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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Technical report on rabbits ears
Does anybody know of a technical report of the "indoor aerial" I was told a
few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.759 / Virus Database: 508 - Release Date: 09-Sep-04 |
#2
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The basic TV rabbit ears are a simple 300 ohm dual dipole antenna. Look
up dipole antennas and you should have some explanations. A dual dipole antenna is based on the simple single dipole antenna. The 2 dipoles work in a parallel type of operation to accommodate having a balanced type of antenna, to match to the 300 ohms. If you were to add on a 300 ohm to 75 ohm converter, then you can use a single dipole antenna (single rod type antenna that most of the newer sets are using for local indoor use). The TV sets that have the single dipole antenna have the their RF entry in the 75 ohm impedance design. On the rabbit ears, each dipole is adjustable (length and angle) to compensate for frequency, reflections, and directivity. Many of the manufactures of rabbit ears added on traps, and other gadget type options to make these more adjustable. Many of these add-ons worsened the rabbit ear performance, and or made them more complicated to use. Most of the sites you will find on the web deal with armature radio. The impedance for communications equipment 50 ohms (52 ohms) by standard. Antenna Basics: http://www.electronics-tutorials.com...nna-basics.htm Antenna Calculator & Information: http://www.csgnetwork.com/antennaedcalc.html -- Jerry G. ====== "Eric" wrote in message ... Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.759 / Virus Database: 508 - Release Date: 09-Sep-04 |
#3
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The basic TV rabbit ears are a simple 300 ohm dual dipole antenna. Look
up dipole antennas and you should have some explanations. A dual dipole antenna is based on the simple single dipole antenna. The 2 dipoles work in a parallel type of operation to accommodate having a balanced type of antenna, to match to the 300 ohms. If you were to add on a 300 ohm to 75 ohm converter, then you can use a single dipole antenna (single rod type antenna that most of the newer sets are using for local indoor use). The TV sets that have the single dipole antenna have the their RF entry in the 75 ohm impedance design. On the rabbit ears, each dipole is adjustable (length and angle) to compensate for frequency, reflections, and directivity. Many of the manufactures of rabbit ears added on traps, and other gadget type options to make these more adjustable. Many of these add-ons worsened the rabbit ear performance, and or made them more complicated to use. Most of the sites you will find on the web deal with armature radio. The impedance for communications equipment 50 ohms (52 ohms) by standard. Antenna Basics: http://www.electronics-tutorials.com...nna-basics.htm Antenna Calculator & Information: http://www.csgnetwork.com/antennaedcalc.html -- Jerry G. ====== "Eric" wrote in message ... Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.759 / Virus Database: 508 - Release Date: 09-Sep-04 |
#4
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Jerry G posted:
The basic TV rabbit ears are a simple 300 ohm dual dipole antenna. Look up dipole antennas and you should have some explanations. A dual dipole antenna is based on the simple single dipole antenna. The 2 dipoles work in a parallel type of operation to accommodate having a balanced type of antenna, to match to the 300 ohms. If you were to add on a 300 ohm to 75 ohm converter, then you can use a single dipole antenna (single rod type antenna that most of the newer sets are using for local indoor use). The TV sets that have the single dipole antenna have the their RF entry in the 75 ohm impedance design. On the rabbit ears, each dipole is adjustable (length and angle) to compensate for frequency, reflections, and directivity. Many of the manufactures of rabbit ears added on traps, and other gadget type options to make these more adjustable. Many of these add-ons worsened the rabbit ear performance, and or made them more complicated to use. Most of the sites you will find on the web deal with armature radio. The impedance for communications equipment 50 ohms (52 ohms) by standard. Antenna Basics: http://www.electronics-tutorials.com...nna-basics.htm Antenna Calculator & Information: http://www.csgnetwork.com/antennaedcalc.html --- A rabbit ears antenna is *not* a dual dipole antenna. It is simply a dipole antenna adjustable to a half-wavelength through, at least, the low (2-13) TV channels. Don |
