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Buck wrote: What he really wants is to illegally broadcast on the FM broadcast band. Look at the original post. 2/3 of his newsgroups are Pirate Radio. My Goodness! I would never break any FCC rules! How dare you accuse me. Even though you can use the Super J-pole up to 1500 watts or so, i would recommend not using more than 1 femtoWatt or so. Good for mowing the lawn with your walkman.... :) Slick |
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My Goodness! I would never break any FCC rules! How dare you accuse me. . . . No need for anyone to accuse you, it's all there on the Web: http://www.talkaboutradioshows.com/g...ages/7526.html Or try a google search of "dr slick" "pirate radio" Anyone interested in knowing a bit more about Garvin Yee, aka "Dr. Slick" can see: http://www.artwanted.com/webjump.cfm?artid=4990 Roy Lewallen, W7EL |
Roy Lewallen wrote: wrote: My Goodness! I would never break any FCC rules! How dare you accuse me. . . . No need for anyone to accuse you, it's all there on the Web: http://www.talkaboutradioshows.com/g...ages/7526.html Don't be silly Roy! I might sell 100 watt broadcast band transmitters, but i only encourage people to use them into 50 Ohm non-radiating dummy loads! Hehe! Makes a great bed-warmer! Or try a google search of "dr slick" "pirate radio" Anyone interested in knowing a bit more about Garvin Yee, aka "Dr. Slick" can see: http://www.artwanted.com/webjump.cfm?artid=4990 Thanks for the free plug! The art is for sale you know.... www.DrSlick.org Slick |
On 7 Feb 2005 21:27:32 -0800, wrote:
I couldn't find anything there that was similar to this: http://www.drslick.org/Temp1/yagiplot.jpg You can lead a horse to water, still can't get it damp. You'd have to look at the data sheet. All the commercial people are aware of this and it's accepted practice. What you missed is a 2 or 4bay dipole is a really nice antenna that can offer gain and pattern control. The usual use is a 4 bay vertically oriented with each of the 4 dipoles spaced 90 degrees around the mast for 5.6db omnidirectional gain. Now, if you want a directional pattern, such as cartioid then put all four on one side, also expect slightly higher gain as well. The commercial version are expensive but are known for their durability but, the good news is they can be built using copper pipe and will give the same perfomance. I might add, the gain numbers I gave are not theory, they are real numbers from proven designs. Ok, here are some links one how to build it.. http://www.repeater-builder.com/rbti...seddipole.html some good info here, the metal used is less desirable than CU pipe. The general design is proven. http://www.w4dex.com/kc4fwc/ant.htm Info on making a phasing harness, needed for a 4bay but not rocket science. http://dipole.w4zt.com/ look at the plumbers dipole page. This can be built as a 1/2/4/8 dipole array. The limit is 4 based mostly on size though I've seen one 8 dipole array and it's long(nearly 45ft!) but very effective. I might add if the mast pipe is made with 1" copper it can also serve as the supporing mast. This is a prefered design and offers good all grounded construction (lightining avoidance and static noise reduction). The two dipole array with both on one side of the mast is the same gain as the super jpole with two differences. the 4 bay will be longer but offers a real gain increase and slightly better pattern control. The gain increase for this type antenna is predictable, being 3DB for each time you double the elements. The single being 0 DBd, 2bays 3Dbd, and 4bays 6Dbd . Thereal world the practical antennas built as omnidirectional are really 0, 2.8 ,5.6dbd due to small but measureable losses in the cables. If the elements are lined up on one side the gain is higher (sme claim 9db) with a cartiod pattern. It's all copper and no required insulators and can be built more robustly. The pattern is predictable, less is left to chance. This type of antenna also works well against the side of a metal building (less tuning difficulties) though you will get a more directional pattern from the building shielding the opposing direction. These designs will you get away from theory and use practical designs. A repeater group I work with locally used the DBproducts 4bay and found it the best antenna they've put on the tower to date. It wasn't cheap and it was heavy. Experience at that site was anything less robust would barely stand a year before the SWR went to unacceptable. I've