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How to install your new antenna [Instructions]
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How to install your new antenna [Instructions]
On Sun, 2 May 2010 20:27:51 +0100, "kim" wrote:
http://i796.photobucket.com/albums/y...structions.jpg Hope that helps? (kim) It does. The last warning is slightly ambiguous. It could be interpreted as "Do not attempt to install (the antenna) if (it is) drunk or pregnant or both". -- Peter Duncanson (in uk.tech.digital-tv) |
How to install your new antenna [Instructions]
"kim" wrote in message ... http://i796.photobucket.com/albums/y...structions.jpg Hope that helps? I found the longer version of that document on the antenas ditect website. http://www.antennasdirect.com/pdf/ge...structions.pdf There are quite a few odd things in there but this one caught my eye. "4. Avoid using an antenna mounted amplifier in urban areas" -- Graham. %Profound_observation% |
How to install your new antenna [Instructions]
In article ,
Graham. wrote: "kim" wrote in message ... http://i796.photobucket.com/albums/y...structions.jpg Hope that helps? I found the longer version of that document on the antenas ditect website. http://www.antennasdirect.com/pdf/ge...structions.pdf There are quite a few odd things in there but this one caught my eye. "4. Avoid using an antenna mounted amplifier in urban areas" perhaps because there will be all sorts of other signals about which might overload the amplifier. -- From KT24 Using a RISC OS computer running v5.16 |
How to install your new antenna [Instructions]
On Sun, 2 May 2010 22:16:14 +0100, "Graham." wrote:
"kim" wrote in message ... http://i796.photobucket.com/albums/y...structions.jpg Hope that helps? I found the longer version of that document on the antenas ditect website. http://www.antennasdirect.com/pdf/ge...structions.pdf There are quite a few odd things in there but this one caught my eye. "4. Avoid using an antenna mounted amplifier in urban areas" It's an American site. What is special about urban areas in the US that would make mast-head amps unwise? -- Peter Duncanson (in uk.tech.digital-tv) |
How to install your new antenna [Instructions]
On May 2, 11:19*pm, Peter Duncanson wrote:
On Sun, 2 May 2010 22:16:14 +0100, "Graham." wrote: "kim" wrote in ... http://i796.photobucket.com/albums/y...structions.jpg Hope that helps? I found the longer version of that document on the antenas ditect website. http://www.antennasdirect.com/pdf/ge...structions.pdf There are quite a few odd things in there but this one caught my eye. "4. Avoid using an antenna mounted amplifier in urban areas" It's an American site. What is special about urban areas in the US that would make mast-head amps unwise? -- Peter Duncanson (in uk.tech.digital-tv) What's special is that in the US the amps are likely to cover everything from 40MHz to 900MHz, so they will be affected by nearby CB, police, ambulance, aeronautical, walkie-talkies, etc. Bill |
How to install your new antenna [Instructions]
In message , Peter Duncanson
writes On Sun, 2 May 2010 20:27:51 +0100, "kim" wrote: http://i796.photobucket.com/albums/y...structions.jpg Hope that helps? (kim) It does. The last warning is slightly ambiguous. It could be interpreted as "Do not attempt to install (the antenna) if (it is) drunk or pregnant or both". Bill, does this mean that when doing your risk assessments for jobs you have to ascertain if the installer is drunk or pregnant? If you answered yes to either what action would you then take? -- Bill ( A different one ) |
How to install your new antenna [Instructions]
On May 3, 1:15*am, Bill wrote:
Bill, does this mean that when doing your risk assessments for jobs you have to ascertain if the installer is drunk or pregnant? *If you answered yes to either what action would you then take? The latest Health and Safety in the Workplace regulations state that if the installer is drunk, but not so drunk as to be legless, he must use a harness with elasticated tether, which must be firmly attached to a skyhook. The skyhook must comply with BS415b. Before the commencement of work the installer must produce a 'Risk Avoidance' certificate signed by God, confirming that the installer is in fact drunk enough for the univeral rule that for the duration of the drunkenness the installer cannot be seriously injured no matter what he does applies. If an accident occurs the installer must laugh hysterically if conscious and anyone in the area must shout "I bet you can't do that again!" Legless drunks are excluded from these requirements for obvious reasons. However there is a duty of care on all other operatives not to run over them with motor vehicles or other plant. Legless drunks should not be placed in skips designated for segregated waste, since they might defectate and/or vomit and contaminate other waste. Operatives in the vicinity of legless drunks must consider if appropriate the use of hearing protection. Pregnant installers have a duty of care to the unborn, so must ensure that if he/she slips out unexpectedly adequate precautions have been taken to catch he/she before he/she falls off the scaffolding. Merely relying on other operatives to catch he/she is not adequate. A proper fall arrest system, such as strong elastic knickers to BS 2009 (Military spec 60098), must be in place. Bill |