#5
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Jerry G posted:
The basic TV rabbit ears are a simple 300 ohm dual dipole antenna. Look up dipole antennas and you should have some explanations. A dual dipole antenna is based on the simple single dipole antenna. The 2 dipoles work in a parallel type of operation to accommodate having a balanced type of antenna, to match to the 300 ohms. If you were to add on a 300 ohm to 75 ohm converter, then you can use a single dipole antenna (single rod type antenna that most of the newer sets are using for local indoor use). The TV sets that have the single dipole antenna have the their RF entry in the 75 ohm impedance design. On the rabbit ears, each dipole is adjustable (length and angle) to compensate for frequency, reflections, and directivity. Many of the manufactures of rabbit ears added on traps, and other gadget type options to make these more adjustable. Many of these add-ons worsened the rabbit ear performance, and or made them more complicated to use. Most of the sites you will find on the web deal with armature radio. The impedance for communications equipment 50 ohms (52 ohms) by standard. Antenna Basics: http://www.electronics-tutorials.com...nna-basics.htm Antenna Calculator & Information: http://www.csgnetwork.com/antennaedcalc.html --- A rabbit ears antenna is *not* a dual dipole antenna. It is simply a dipole antenna adjustable to a half-wavelength through, at least, the low (2-13) TV channels. Don |
#6
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"Eric" wrote in message Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. - - - - - - - - - - - Eric: Actually, since rabbit ears are an "open dipole" not a folded dipole, the impedance of a simple dipole is closer to a nominal 75 ohms..... and that is only the case if the ears are in a straight line and are not in a typically found "V" formation. Since rabbit ears are fed with a 300 ohm twin-lead and usually fed into a 300 ohm to 75 ohm transformer/adapter so it will plug into the 75 ohm "F" connector on the back of a television or VCR....... all of these mis-matches significantly reduce the efficiency on the whole operation...... however..... since rabbit ears are usually only used in local strong signal areas all of these mismatches in reality are simply overlooked..... and can work surprisingly well in some areas. A "folded" dipole, similar to the cheap FM tuner "T" antennas, is optimally a 300 ohm device and are usually made entirely out of 300 ohm twin-lead including the nominally 5 to 6 foot long horizontal antenna element that forms a closed loop.... or "folded dipole." Some cheaper versions of the FM "T" antenna do not utilize 300 ohm twin-lead and are just a simple "open" dipole and are usually and properly connected to the 75 ohm terminals on the back of the FM tuner. -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .. .. .. .. .. |
#7
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"Eric" wrote in message Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. - - - - - - - - - - - Eric: Actually, since rabbit ears are an "open dipole" not a folded dipole, the impedance of a simple dipole is closer to a nominal 75 ohms..... and that is only the case if the ears are in a straight line and are not in a typically found "V" formation. Since rabbit ears are fed with a 300 ohm twin-lead and usually fed into a 300 ohm to 75 ohm transformer/adapter so it will plug into the 75 ohm "F" connector on the back of a television or VCR....... all of these mis-matches significantly reduce the efficiency on the whole operation...... however..... since rabbit ears are usually only used in local strong signal areas all of these mismatches in reality are simply overlooked..... and can work surprisingly well in some areas. A "folded" dipole, similar to the cheap FM tuner "T" antennas, is optimally a 300 ohm device and are usually made entirely out of 300 ohm twin-lead including the nominally 5 to 6 foot long horizontal antenna element that forms a closed loop.... or "folded dipole." Some cheaper versions of the FM "T" antenna do not utilize 300 ohm twin-lead and are just a simple "open" dipole and are usually and properly connected to the 75 ohm terminals on the back of the FM tuner. -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .. .. .. .. .. |
