Safety of Indoor Antennas
Mario Boccarossa (N8XY)
on
October 27, 2004
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Recently N2LK talked about how surprisingly effective indoor antennas can be. Throughout the discussion people mentioned safety precautions but were very non-specific.
I'm curious as to what are the safety issues to be concerned with, and any catastrophic experiences anyone has had with an indoor antenna. It makes me a little nervous in trying out an indoor antenna. I just took down my tower and beam, (sob) and am moving into a condo. There is a relatively large area of unused space that is roughly 16 feet high and approximately 8 X 8 large, which begins on the second story floor of the building and through to the roof.
I don't know why they didn't utilize this space, but it's good space for an antenna. There are some truss supports that run through every two feet. I have a large tarheel mobile vertical, model 100, that I'd like to mount in there with some radials. It has a rather large capacitance hat of approximately 8 elements 10 to 12 inches long.
What I'm concerned of are the safety issues, or any problems that might arise if I decide to do this. Also, if anyone has experience with an indoor short vertical verses an indoor short dipole.
Thanks for any responses.
Mario, N8XY
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Safety of Indoor Antennas
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by LNXAUTHOR on October 27, 2004
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- indoor antennas can be a real hobby saver and make ham radio fun for folks who, for some reason or another, cannot put up an outdoor antenna...
- indoor antennas work, but some of the modern tech items in homes today can cause problems... i'll give you several instances:
1. touch lamps - notorious noise generator and very sensitive to RF; had one on the kitchen table when the shack was upstairs; antenna was a 'stealth; windom with a horiz leg inside attic and vertical leg down the outside of townhouse; ladder-line fed system with feedpoint at attic vent through ceiling to bedroom shack; on keyup, even using 20W or so, the lamp would flash on/off, and the lamp generated lots of noise (i understand halogen lamps, those cute, tiny, bright, fire-hazard thingies, besides being a fire hazard, also generate lots of noise)
2. nearly gave the XYL a heart attack one day: she was in the basement (which was six feet below ground), doing laundry when i keyed up on Sat. afternoon... even though antenna was in the attic and nearly 40 feet away, she suddenly heard loud noise emanating from the computer speakers on one of my servers in the basement - i was only using 50W...
3. fire/burglar alarms; ADT installed system: i could ragchew all day on 17M even at 100W, but God forbid i used 65W or more on certain portions of certain bands (in my case, 75M and 20M), as the fire alarm would go off... normally this wouldn't be a problem, but in our case the system directly calls the local FD! NOT GOOD! even though i was very careful to route feedline well away from any of the system's lines, the system would trip... called ADT out, and the tech said, "Oh, it must be dust in the sensors" - so we ran some tests... although it didn't happen when i tried 100W (i don't have an amp) during the test, it happened a day or so afterwards - i talked with the FD and was given a non-emergency number to call to cancel any summons (those folks work hard enough)... but this forced me to operate QRP on the problem areas of the bands (not a bad thing, mind you)... i suppose different sensor-driven units might have solved the problem...
- all in all, it was fun using an indoor antenna, and i worked many, many stations at that QTH with that arrangement... you can find workarounds, but there are some considerations when using an indoor antenna.. also, i would never use an HF or VHF amp, especially if loved ones may be too near the radiating elements...
just my $0.02
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RE: Safety of Indoor Antennas
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by LNXAUTHOR on October 27, 2004
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- oh, and don't forget the FCC rules, especially 97.307 - they're not just a good idea - it's the LAW!
:-)
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RE: Safety of Indoor Antennas
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by LNXAUTHOR on October 27, 2004
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- and don't forget some of the ARRL info available on RFI... also, consider a counterpoise (i used a tuned artificial ground as well)...
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Safety of Indoor Antennas
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by VA2CSI on October 27, 2004
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One thing that worries me about putting an antenna oin the roof is lightning, and the fact that I don't have much inclination to put one there for now... :)
Do I run the same risks with an attic antenna? Should I be extra careful about lightning, and grounding it properly to prevent such an occurence?
Thanks :)
73 de VA2 CSI
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RE: Safety of Indoor Antennas
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by KC8VWM on October 27, 2004
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97.307 refers to the idea that we must take every measure possible to reduce any possibility of unwanted radiation to the fullest extent possible.
W8JI has an excellent explanation on his website.
http://www.w8ji.com/fcc_97_307.htm
73
Charles - KC8VWM
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Safety of Indoor Antennas
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by KG4GSC on October 27, 2004
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Ah, indoor antennas...the solution to the bain of CC&R's. Got my ticket after buying a house in a nice country location...small neighborhood about 5mi away from the nearest town. Guess what? CC&Rs prohibit external antenni! (more directed at TV antennas, but poorly written). So, I got some ladder line and copperweld and whipped up a "Z" formatted dipole in the attic, based loosely on G5RV's design. Make sure you insulate it...I have egg ceramics in the corners to keep the wire away from wood contact, just in case. It hangs a few inches below the ridgeline and well above ducting, etc. That, along with my 2M and 70 CM antennas (hanging from the ridgepole w/the rotor mounted upsidedown) allows me to work most all bands.
Not a 3 ele SteppIR, but it works. For your site, if you have enough free space to spin a small beam, look at the HexBeam...some of those are pretty small. I'd forget the Tarheel and go with wire.
