Hello, for excess galavizado , on the crests of the threads of the screw is very good place you , grassa graphite , so it does not engage , as when arming with 304 stainless steel , non-fat lock nuts , with the screw fillets . In the assemblies , stainless steel, taking into account the level of torque, if pressed by other steel material is stretched and nails , having to cut it, to withdraw . I do the same job as you, but at my age now , I'm NOKIA supervisor for assemblies microondas.Es one hemosa activity and work . always something new to do and learn hug from Argentina . George
+Jorge Moretti Thanks for the tip Jorge. "Your age"? Just how old are you. :-) I'm still young at 71. Actually I'm truly blessed to be able to do what I do at my age. But when I think of it sometimes It occurs to me that perhaps I'm "cursed" to have to do it. Still, I love my work and my sense of humor is intact. Stainless steel components used in tower work have been quite difficult to deal with at times. When we disassemble broadcast rigid transmission line, especially the older studd, we often have to break the 3/8" bolt when the nut galls. Topday companies like Dielectric, ERI and others have come up with a stainless steel nut that is coated with a non galling substance. The nuts are gray in color, not shiny. We never throw salvaged gray nuts away. Continued success to you and as we say, be safe. I prefer "be aware" and try not to trip over your safety equipment. John
Looks like you could benefit from tossing a thread file in your truck. They come in handy for cleaning up messy coatings like that, fixing minor thread problems, and make taking a nut off a rusty stud or bolt a bit easier.
Not if the power is sufficient low . To tune you need just to analyze the impedance for required frequency. The structures could be a problem when you have more power and the distance between structure and antenna is so short that you are "coupling" both. This coupling changes the anntenna impedande mismatching the conection with Xmiter...
I don't climb towers for a living, but I'd guess the more work you can do on the ground, the better. Especially breaking in that aggressively galvanized hardware. Thanks for another fine video!
We have galvanized "all-thread" left over from other jobs and were about ready to use our own. That antenna was well put together but someone really screwed up with the zinc. You may notice also that the threaded rods could have used backing nuts to keep them in place while the tower-tech installed them on the tower. Good antennas and out door radio units (ODU) are designed to be easy to install outside. Many of the new generation WIFI items seem to be designed with absolutely no thought of weather proofing or what it's like to bolt down something above the ground while standing on pieces of steel. I've seen good designs but most fall into the bad category.
+jude joseph Thanks for the comment. I wish I had more time to create more videos but at the moment the work and some personal commitments keep me from editing and uploading new videos. If you just found the site there are 98 public videos. Seeing all those should take a while.
Recovery from shoulder injuries is slow but I am making progress. I finally got a bunch of my bench-work caught up once out of the sling. I'm thinking about doing another V-Blog concerning my recovery and showing some of the items I use to record. For example, the last video I uploaded was done with a Go-Pro but the results weren't very pretty. Most of my videos are done with the "Contour" camera which is less vulnerable when mounted on a helmet. That's just stuff for the channel, rolling around in my head.
If you tune the SWR at ground level, won't it change when the aerial is moved to the top of the mast?. I had an SWR of 1.3 at ground level, then it climbed to 1.6 when fixed to the top of the mast. There was a lot of taking down the aerial, tuning, putting it back up, but it payed off, the SWR was 1.2 after a lot of up and down the mast.
No it won't change unless there's a mismatch somewhere.. What kind of antenna were you trying to tune. Was it home made, like a J-pole or a dipole. Most of the antennas I deal with have a very narrow resonant point. With HF ham gear or CB radios we're usually trying to cover a wide bandwidth of frequencies. One frequency will match the length of the antenna while others won't. That's why we use tuning units for HF ham gear, to fool the transmitter into thinking it's transmitting into a perfect antenna when the truth is that the antenna is nowhere near perfect. We tune the output of the matching device to the actual impedance of the "imperfect" antenna while the input remains at 50 ohms. In broadcasting, especially FM, we see antennas with a very specific resonant point. Once that point is ascertained it won't change from the ground to the tower unless it's being affected by other items on the tower. Causing an antenna to have a wide range of frequencies that is done during the design process, not in the field. One last thing. 3:1 is not a good Voltage Standing Wave (VSWR). I usually look for a VSWR of 1.1 :1 or better. I often see 1.03:1 or 1.05:1. 3:1 returns 25% of the power. 100 watts out, 25 watts back, not good in anyone's book. I hope some or all of this makes sense. My wife keeps interrupting my train of thought by complaining about some recent remodeling, contractor and supplier problems. Once derailed it's hard to get the train going again.
I had meant to add a link to the relationship between VSWR and power loss. This link is to a chart so there's no math to work out. I find such charts helpful in my work. Remember we're looking for efficiency from our antenna system, not power loss. www.skyworksinc.com/uploads/documents/VSWRreturn.pdf
Thanks for the comment. I truly appreciate all comments, especially those coming from those who know what they're doing. I prefer to test new antennas with a sweep device before spending time on a tower. I also find it useful to research the specifications on a given antenna. In low power FM some manufacturers spec their antennas at 1.3:1, a really lousy VSWR. Sometimes I get responses from sponsors or contract engineer that sound like, "you don't need to do anything. It's fine. I tuned it myself." I hate that one as much as I dislike the old statement, "don't touch it. It's working." I've found and repaired massive errors after sweeping the antenna with a reliable device such as the "Anritsu Sitemaster 332D". John
@@jhettish I like to see a better match on anything better than 1.3:1. Even in my old cb radio days I took time to tune antennas as perfect as possible.
You would have thought the inside of the bolts and the threads would be anodised, then, when fitted, painted with aluminium. Heck, I guess in the land of the Ferengi the profit comes before quality (grins).