#8
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I heard a engineering school did tests and came up with the conclusion it
looks like a aerial but that was as far as it got. Then I told this to a owner that started & owned a aerial manufacturing company, who agreed. Now personally I don't give too ****s what the out come is, but I wonder who other people talk too before that make a issue of nothing "Jerry G." wrote in message ... The basic TV rabbit ears are a simple 300 ohm dual dipole antenna. Look up dipole antennas and you should have some explanations. A dual dipole antenna is based on the simple single dipole antenna. The 2 dipoles work in a parallel type of operation to accommodate having a balanced type of antenna, to match to the 300 ohms. If you were to add on a 300 ohm to 75 ohm converter, then you can use a single dipole antenna (single rod type antenna that most of the newer sets are using for local indoor use). The TV sets that have the single dipole antenna have the their RF entry in the 75 ohm impedance design. On the rabbit ears, each dipole is adjustable (length and angle) to compensate for frequency, reflections, and directivity. Many of the manufactures of rabbit ears added on traps, and other gadget type options to make these more adjustable. Many of these add-ons worsened the rabbit ear performance, and or made them more complicated to use. Most of the sites you will find on the web deal with armature radio. The impedance for communications equipment 50 ohms (52 ohms) by standard. Antenna Basics: http://www.electronics-tutorials.com...nna-basics.htm Antenna Calculator & Information: http://www.csgnetwork.com/antennaedcalc.html -- Jerry G. ====== "Eric" wrote in message ... Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.759 / Virus Database: 508 - Release Date: 09-Sep-04 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.760 / Virus Database: 509 - Release Date: 10-Sep-04 |
#9
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I heard a engineering school did tests and came up with the conclusion it
looks like a aerial but that was as far as it got. Then I told this to a owner that started & owned a aerial manufacturing company, who agreed. Now personally I don't give too ****s what the out come is, but I wonder who other people talk too before that make a issue of nothing "Jerry G." wrote in message ... The basic TV rabbit ears are a simple 300 ohm dual dipole antenna. Look up dipole antennas and you should have some explanations. A dual dipole antenna is based on the simple single dipole antenna. The 2 dipoles work in a parallel type of operation to accommodate having a balanced type of antenna, to match to the 300 ohms. If you were to add on a 300 ohm to 75 ohm converter, then you can use a single dipole antenna (single rod type antenna that most of the newer sets are using for local indoor use). The TV sets that have the single dipole antenna have the their RF entry in the 75 ohm impedance design. On the rabbit ears, each dipole is adjustable (length and angle) to compensate for frequency, reflections, and directivity. Many of the manufactures of rabbit ears added on traps, and other gadget type options to make these more adjustable. Many of these add-ons worsened the rabbit ear performance, and or made them more complicated to use. Most of the sites you will find on the web deal with armature radio. The impedance for communications equipment 50 ohms (52 ohms) by standard. Antenna Basics: http://www.electronics-tutorials.com...nna-basics.htm Antenna Calculator & Information: http://www.csgnetwork.com/antennaedcalc.html -- Jerry G. ====== "Eric" wrote in message ... Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.759 / Virus Database: 508 - Release Date: 09-Sep-04 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.760 / Virus Database: 509 - Release Date: 10-Sep-04 |
#10
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....as practiced by "harm" operators...
Leonard "Mark D. Zacharias" wrote in message ... "armature radio" Tee-Hee. mz "Jerry G." wrote in message ... snip Most of the sites you will find on the web deal with armature radio. snip |
#11
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....as practiced by "harm" operators...