Also, I am almost finished with my "birdhouse" pole. It is a deck-mounted Cushcraft R5 with birdhouses (non-metallic, natch) over the traps. Heh...I might even get away with that one!
Andrew
N4ABA
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Safety of Indoor Antennas
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by W0MHZ on October 27, 2004
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I see four issues with an indoor antennas:
1. Fire - arcing to combustible building materials shouldn't be a problem with 100 watts or less, good insulation and adequate spacing.
2. Lightning - no guarantees, but I would expect an indoor antenna to be less attractive to lightning than taller objects (trees, antennas) outside the house.
3. RF exposure - do the ARRL evaluation.
4. RFI - I found it necessary to use ferrite beads on the phones, computers, intrusion alarm, door opener, etc.
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Safety of Indoor Antennas
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by KC2HTP on October 27, 2004
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Mario et al,
I have been using an indoor ant on 80 meters (cw traffic nets) for some time now, started at 20 watts and gradually worked up to 100, with no problems. In addition to the RFI advice others have addressed, take a look at
http://n5xu.ae.utexas.edu/rfsafety/ and do the safety calculations for the bands you plan to use.
John, KC2HTP
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RE: Safety of Indoor Antennas
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by K5UJ on October 27, 2004
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The idea that RF at amateur power levels below 30 MHz is somehow dangerous is utter nonsense. This boogyman has been the product of junk science stemming from cell phone = brain cancer hysteria and the 100% baloney from the high voltage power lines causes cancer crowd. There has never been, and never will be, one single provable case of impaired or damaged health due to HF RF but FUD has been having its day due to political expediency (politicians who have no idea what nonionizing radiation is, wanting to placate equally ignorant constituents) and the FCC and apparently ARRL, finding it easier to simply go along.
Show me one single engineer who was worked for years at SW broadcast tx sites who has health problems.
Show me one single ham out of millions who over the past 100 years have spend decades running HF ham stations, who has some sort of RF related health problem (and no, grabbing hold of a hot antenna doesn't count). You can't. Because there are none. Yet now this is a big concern due to the effects of the quack health issue of the month crowd.
But amazingly, hams have bought into this, perhaps because they think maybe there is something to it. There is nothing to it but fear, uncertaintly and doubt. There has not been a single scientifically valid test that has proved a connection between radiated HF RF energy and ill health. Do yourselves a favor and focus on cigarette smoking, eating too much sugar and saturated fats, and not enough exercise if you are worried about health.
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Safety of Indoor Antennas
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by N4ZOU on October 27, 2004
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Magnetic loop or Magloop antennas are small and popular for use inside the house but they can have thousands of volts on the loop element and the capacitor. If the capacitor is not rated for the power used it can arc over and flammable items near it can catch fire. The best place for a Magloop is in the attic where no one will come in contact with it and nothing is stored anywhere around it. This is also a problem with dipole antennas where the voltages can be very high on the elements. Be safe and keep stored items away from the elements and use real insulators rated for at least 5,000 volts at a minimum. You can drop by a hardware store and find electric fence insulators at very little cost and will not melt or catch fire like PVC pipe. When you load up a short dipole you can get very high voltages on the wire just like a Magloop element.
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RE: Safety of Indoor Antennas
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by W0FM on October 27, 2004
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I've had good success with the Alpha-Delta DX-EE (10-20-15 & 40M) dipole in my attic. I have also used a small loop antenna formerly from AEA (Iso-Loop 10-30). MFJ currently offers a similar HI-Q loop. They work fine in the attic and the loop can often be used on the patio or deck without attracting attention. It does not look like an antenna.
Either way, I'd go with a loop or a dipole over the Tarheel. Just my $0.02.
73,
Terry, WØFM
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Safety of Indoor Antennas
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by WB2WIK on October 27, 2004
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Not sure about the Tarheel, but the large screwdriver antennas I've used over the years made motor noise and created some vibration which easily transmitted through whatever they were mounted on.
When operating mobile, this doesn't bother anybody; but with one mounted in the attic, the vibration and noise from the motor turning might drive whoever is directly below the antenna (or even a neighbor) a bit crazy. You might experiment with that before you do anything permanent.
I'd probably go for wire antennas in the attic instead of the screwdriver antenna, since you'd need to run a lot of radial wires to make a vertical work, anyway.
WB2WIK/6
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Safety of Indoor Antennas
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by SWANMAN on October 27, 2004
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Make sure your coax is neatly tucked away so you don't trip over it and spill your beer! ;)
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Safety of Indoor Antennas
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by K4NR on October 27, 2004
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I decided to live in one of those areas this time for a number of reasons. Despite a total ban on antennas, I have a decent antenna farm. A Ventenna for 2 meter local work, M2 Eggbeaters for 2 / 440, and a Flagpole Vertical for 80 - 6 meters. When I put the Eggbeaters on the roof, the HOA Police showed up. I told them they were satelite receiving antennas and covered under the OTARD rules. They were curious why they were not the dish type antennas, but I managed to get past that with a complicated discussion of polarization. They wanted to limit me to one antenna but I pointed at every other house in the area that has two or more dish antennas and they went away. My flagpole is the 18 foot mast from my beam antenna. One end is sitting on a beer bottle insulator and loaded at the base with my Icom AH-4. It loads on 80 - 6 meters and I've had no RFI issues despite having the shack on the second floor. I've also used and SGC-230 with indoor wires wth great success although I'd rather have the antennas outdoors.
