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Wolverine
| | Posted on Tuesday, October 14, 2003 - 5:53 am: | 
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Over the past 3 years, I have lost at least 11 dear friends to "Cancer". All of them were CBers, age 48 years and up. All of them used in excess of 1500 watts on a daily basis while Dxing. My question is, which is more deadly: using high power on 11 meters, or is HF/UHF radio waves just as deadly no matter the band or meters?? Or could it be, that it was just their time to go, coincidence notwhithstanding. |
Bruce
| | Posted on Tuesday, October 14, 2003 - 8:38 am: |
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wolverine
For years i worked in defence contract companys
Most of that time of radios or radar. When i worked for sperry microwave our radar systems exposed us to high levels all the time.....
Now this is where it gets intresting
1) im diebetic the only one in my family gean mutation? who knows but it started after i worked in high power radar for several years
2) out of 26 babys born to sperry lab workers 1980-1984 25 were girls all normal.
3) I had the only boy who was born profoundly retarded and autisic boys are 7 times as likely to be autisic as girls.
4) Other lab employees have died young while production employees .... and i see some still after all these years have no health problems ....hummmm.
RF IN NOTHING TO FOOL AROUND WITH CB or microwave dosnt realy matter. |
Mr_Rf
| | Posted on Tuesday, October 14, 2003 - 10:08 am: |
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The experts call it "MPE" (Maximum Permissible Exposure). There have been serveral studies of RF effects on the body, and on big ongoing study by the Fed's. They have studied the effects on the specific body parts, ear lobe, tongue, liver, etc. It's gets boring looking at all the scientific data but the bottom line the experts came up with a mathematical formula to determine the combined overall effect of RF at a specified frequency at a specified distance from the body. Did you know your typical 100 watt mobile installation exhibits too much RF energy for safety.
Goto //n5xu.ae.utexas.edu/rfsafety/ and follow the instructions. Be sure to use the "Ground Reflections" choice at the bottom of the page. There you can enter system details and deetermine how safe you really are! |
Sandbagger106
| | Posted on Tuesday, October 14, 2003 - 10:51 am: |
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I think what Bruce says has lots of merit, RF at high frequencies and in large power can be dangerous, but also you must consider your CB buddies life style as well. you know coffin nails, alcohol, and bad diet. I for one try to stay as far as I can from my antennas, although the only bands that I use much power is at 7Mhz, and the antenna is 90 feet from the shack. Caution is wise. What are peoples thought on cell phones? High freqs. and the antenna is radiating an inch from your noggin. That can't be good. I've always wondered how much power do cell phones have? Anyone know. 73's. sb106 |
Kg4ryt
| | Posted on Tuesday, October 14, 2003 - 11:24 am: |
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Just think about a big power station with a beam pointed right at the radio shack. Feel the sensation!!!! |
RCI 2990
| | Posted on Tuesday, October 14, 2003 - 12:52 pm: |
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They probably died of lung cancer! Most CBers i know all smoke at least 2 packs a day!!!!!!!!!!!!!!!! |
Kirk
| | Posted on Tuesday, October 14, 2003 - 5:24 pm: |
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Based on data we "have" (which is somewhat subjective to opinion) Wolverine, the higher the frequency, the more caution must be used at RF output levels. i.e 10 watts at 7Mhz poses less of a "threat" than does 10 watts at 400 Mhz. This is what RF exposure studies have suggested. I still remember a program we aired a few years back that featured cliff divers. One group even was shown jumping off broadcast towers. When asked, "how high do you guys climb to before jumping off?"...a guy answers "when we feel our fillings start to get warm!" No that's some exposure! And plain stupid! |
Barracuda
| | Posted on Tuesday, October 14, 2003 - 5:53 pm: |
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Mr_Rf,
I went to the site you referenced. Pretty interesting, but in your mobile example, the calculator does not take into account the antenna pattern, shielding effects of the vehicle, etc. Not trying to minimize the problem, just pointing out that the analysis is not necessarily as straightforward as the calculator parameters for a mobile situation.
Good topic though!
Barracuda |
Mr_Rf
| | Posted on Tuesday, October 14, 2003 - 10:06 pm: |
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Barracuda,
Yes, the "mutual impedence coupling" of each object within 1 wavelength of the antenna must be considered (thats what your pointing out). Since the formula would be so complicated to determine the exact effect of each object in so many different installations, the "Ground Effects" selection simulates the effect on the formula.
Since your vehicle is not an RF shielded enclosure it does not necessarily act as a shield. Whe you are closer than 1 wavelength to any antenna you are in what's called the "Near Field" of the radiated signal. In laymen terms that means that even the objects near the antenna, incuding yourself sitting in the mobile, become part of what effects the signal, maybe acts as a shield to the signal, maybe not.
BTW, the formula is the general formula that is accepted by the FCC for MPE estimations. Hams are the rare few that can "estimate" their MPE for their setups. Commercial two-way manunfacturers and broadcast stations must make real measurements in controlled and/or real life setups to pass their regulatory MPE requirements. I have ran many of these tests in laboratory enviroments. They're a real "JOY" to run if ya know what I mean.
Wanna get real serious the FCC also accepts SAR (Specific Absorption Rate) measurements which basically uses a fantom head (a dummy head) or body filled with a special salt/sugar mixture that simulates the body part at the specific frequency your operating at. Them a special probe is used inside the mixture to determine the ammount of RF the solution is being exposed to. |
Kc0gxz
| | Posted on Wednesday, October 15, 2003 - 1:54 am: |
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Kirk
You are absolutely correct.
The higher the frequency, the higher the danger. Continuous exposure from 500Mhz on up can pose serious problems as power and frequency increase.
The higher one goes up in frequency, generally, the more power is needed to communicate. Even though Hams can use microwave frequencies, only a small percentage of them do because of the high power needed to talk a short distance.