Leonard "Mark D. Zacharias" wrote in message ... "armature radio" Tee-Hee. mz "Jerry G." wrote in message ... snip Most of the sites you will find on the web deal with armature radio. snip |
#12
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My step father had a indoor aerial, it was heap of rubbish, the house was
in view of the transmitter, if you walked around, the color would come & go, I took it apart, there was no balum the earth was going direct to one rod and the active part of the coax was going direct to the other rod, I made a balum for it, after much experiment (reinventing the wheel using my aerial theory) came up with the "standard 75 to 300 Ohm balum" giving the best result. After that the color stayed when you walked around the room. It seems to me a lot of people don't know "Jack ****" about the indoor aerials or aerial theory when it comes to talking about them, including the people who make them. "Sofie" wrote in message ... "Eric" wrote in message Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. - - - - - - - - - - - Eric: Actually, since rabbit ears are an "open dipole" not a folded dipole, the impedance of a simple dipole is closer to a nominal 75 ohms..... and that is only the case if the ears are in a straight line and are not in a typically found "V" formation. Since rabbit ears are fed with a 300 ohm twin-lead and usually fed into a 300 ohm to 75 ohm transformer/adapter so it will plug into the 75 ohm "F" connector on the back of a television or VCR....... all of these mis-matches significantly reduce the efficiency on the whole operation...... however..... since rabbit ears are usually only used in local strong signal areas all of these mismatches in reality are simply overlooked..... and can work surprisingly well in some areas. A "folded" dipole, similar to the cheap FM tuner "T" antennas, is optimally a 300 ohm device and are usually made entirely out of 300 ohm twin-lead including the nominally 5 to 6 foot long horizontal antenna element that forms a closed loop.... or "folded dipole." Some cheaper versions of the FM "T" antenna do not utilize 300 ohm twin-lead and are just a simple "open" dipole and are usually and properly connected to the 75 ohm terminals on the back of the FM tuner. -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .. .. .. .. .. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.760 / Virus Database: 509 - Release Date: 10-Sep-04 |
#13
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My step father had a indoor aerial, it was heap of rubbish, the house was
in view of the transmitter, if you walked around, the color would come & go, I took it apart, there was no balum the earth was going direct to one rod and the active part of the coax was going direct to the other rod, I made a balum for it, after much experiment (reinventing the wheel using my aerial theory) came up with the "standard 75 to 300 Ohm balum" giving the best result. After that the color stayed when you walked around the room. It seems to me a lot of people don't know "Jack ****" about the indoor aerials or aerial theory when it comes to talking about them, including the people who make them. "Sofie" wrote in message ... "Eric" wrote in message Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. - - - - - - - - - - - Eric: Actually, since rabbit ears are an "open dipole" not a folded dipole, the impedance of a simple dipole is closer to a nominal 75 ohms..... and that is only the case if the ears are in a straight line and are not in a typically found "V" formation. Since rabbit ears are fed with a 300 ohm twin-lead and usually fed into a 300 ohm to 75 ohm transformer/adapter so it will plug into the 75 ohm "F" connector on the back of a television or VCR....... all of these mis-matches significantly reduce the efficiency on the whole operation...... however..... since rabbit ears are usually only used in local strong signal areas all of these mismatches in reality are simply overlooked..... and can work surprisingly well in some areas. A "folded" dipole, similar to the cheap FM tuner "T" antennas, is optimally a 300 ohm device and are usually made entirely out of 300 ohm twin-lead including the nominally 5 to 6 foot long horizontal antenna element that forms a closed loop.... or "folded dipole." Some cheaper versions of the FM "T" antenna do not utilize 300 ohm twin-lead and are just a simple "open" dipole and are usually and properly connected to the 75 ohm terminals on the back of the FM tuner. -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .. .. .. .. .. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.760 / Virus Database: 509 - Release Date: 10-Sep-04 |
#14
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"armature radio"
Tee-Hee. mz "Jerry G." wrote in message ... snip Most of the sites you will find on the web deal with armature radio. snip |
#15
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"armature radio"
Tee-Hee. mz "Jerry G." wrote in message ... snip Most of the sites you will find on the web deal with armature radio. snip |
#16
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"Sofie" bravely wrote to "All" (10 Sep 04 11:04:40)