Yep. The antenna is sold under the brand name Nicom and I believe the product to be manufactured in San Diego, CA. I don't usually run into the kinds of problems we found with this particular antenna. I'm thinking that the quality control guy may have had a hangover the day they packaged this antenna for shipping. I truly prefer the antenna from SWR that uses the same design as what you see from the NICOM. www.swr-rf.com/
You guys have a bad time of it as it is. My tower is only 137 feet and I get dizzy just looking up (sheepish smile). Still, there comes a point, where, for the sake of safety, you must refuse to climb with such components? I wonder how compromised the threads are. Still, the customer can always look for another contractor, until the kit starts falling off the tower and kills someone, of course. You guys have my every respect. Cheers 73
Roy Amberg We see antennas and especially wireless ethernet bridges that were designed and manufactured with no thought to the problems an installer might encounter on site. I think the poor galvanization probably came from China. It probably has a lot to do with giving a s..t.
I've noticed broadcasters use very different antennas to what you see anywhere else including amateur communications. I've never seen that style of antenna on any non commercial VHF station. What's up with that?
The antenna in question is an ERI 100A-2. This one was manufactured by one of the best known companies in the FM broadcast field. The "dash 2" means it has two bays, or radiating elements.. The basic model number is 100A. You can see it at this link: www.eriinc.com/catalog/antennas/fm-antennas It took a little bit of research to find the model number. This is quite well known to broadcast engineers. John
Hi I mention that when you assemble an antenna, as you show , where aluminum in physical contact with copper, takes place a layer of fat of electrical contact between the two materials , copper and aluminum, so that no sulfation , aluminum, per share ,. electrochemistry , therebetween. this sulftato aluminum oxide , it becomes an insulator, in the best of times , but occur , detections radio frequency calls, nonlinear , and produce , radiation of spurious frequencies , note that your ringer, understands little bit of JAJAJAJAJA assembly and handling tools . A hug . Sorry, my mistake in translation , sent by Gooogle translator. again Hug
+Jorge Moretti When I reply in spanish or some other language I also use Google Translate. I'm sure my messages are harder to understand than yours. You were describing intermodulation quite well. Intermod used to be more of a problem than it is now. Paging transmitters and other high power radio systems are fewer these days. Intermod affects cell phone systems more than it does two-way and broadcast systems. Years ago intermod was very difficult to solve. John
I have been watching you for a while. I find you to be so fascinating. I do need to learn a few things and you are a very good teacher. I do appreciate you. Could you please help me if I have questions in the future? Now, I have to ask you, how do you do that? You take my breath away. Is it as exciting as it looks? One more thing if I may. Could you please tell me the episode that is the most exciting. I would love to see that one.
Barbara Grisafi Hello Barbara, I don't go for "exciting" so much. There's a documentary on the PBS Frontline web site called "Cell Tower Deaths". I was interviewed for that documentary but wasn't deemed "exciting enough". I recommend the PBS video to everyone because if the person watching is focused those who die in my business become obvious. It's the cell antenna and line worker with usually less than one year of experience. We do primarily broadcast and public safety and thereby avoid life on the road. I'm going to do an "on-the-road" thing this week and spend one whole night away from home. :-) There's a video that I think is on RUclips called "Tower Dogs" or something like that. The serious and thought provoking documentary can be seen in its entirety at www.pbs.org/wgbh/pages/frontline/cell-tower-deaths/ The producer and his staff did a wonderful job investigating this topic. For us, this is a profession, a job. I've been doing it for more than 40 years. My crew leader has been doing it for 7 years. The other climber in the company has been working on the steel for 3 years. My people tend to stay with me for long periods. The other six people in the company have more than 10 years with the company. Cell tower workers are considered disposable by their employer. When the work is done the jobs are gone. Keep in mind all this is only opinion but I think I'm on pretty firm ground in those opinions. John
Hi I mention that when you assemble an antenna, as you show , dode no aluminum in physical contact with copper , you need to place a layer of fat of electrical contact between the two materials , copper and aluminum, so that no sulfation , aluminum, per share ,. electrochemistry , among sulftato mismos.Este aluminum oxide , granting asylum becomes , in the best of times , but detections radio frequency calls, nonlinear , and produce , spurious radiation frequencies occur, you can see that your RINGER , understands little bit of assembly and JAJAJAJAJA management tools . A hug
+malytino The antenna is made by Electronics Research Inc (ERI), a really good company. You can see this model at the following link: eriinc.com/Catalog/Antennas/FM-Antennas/100A-Series.aspx
I am surprised you got it to tune so close to the ground. I thought the antenna needed to be almost 10 feet up and no buildings or obstructions around for an accurate SWR.............Solid State transmitters don't like very much SWR....and high SWR can cause pattern distortion that hurts coverage
You would think so but it doesn't. We had to assemble it, something we would not want to do once it was mounted on the tower. Once it was actually on the tower my readings were virtually the same as they were on the ground. However, since there were two bays Voltage Standing Wave Ratio (VSWR) doesn't tell the entire story. I can have a reading at the ground that indicates excellent tuning but if the bays are not mounted correctly and separated by the mandated wavelengths the antenna will not work properly even with an excellent VSWR reading. At least the transmitter will be happy. When colleagues tend to talk about VSWR I often have to remind them that with an antenna we're looking for resonance more than low reflected power. The device with the lowest reflected power over the greatest range of frequencies is a dummy load and we don't want our antenna to mimic one.
I would have thought it would, but I assume that yes, the proper mounting and ground tuning dose get it acceptable. I normally test my antennas at about 30 feet, and tend to see higher reflected power at about 6 foot of the ground then 30, but my stuff is hobby level.