GL es 73 de Tom, K4NR
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RE: Safety of Indoor Antennas
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by KT8K on October 27, 2004
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With a decent indoor antenna you can run low power. 20 watts or less can provide a lot of fun contacts, and avoids a lot of RFI you might get at higher power levels.
Good reception & hope to catch you on the air! 73 de kt8k - Tim
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comments
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by KZ1X on October 27, 2004
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N8XY: if you have a Tarheel motorized antenna, and presumably some HF rig(s), have you considered a remote-controlled HF station? You may have most of the needed pieces already ... get everything you want and more ...
K5UJ: excellent post, could not have said it better myself, and I *have* been saying the same thing, for years! The lunatics are running the asylum.
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RE: Safety of Indoor Antennas
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by NI0C on October 27, 2004
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VA2CSI asked: "Do I run the same risks with an attic antenna? Should I be extra careful about lightning, and grounding it properly to prevent such an occurence?"
Although lightning is much more likely to be attracted to an outdoor antenna, indoor antennas aren't entirely immune, and could end up coupling large amounts of energy into your radio during a lightning strike to the house. About twenty years ago, I had lightning strike the flashing on my roof. It vaporized a portion of 14 gage copper wire (that fed an electrical outlet)in my attic directly below the flashing. This lightning strike also wiped out a lot of electronics in the house.
73 de Chuck NI0C
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Safety of Indoor Antennas
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by WM3X on October 27, 2004
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K5UJ is absolutely correct, but omits one interesting wrinkle. The people who got this manure wagon rolling in the first place created the scare, and then claimed that more money was required for research to really pin it down. Knowing it was unproveable, they were able to milk the government funding cash cow for quite awhile.
I have personally used indoor antennas of various (wire) configurations for a number of years. Power has ranged 4-100 watts. I've been able to make lots of contacts, even in contests. It's not the equivalent of stacked monobanders on high towers, but it is a lot of fun.
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RE: Safety of Indoor Antennas
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by W9WHE-II on October 27, 2004
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If you want to calculate the RF exposure with an indoor antenna go here:
http://n5xu.ae.utexas.edu/rfsafety/
The site allows you to enter power, frequency and distance and then tells you whether you are in compliance.
Be sure to use insulated wire, WELL supported wire, keep away from AC lines, with heavily taped ends where high voltage is.
W9WHE
Proud to have cancelled my ARRL membership
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RE: Safety of Indoor Antennas
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by KC8VWM on October 27, 2004
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Homeowner Associations Got Your Antenna Installations Down?
So, is erecting a tripod on your roof with a PVC mastpipe an antenna..., or not an antenna? That is the question... Confuses them everytime.
How about placing a plastic spinning weather vane on the top of a J-pole antena and a smaller one on the side of lower element of the Jpole antenna. You can even place a cheap themometer on the side of it just for kicks and start calling it a weather instrument?
Show me where "no weather instruments are allowed" is located in the HOA handbook?
Anyone like to play soccor or baseball in the back yard? I hear that Sterba curtains make nice sport nets for this purpose. After all, you don't want the balls ending up in someone else's back yard right?
Dipoles can also be disguised when placed into backyard tennis nets. Be sure and guy your tennis nets well with an inverted "V" for another band.
Fancy and elaboratly constructed gazebos compliment and look rather nice in the back yard. Especially, when the "quad" element radiates very well.
Have a long aluminum extension ladder you don't quite know where to store at your home?
How about hanging it on your backyard fence with a feedline attached to it? Shorten or lenghten the ladder for resonance if required. You can even place markings on it for your favorite bands if you like.
Want to run your extension ladder vertical? No problem..!! Just sit it up against the side of the house all weekend while you chase DX. For maximum effect, you can hang an empty paint can off of it and surround the ladder with old rags, a drop cloth and a paint brush.
Own a dog? How about installing a "dog run"? You know.. that long piece of resonate HF wire you attach a dog leash to -, so you can keep your dog under control in in the back yard? After all, you are a responsible homeowner and you wouldn't want a stray dog running about in the neighborhod right?
.. And finally, my favorite outdoor stealth antenna idea is to completely install a fake satellite dish installation.
The feedline to the dish is actually a resonate length HF antenna. Of course all satellite dish installations DO.., require the addition of an 8 foot copper ground rod for proper installation... right?
Good Luck!
73
Charles - KC8VWM
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RE: Safety of Indoor Antennas
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by AB8TM on October 27, 2004
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"Also, if anyone has experience with an indoor short vertical verses an indoor short dipole."
I use a lot of wires mostly, but I do have one top loaded mobile antenna with a 'homebrew groundplane' that tunes to 10 meters, but it will tune satisfactorilly to 12 meters too.
I could have fit the wires for ten and 12, but it looked like a jungle up there anyway, and maintenance gets a little hard sometimes, if I want to take one down, replace one or work on it.
As for your situation, I would get the longest half wave length possible I could fit in any configuration at height, and feed it with ladderline if I had to. Also, one of the mutliband dipoles (so called compromise antennas) would be helpful.