built the 4bay for UHF and it's a solid performer. The all copper design weathers very well, is very cheap to build and performs just as well as the commercial versions which are welded up from aluminum. I'm sure your getting results from the Jpole but, I can be certain from using them myself that your results are part luck and can easily be attributed to the added height (the 70+inches can really help) and placement more than the presumed gain. If you compare a yagi or dipole to a J-pole the radiating element must be the same height. Since the J-pole is really an end fed dipole it has a 38 inch advantage. For a yagi the centerpoint is the boom.. In direct comparisons the yagi you built would have to be minimally 3ft higher to compete on fair ground. J-poles in general do not like to be near (less than 1/2wave) metalic structures as it detunes them. Yagi behavour is also sensitive to metalic structures close to them. The Yo model is not complete enough for those cases. Allison KB1GMX |
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I challenge anyone else to use whatever Yagi Optimizers they have to come up with a 3 element design (to keep the size down) with a 180 degree front lobe, and with an 11dB F/B ratio, that has a greater than 4.5 dBi in the front lobe. Why would anyone want such an antenna? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Tue, 08 Feb 2005 01:25:45 -0800, Roy Lewallen
You likely pegged it. Why anyone would use a yagi structure to get a pattern like that, it's not the forte` of that kind of design. That badly a detuned yagi would likely not perform as expected as well. I kinda figured that out between the hacked up beam and the almightly Jpole claims. Jpoles seem to be the holy grail of the pirates. Not to put down the Jpole but it's suffered more snakeoil and used car salesmanship than deserved. Oh well, if someone wanted to do it right at least the recipie is there even if Dr Slick doesn't fully appreciate it. Allison |
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Roy Lewallen wrote: wrote: My Goodness! I would never break any FCC rules! How dare you accuse me. . . . No need for anyone to accuse you, it's all there on the Web: http://www.talkaboutradioshows.com/g...ages/7526.html Don't be silly Roy! I might sell 100 watt broadcast band transmitters, but i only encourage people to use them into 50 Ohm non-radiating dummy loads! Hehe! Makes a great bed-warmer! This is an outright lie. On Ebay and at http://www.talkaboutradioshows.com/g...ages/7526.html you say: "...WHETHER 50 OHM DUMMY LOAD OR A PROPERLY TUNED ANTENNA..." An antenna is not in the category of "...non-radiating dummy loads!". John |
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wrote: On 7 Feb 2005 21:27:32 -0800, wrote: I couldn't find anything there that was similar to this: http://www.drslick.org/Temp1/yagiplot.jpg You can lead a horse to water, still can't get it damp. I would like an H-plane plot, if possible, and i'm looking for a cardiod pattern, as above, but with higher dBi if possible. You'd have to look at the data sheet. All the commercial people are aware of this and it's accepted practice. What you missed is a 2 or 4bay dipole is a really nice antenna that can offer gain and pattern control. The usual use is a 4 bay vertically oriented with each of the 4 dipoles spaced 90 degrees around the mast for 5.6db omnidirectional gain. Now, if you want a directional pattern, such as cartioid then put all four on one side, also expect slightly higher gain as well. The commercial version are expensive but are known for their durability but, the good news is they can be built using copper pipe and will give the same perfomance. I might add, the gain numbers I gave are not theory, they are real numbers from proven designs. 2 bays is big and heavy enough! 4 would be a bit overkill in this situation. http://dipole.w4zt.com/ look at the plumbers dipole page. This can be built as a 1/2/4/8 dipole array. The limit is 4 I've tried using an SO-239 attached to the antenna itself (as they have done here), and it's a bad idea...pot metal is very weak. direction. These designs will you get away from theory and use practical designs. The theory is close to reality in my case! Except for the F/B ratio, which seems a bit exaggerated. A repeater group I work with locally used the DBproducts 4bay and found it the best antenna they've put on the tower to date. It wasn't cheap and it was heavy. Experience at that site was anything less robust