Jeff Schefke Are you sweep testing or using a watt meter? Are your antennas home-brew or manufactured? Are they broad band or high-q? What is the frequency range. I'm usually tuning within the FM broadcast band (88 to 108 Mhz). I rarely tune antennas in other bands but I do try to see what part of the spectrum they favor. Many of the UHF-VHF commercial antennas are somewhat broad but usually favoring the upper or lower part of the band in question.
Watt meter, I'm not that rich. I use a mix of home built and manufactured antennas. Most antennas are "broadband" over 3-4 MHZ, and anywhere from 20 to 2ghz in the band.
I took over a project of a folding wind turbine tower that was part way done the guy had an outfit in India do part of the drawings. What a disaster to straighten out. When I got done the out come was great. 120' ,concrete or helical anchers foundation.
james borg I believe the antenna manufacturer is Nicom but I'm not sure. I have the paperwork at my office and I'm at home. The frequency was 98.7 I believe. It was so close to another channel owned by the customer that the sidebands of the other, higher power, station was initially wiping out coverage in one direction. The engineer, who I regard as genius, figured out the problem and adjusted the other station. The station the antenna was to be used for was a real flame-thrower, 250 watts ERP. :-) The other station that originally was wiping this one out runs about 50 KW ERP. www.nicomusa.com The antenna is similar to the BGK-77 but may not be that particular one.
+CowboyFrankHarrell I'm not sure I understand the "wastage" question. I could look up the license but I have to admit to being too lazy at 5:39pm and still here in the office. A single bay is less than "unity". With a single bay and 7/8" coax the transmitter probably has to run (don't hold me to this) 500 watts in order to create an Effective Radiated Power of 200 watts. The low power stations springing up all over seem to do a pretty good job once the engineering aspects are taken care of.
Hi John, as usual a pleasure to watch your vids. What ( watt, sorry, bad pun ) wattage do you regard as ' low power' in the States. Our local fm stations run 5kw, i think, and our tv is 75kw vsn and 10kw aur on vhf, and 375kw vsn and ??kw aur on uhf. I dont know much about it, but its interesting, nonetheless. Cheers from Northern Victoria, Australia, Mike. Many happy returns and good luck with the rehab.
G'day. I looked into emigrating to Australia back in the late 60s but never pushed it. Sometimes I regret it didn't happen but things have worked out well for me where I am. Life is good, but then, it would probably be good down under also. LPFM (Low Power FM) here is limited by license to 100 watts if it's a stand alone station. Translators, which are essentially repeaters of another station, are allowed 250 watts. Now, I should have set some parameters. Those figures are Effective Radiated Power (ERP). It's a sort of "virtual" power figure which depends on an antenna type its gain and the loss of the coaxial cable feeding it. The actual RF transferred to the antenna may be less or it may be more than what the licensed number seems to indicate. As a simple example, if the coaxial cable running to the antenna has a loss at the specific frequency of 3db that's considered 1/2 power loss. So if you have a license for 250 watts ERP and the antenna has a gain of one, putting 250 actual watts into the cable is only going to produce 125 watts at the antenna due to the 3db loss. In order to get 250 watts ERP in that situation the transmitter would have to be capable of generating 500 watts in order to overcome the power loss caused by the coaxial cable. A two-bay FM broadcast antenna has a gain of something like .96 (point nine six) A single bay has a negative gain. If a theoretical antenna has a gain of 3db and the cable had a loss of 3db then the transmitter would only be required to create 250 watts of RF energy in order to create 250 watts ERP at the antenna. I hope I've been clear. Often I am not. :-) John
John Hettish Good explanation John. The figures I've cited are also ERP ( I failed to mention ) off multi bay antenna's with reflectors, in the case of the TV. Home is where your heart is, and that's all that matters. When I reach retirement, I fully intend having a good look around the States and Canada, oh, and hopefully a tour of the old 500kw WLW site in Mason OH. Cheers Mike.
harrothepilot Is that old station still in Mason? Have not been near the station in a long time. Will check it out the next time I am in the area. Looks like coax coming out the bottom of the antenna support. Must be under 5kw to use that type of coax. 40 Years ago I installed am FM antenna for a local college, was 200 watts! The lowest powered station I ever installed an antenna for. Fun days though. Now I just watch.
Kevin Busto Hi Kevin, I'm only going by a vid from K7AGE Tour of WLW 500Kw site. Worth a look if you like this stuff. I've never visited the States, but when I do, a tour of this facility will be on the agenda for me. I have looked at the site on Google street, and it looks pretty intact, I think. Cheers.
Kevin Busto Hi Kevin, The tower is in Brentwood Tennessee. I don't know where "Mason" is. The antenna only handles 125 watts or so. The station's Effective Radiated Power is only 250 watts. There is a 3db loss over 875 feet of 7/8 inch Heliax so the transmitter pushes 510 towers up the tower only to have it drop to half power by the time it gets to the antenna. A single Broadcast antenna (bay) has a negative gain. When combined with a power divider and properly spaced the gain goes to something like .96 so it takes two bays to create the power needed in this system, each bay carrying half the load, so to speak. It would take a more powerful transmitter to cause a single bay to create 250 watts ERP since the single bay has a gain below 1.
If you climb long enough you'll also discover that Stainless Steel can be a problem in that it tends to "gall". Once galled the only option is to cut and replace the bolt and nut. Most of the galvanized hardware in the 70s through the 80s was pretty good about not rusting but it still happened. During this century (21st) we haven't had problems with galvanized steel hardware with the occasional exception, like we did in this video. John
Yes you are right the person that's not doing quality control properly should have to deal with it directly them self then the problem would go away. Another country is India. The workmanship of there products are sore spot with me worse then China thanks john
Saludos amigos, muy buen trabajo. Me podrían ayudar con las medidas para la frecuencia 104.1 Mhz ? De hace tiempo quiero instalar esa tipo de antena penetradora a mi pequeña emisora. Gracias espero su respuesta!