But every situation is different, especially with indoor antennas. You are going to have to experiment with everything, including the short verticals.
As for safety, I have been running indoor antennas for 3 years (since I was a CBer and then when I got my ticket) and the only issues that have arisen are RFI to some television channels, and my neighbors phone. With a little research, all problems were solved.
Just don't go QRO and you'll be ok...100 watts, 150 watts is my max (150 is probably pushing it).
Have fun, indoor antennas add a little bit more to the hobby in my opinion and force you to think of new things.
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Safety of Indoor Antennas
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by AC5AA on October 27, 2004
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This is a purely anecdotal tale, but I'm now a believer in the RF exposure rules. WHen I had a small apartment and a "U" shaped dipole stapled to the wall about 6' above my head as I operated (100w thru an MFJ tuner), I suddenly developed cataracts in both eyes at the age of ~43. My opthalmologist said they were unusual at my age, and that because they showed up this early they would progress rapidly and I'd have lens replacement surgery within 5 years. I was suspicious and took the opportunity to move to where I could erect an outdoor antenna and get some distance between me and it. Lo and behold, it's now 12 years later and the cataracts stopped developing almost immediately - there is no eye surgery for me yet for a few years. So, in my mind, being part of the near-field equation for the antenna was the cause of the cataracts showing up, and moving myself out of the RF field cured the problem. As noted above, this is purely anecdotal, and may just be coincidental. But the doc sure was baffled until I suggested RF as a possibility.
73, Duane
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RE: Safety of Indoor Antennas
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by N0TONE on October 27, 2004
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Safety - First, make sure mechanical safety doesn't become an issue. Tripping over coax, etc. Then, just make sure that "live" parts of the antenna cannot be casually contacted by people, and you'll be set. Lightning is an unlikely issue for indoor antennas, or even for antennas that are outdoors, but not one of the highest local structures. On 30MHz and below, you do not have an RF exposure hazard more than a few inches from the antenna
Effectiveness - I always encourage you to look for clever solutions. I've used and known others who've used gutters, downspouts, and the like, to have very effective outdoor antennas that nobody knew were antennas. There's a semi-famous story of someone who ran a string of Christmas lights through some trees in the yard of the condo - encouraged by the HOA no less - who had laced a third wire through the string - voila! A full size 40 meter loop! Don't restrict yourself to only using commercially-built antennas. They are rarely a good solution in a limited-space application.
AM
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RFI procedure
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by N0TONE on October 27, 2004
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RFI - when you're comating RFI, the first thing you should do is power level experiments. Find the power level at which you're first causing interference. Then start doing ferrite beads, grounding, etc while operating at that power level.
Let's say you create RFI at the one watt level, but do your testing at the 100 watt level. In this case, you need at least 20dB improvement in order to reduce the RFI. You might try grounding, for instance, the hifi that's being RFI'd. When you add the ground, you hear a subjective change in the sound of the RFI, therefore you presume that since a ground must be good, and there was a change, you have improved things. In reality, you may have, by grounding the hifi, improved its ability to pick up your transmissions, by maybe 10dB. But you couldn't tell- you had RFI before and RFI after. If, instead, you had carefully checked to see at what power level you were causing RFI, before and after, then you'd have known you made things worse.
Most of the time, I have found the most effective cures for RFI is to put the correct ferrite materials (type 77 is best general purpose, type 73 is nearly as good and often easier to get) on leads. You need more than just one, though. They must appear on the leads every quarter wavelength at the highest frequency you operate, and usually at least on each end. That includes your own antenna cables, too. My usual approach is to create a list of "power thresholds" on each band, then apply a bunch of ferrites at one end of a cable. Then re-measure the thresholds. If there's a change at all, then I know that I've found a sensitive lead, and I spread the ferrites out to the more-than-quarter-wave rule. Take threshholds again, and usually see an improvement on all bands. Double the number of ferrites, and measure again. When you see no drop in the threshold, then you know you've reduced that particular lead's sensitivity to RF to the point where something else is now the more significant problem. Find that lead, do the same thing. You might have to go back to the first lead and increase the ferrite loading again.
When I'm done with ferrites, I then try grounding. It is rare that this helps, though.
Bypass caps can cause problems just like the grounding can, because in both cases you are creating a low-impedance path, which may be just what a particular cable or lead needs in order to become a great vertical receive antenna. Use bypass caps sparingly. Sometimes they can add just the right amount of "help" if you've already de-coupled the lead with ferrites.
AM
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RE: RFI procedure
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by K1OU on October 27, 2004
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Hey,
Did anybody see that W9WHE cancelled his ARRL membership? A year later he's still beating his chest about it and a year later we still care.....
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RE: RFI procedure
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by W6TH on October 27, 2004
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I talked to several using indoor antennas. One had a R5 and another had a R7 in their garage.
Horizontal of course.
.:
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Safety of Indoor Antennas
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by W8AD on October 27, 2004
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Other than the safety/RFI issues discussed here, the other important point to remember is that an attic antenna, particularly for HF, is not "in the clear" like an outside antenna. Attic antennas can be significantly affected by attic wiring and HVAC ducting. Also, the height of attic antennas is usually lower than optimum.