--- on the heady topic of " Technical report on rabbits ears" So From: "Sofie" So "Eric" wrote in message Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. So - - - - - - - - - - - So Eric: So Actually, since rabbit ears are an "open dipole" not a folded dipole, So the impedance of a simple dipole is closer to a nominal 75 ohms..... So and that is only the case if the ears are in a straight line and are So not in a typically found "V" formation. Since rabbit ears are fed So with a 300 ohm twin-lead and usually fed into a 300 ohm to 75 ohm So transformer/adapter so it will plug into the 75 ohm "F" connector on So the back of a television or VCR....... all of these mis-matches So significantly reduce the efficiency on the whole operation...... So however..... since rabbit ears are usually only used in local strong So signal areas all of these mismatches in reality are simply So overlooked..... and can work surprisingly well in some areas. A So "folded" dipole, similar to the cheap FM tuner "T" antennas, is So optimally a 300 ohm device and are usually made entirely out of 300 ohm So twin-lead including the nominally 5 to 6 foot long horizontal antenna So element that forms a closed loop.... or "folded dipole." Some So cheaper versions of the FM "T" antenna do not utilize 300 ohm twin-lead So and are just a simple "open" dipole and are usually and properly So connected to the 75 ohm terminals on the back of the FM tuner. How about running a wire across connecting both ends together, then it would behave more like a large closed loop (triangle?) and having perhaps a better match it might even show some gain... not sure. A*s*i*m*o*v .... Bald spot? It's a solar panel for a sex machine. |
#17
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"Sofie" bravely wrote to "All" (10 Sep 04 11:04:40)
--- on the heady topic of " Technical report on rabbits ears" So From: "Sofie" So "Eric" wrote in message Does anybody know of a technical report of the "indoor aerial" I was told a few years ago the there is no resemblance between the rabbits ears and aerial theory, just I have a few people who want to argue the point, and hoping there might be a URL around that might show I'm right or partly right. So - - - - - - - - - - - So Eric: So Actually, since rabbit ears are an "open dipole" not a folded dipole, So the impedance of a simple dipole is closer to a nominal 75 ohms..... So and that is only the case if the ears are in a straight line and are So not in a typically found "V" formation. Since rabbit ears are fed So with a 300 ohm twin-lead and usually fed into a 300 ohm to 75 ohm So transformer/adapter so it will plug into the 75 ohm "F" connector on So the back of a television or VCR....... all of these mis-matches So significantly reduce the efficiency on the whole operation...... So however..... since rabbit ears are usually only used in local strong So signal areas all of these mismatches in reality are simply So overlooked..... and can work surprisingly well in some areas. A So "folded" dipole, similar to the cheap FM tuner "T" antennas, is So optimally a 300 ohm device and are usually made entirely out of 300 ohm So twin-lead including the nominally 5 to 6 foot long horizontal antenna So element that forms a closed loop.... or "folded dipole." Some So cheaper versions of the FM "T" antenna do not utilize 300 ohm twin-lead So and are just a simple "open" dipole and are usually and properly So connected to the 75 ohm terminals on the back of the FM tuner. How about running a wire across connecting both ends together, then it would behave more like a large closed loop (triangle?) and having perhaps a better match it might even show some gain... not sure. A*s*i*m*o*v .... Bald spot? It's a solar panel for a sex machine. |
#18
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"Asimov" ) writes: How about running a wire across connecting both ends together, then it would behave more like a large closed loop (triangle?) and having perhaps a better match it might even show some gain... not sure. A*s*i*m*o*v ... Bald spot? It's a solar panel for a sex machine. When I went off cable back in 1997, given that most of the channels I wanted were UHF, I just stuck a UHF loop on the set. Actually, I've got some length of cable between it and the set, so I can move it around, and hang it high. It works fine for the local VHF channels (the ones over the line in Vermont and New York being adjacent to local channels would at the very least need something better than rabbit ears), though it does indeed need to be placed right to avoid ghostings. On UHF, it does well enough, and most of those channels are of course down in New York and Vermont. It's not perfect, but better than nothing. The loop might not be the solution in other locales, where there are non-local VHF channels. Michael |
#19
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"Asimov" ) writes: How about running a wire across connecting both ends together, then it would behave more like a large closed loop (triangle?) and having perhaps a better match it might even show some gain... not sure. A*s*i*m*o*v ... Bald spot? It's a solar panel for a sex machine. When I went off cable back in 1997, given that most of the channels I wanted were UHF, I just stuck a UHF loop on the set. Actually, I've got some length of cable between it and the set, so I can move it around, and hang it high. It works fine for the local VHF channels (the ones over the line in Vermont and New York being adjacent to local channels would at the very least need something better than rabbit ears), though it does indeed need to be placed right to avoid ghostings. On UHF, it does well enough, and most of those channels are of course down in New York and Vermont. It's not perfect, but better than nothing. The loop might not be the solution in other locales, where there are non-local VHF channels. Michael |
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