would barely stand a year before the SWR went to unacceptable. I've built the 4bay for UHF and it's a solid performer. The all copper design weathers very well, is very cheap to build and performs just as well as the commercial versions which are welded up from aluminum. yeah, but UHF versus VHF is gonna be a huge difference weight and size wise! I'm sure your getting results from the Jpole but, I can be certain from using them myself that your results are part luck and can easily be attributed to the added height (the 70+inches can really help) and placement more than the presumed gain. If you compare a yagi or dipole to a J-pole the radiating element must be the same height. Since the J-pole is really an end fed dipole it has a 38 inch advantage. For a yagi the centerpoint is the boom.. In direct comparisons the yagi you built would have to be minimally 3ft higher to compete on fair ground. The Super J-pole was actually about 5 ft. lower than the Yagi, so it evened out in the end. S. |
John Smith wrote: wrote: Roy Lewallen wrote: wrote: My Goodness! I would never break any FCC rules! How dare you accuse me. . . . No need for anyone to accuse you, it's all there on the Web: http://www.talkaboutradioshows.com/g...ages/7526.html Don't be silly Roy! I might sell 100 watt broadcast band transmitters, but i only encourage people to use them into 50 Ohm non-radiating dummy loads! Hehe! Makes a great bed-warmer! This is an outright lie. On Ebay and at http://www.talkaboutradioshows.com/g...ages/7526.html you say: "...WHETHER 50 OHM DUMMY LOAD OR A PROPERLY TUNED ANTENNA..." An antenna is not in the category of "...non-radiating dummy loads!". But if you read it carefully, you will note that i only am stating the conditions whereby the final transistors will not be blown, which is a 50 Ohm dummy load or a properly tuned antenna. But I don't encourage anyone to break the law, heaven forbid! :^/ S. |
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On 07/02/2005 4:52 PM, wrote:
Richard Clark wrote: On 7 Feb 2005 01:44:10 -0800, wrote: Come listen for yourself... ????? Volume has nothing to do with this! You could throw a dead carrier and still have an idea of how close to full quieting you are.... Obviously your hearing perception exceeds the characteristics of a larger part of mankind. This makes any claims for someone ELSE to listen to the difference even more problematic. Hearing is the poorest measure second only to "seeing" for one self. Leave this type of testimonial for the Sunday services. A good receiver actually gives you TONS of information. You can hear overmodulation, sideband "splatter" to adjacent channels, spurious oscillations on other channels, dead carrier hum in your signal, the overall intelligibility of your signal and the audio frequency response (roughly). No field strength meter can tell you this information! Bottom line is, human hearing is the ultimate destination. It can be more qualitative that quantity. However, it is exactly these aspects that make human hearing terrible for side-by-side comparisons like the one initially described by the OP. There are plenty examples of double-blind tests that indicate that the participating observer often makes the worst sort of qualitative judgements. Human judgement is a useful tool, especially when trying to understand the hard-to-quantify. However, I find it dubious that anyone has ears good enough to hear the quality of an audio signal that is the result of +- 1dB of RF gain presented to the front-end. (This is not to say I think that the OP only used this method to get his/her results. Clearly, the OP used some sort of methodology to obtain the +1dB gain claim. I only suggest that we should be critical of qualitative results that back up the results we want.) Results to the contrary from a proper double-blind test backed up by multiple datasets based on what we /can/ measure would convince me otherwise. A better qualitative test would be to simply live with the antenna for a few weeks, and see what DX one could pull in. Again, totally unscientific; but this is what average radiopersons (like me, I'm afraid!) have been doing for decades now. I look at this sort of thing as an example of the "right tool for the right job." |