All this means that detuning effects can alter the "resonant" frequency in terms of SWR and tuning. So, keep in mind a wide range external antenna tuner is often necessary to compensate for these effects. These effects can range from moderate to severe depending on the distance and coupling to these items. There is no "pat" formula for this but experimentation is usually the best course of action.
As has been stated here, attic antennas can work very well, including really good DX, but many things must be considered. Look at the tremendous DX countries total (over 230) of W0FM's attic dipole, for example.
Don, W8AD
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RE: RFI procedure
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by WB4QNG on October 27, 2004
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I have used attic antennas for about three years without any problems. I believe they are safe or by now I think I would have had a problem. I use four slinkies streched about 40 foot. This is roughly a 80 meter dipole. With my old Dentron super tuner I can use it on all the bands. I also have iron horse mini vericles for 10-15-20. I just have 4 short radials on each one of these antennas. They seem to work a little better than the slinkies on these bands. Good luck.
Terry
WB4QNG
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RE: Safety of Indoor Antennas
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by AK0N on October 27, 2004
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> There has never been, and never will be, one single
> provable case of impaired or damaged health due to
> HF RF but FUD has been having its day due to political
> expediency (politicians who have no idea what
> nonionizing radiation is, wanting to placate equally
> ignorant constituents) and the FCC and apparently
> ARRL, finding it easier to simply go along.
Hmm. Interesting viewpoint, however I've always been a big'n on RF safety since well before the days of the RF exposure rules.
While I certainly agree that the combination of frequency, power levels, and duty cycle that most hams run at is almost certainly not a risk, why in the world would I take even the shadow of a risk with my own health, much less the health of family? After all, I'm husband & dad first, not ham. Anything else would be grossly irresponsible, IMO.
*shrug* - maybe I'm in the minority, but that's my $0.02.
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HOA Solution
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by KV6O on October 27, 2004
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I live in a townhouse now, and even when I had HF wire antennas installed stealthy up in the trees, I had to deal with high noise levels and annoyed my neighbors. I do most of my HF mobile now, or QRP from a park. Last weekend I ran QRO from a park with a Metron 1000B @~500W driven by a TS-2000 into a Hy-Gain AVQ-12 – lots of fun!
One of them most ingenious ways around the HOA restrictions I have heard of (I don’t claim credit for coming up with this one) is to get a old, beat up junker pickup (the uglier the better), put a small fold-over crank up tower in the bed and park it in your driveway (after, of course, you have attempted negotiation with you HOA for a “reasonable accommodation”). If it’s a registered, vehicle and safe to drive, the HOA can’t touch it. Make sure that it doesn’t fit in the garage to squash that issue. When you want to operate, crank it up and run the coax inside. After about a week of this, approach your HOA and see if you cane come up with a “reasonable accommodation” - I bet that your HOA will be willing to negotiate – they have no control over what you drive.
Better yet, every metro area that has a club should own one of these to loan out. And make it as ugly as you can.
SteveL
KV6O
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RE: HOA Solution
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by AB8TM on October 27, 2004
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"One of them most ingenious ways around the HOA restrictions I have heard of (I don?t claim credit for coming up with this one) is to get a old, beat up junker pickup (the uglier the better), put a small fold-over crank up tower in the bed and park it in your driveway (after, of course, you have attempted negotiation with you HOA for a ?reasonable accommodation?). If it?s a registered, vehicle and safe to drive, the HOA can?t touch it."
I've heard that too, but never have seen it! Boy I'd love to see it though. :)
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RE: HOA Solution
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by K5LXP on October 28, 2004
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Many HOA's restrict parking even in your own driveway (must be garaged at all times), and some get as specific as to prohibiting "trucks or other work vehicles" being visible except during actual work being performed at your property. I like WB2WIK's suggestion of having a crank up tower on a trailer. Easy to move around and deploy at will.
Mark K5LXP
Albuquerque, NM
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RE: Safety of Indoor Antennas
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by N6XJP on October 28, 2004
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What fantastic information on indoor antennas. I too am faced with antenna restrictions. I have chosen to park the PU in the driveway and magmount hamsticks on it. I hope this works as I won't try it until next week. If that fails, I'll mount my R5 on the truck and see what the association says... hey, it's part of the truck, not a permanent mount in the yard.
I also have ADT and will let you know what happens, as the shack is in the garage and there is one sensor there. Nice of you to provide the info, thanks. D
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RE: Safety of Indoor Antennas
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by N6XJP on October 28, 2004
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Andrew: KG4GSC
I have an R5 and restrictions... tell me about your "birdhouse R5" How high are you able to get it up? Front yard or back? Is it really disguised? Can you send me a jpg? Are the houses hanging on fiberglass arms? What a cool idea.
Thanks
Dave
N6XJP
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Safety of Indoor Antennas
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by WW6J on October 28, 2004
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Love the Pickup idea. Some years ago my dad bought a used crank up aluminum tower. CC&R's and the fact that at that time the manufacturer was out of business (They have since resumed business) prevented the permanent installation. So, we built a really nice trailer/tower combo and put it in his back yard. Got it registered as a special vehicle (typicaly reserved for farm equipment and the like in CA at least) this way for about $10 every two years plus the cost of construction, we solved the issue. Every year for several years, it was a blast to take out on field day too. Hams should always look for creative solutions, no?