How to install your new antenna [Instructions]
" wrote in message
... On May 3, 1:15 am, Bill wrote: Pregnant installers have a duty of care to the unborn, so must ensure that if he/she slips out unexpectedly adequate precautions have been taken to catch he/she before he/she falls off the scaffolding. Merely relying on other operatives to catch he/she is not adequate. A proper fall arrest system, such as strong elastic knickers to BS 2009 (Military spec 60098), must be in place. Bill Potentially pregnant installers should be equipped with the Practical Wireless body worn pregnancy detector April edition around 1973 Steve Terry -- Get a free Three 3pay Sim with £2 bonus after £10 top up http://freeagent.three.co.uk/stand/view/id/5276 |
How to install your new antenna [Instructions]
In message
, " writes On May 3, 1:15*am, Bill wrote: Bill, does this mean that when doing your risk assessments for jobs you have to ascertain if the installer is drunk or pregnant? *If you answered yes to either what action would you then take? The latest Health and Safety in the Workplace regulations state that if the installer is drunk, but not so drunk as to be legless, he must use a harness with elasticated tether, which must be firmly attached to a skyhook. The skyhook must comply with BS415b. Before the commencement of work the installer must produce a 'Risk Avoidance' certificate signed by God, confirming that the installer is in fact drunk enough for the univeral rule that for the duration of the drunkenness the installer cannot be seriously injured no matter what he does applies. If an accident occurs the installer must laugh hysterically if conscious and anyone in the area must shout "I bet you can't do that again!" Legless drunks are excluded from these requirements for obvious reasons. However there is a duty of care on all other operatives not to run over them with motor vehicles or other plant. Legless drunks should not be placed in skips designated for segregated waste, since they might defectate and/or vomit and contaminate other waste. Operatives in the vicinity of legless drunks must consider if appropriate the use of hearing protection. Pregnant installers have a duty of care to the unborn, so must ensure that if he/she slips out unexpectedly adequate precautions have been taken to catch he/she before he/she falls off the scaffolding. Merely relying on other operatives to catch he/she is not adequate. A proper fall arrest system, such as strong elastic knickers to BS 2009 (Military spec 60098), must be in place. Bill Ah Ha, thank you Bill, I had a feeling that may be the case. As always a most informative answer. -- Bill ( A different one ) |
How to install your new antenna [Instructions]
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How to install your new antenna [Instructions]
In article ,
Brian Gaff wrote: Hmm, well, surely though, they must have filters as we do hear for troublesome frequencies? Filters can only do so much -- From KT24 Using a RISC OS computer running v5.16 |
How to install your new antenna [Instructions]
In message , Brian Gaff
writes Pity its not OCRed as I cannot read it. Brian Brian, I've taken this from their web site, as mentioned by Graham. It is basically the same as the image that was posted. Part of the installation instructions for a domestic aerial. WARNING Installing antennas on windy days can be dangerous. Because of the antenna surface, even slight winds create strong forces. Be prepared to safely handle these forces at unexpected moments. Do not attempt to assemble, move or mount antenna on windy days or serious, even fatal accidents may occur. Antennas Direct Inc. is not responsible or liable for damage or injury resulting from antenna installations. WARNING Antennas improperly installed or installed to an inadequate structure are very susceptible to wind damage. This damage can be very serious or even life threatening. The owner and installer assumes full responsibility that the installation is structurally sound to support all loads (weight, wind & ice) and properly sealed against leaks. Antennas Direct Inc. will not accept liability for any damage caused by an antenna system due to the many unknown variable applications. WARNING Do not attempt to install if drunk, pregnant or both. Do not eat antenna. Do not throw antenna at spouse. 1699 West Fifth Street Eureka, MO 63025 www.terrestrial-digital.com -- Bill ( A different one ) |
How to install your new antenna [Instructions]
In message , charles
writes In article , Brian Gaff wrote: Hmm, well, surely though, they must have filters as we do hear for troublesome frequencies? Filters can only do so much In the UK, many 40-to-860MHz TV masthead amplifiers were made/sold. They were invariably in totally unscreened plastic housings, with saddle-clamps for the cable. I recall a certain Labgear (of Belling-Lee) unit which caused several radio amateurs a lot of grief (or rather, the radio amateurs caused the TV viewers a lot of grief) when literally ANY amateur frequency was used. It's fortunate that, these days, the manufacturers are more aware of the possibility of interference problems, and use metal housings and filtering. -- Ian |