Barbara Grisafi By the way, go to my channel ruclips.net/user/jhettish Select the tab "Videos". There is a sort button on the upper right corner of that page. Sort for "most popular" and you'll see which videos have the most views. Some videos I think a lot of don't get the views that others do. My favorite video is #8 ruclips.net/video/MEfoVD5Q-aU/видео.html in popularity and the second part of that video is #32. ruclips.net/video/6DxRuqpKCYs/видео.html Clearly I don't know what people like or why they like it. John
John Hettish Thank you for all of your correspondence. I do enjoy it. I am extremely impressed. I do not mean to take up your time. But I do use the your videos as entertainment. I love all your crew they work with you so well. Amazing, Do you ever try robotics? The droid technology. You never have any trouble with reception up that high. Nice talking I will be watching you. Why does my insides tickle so much. Did you ever study that. Does anyone ever say anything about that. I will keep in touch.
Hello Brad, and thanks for the comment. I had to look at the video again to make sure I remembered what we did and why we did it. I am aware that the results can be different on the ground than what will be seen on the tower. The thumbnail for the video only shows us mechanically assembling the antenna almost on the ground. As seen in the video when I'm actually tuning the antenna it had been mounted on one of the Ice bridge supports. The design spacing was 1/4 wave. A rough bit of math at 99 Mhz gives a full wave length of 9.9 feet. The antenna design specified 1/4 wave spacing which would be around 2.5 feet. I mounted the antenna about 3.5 feet up the ice bridge pole and got a clean sweep. More importantly and once installed on the tower we got the same results at 800 feet as we had achieved at the base of the tower. Some of these low power antennas are spec'ed at 1.30:1, a horrible VSWR. The aforementioned antennas (cheap LPFM) cannot be easily tuned in the field. The antenna in the video from a company called "SWR" tuned quite simply creating a sharp notch at the exact resonant point of the antenna. On a similar note, several years back when I was trying to do the same things with a Wiltron S331, I discovered that tuning could not be accomplished on a concrete floor. The rebar in the concrete causes all sorts of havoc with the sweep. I usually tune those over asphalt or dirt (grass) and get the job done. I wish I could find the sweep but I've had several hard drive changes since 2014. John
I made a mistake in my previous response. The antenna was actually designed, manufactured and sold by Electronics Research Incorporated (ERI), not SWR. It's model number is 100A-2, It's spacing is 1/2 wave or 5' and not 1/4 wave. Everything else in the original response is correct. I had to dig back into One hundred or more antenna installations since 2014 to remember the specifics.
I believe you are correct but I rarely remember such things as model names. I've just learned a lot more about these kinds of antennas in relation to how they're tuned. We had to apply a retuning kit to an antenna recently that solved a lot of the mystery. John
John Hettish He usado e instalado este modelo de antena en muchas emisoras de Fm en Chile y su rendimiento y penetración es extraordinario.Recomiendo las Aldena,fabricación italiana.
Normalmente, instalamos o que o cliente fornece. Eu preferiria vender as antenas e instalá-las porque eu vou ganhar mais dinheiro no processo. Quando apresentado com uma antena como esta, muitas vezes eu acho que o VSWR não está correto e há muito pouco que eu possa fazer sobre isso. Quando o cliente compra a antena eu prefiro um como ACG.01.02.23x porque ele pode ser retuned no local, desde que a freqüência não é muito baixa ou muito alta. Eu tenho um Anritsu 332D que é muito útil para retuning. Eu gosto das antenas Itialian embora, como RVR. Eles são melhores do que outros. Alguns outros especificam 1.3: 1, um VSWR horrível. Eu quero algo que pode render pelo menos 1,09: 1 mínimo. Pensei que a língua chilena fosse espanhola. Você é do Brasil? (Tradução do Google.) John
I hate why they zinc the hoojahs out of bolts and nuts! 😡 we use a cold galvanising zinc spray in the UK so we can fit regular bolts EASILY then when up the mast give the bolts a spray with the Galvanising spray. Im not a mast rigger only an engineer, the highest ive been is 125 feet to replace a anti Col lamp on a light tower.....thats ALL THE CLIMBING i ever did or will EVER DO! Compared to some of those 12 inch wide ladders or masts where you have to climb the diagonals my climb was easy! Sloping ladders with ‘rest platforms’ every 20 feet and a nice platform at the top. Even then the thing was swaying in the breeze! HOW you guys climb 1850 feet or more is beyond me😧 I wouldnt work at that height WITHOUT a parachute with the drogue clipped to the tower! So if I fell POP i get a safe ride down😊 a chute can safely deploy above 800 feet 👍🏻
I really like your videos but please, no “f-bombs”. For me, it’s like finding a cockroach in my favorite piece of pie, it’s just disappointing. Thank you for hearing me out. Respectfully submitted.
Hello, for excess galavizado , on the crests of the threads of the screw is very good place you , grassa graphite , so it does not engage , as when arming with 304 stainless steel , non-fat lock nuts , with the screw fillets . In the assemblies , stainless steel, taking into account the level of torque, if pressed by other steel material is stretched and nails , having to cut it, to withdraw . I do the same job as you, but at my age now , I'm NOKIA supervisor for assemblies microondas.Es one hemosa activity and work . always something new to do and learn hug from Argentina . George
+Jorge Moretti Thanks for the tip Jorge. "Your age"? Just how old are you. :-) I'm still young at 71. Actually I'm truly blessed to be able to do what I do at my age. But when I think of it sometimes It occurs to me that perhaps I'm "cursed" to have to do it. Still, I love my work and my sense of humor is intact. Stainless steel components used in tower work have been quite difficult to deal with at times. When we disassemble broadcast rigid transmission line, especially the older studd, we often have to break the 3/8" bolt when the nut galls. Topday companies like Dielectric, ERI and others have come up with a stainless steel nut that is coated with a non galling substance. The nuts are gray in color, not shiny. We never throw salvaged gray nuts away.