Now as soon as the Russian authorities give me my permission (already waiting 6 mos. have permission from one branch already to operate as R3/WW6J but this is Russia and there are others,When you guys/gals get fed up with red tape, remember that somewhere it is certainly worse!) I will see how well a screwdriver antenna works from the 6th floor in Moscow. I will mount it on the metal window sill and use a conduit on one side and a downspout on the other for gp. We shall see
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Safety of Indoor Antennas
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by W8KQE on October 28, 2004
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Oftentimes, without realizing it, an outdoor rooftop antenna can be almost as close to the operating position as an indoor attic antenna. Case in point: I have my Mosley TA-32 Junior, 2 element tribander mounted on the roof on a small chimney, only about 28 feet off the ground. My operating position is in an upstairs bedroom, directly underneath where my beam is! I would say only about 15 feet or so separate me from the antenna elements. Because of this, I try not to run more than 100w total, or what the FCC rules say for RF. I have had immense luck with this simple antenna setup, 'wife acceptance-wise', and DX-wise. My only concern is potential RF danger. But then again, how many Hams run hundreds of watts from a mobile installation, where much RF gets in through windows?
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RE: Safety of Indoor Antennas
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by WB4QNG on October 28, 2004
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I wouldn't want a beam with a 1000 watts pointed directly at my head but a 100 watts 15 foot away in the attic doesn't worry me. You can't worry about every thing or you couldn't live. You would have to have to have a gas mask on all the time. Heaven forbid if you ever drove a car. You would have to have it built like a nascar and have a helmet and fireproof suit. Just be pratical is my motto
Terry
WB4QNG
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Safety of Indoor Antennas
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by W4KPA on October 28, 2004
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Check out this article on the ARRL home page.
http://www.arrl.org/news/features/2004/10/28/1/?nc=1
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RE: Safety of Indoor Antennas
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by KF6NBF on October 28, 2004
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I would worry less about 100 watts of rf on 20 meter band 15 feet from my head than a 1/4 of a watt of 900mhz cell phone rf pressed up against my skull.
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RE: Safety of Indoor Antennas
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by KC8VWM on October 29, 2004
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...Of course you could just install that product called "the wave shield" which simply sticks to your phone. It supposed to deflect 99% of the radiation away from your transmitting device...
http://www.wavebuster.co.uk./
Another example of people cashing in on modern day RF quackery.
Also See:
http://www.ftc.gov/opa/2003/12/interactcomm.htm
Selling such devices, or making such claims about RF radiation using scare tactics are just another example of how circuis show snake oil salesmen are making a buck.
Often, using phrases such as:
"Actually proven by scientists"
"Reduces RF radiation exposure by 70%"
"Prevents Brain Cancer"
etc. etc.
There may be spurious, anecdotal cases of people claiming to be harmed by RF emissions from their phone and other sources of RF, but they probobly have also frequently encountered black helicopters and have neurotic personalities to begin with anyways.
The only "documented" cases of RF related health problems is a sharp rise in traffic accidents and rising blood pressure when some people attempt to multitask using cellphones on a frequent and regular basis. These health problems are mainly due to the fact that they have high strung lifestyles and does not in any way relate to RF exposure itself.
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RE: Safety of Indoor Antennas
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by K5UJ on October 29, 2004
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<<<Oftentimes, without realizing it, an outdoor rooftop antenna can be almost as close to the operating position as an indoor attic antenna. Case in point: I have my Mosley TA-32 Junior, 2 element tribander mounted on the roof on a small chimney, only about 28 feet off the ground. My operating position is in an upstairs bedroom, directly underneath where my beam is! I would say only about 15 feet or so separate me from the antenna elements. Because of this, I try not to run more than 100w total, or what the FCC rules say for RF. I have had immense luck with this simple antenna setup, 'wife acceptance-wise', and DX-wise. My only concern is potential RF danger. But then again, how many Hams run hundreds of watts from a mobile installation, where much RF gets in through windows?>>>
How many professional transmitter technicians have spent their careers working 8 or 12 hour shifts on the top floors of Empire, Sears, World Trade (RIP), Hancock and other skyscrapers with millions of watts ERP of VHF and UHF FM and TV coming out of the sticks above them, and never had a problem? Don't get me wrong, I'm not saying you can take a nap in front of a high power radar dish, but the idea that a 1.5 Kw or less HF ham station, normally on the air for only a few hours a week is dangerous, is laughable.
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RE: Safety of Indoor Antennas
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by W4CNG on October 29, 2004
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Ok folks. 1500Watts SSB output into a dipole in my attic or yours if you are more than 8 feet away from the antenna is Uncontrolled Space, not an issue 3-30mhz. However a couple hundred watts plus a gain antenna on 150-450Mhz. can be. The calculators are out there (Texas and other), and I have a Yellow sign in my attic just above the ladder entrance to the attic. Do not know what a yellow sign is, you need to do more reasearch into controlled and uncontrolled RF Space is. Lots of reading to do.
Steve W4CNG Living in Controlled Space.
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Safety of Indoor Antennas
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by K3YT on October 30, 2004
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I've had a fan dipole in the attic for 17 and 20 for years. Worked Europe, Africa Middle East no problem, 59 with 100w. Replaced with a Smartuner auto coupler and dipole configuration and get all bands. That is the way to go indoor, as much wire as you can and a Smartuner.