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. . . But I don't encourage anyone to break the law, heaven forbid! Most of these are no longer on the web, but they were on 9-19-03 when I originally posted them he From http:http://www.metroactive.com/papers/me...eat-9735.html: I missed Creech but got to hear a tape of the band's performance two days later on a micropowered radio station broadcasting at 91.3FM out of Los Gatos known as Radio Free Lost Gatos. The guys in Creech guest DJed, heckled callers and played the whole of their set along with some of their favorite bands. According to RFLG owner/manager/DJ Dr. Slick, the station has been operating out of a house "buried in the Los Gatos hills" for three years. "I do it for fun," Slick says. "I don't do it because I'm an 'anarchist.' I don't go out and say, 'Kill the cops.' I'm positive with radio." Slick was mum on the wattage but said that 91.3 reaches all of Los Gatos and parts of Campbell. Slick plays classic rock, jazz and "a little bit of Bach" when not turning the controls over to guest DJs like the members of Creech. The station can be heard Sundays and Wednesdays, 8pm*3am. Meanwhile, the next Gaslighter Theater show stars Monkey, Blue Beat Stompers, Steadyups, Lucky Strike and Pigs in Space on Friday (Sept. 5). As always: all ages and five bucks. From http://www.svcn.com/archives/lgwt/05...PirateCat.html Monkey Man stepped into the world of microbroadcasting about a year ago, with his friend Michael Magic at Free-Radio San Jose, 93.7 FM, but had to leave the station after some of his on-air hi-jinks went too far. After that, he started working with Dr. Slick, whose station, Free-Radio Los Gatos, is on 91.3 FM on Sunday and Wednesday nights from 8 p.m. to 11 p.m. "Then Dr. Slick said I should get my own station, so I went down to Fry's and got one of those little radio kits for, like, $30." Dr. Slick gave Monkey Man an old one-watt amplifier, and another friend, Austin Tatious of KKUD 104.1 in Willow Glen, donated a mixing board. Pirate Cat was on the air. ------------- end of Web quotes --------------- At the time, I asked: "It looks like we can look forward to a bigger signal from Radio Free Lost Gatos (or is it Free-Radio Los Gatos?). No more 'all of Los Gatos and parts of Campbell'! Or are you be building FM transmitters and amplifiers for sale?" It looks like we now have the answer. Roy Lewallen, W7EL |
clvrmnky wrote: A good receiver actually gives you TONS of information. You can hear overmodulation, sideband "splatter" to adjacent channels, spurious oscillations on other channels, dead carrier hum in your signal, the overall intelligibility of your signal and the audio frequency response (roughly). No field strength meter can tell you this information! Bottom line is, human hearing is the ultimate destination. It can be more qualitative that quantity. However, it is exactly these aspects that make human hearing terrible for side-by-side comparisons like the one initially described by the OP. There are plenty examples of double-blind tests that indicate that the participating observer often makes the worst sort of qualitative judgements. But any radio broadcaster worth his or her salt will be able to tell APPROXIMATELY how many watts a signal is producing (or ERP), especially since we don't have ionospheric skip in the broadcast band, all line of sight. Human judgement is a useful tool, especially when trying to understand the hard-to-quantify. However, I find it dubious that anyone has ears good enough to hear the quality of an audio signal that is the result of +- 1dB of RF gain presented to the front-end. -1 dB at 100 watts is about 79 watts, so yeah, most people with a good receiver aren't going to hear the difference. But some people very familiar with the signal might notice the difference. -2 dB at 100 watts is about 63 watts, which most people should notice, especially on the fringe of the service area. -3 dB is 100 versus 50 watts, and no **** there's an audible difference! (This is not to say I think that the OP only used this method to get his/her results. Clearly, the OP used some sort of methodology to obtain the +1dB gain claim. I only suggest that we should be critical of qualitative results that back up the results we want.) +1 dB was what our theoretical difference was, but it may have been more. Sorry, but we don't have a huge VHF anechoic chamber, and the proper signal strength meter to do this properly! A better qualitative test would be to simply live with the antenna for a few weeks, and see what DX one could pull in. Again, totally unscientific; but this is what average radiopersons (like me, I'm afraid!) have been doing for decades now. Like i said, I would love to have a big VHF anechoic chamber, and place each antenna on a rotor, and measure every 2 degrees or so, with the proper uV/meter equipment, but we don't have the $$ for that. Most people don't, i don't know anyone who does. It may be unscientific, but in a certain way NOT, because you can get field reports from many people, who all have different receivers, and different antennas on their cars, etc... so the results are more of an averaged response. Bottom line is, is the signal more intelligible and listenable? Slick |