Continued success to you and as we say, be safe. I prefer "be aware" and try not to trip over your safety equipment. John
Looks like you could benefit from tossing a thread file in your truck. They come in handy for cleaning up messy coatings like that, fixing minor thread problems, and make taking a nut off a rusty stud or bolt a bit easier.
+Sean Zobl Good idea. John
doesnt tuning the antenna next to a building affect the swr?
Not if the power is sufficient low . To tune you need just to analyze the impedance for required frequency. The structures could be a problem when you have more power and the distance between structure and antenna is so short that you are "coupling" both. This coupling changes the anntenna impedande mismatching the conection with Xmiter...
I don't climb towers for a living, but I'd guess the more work you can do on the ground, the better. Especially breaking in that aggressively galvanized hardware.
Thanks for another fine video!
We have galvanized "all-thread" left over from other jobs and were about ready to use our own. That antenna was well put together but someone really screwed up with the zinc. You may notice also that the threaded rods could have used backing nuts to keep them in place while the tower-tech installed them on the tower. Good antennas and out door radio units (ODU) are designed to be easy to install outside. Many of the new generation WIFI items seem to be designed with absolutely no thought of weather proofing or what it's like to bolt down something above the ground while standing on pieces of steel. I've seen good designs but most fall into the bad category.
@@jhettish I have had brand new hardware seize up if you do not coat it with anti-seizing goo....makes one want to say bad words
What is the name of this kind of fm antenna? It is similar to jampro antenna
i been watching this video over and over how you do it?really a great job done well
+jude joseph Thanks for the comment. I wish I had more time to create more videos but at the moment the work and some personal commitments keep me from editing and uploading new videos. If you just found the site there are 98 public videos. Seeing all those should take a while.
Thanks great video as always, hope your recovering well :)
Recovery from shoulder injuries is slow but I am making progress. I finally got a bunch of my bench-work caught up once out of the sling. I'm thinking about doing another V-Blog concerning my recovery and showing some of the items I use to record. For example, the last video I uploaded was done with a Go-Pro but the results weren't very pretty. Most of my videos are done with the "Contour" camera which is less vulnerable when mounted on a helmet. That's just stuff for the channel, rolling around in my head.
If you tune the SWR at ground level, won't it change when the aerial is moved to the top of the mast?. I had an SWR of 1.3 at ground level, then it climbed to 1.6 when fixed to the top of the mast. There was a lot of taking down the aerial, tuning, putting it back up, but it payed off, the SWR was 1.2 after a lot of up and down the mast.
No it won't change unless there's a mismatch somewhere.. What kind of antenna were you trying to tune. Was it home made, like a J-pole or a dipole. Most of the antennas I deal with have a very narrow resonant point. With HF ham gear or CB radios we're usually trying to cover a wide bandwidth of frequencies. One frequency will match the length of the antenna while others won't. That's why we use tuning units for HF ham gear, to fool the transmitter into thinking it's transmitting into a perfect antenna when the truth is that the antenna is nowhere near perfect. We tune the output of the matching device to the actual impedance of the "imperfect" antenna while the input remains at 50 ohms.
In broadcasting, especially FM, we see antennas with a very specific resonant point. Once that point is ascertained it won't change from the ground to the tower unless it's being affected by other items on the tower. Causing an antenna to have a wide range of frequencies that is done during the design process, not in the field.
One last thing. 3:1 is not a good Voltage Standing Wave (VSWR). I usually look for a VSWR of 1.1 :1 or better. I often see 1.03:1 or 1.05:1. 3:1 returns 25% of the power. 100 watts out, 25 watts back, not good in anyone's book.
I hope some or all of this makes sense. My wife keeps interrupting my train of thought by complaining about some recent remodeling, contractor and supplier problems. Once derailed it's hard to get the train going again.
I had meant to add a link to the relationship between VSWR and power loss. This link is to a chart so there's no math to work out. I find such charts helpful in my work. Remember we're looking for efficiency from our antenna system, not power loss. www.skyworksinc.com/uploads/documents/VSWRreturn.pdf
Nice thorough job.
Thanks for the comment. I truly appreciate all comments, especially those coming from those who know what they're doing. I prefer to test new antennas with a sweep device before spending time on a tower. I also find it useful to research the specifications on a given antenna. In low power FM some manufacturers spec their antennas at 1.3:1, a really lousy VSWR. Sometimes I get responses from sponsors or contract engineer that sound like, "you don't need to do anything. It's fine. I tuned it myself." I hate that one as much as I dislike the old statement, "don't touch it. It's working." I've found and repaired massive errors after sweeping the antenna with a reliable device such as the "Anritsu Sitemaster 332D". John
@@jhettish I like to see a better match on anything better than 1.3:1. Even in my old cb radio days I took time to tune antennas as perfect as possible.
You would have thought the inside of the bolts and the threads would be anodised, then, when fitted, painted with aluminium.
Heck, I guess in the land of the Ferengi the profit comes before quality (grins).
Yep. The antenna is sold under the brand name Nicom and I believe the product to be manufactured in San Diego, CA. I don't usually run into the kinds of problems we found with this particular antenna. I'm thinking that the quality control guy may have had a hangover the day they packaged this antenna for shipping. I truly prefer the antenna from SWR that uses the same design as what you see from the NICOM. www.swr-rf.com/
You guys have a bad time of it as it is. My tower is only 137 feet and I get dizzy just looking up (sheepish smile). Still, there comes a point, where, for the sake of safety, you must refuse to climb with such components?
I wonder how compromised the threads are.
Still, the customer can always look for another contractor, until the kit starts falling off the tower and kills someone, of course.