How to install your new antenna [Instructions]
On 03/05/2010 13:00, Java Jive wrote:
Looks to me like a bored or disgruntled employee decided to have a laugh, and as he was probably translating the original instructions from a foreign language, he thought he could probably get away with it! http://atbash.net/images/bagtag.gif "We are sorry that our President is an idiot. We didn't vote for him." -- Adrian C |
How to install your new antenna [Instructions]
On May 3, 11:05*am, "Brian Gaff" wrote:
Hmm, well, surely though, they must have filters as we do hear for troublesome frequencies? Brian Yes they do. A popular one is a stop filter for frequencies in the FM band, since they have local FM stations all over the place. Of course this is becoming a problem in the UK. See http://www.wrightsaerials.tv/referen...terference.pdf But as Charles so sagely remarks, filters can only do so much. Bill PS you make sage remarks when you know your onions... |
How to install your new antenna [Instructions]
On Sun, 02 May 2010 22:29:04 +0100, Charles wrote:
perhaps because there will be all sorts of other signals about which might overload the amplifier. Indeed so, and because signal strengths tend to be higher in urban areas than rural areas, because the transmitter is so much nearer. |
How to install your new antenna [Instructions]
On Mon, 03 May 2010 14:07:04 +0100, Adrian C wrote:
"We are sorry that our President is an idiot. We didn't vote for him." Any clue as to which president the label was referring -- maybe Chirac or Sarkozy? |
How to install your new antenna [Instructions]
On 03/05/2010 17:02, J G Miller wrote:
On Mon, 03 May 2010 14:07:04 +0100, Adrian C wrote: "We are sorry that our President is an idiot. We didn't vote for him." Any clue as to which president the label was referring -- maybe Chirac or Sarkozy? GWB http://urbanlegends.about.com/library/bl_anti_bush_label.htm -- Adrian C |
How to install your new antenna [Instructions]
On Monday, May 3rd, 2010 at 19:56:38h +0100, Adrian C wrote:
http://urbanlegends.about.com/library/bl_anti_bush_label.htm Thanks for the link -- most interesting. |
How to install your new antenna [Instructions]
On 02/05/2010 22:16, Graham. wrote:
wrote in message ... There are quite a few odd things in there but this one caught my eye. "4. Avoid using an antenna mounted amplifier in urban areas" Put simply, in an _urban area_ the device isn't bling enough. In order to avoid upsetting the sensibilities of the controlling wan-doody hip-hop massive, ye just have to ensure roof mounted trophies show a wholesome degree of glitzy opulence. A weedy little antenna with an amplifier is a sign of weakness and will ensure that ya property and peeps within will be dissed and abused. It's more manly (and anyway recommended on daytime TV shopping channels compulsory watched by bling impressed females) to go for the bigger DAT45, gold plated if ye can. That will also gain respect with the hood, and ye will enjoy better gang rep.... cough cough Excuse me, somthing is up with this joint I'm puffing ... -- Not Me |
How to install your new antenna [Instructions]
On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote:
Put simply, in an _urban area_ the device isn't bling enough. Maybe not. But how about this one? http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. |
How to install your new antenna [Instructions]
In message , J G Miller
writes On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote: Put simply, in an _urban area_ the device isn't bling enough. Maybe not. But how about this one? http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. If I'm not mis-reading the information, that's a single-channel aerial, available for your specified UHF channel. Not much good for multi-channel TV use. -- Ian |
How to install your new antenna [Instructions]
In article , J G Miller
scribeth thus On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote: Put simply, in an _urban area_ the device isn't bling enough. Maybe not. But how about this one? http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. Respectable make that if it is the same as the German company and seeing that they make most of the transmitter aerials in the UK.!.. -- Tony Sayer |
How to install your new antenna [Instructions]
On May 3, 9:25*pm, J G Miller wrote:
On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote: Put simply, in an _urban area_ the device isn't bling enough. Maybe not. *But how about this one? * * http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. The parabola doesn't really seem to be enough wavelengths across to function efficiently. The aerial doesn't seem to do particularly well regarding the mV/kilo test (see http://www.wrightsaerials.tv/ymbj/mv-per-kilo.shtml ). The quoted gain figures are easily achievable by narrowband UHF yagis, which would have less weight and windage. Since the parabola is inherently wideband I wonder if a version is produced with a wideband dipole, for RX use in places where this is required. Note that there is a reflector in front of the dipole to prevent direct reception, which might have a destructive phase relationship with the reflected signal. See also http://www.wrightsaerials.tv/aerialp...ngus/017.shtml I have been fascinated by the idea of using parabolas for UHF ever since UHF was invented. When we went to the maternity hospital for the birth of out first child (now 35) I anticipated a long wait and took a notebook and a textbook, and set about planning the construction of a monster. However the child was born very rapidly, and thereafter was such a drain on time and resounces that I soon had to abandon the project. Still in my loft to this day are some curved members. the start of the prototype. Bill |