Roy Lewallen wrote: wrote: . . . But I don't encourage anyone to break the law, heaven forbid! Most of these are no longer on the web, but they were on 9-19-03 when I originally posted them he From http:http://www.metroactive.com/papers/me...eat-9735.html: I missed Creech but got to hear a tape of the band's performance two days later on a micropowered radio station broadcasting at 91.3FM out of Los Gatos known as Radio Free Lost Gatos. The guys in Creech guest DJed, heckled callers and played the whole of their set along with some of their favorite bands. According to RFLG owner/manager/DJ Dr. Slick, the station has been operating out of a house "buried in the Los Gatos hills" for three years. "I do it for fun," Slick says. "I don't do it because I'm an 'anarchist.' I don't go out and say, 'Kill the cops.' I'm positive with radio." Slick was mum on the wattage but said that 91.3 reaches all of Los Gatos and parts of Campbell. Slick plays classic rock, jazz and "a little bit of Bach" when not turning the controls over to guest DJs like the members of Creech. The station can be heard Sundays and Wednesdays, 8pm=AD3am. Meanwhile, the next Gaslighter Theater show stars Monkey, Blue Beat Stompers, Steadyups, Lucky Strike and Pigs in Space on Friday (Sept. 5). As always: all ages and five bucks. From http://www.svcn.com/archives/lgwt/05...PirateCat.html Monkey Man stepped into the world of microbroadcasting about a year ago, with his friend Michael Magic at Free-Radio San Jose, 93.7 FM, but had to leave the station after some of his on-air hi-jinks went too far. After that, he started working with Dr. Slick, whose station, Free-Radio Los Gatos, is on 91.3 FM on Sunday and Wednesday nights from 8 p.m. to 11 p.m. "Then Dr. Slick said I should get my own station, so I went down to Fry's and got one of those little radio kits for, like, $30." Dr. Slick gave Monkey Man an old one-watt amplifier, and another friend, Austin Tatious of KKUD 104.1 in Willow Glen, donated a mixing board. Pirate Cat was on the air. Cool article! Yeah, i remember those days well....sigh. Great times! At the time, I asked: "It looks like we can look forward to a bigger signal from Radio Free Lost Gatos (or is it Free-Radio Los Gatos?). No more 'all of Los Gatos and parts of Campbell'! Or are you be building FM transmitters and amplifiers for sale?" It looks like we now have the answer. Radio Free Los Gatos doesn't exist anymore, but thanks for bringing up good memories! We serve the San Jose/Milpitas area now. Just because i build transmitters, don't mean i encourage people to use radiating loads with them! Dummy loads are a wonderful thing, and you can learn so much about RF circuit design and the phase-locked-loop! Slick |
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Radio Free Los Gatos doesn't exist anymore, but thanks for bringing up good memories! Remember KFAT? "The Free Mexican Air Force"? Those were the days. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On 8 Feb 2005 18:49:05 -0800, wrote:
-3 dB is 100 versus 50 watts, and no **** there's an audible difference! Only to a piece of toast. |
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Cecil Moore wrote: wrote: Radio Free Los Gatos doesn't exist anymore, but thanks for bringing up good memories! Remember KFAT? "The Free Mexican Air Force"? Those were the days. -- 73, Cecil http://www.qsl.net/w5dxp How about KPIG, which indeed started out as a pirate station? S. |
Cecil Moore wrote: wrote: Radio Free Los Gatos doesn't exist anymore, but thanks for bringing up good memories! Remember KFAT? "The Free Mexican Air Force"? Those were the days. -- 73, Cecil http://www.qsl.net/w5dxp How about KPIG, which indeed started out as a pirate station? S. |
Richard Clark wrote: On 8 Feb 2005 19:01:01 -0800, wrote: Just because i build transmitters, don't mean i encourage people to use radiating loads with them! Just encourage them to buy expensive toasters, hmmm? Toasters? No, you mean bed-warmers! So basically, i sell bed-warmers for the furtherance of one's knowledge of FM broadcast electronics. For the future I plan on marketing an excellent line of specially shaped dummy-loads that can accept a coffee mug on the top, for keeping your coffee warm all day! Heehee! :^) Slick |