You guys have my every respect. Cheers 73
All this technology we have and they can't galvanize bolts right. Just think what that cost in labor thats hard to bill for. Great work
Roy Amberg We see antennas and especially wireless ethernet bridges that were designed and manufactured with no thought to the problems an installer might encounter on site. I think the poor galvanization probably came from China. It probably has a lot to do with giving a s..t.
John, don't the antenna come pre tuned to your frequency?
Sometimes an antenna will, but this one had to be assembled there do to size.
I've noticed broadcasters use very different antennas to what you see anywhere else including amateur communications. I've never seen that style of antenna on any non commercial VHF station. What's up with that?
The antenna in question is an ERI 100A-2. This one was manufactured by one of the best known companies in the FM broadcast field. The "dash 2" means it has two bays, or radiating elements.. The basic model number is 100A. You can see it at this link: www.eriinc.com/catalog/antennas/fm-antennas It took a little bit of research to find the model number. This is quite well known to broadcast engineers. John
Great video - Thanks for posting.
Thanks, I hope to be doing a "How to" video on my Sitemaster soon. John
Hi I mention that when you assemble an antenna, as you show , where aluminum in physical contact with copper, takes place a layer of fat of electrical contact between the two materials , copper and aluminum, so that no sulfation , aluminum, per share ,. electrochemistry , therebetween. this sulftato aluminum oxide , it becomes an insulator, in the best of times , but occur , detections radio frequency calls, nonlinear , and produce , radiation of spurious frequencies , note that your ringer, understands little bit of JAJAJAJAJA assembly and handling tools . A hug . Sorry, my mistake in translation , sent by Gooogle translator. again Hug
+Jorge Moretti When I reply in spanish or some other language I also use Google Translate. I'm sure my messages are harder to understand than yours. You were describing intermodulation quite well. Intermod used to be more of a problem than it is now. Paging transmitters and other high power radio systems are fewer these days. Intermod affects cell phone systems more than it does two-way and broadcast systems. Years ago intermod was very difficult to solve. John
I have been watching you for a while. I find you to be so fascinating. I do need to learn a few things and you are a very good teacher. I do appreciate you. Could you please help me if I have questions in the future? Now, I have to ask you, how do you do that? You take my breath away. Is it as exciting as it looks? One more thing if I may. Could you please tell me the episode that is the most exciting. I would love to see that one.
Barbara Grisafi Hello Barbara, I don't go for "exciting" so much. There's a documentary on the PBS Frontline web site called "Cell Tower Deaths". I was interviewed for that documentary but wasn't deemed "exciting enough". I recommend the PBS video to everyone because if the person watching is focused those who die in my business become obvious. It's the cell antenna and line worker with usually less than one year of experience. We do primarily broadcast and public safety and thereby avoid life on the road. I'm going to do an "on-the-road" thing this week and spend one whole night away from home. :-) There's a video that I think is on RUclips called "Tower Dogs" or something like that. The serious and thought provoking documentary can be seen in its entirety at www.pbs.org/wgbh/pages/frontline/cell-tower-deaths/ The producer and his staff did a wonderful job investigating this topic. For us, this is a profession, a job. I've been doing it for more than 40 years. My crew leader has been doing it for 7 years. The other climber in the company has been working on the steel for 3 years. My people tend to stay with me for long periods. The other six people in the company have more than 10 years with the company. Cell tower workers are considered disposable by their employer. When the work is done the jobs are gone. Keep in mind all this is only opinion but I think I'm on pretty firm ground in those opinions. John
Hi I mention that when you assemble an antenna, as you show , dode no aluminum in physical contact with copper , you need to place a layer of fat of electrical contact between the two materials , copper and aluminum, so that no sulfation , aluminum, per share ,. electrochemistry , among sulftato mismos.Este aluminum oxide , granting asylum becomes , in the best of times , but detections radio frequency calls, nonlinear , and produce , spurious radiation frequencies occur, you can see that your RINGER , understands little bit of assembly and JAJAJAJAJA management tools . A hug
Hi John! What a model of the antenna?
The name of the manufacturer?
+malytino The antenna is made by Electronics Research Inc (ERI), a really good company. You can see this model at the following link:
eriinc.com/Catalog/Antennas/FM-Antennas/100A-Series.aspx
Thank you John for your reply!
Wbats the price for this antana plz
I am surprised you got it to tune so close to the ground. I thought the antenna needed to be almost 10 feet up and no buildings or obstructions around for an accurate SWR.............Solid State transmitters don't like very much SWR....and high SWR can cause pattern distortion that hurts coverage
It depends on the Fresnel Zone at that frequency. Probably OK near the ground.
@@thecw301 Freznel Zones come into play at frequencies higher than the FM band...like microwave
Dosent testing that low to the ground make it a bit off on tuning?
You would think so but it doesn't. We had to assemble it, something we would not want to do once it was mounted on the tower. Once it was actually on the tower my readings were virtually the same as they were on the ground. However, since there were two bays Voltage Standing Wave Ratio (VSWR) doesn't tell the entire story. I can have a reading at the ground that indicates excellent tuning but if the bays are not mounted correctly and separated by the mandated wavelengths the antenna will not work properly even with an excellent VSWR reading. At least the transmitter will be happy. When colleagues tend to talk about VSWR I often have to remind them that with an antenna we're looking for resonance more than low reflected power. The device with the lowest reflected power over the greatest range of frequencies is a dummy load and we don't want our antenna to mimic one.
I would have thought it would, but I assume that yes, the proper mounting and ground tuning dose get it acceptable.
I normally test my antennas at about 30 feet, and tend to see higher reflected power at about 6 foot of the ground then 30, but my stuff is hobby level.