How to install your new antenna [Instructions]
wrote:
On May 3, 9:25 pm, J G Miller wrote: On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote: Put simply, in an _urban area_ the device isn't bling enough. Maybe not. But how about this one? http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. The parabola doesn't really seem to be enough wavelengths across to function efficiently. The aerial doesn't seem to do particularly well regarding the mV/kilo test (see http://www.wrightsaerials.tv/ymbj/mv-per-kilo.shtml ). The quoted gain figures are easily achievable by narrowband UHF yagis, which would have less weight and windage. Since the parabola is inherently wideband I wonder if a version is produced with a wideband dipole, for RX use in places where this is required. Note that there is a reflector in front of the dipole to prevent direct reception, which might have a destructive phase relationship with the reflected signal. See also http://www.wrightsaerials.tv/aerialp...ngus/017.shtml I have been fascinated by the idea of using parabolas for UHF ever since UHF was invented. When we went to the maternity hospital for the birth of out first child (now 35) I anticipated a long wait and took a notebook and a textbook, and set about planning the construction of a monster. However the child was born very rapidly, and thereafter was such a drain on time and resounces that I soon had to abandon the project. Still in my loft to this day are some curved members. the start of the prototype. If you want one to play with, there might be one going spare in Belgium now that they use satellite feeds for UK channels on the cable network. One company (used to be called TeleWest) used a water tower in the Maria Hendrikapark on the outskirts of Ostend as a receiving site. As well as conventional UHF arrays pointing across the North Sea to Dover, there was also a yagi pointing at a mesh parabolic dish. Reception from Dover was usually excellent - it certainly was on all the occasions that I witnessed it over the years - but, under certain atmospheric conditions, apparently, there was ghosting which they believed was caused by a reflection off a rock headland on the French coast. The parabolic array was an experiment to cure the problem (though I've no idea what difference, if any, there was.) -- Terry |
How to install your new antenna [Instructions]
In article
s.com, scribeth thus On May 3, 9:25*pm, J G Miller wrote: On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote: Put simply, in an _urban area_ the device isn't bling enough. Maybe not. *But how about this one? * * http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. The parabola doesn't really seem to be enough wavelengths across to function efficiently. Why might that be?.. The aerial doesn't seem to do particularly well regarding the mV/kilo test (see Never seen that spec quoted before;?.. http://www.wrightsaerials.tv/ymbj/mv-per-kilo.shtml ). The quoted gain figures are easily achievable by narrowband UHF yagis, which would have less weight and windage. Might it be something to do with front back ratio?.. -- Tony Sayer |
How to install your new antenna [Instructions]
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember " saying something like: I have been fascinated by the idea of using parabolas for UHF ever since UHF was invented. When we went to the maternity hospital for the birth of out first child (now 35) I anticipated a long wait and took a notebook and a textbook, and set about planning the construction of a monster. However the child was born very rapidly, and thereafter was such a drain on time and resounces that I soon had to abandon the project. Still in my loft to this day are some curved members. the start of the prototype. Not unknown for old sat dishes to be used as wi-fi and 3G antennas. |
How to install your new antenna [Instructions]
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Grimly Curmudgeon saying something like: We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember " saying something like: I have been fascinated by the idea of using parabolas for UHF ever since UHF was invented. When we went to the maternity hospital for the birth of out first child (now 35) I anticipated a long wait and took a notebook and a textbook, and set about planning the construction of a monster. However the child was born very rapidly, and thereafter was such a drain on time and resounces that I soon had to abandon the project. Still in my loft to this day are some curved members. the start of the prototype. Not unknown for old sat dishes to be used as wi-fi and 3G antennas. To follow up... UHF and VHF on an old 1.8m dish http://www.dtvforum.info/index.php?showtopic=84979 The pics from that post... http://i46.tinypic.com/scwd1h.jpg http://i50.tinypic.com/necpjl.jpg This has got my juices flowing and I've stuck an old 1m MMDS dish up in my attic space, pointing out through the roof structure with a folded dipole cut for ~580MHz at the focal point. My reasoning is that the gain of the dish will compensate for the roof thickness. Last night it was providing a cracking signal to my PC telly card and today I intend to connect it to the digitelly and see what I can pull in. This avoids ****ing around with poles and external antennas on top of them. |