I have antenna restrictions (CCR's say NONE) but used some blackmail. Told the HOA I was going to put a TV antenna up per Comm. Act of 96. Can go 10 feet over roof per act, and had to be a big log periodic to get ABC in Ft. Pierce or Miami (I'm in between) for Monday Night Football. Now I have an R7000 vertical up since 96 and have permission in writing.
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Safety of Indoor Antennas
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by EXPRO on October 30, 2004
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Ok guys after working for years at a comm telegraph/ hi-seas station with a crew of 5 each of use being exposed to high levels of rf and even ship board radar sets I am sorry to report that 3 of us have passed on. Yes the 3 that passed away were in their late 80's so I guess the bozo's that came up with this bullsh*t are right rf is really bad for you. Hey how we as hams can't find a cash cow to milk like that?
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RE: HOA Solution
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by N1EY on October 30, 2004
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:or coming up with this one) is to get a old, beat up
:junker pickup (the uglier the better), put a small
:fold-over crank up tower in the bed and park it in
:your driveway (after, of course, you have attempted
:negotiation with you HOA for a “reasonable
:accommodation”). If it’s a registered, vehicle and
:safe to drive, the HOA can’t touch it. Make sure that
:it doesn’t fit in the garage to squash that issue.
Nice Try! However, there are actually communities
that require you to garage the pickup. Failure to
garage the pickup will lead to fines. It doesn't
have to be the HOA.
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Safety of Indoor Antennas
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by VE4HAM on October 31, 2004
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This is no joke.
I have a confirmed very large area of my back which has been diagnosed as low radiation electrical burns of which I haven't felt at all until one day I noticed it. It was due to close proximity to AC currents for long periods of time, but not in proximity close enough to cause actual burns. The skin is all black and blue and green. It will never heal, doesn't hurt, and the doc said I won't live long enough to get cancer from it , for that's what it may lead to.
Now, I don't care if what AC, right into the RF, it's all AC. Anything in close promixity to strong RF fields which may be concentrated in a stucco wire framed home, a home insulated with aluminum foil or other, you're cooking yourself slowly. The cells on the outside of the skin can get damaged under intense and prolonged use. In my case it was a necessity due to a strange illness which attacked the skin and nerves and what i suffered was close proximity to ac heating pads which eased the pain. A bit too close too long.......what's more penetrating......RF or low freq. AC ????? No, if you are young, get that antenna away, even at 100 watts, or shield the major currents out. All is ambiguous on this subject, so it' s best to be safe. Ten, 20 yrs from now may the truth be known of this cell phone stuff or anything else. You would not want to see the ugliness of low radiation burns, and as living proof..........you'd be shocked.
Outdoor antennas for me all the way, one way or the other.
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RE: Safety of Indoor Antennas
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by KE5CSG on October 31, 2004
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Thanks for the input. I am brand new to ham-hood, and am using a HT on loan for the time being.(I am having fun, but admit I know NOTHING about what I am doing. I DID pass the tech test, but still...) I had some concerns about a friend's suggestions to put up an attic antenna, and now I think I will look instead into mounting one up alongside the chimney outside. I plan to get a portable radio soon, probably only 25 or at most 50 watts. But I have children and I want to be safe. Thanks for adding your story to the discussion and I hope nothing bad ever develops for you in that area.
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RE: Safety of Indoor Antennas
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by KC8VWM on November 1, 2004
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Many people fear that EMFs cause cancer; however, a causal connection between EMFs and cancer has not been established.
The National Research Council (NRC) spent more than three years reviewing more than 500 scientific studies that had been conducted over a 20 year period and found "no conclusive and consistent evidence" that electromagnetic fields harm humans.
http://www.niehs.nih.gov/emfrapid/home.htm
500 studies - 20 years - No conclusive evidence.
VE4HAM Said,
>>> This is no joke.
I have a confirmed very large area of my back which has been diagnosed as low radiation electrical burns of which I haven't felt at all until one day I noticed it. It was due to close proximity to AC currents for long periods of time, but not in proximity close enough to cause actual burns. <<<
While I do sympathize with you regarding your health problem, It is noteworthy to indicate that there are many various reasons why people start exhibiting health problems.
I would be interested in knowing what Doctor would make such a definitaive diagnosis when hundreds of studies conducted over many years cannot confirm any direct relationship to RF exposure and human health.
73
Charles - KC8VWM
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RE: Safety of Indoor Antennas
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by AE6IP on November 1, 2004
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direct correlation between RF exposure and human health is well documented. The two least controversial examples are RF burns and melanoma.
What is not well documented is the relationship between RF frequency, duty cycle, exposure duration, et cetera and health consequences.
We know: too much radiation will kill you.
We don't know: how much is safe.
So, standards are set based on conservative engineering practice. IE: no study has ever shown harm from radiation at a particular power level and frequency combination. So we set a limit as some safe fraction of that power level and frequency combination.
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RE: Safety of Indoor Antennas
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by KC8VWM on November 1, 2004
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"January 2001 issue of the journal Epidemiology .
