen great ones, and not-so-great ones. There are a lot of chances for going wrong - for instance, it's easy to screw up the braid when trying to insert a crimp-on connector under the outer jacket and shield. And soldering connectors (i.e. PL-259 and N) is almost sure to give you a huge bump (and loss) because it's almost impossible to solder the shield without melting the inner insulator to some point. It may not short out, but that doesn't mean you don't have loss there. Actually, it's not the crimp job that kills the connection. It's the stripping of the coax that causes the most problems. I use various rotary contrivances that have razor blades to make the cuts at the correct spacing. Those work well initially, but after about 50 connectors, the blades become dull and useless. Of course, nobody has spare blades or knows how to adjust them. They either continue to use a dull razor or steal my new stripper. Oops... dinner... gone. Stripping is almost never a problem, unless you're a real klutz. Even if you nick the braid a bit it isn't very critical. We use the same type of rotary stripper - but just because it's much faster. One of our techs can install an F connector in a minute or less with one of them. I never counted how many connections we get out of a stripper, but it's got to be in the thousands. We replace some screwdrivers more often than the strippers :) -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
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