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Cecil Moore wrote: Remember KFAT? "The Free Mexican Air Force"? Those were the days. How about KPIG, which indeed started out as a pirate station? Search results: KPIG remembers KFAT [New Window] http://www.kfat.com/kfat.html -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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On 8 Feb 2005 18:49:05 -0800, wrote:
+1 dB was what our theoretical difference was, but it may have been more. First the average reciever will not see the differnce unless right at the threshold of detection (MDS). The only place I've seen a 1db difference that was detectable is in really weak signal systems. In those systems the 1DB differnce cosses the threshold from just noise to marginally detectable. Such as EME or my favortie mode troposcatter. The average FM broadcast system TX and RX runs at high power because the average FM rx has limited sensitvity due to the required wide bandwidth. Those recievers require a much larger signals to hit an acceptable signal to noise and rarely can differentiate between a 1db difference. Sorry, but we don't have a huge VHF anechoic chamber, and the proper signal strength meter to do this properly! Measuring 1db difference does not require all of that. As to a propper field strength meter, specify a brand. They are not rocket science and are easy to build. If you really want to see something attend a Central states VHF society antenna gain test. They usually hit .1db or better accuracy and have tested Jpoles. The results of past years are posted at their site. http://www.csvhfs.org/CSVHFANT.HTML I'll point you to the 2004 results and specifically to the 144mhz section where a Jpole entered scored a -2.8db gain compared to a reference dipole (0db) These things are easily tested and easy to verify. If your trying to resolve to bettern than .1DB that may be harder but, 3DB is easy and tends to jump at you. Allison |
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wrote: Definitely! You try putting up a VHF Super J-pole yourself! You are probably more used to UHF, so 4 bays doesn't scare you, but at the broadcast band, you will need some serious help. I have done both the super J-pole and 4 bays of Dipole at both UHF and VHF. I've also tested the result with far better hardware than you have. Beside being a ham I'm also commercial licensed and have an extensive radio lab. What brand and model # field strength meter do you have? Or did you build a homemade RF rectifying "sniffer" amplified with an Op-amp? Not saying the later couldn't be calibrated correctly... I would love to see what a 4 bay would do though, but you need serious bucks to do that, plus alot of manual labor... Your kidding right? I figure using both 1" copper water pipe, 1/2" copper pipe and the various fittings to be cheap. How cheap? Likely if you spent 50$us you spent too much for your materials. Yeah, but you need a serious tower to put 4 bays on, esp. at VHF, which we don't have the money for. He doesn't explicitely say brass in his website, and looking at the picture, it looks like a cheapie SO-239 made of pot metal. Looks aren't everything. Also potmetal is not solderable and his was. I'm normal so I have to test with a file to know what material the connector is. I can never tell from picture. He should explicitely state that it should be made of brass. Also, solder has VERY little mechanical strength. Almost none. It's a bad idea. It's a bad idea overall. I would mount it with 4-40 nuts and bolts on an aluminum plate, and then attach that to the antenna. You can but, you are making work thats not required and you run into dissimilar metal electrolytic corrosion and plain old rust. Water intrusion is the death of coax most often. I've worked in marine environments (salt is corrsive) so I have seen what works. Buy a decent waterproof connector. I'd say Type N if your really fussy. You're correct on this one: http://www.ssina.com/galvanic/ So then use a brass plate, and stainless-steel 4-40 bolts and nuts. But don't rely on solder and the corner of an SO-239 for strength. Ah yes, you know all. Some day I"ll post a picture of the antenna farm both UHF and VHF. Never minding the ones I've given away. I know what type M and type L 1/2inch copper pipe weigh, do you? Two bays would use approximately: 6 19" lengths of 1/2" copper (less than 5$) 4 1/2 inch pipe caps (usually less than 20 cents each) 1 10ft length (partial) of 3/4 copper water pipe for the mast (Runs about 8$ last I paid for one) 2 1/2 inch tees ( 79 cents) 2 3/4" to 1/2" tees ( $1.49 expensive ones). This is under 12 pounds and is self supporting to that height. Plenty light enough for this girl. You could use Aluminum tube to build this and really cut the weight. Opps! I meant to say 1" copper. 