How to install your new antenna [Instructions]
On May 13, 12:58*pm, Grimly Curmudgeon
wrote: We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Grimly Curmudgeon saying something like: We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember " saying something like: I have been fascinated by the idea of using parabolas for UHF ever since UHF was invented. When we went to the maternity hospital for the birth of out first child (now 35) I anticipated a long wait and took a notebook and a textbook, and set about planning the construction of a monster. However the child was born very rapidly, and thereafter was such a drain on time and resounces that I soon had to abandon the project. Still in my loft to this day are some curved members. the start of the prototype. Not unknown for old sat dishes to be used as wi-fi and 3G antennas. To follow up... UHF and VHF on an old 1.8m dishhttp://www.dtvforum.info/index.php?showtopic=84979 The pics from that post...http://i46.tinypic.com/scwd1h.jpghtt...com/necpjl.jpg This has got my juices flowing and I've stuck an old 1m MMDS dish up in my attic space, pointing out through the roof structure with a folded dipole cut for ~580MHz at the focal point. My reasoning is that the gain of the dish will compensate for the roof thickness. Last night it was providing a cracking signal to my PC telly card and today I intend to connect it to the digitelly and see what I can pull in. This avoids ****ing around with poles and external antennas on top of them. Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? Bill Bill |
How to install your new antenna [Instructions]
On Thursday, May 13th, 2010 at 05:54:55h -0700, Wrights Aerials wrote:
Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? But some people claim that the Channelmaster CM 4251 UHF 7 foot parabolic antenna was the best and most powerful production consumer UHF TV antenna ever manufactured. http://www.rocketroberts.COM/cm4251/cm4251.htm I have always been fascinated at what would be the results of comparing one of these to a Plemi-Margon 103 element or Fuba 92 element UHF wideband antenna for long distance (80 miles or more) reception, or with the closest currently available equivalent, the AntennasDirect 91XG. http://www.antennasdirect.COM/91XG_HDTV_Antenna.html |
How to install your new antenna [Instructions]
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember " saying something like: Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? I dunno, maybe it all goes to cock at certain freqs but it's working well enough now. I hooked it up to the digitelly and it's just fine, which actually surprised me. This is pretty much the type of dish I have url:http://www.wi-pipe.com/24sd27-24dbi-...85022ece8707f7 with a folded dipole of 1.5mm insulated wire taped to a wooden former and connnected to an old 300/75 matcher salvaged from the back of an ancient portable. Over here the old MMDS dishes are to be found laying around as a lot of people ditched the system and moved to Sky/Freesat. Previously, I was using this dish as a 3G link for across-field treetop datalinkage, with a flat plate antenna mounted at the focal point. Talk about cheekiness - get this for a price... http://www.dtvs.co.nz/index.php?main...oducts_ id=85 Same idea, but with a log-periodic. Now, I just happen to have an old indoor LP set-top antenna and the backbone of it just happens to be the right size to insert into the boom of the MMDS dish. I'll leave that for another day. |
How to install your new antenna [Instructions]
On Thu, 13 May 2010 05:54:55 -0700 (PDT), "
wrote: Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? I was hoping someone would add to this. I used a parabolic reflector with a microphone before the days of shotgun mikes and can remember *something* about the frequency response drop-off being related to the distance of mic to dish or similar, but the brain no longer recalls the details http://en.wikipedia.org/wiki/Parabolic_reflector http://www.antenna-theory.com/antenn...ctors/dish.php |
How to install your new antenna [Instructions]
On May 15, 1:56*pm, Albert Ross wrote:
On Thu, 13 May 2010 05:54:55 -0700 (PDT), " wrote: Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? I was hoping someone would add to this. I used a parabolic reflector with a microphone before the days of shotgun mikes and can remember *something* about the frequency response drop-off being related to the distance of mic to dish or similar, but the brain no longer recalls the details Don't you have to apply bass boost and treble cut when you use a parabolic mike, for that reason? Bill |
How to install your new antenna [Instructions]
On Sat, 15 May 2010 06:27:57 -0700 (PDT), "