Jeff Schefke Are you sweep testing or using a watt meter? Are your antennas home-brew or manufactured? Are they broad band or high-q? What is the frequency range. I'm usually tuning within the FM broadcast band (88 to 108 Mhz). I rarely tune antennas in other bands but I do try to see what part of the spectrum they favor. Many of the UHF-VHF commercial antennas are somewhat broad but usually favoring the upper or lower part of the band in question.
Watt meter, I'm not that rich.
I use a mix of home built and manufactured antennas.
Most antennas are "broadband" over 3-4 MHZ, and anywhere from 20 to 2ghz in the band.
I took over a project of a folding wind turbine tower that was part way done the guy had an outfit in India do part of the drawings. What a disaster to straighten out. When I got done the out come was great. 120' ,concrete or helical anchers foundation.
must be near 105 MHz with the short extensions. I home make my dipoles with copper pipe!
Actually it's 98.3 Mhz
I forgot to account for the end pieces.
John Hettish hello john..what is website of the antenna manufacturer thanks
james borg I believe the antenna manufacturer is Nicom but I'm not sure. I have the paperwork at my office and I'm at home. The frequency was 98.7 I believe. It was so close to another channel owned by the customer that the sidebands of the other, higher power, station was initially wiping out coverage in one direction. The engineer, who I regard as genius, figured out the problem and adjusted the other station. The station the antenna was to be used for was a real flame-thrower, 250 watts ERP. :-) The other station that originally was wiping this one out runs about 50 KW ERP. www.nicomusa.com The antenna is similar to the BGK-77 but may not be that particular one.
What wastage is considered low power? Thanks for all your videos. I've been enjoying them all day.
+CowboyFrankHarrell I'm not sure I understand the "wastage" question. I could look up the license but I have to admit to being too lazy at 5:39pm and still here in the office. A single bay is less than "unity". With a single bay and 7/8" coax the transmitter probably has to run (don't hold me to this) 500 watts in order to create an Effective Radiated Power of 200 watts. The low power stations springing up all over seem to do a pretty good job once the engineering aspects are taken care of.
John Hettish
Thanks. That gives me a general idea.
Hi John, as usual a pleasure to watch your vids. What ( watt, sorry, bad pun ) wattage do you regard as ' low power' in the States. Our local fm stations run 5kw, i think, and our tv is 75kw vsn and 10kw aur on vhf, and 375kw vsn and ??kw aur on uhf. I dont know much about it, but its interesting, nonetheless.
Cheers from Northern Victoria, Australia,
Mike.
Many happy returns and good luck with the rehab.
G'day. I looked into emigrating to Australia back in the late 60s but never pushed it. Sometimes I regret it didn't happen but things have worked out well for me where I am. Life is good, but then, it would probably be good down under also.
LPFM (Low Power FM) here is limited by license to 100 watts if it's a stand alone station. Translators, which are essentially repeaters of another station, are allowed 250 watts. Now, I should have set some parameters. Those figures are Effective Radiated Power (ERP). It's a sort of "virtual" power figure which depends on an antenna type its gain and the loss of the coaxial cable feeding it.
The actual RF transferred to the antenna may be less or it may be more than what the licensed number seems to indicate. As a simple example, if the coaxial cable running to the antenna has a loss at the specific frequency of 3db that's considered 1/2 power loss. So if you have a license for 250 watts ERP and the antenna has a gain of one, putting 250 actual watts into the cable is only going to produce 125 watts at the antenna due to the 3db loss. In order to get 250 watts ERP in that situation the transmitter would have to be capable of generating 500 watts in order to overcome the power loss caused by the coaxial cable. A two-bay FM broadcast antenna has a gain of something like .96 (point nine six) A single bay has a negative gain. If a theoretical antenna has a gain of 3db and the cable had a loss of 3db then the transmitter would only be required to create 250 watts of RF energy in order to create 250 watts ERP at the antenna. I hope I've been clear. Often I am not. :-) John
John Hettish Good explanation John. The figures I've cited are also ERP ( I failed to mention ) off multi bay antenna's with reflectors, in the case of the TV.
Home is where your heart is, and that's all that matters. When I reach retirement, I fully intend having a good look around the States and Canada, oh, and hopefully a tour of the old 500kw WLW site in Mason OH.
Cheers
Mike.
harrothepilot Is that old station still in Mason? Have not been near the station in a long time. Will check it out the next time I am in the area.
Looks like coax coming out the bottom of the antenna support. Must be under 5kw to use that type of coax. 40 Years ago I installed am FM antenna for a local college, was 200 watts! The lowest powered station I ever installed an antenna for. Fun days though. Now I just watch.
Kevin Busto Hi Kevin, I'm only going by a vid from K7AGE Tour of WLW 500Kw site. Worth a look if you like this stuff. I've never visited the States, but when I do, a tour of this facility will be on the agenda for me. I have looked at the site on Google street, and it looks pretty intact, I think. Cheers.
Kevin Busto Hi Kevin, The tower is in Brentwood Tennessee. I don't know where "Mason" is. The antenna only handles 125 watts or so. The station's Effective Radiated Power is only 250 watts. There is a 3db loss over 875 feet of 7/8 inch Heliax so the transmitter pushes 510 towers up the tower only to have it drop to half power by the time it gets to the antenna. A single Broadcast antenna (bay) has a negative gain. When combined with a power divider and properly spaced the gain goes to something like .96 so it takes two bays to create the power needed in this system, each bay carrying half the load, so to speak. It would take a more powerful transmitter to cause a single bay to create 250 watts ERP since the single bay has a gain below 1.
I hate galvanized hardware. It's still rusts anyway. Stainless is where it's at. Sure there wasnt an option though.