1/2" copper is not strong enough for a VHF super J-pole. Aluminum is not solderable. The Super J-pole at VHF is big, and it's worse depending on how high you want to get it. Especially for something like the Super J. Since the super-j doesnt offer the same performance your claim is specious. As to structural, The super-J often fails badly at the center insulator and the phasing loop as descrbed often rarely makes the winter here in the east due to ice, wind and snow. New England winters are harsh on antennas. We used a length of Delrin rod for the center conductor, it's slightly flexible but ultra strong. Don't use a wooden dowel coated w/epoxy, it will break. The phasing loop was something like AWG#4 solid copper wire. Hasn't failed for 3 years, but Ca. is a bit less harsh, indeed! Slick |
wrote: On 8 Feb 2005 18:49:05 -0800, wrote: +1 dB was what our theoretical difference was, but it may have been more. First the average reciever will not see the differnce unless right at the threshold of detection (MDS). The only place I've seen a 1db difference that was detectable is in really weak signal systems. In those systems the 1DB differnce cosses the threshold from just noise to marginally detectable. Such as EME or my favortie mode troposcatter. The average FM broadcast system TX and RX runs at high power because the average FM rx has limited sensitvity due to the required wide bandwidth. Those recievers require a much larger signals to hit an acceptable signal to noise and rarely can differentiate between a 1db difference. Then we agree. Most listeners will not notice a 1dB difference. These things are easily tested and easy to verify. If your trying to resolve to bettern than .1DB that may be harder but, 3DB is easy and tends to jump at you. 3 dB? 100 watts versus 50? Yeah, I should hope so! Slick |
Richard Clark wrote: On 9 Feb 2005 02:16:27 -0800, wrote: So basically, i sell bed-warmers I'm sure some of your customers agree - the population that has survived the first self thinning of the genetic pool :-) And your antennas? I suppose they are probes for warming delicate tissues? No, they just look BEAUTIFUL on top of a roof! :) S, |
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In article .com,
wrote: We serve the San Jose/Milpitas area now. Just because i build transmitters, don't mean i encourage people to use radiating loads with them! Dummy loads are a wonderful thing, and you can learn so much about RF circuit design and the phase-locked-loop! Do the transmitters and/or amplifiers that you advertise and/or sell, comply with the current FCC rules regarding certification? If so, under which Part number are they certificated? -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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wrote: On 9 Feb 2005 18:24:44 -0800, wrote: Sure you better have strain relief, but i still wouldn't rely on the soldered corner of an SO-239. Try it someday. I did. The SO-239 broke, and we had to haul the antenna down just to replace it....pain in the ass. Ok, you can solder aluminum, but most people don't know how, and it's not done often. There are fluxes and solders for this at every local hardware. But few people ever solder aluminum. Delrin is perfect for the Super J. Don't use wood. Wood is poor. Wood sucks. Delrin is great, and it carves and shapes very easily, yet is extremely strong. Our phasing loop doesn't sag and hasn't failed yet. Wouldnt last through the 30 inches of snow we got here. Oh yes it would. Snow ain't THAT heavy! It may have been #6, but it was fine for our purposes. Marginal. In what way? Hollow tubing would have been too weak. Wanna try a real broadcast FM antenna, try a dual cycloid. Not to hard to build but has both vertical and horizontal polarization. good gain too. Yeah, this one is our next one: http://members.tripod.com/AMN92/cp_ant.htm A full report when we get it together! Slick |
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