wrote: On May 15, 1:56*pm, Albert Ross wrote: On Thu, 13 May 2010 05:54:55 -0700 (PDT), " wrote: Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? I was hoping someone would add to this. I used a parabolic reflector with a microphone before the days of shotgun mikes and can remember *something* about the frequency response drop-off being related to the distance of mic to dish or similar, but the brain no longer recalls the details Don't you have to apply bass boost and treble cut when you use a parabolic mike, for that reason? Yes, and the bass cutoff especially relates not only to the diameter of the dish but to the depth AFAICR (or think I can remember). The Grampian was a yard in diameter (pre-metric I suspect) and relatively flat compared to some of the smaller more tulip-shaped jobbies which had a sharp loss of lower frequencies. |
How to install your new antenna [Instructions]
Ian Jackson wrote:
In message , J G Miller writes On Monday, May 3rd, 2010 at 20:22:29h +0100, Adrian C wrote: Put simply, in an _urban area_ the device isn't bling enough. Maybe not. But how about this one? http://www.kathrein-scala.COM/catalog/PR-TV.pdf I would be most interested to know the proprietor of Wright's Aerials opinion on this type of design and its performance compared to the Yagi-Uda. If I'm not mis-reading the information, that's a single-channel aerial, available for your specified UHF channel. Not much good for multi-channel TV use. Not very small either, 5ft 8 tall, 3ft wide and 18" deep. Fnarr.. |
How to install your new antenna [Instructions]
In article , Albert Ross
wrote: On Thu, 13 May 2010 05:54:55 -0700 (PDT), " wrote: Somewhere I've got some info on this. I believe there's something about a parabola not acting properly as a parabola below a certain number of wavelengths -- about 20? I was hoping someone would add to this. Afraid I've only just noticed the thread and this topic, and the interest in mic parabolas rather than EH ones. FWIW I have two AES publications on this. One a Journal paper from 1985, the other a (better, I think) Convention Paper from 2002. Parabolic Reflector Microphones Juha Backman Paper 5499 112th Convention Munich 2002 May 10-13 I used a parabolic reflector with a microphone before the days of shotgun mikes and can remember *something* about the frequency response drop-off being related to the distance of mic to dish or similar, but the brain no longer recalls the details The gain will depend on how close the mic is to the actual focus produced by the reflected source. In part due to the real source not being at 'infinity' but also because the mic may not be at the parabolic focus. Also, as you'd expect, due to the relationship between the size/shape of the parabola and the wavelength. The above gives both theory and some measurements. I was surprised, looking at it, to see that the gain behaviour seems to hold up fairly well until you reach almost down to the wavelength being similar to the size of the parabola. i.e. much longer wavelengths than assuming a parabola needs to be twenty times the wavelength. However again as you'd expect the gain does vary with wavelength. Just that the simple scaling breaks down when you approach long wavelengths. Slainte, Jim -- Please use the address on the audiomisc page if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
How to install your new antenna [Instructions]
On Wed, 19 May 2010 18:23:34 +0100, Jim Lesurf
wrote: In article , Albert Ross wrote: Afraid I've only just noticed the thread and this topic, and the interest in mic parabolas rather than EH ones. FWIW I have two AES publications on this. One a Journal paper from 1985, the other a (better, I think) Convention Paper from 2002. Parabolic Reflector Microphones Juha Backman Paper 5499 112th Convention Munich 2002 May 10-13 I used a parabolic reflector with a microphone before the days of shotgun mikes and can remember *something* about the frequency response drop-off being related to the distance of mic to dish or similar, but the brain no longer recalls the details The gain will depend on how close the mic is to the actual focus produced by the reflected source. In part due to the real source not being at 'infinity' but also because the mic may not be at the parabolic focus. Also, as you'd expect, due to the relationship between the size/shape of the parabola and the wavelength. The above gives both theory and some measurements. It's beginning to come back to me now! Yes the source isn't really at infinity and the mic diaphragm is *near* the focus but it's close enough to work in the Real World. I was surprised, looking at it, to see that the gain behaviour seems to hold up fairly well until you reach almost down to the wavelength being similar to the size of the parabola. i.e. much longer wavelengths than assuming a parabola needs to be twenty times the wavelength. However again as you'd expect the gain does vary with wavelength. Just that the simple scaling breaks down when you approach long wavelengths. Ah yes that was the interesting bit where the wavelength was involved. Thanks! I think what I may have been semi-remembering was to do with phase relationships. Or I may just be confused . . . |
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