If you climb long enough you'll also discover that Stainless Steel can be a problem in that it tends to "gall". Once galled the only option is to cut and replace the bolt and nut. Most of the galvanized
hardware in the 70s through the 80s was pretty good about not
rusting but it still happened. During this century (21st) we haven't
had problems with galvanized steel hardware with the occasional exception, like we did in this video. John
good work
Very interesting!
Yes you are right the person that's not doing quality control properly should have to deal with it directly them self then the problem would go away. Another country is India. The workmanship of there products are sore spot with me worse then China thanks john
Saludos amigos, muy buen trabajo. Me podrían ayudar con las medidas para la frecuencia 104.1 Mhz ? De hace tiempo quiero instalar esa tipo de antena penetradora a mi pequeña emisora. Gracias espero su respuesta!
oh, and thank you very much.
Barbara Grisafi By the way, go to my channel ruclips.net/user/jhettish Select the tab "Videos". There is a sort button on the upper right corner of that page. Sort for "most popular" and you'll see which videos have the most views. Some videos I think a lot of don't get the views that others do. My favorite video is #8 ruclips.net/video/MEfoVD5Q-aU/видео.html in popularity and the second part of that video is #32. ruclips.net/video/6DxRuqpKCYs/видео.html Clearly I don't know what people like or why they like it. John
John Hettish Thank you for all of your correspondence. I do enjoy it. I am extremely impressed. I do not mean to take up your time. But I do use the your videos as entertainment. I love all your crew they work with you so well. Amazing, Do you ever try robotics? The droid technology. You never have any trouble with reception up that high. Nice talking I will be watching you. Why does my insides tickle so much. Did you ever study that. Does anyone ever say anything about that. I will keep in touch.
testing so close to the ground is going to effect your results .
Hello Brad, and thanks for the comment. I had to look at the video again to make sure I remembered what we did and why we did it. I am aware that the results can be different on the ground than what will be seen on the tower. The thumbnail for the video only shows us mechanically assembling the antenna almost on the ground. As seen in the video when I'm actually tuning the antenna it had been mounted on one of the Ice bridge supports. The design spacing was 1/4 wave. A rough bit of math at 99 Mhz gives a full wave length of 9.9 feet. The antenna design specified 1/4 wave spacing which would be around 2.5 feet. I mounted the antenna about 3.5 feet up the ice bridge pole and got a clean sweep. More importantly and once installed on the tower we got the same results at 800 feet as we had achieved at the base of the tower.
Some of these low power antennas are spec'ed at 1.30:1, a horrible VSWR. The aforementioned antennas (cheap LPFM) cannot be easily tuned in the field. The antenna in the video from a company called "SWR" tuned quite simply creating a sharp notch at the exact resonant point of the antenna. On a similar note, several years back when I was trying to do the same things with a Wiltron S331, I discovered that tuning could not be accomplished on a concrete floor. The rebar in the concrete causes all sorts of havoc with the sweep. I usually tune those over asphalt or dirt (grass) and get the job done. I wish I could find the sweep but I've had several hard drive changes since 2014. John
I made a mistake in my previous response. The antenna was actually designed, manufactured and sold by Electronics Research Incorporated (ERI), not SWR. It's model number is 100A-2, It's spacing is 1/2 wave or 5' and not 1/4 wave. Everything else in the original response is correct. I had to dig back into One hundred or more antenna installations since 2014 to remember the specifics.
Penetrator Antenna.-
I believe you are correct but I rarely remember such things as model names. I've just learned a lot more about these kinds of antennas in relation to how they're tuned. We had to apply a retuning kit to an antenna recently that solved a lot of the mystery. John
John Hettish He usado e instalado este modelo de
antena en muchas emisoras de Fm en Chile y su rendimiento y penetración es extraordinario.Recomiendo las Aldena,fabricación italiana.
Normalmente, instalamos o que o cliente fornece. Eu preferiria vender as antenas e instalá-las porque eu vou ganhar mais dinheiro no processo. Quando apresentado com uma antena como esta, muitas vezes eu acho que o VSWR não está correto e há muito pouco que eu possa fazer sobre isso. Quando o cliente compra a antena eu prefiro um como ACG.01.02.23x porque ele pode ser retuned no local, desde que a freqüência não é muito baixa ou muito alta. Eu tenho um Anritsu 332D que é muito útil para retuning. Eu gosto das antenas Itialian embora, como RVR. Eles são melhores do que outros. Alguns outros especificam 1.3: 1, um VSWR horrível. Eu quero algo que pode render pelo menos 1,09: 1 mínimo. Pensei que a língua chilena fosse espanhola. Você é do Brasil? (Tradução do Google.) John
@@DjTochRadiosaludos la marca italiana sira la recomiendas ? Te agradezco la info me puedas brindar gracias
I hate why they zinc the hoojahs out of bolts and nuts! 😡 we use a cold galvanising zinc spray in the UK so we can fit regular bolts EASILY then when up the mast give the bolts a spray with the Galvanising spray. Im not a mast rigger only an engineer, the highest ive been is 125 feet to replace a anti Col lamp on a light tower.....thats ALL THE CLIMBING i ever did or will EVER DO! Compared to some of those 12 inch wide ladders or masts where you have to climb the diagonals my climb was easy!
Sloping ladders with ‘rest platforms’ every 20 feet and a nice platform at the top. Even then the thing was swaying in the breeze!
HOW you guys climb 1850 feet or more is beyond me😧 I wouldnt work at that height WITHOUT a parachute with the drogue clipped to the tower! So if I fell POP i get a safe ride down😊 a chute can safely deploy above 800 feet 👍🏻
How to build your own FM radio
ruclips.net/video/6HArlDIf-NI/видео.html
I really like your videos but please, no “f-bombs”. For me, it’s like finding a cockroach in my favorite piece of pie, it’s just disappointing. Thank you for hearing me out. Respectfully submitted.
good work