A total of 118 individuals with uveal melanoma were compared with a control group of 475 people without this condition. Participants were asked about their exposure to several sources of electromagnetic radiation, including cellular telephones. Researchers found that an elevated risk of uveal melanoma was associated with exposure to electromagnetic radiation. This small study was the first to examine the risk of uveal melanoma in relation to RF radiation exposure, and it did not measure the amount of RF radiation exposure in each participant. Future studies may clarify this hypothesized association."
"The wireless industry has long turned to scientific experts on this issue," said Travis Larson, spokesman for the Cellular Telecommunications and Internet Association."
http://www.wow-com.com/
"In response to public concerns, WHO established the International Electromagnetic Fields (EMF) Project to assess the scientific evidence of possible health effects of EMF. Specific studies have been identified to address the problem of localised exposure. The project has established a formal mechanism for reviewing the research results and conducting risk assessments of RF exposure.
Cancer: Current scientific evidence indicates that exposure to RF fields, such as those emitted by mobile phones and their base stations, is unlikely to induce or promote cancers.
Other health risks: Scientists have reported other effects of using mobile phones including changes in brain activity, reaction times, and sleep patterns. These effects are small and have no apparent health significance."
Source: http://www.who.int/mediacentre/factsheets/fs193/en/
"A study of 195,775 wireless communications workers was published in the March 2000 issue of the journal Epidemiology .
These workers were exposed to RF radiation during the manufacturing and testing of cellular telephones.
The results of this study found no association between occupational RF radiation exposure and cancers of the brain and nervous system, or between RF radiation exposure and all types of lymphoma and leukemia. "
The idea of using SAR safe RF exposure guidelines is a preventative measure to prevent what we don't know from occuring.
SAR guidelines does not in any way confirm that RF exposure does in fact harm the human body.
It is considered "good engineering" practice to conform to SAR priciples and guidelines when installing antennas.
However, be aware that you may also be exposing yourself to many other electromagnetic radiation sources around your home.
Human beings are, in reality, bio-electric machines usually operating at between 2 and 12 hz. Normal household current is 60hz.
Although no conclusive evidence can support it, some studies have suggested that household current is completely incompatible and disruptive to the body's natural electric frequency range, neural transmission system, and its sensitive neuro-chemical equilibrium.
Some researchers assert that an electric field of only 1/1000th milligauss should be the maximum permissible exposure.
By these standards, we are all in big trouble. We are exposed to EMF 24 hours a day from electric shavers (14-1600 milligauss), hair dryers (3-1400 milligauss), electric blankets (extremely dangerous), TV's, stereos, VCR's, radios, computers, copiers, toasters, ovens, electric heaters, all electric appliances, microwaves, lamps, fluorescent lighting, dimmer switches, home and office wiring, electric toothbrushes, and waterbed heaters (all of which use AC to DC conversion for their operation).
Many of these electronic devices are used intermittently and that is why consistent exposure to overhead high voltage power lines is considered the most dangerous of all.
Strangely, in the summer of 1996, a U.S. Federal Court ruled that citizens may not bring suit against electric power companies over electromagnetic radiation emissions.
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RE: Safety of Indoor Antennas
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by AE6IP on November 1, 2004
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Oops. I miswrote. For "RF" substitute "EM". For melanoma, I had in mind that there is no controversy that exposure to UVB causes genetic damage which causes the actual melanoma. See http://www.oncologychannel.com/melanoma/causes.shtml
The point is that we *do* know that EM exposure can cause cancer. We just don't the full extent.
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Safety of Indoor Antennas
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by KB8PMD on November 8, 2004
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I really think its better to proceed with caution. While we are bombarded with signals all around us (one can't really avoid it), there are still unknown risks involved. The first color broadcast cameras were know to quietly squeal like a pig because they used a lot of energy on power-up and operation. I've known some cameramen from the early days who developed health problems - including cancer - because of their exposure - some cameras would be operated without their side panels intact.
However, even in this modern world of ours, people are warned about having cell phone antennas close to their head in fear of causing nurological problems. As to installing an indoor antenna, if you can - avoid it - or at least have it in an attic, rather than a room where people will be from-time-to-time. I once lived in a seventh floor apartment and had my HF transceiver and was trying out an HF whip antenna - the first time I hit the transmit power, I felt a jolt and have since refraned putting up another indoor antenna. Thankfully my current apartment has an outside deck and I have one outside by putting the cable through the side of an air-conditioner unit - also there are more antennas being made for portable and stealth use. Good luck and as a final thought, work with a club in getting your antenna in order.
-73-
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Safety of Indoor Antennas
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by N2LK on November 10, 2004
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Well safety wise I dont ever run more than 100 watts, and being a avid PSK fan, 30-50 is more my norm. Though in rtty/cw tests the 100 watts is used.
I just followed basic commen sense in my indoor wires: Dont touch any wood directly, leave a couple of inches and use hook eyes for mounting. Use like 16 or larger gauge insulated wire. Keep the wire ends away from anything and insulate them ( I just wrap with elect tape). Stay away from metal objects as best you can (my HVAC is in my attic of all places) and thats really it.
Never had any issues with lightning, static buildup or fire obviousely. As too RFI exposure, that is really a bunch of plain non-sense. My wires at full 100 watts dont radiate closer than 12 feet to anyone if they are upstairs on the second floor. Least thing I worry about, especially with intermittent modes we use where its not constant full blown RF exposure.
My .02 for what its worth.
73 All
N2LK
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