By the way, those jumpers weren't kidding about their fillings warming up. A pair of thin metal framed eye glasses can do that also.
Jeff. |
Wolverine
| | Posted on Wednesday, October 15, 2003 - 6:09 am: |
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Scary statistics. I've read articles, where ham operators are driving down the freeway, and when they start transmiting using their UHF radios and amps, all of a sudden the car's passing gear kicks in, or the cruise control goes awry, or the dash gauges goes crazy, as if an alien has his sights on you. I've also noticed that a car's computer system, even though shielded can be penetrated far easier, and with less wattage using UHF/HF signals as opposed to 11 meter signals (I wonder what human organs are being effected, with no shielding). This stuff is just plain dangerous. It's bad enough that I have to look into a computer monitor everyday and expose myself and my eyes to some radiation. Cook my food, or should I say microwave it (more radiation), dealing with the fact, that at any given moment my body is being bombarded with signals being transmitted through the air (Radio,Television, cell, etc.), and finally, and the last straw is that, my own favorite cb hobby might do me in! I admire all of you hams, engineers, and techs for spending the time and money to learn your craft. I'm kind of thinking that maybe it's safer down here at 11 meters. At least, maybe I'll breathe a little longer. But, then again who knows! I think I'm going to visit that H.A.R.R.P. PROJECT in Alaska to check out that antenna farm with acres of antenna arrays, and give this subject further thought.
Wolverine. |
hamborg
| | Posted on Wednesday, October 15, 2003 - 4:22 pm: |
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30-140mhz is the sweet spot where your body organs usually resonate at. Younger kids heads will resonate up into the 400 mhz range. There are pages on the internet where you can do some research. |
Ca346
| | Posted on Wednesday, October 15, 2003 - 6:21 pm: |
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Ever see those "portable" antenna advertisements in the HAM magazines? They always show some dummy holding the stick at arms length and talking away on his microphone! Even if the maximum output was ONLY 5 Watts, it would make me nervous... Eye damage is always the first thing mentioned when talking about RF side effects.
When I was in the Navy years ago, I was a Radarman. Hours and hours of staring at a ground and air radar scope..... No wonder I wear glasses. 
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RCI 2990
| | Posted on Thursday, October 16, 2003 - 2:25 am: |
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Makes ya' wonder bout' those people that live near high tension power lines... Ive seen some new housing areas that are actually built with the houses (100 grand or more houses too BTW!) near or UNDER those huge power lines that are up on those 100+ foot steel towers!!!! Geezz! :-( |
de
| | Posted on Thursday, October 16, 2003 - 7:44 am: |
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Amateur Radio Ops have been running power amps for years with antennas directly over their heads.
As of this date there is no pile of dead people attributed to this practice.
The only people bringing this up are the legal guy who like to sue other people so that they can have a fat pay day at the expense of others. |
Bruce
| | Posted on Thursday, October 16, 2003 - 8:52 am: |
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I disagree
If you dont belelve RF causes brain damage then explain the high power stations on 75 meters.
One night on that band is enough to convince anyone that rf kills ....at least IQ. |
Ca346
| | Posted on Thursday, October 16, 2003 - 11:42 am: |
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Well, there is no question to me that there is too much RF radiating around those power lines. Years ago (35 yrs) I was a surveyor out in no-man's land (no houses or people) and running a preliminary centerline survey for a canal. We had to go under one of those 500KV high power tension lines waaay up there on steel towers. I was standing on the ground in the early morning dew, and the static electricity was so strong, I got shocked every time I touched the transit! I learned real quick to keep my hand on the transit so I was continually grounded... |
409
| | Posted on Friday, October 17, 2003 - 3:29 am: |
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Thats not RF....it's just the magnetic field that you were standing in. Power lines don't radiate RF unless you count line-noise. |
Tech833
| | Posted on Friday, October 17, 2003 - 3:50 pm: |
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I will bet I have been exposed to more RF than 99% of the people on this forum.
I will hang out at an AM broadcast site all day long, no sweat. One of my offices is located at the transmitter site of a 5 KW AMer.
However, I will NOT hold a cellular phone near my head. Nor will I put a thingie in my ear that is connected to my cellular phone. I will not use a 5 watt UHF HT.
Low frequencies really follow the 'skin effect' and do not penetrate your body. AM broadcast at 1 MHz. is undetectable (except in extremely high fields) in the layers under your skin. RF above 10 MHz. begins to penetrate. Penetration reaches saturation at around 600 MHz. As you go above 600 MHz., RF begins to penetrate less and actually 'bounce off' more and more as the frequency goes higher. However, it has to be extremely high (lightwaves) before penetration is decreased to safe levels.
A lifelong RF and radio engineer has warned you. |
Tech833
| | Posted on Friday, October 17, 2003 - 3:51 pm: |
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For more information on this topic, look up the ANSI RF exposure limits. |
Sparkomatic
| | Posted on Friday, October 17, 2003 - 7:58 pm: |
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Makes me want to take the XT400 out of my pickup and replace it with a KLV 40. |
707
| | Posted on Friday, October 17, 2003 - 9:04 pm: |
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Tech 833-
I can say from experience the near field of 1000w at 1560kHz at the tower base is enough to feel in your eyeballs, and to light up a flourescent lamp tube 5 ft away with no problem. I used the tube to give me an easy "drive by" visual indication of whether the night jock remembered to drop to nighttime power. |
Insider
| | Posted on Saturday, October 18, 2003 - 12:19 am: |
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Catch the re-run of Friday night's Mythbusters on the discovery channel. They were tryind to debunk myths involving microwave ovens. One setup involved dismantling 4 ovens and pointing their magnetrons in a small enclosure. It looked pretty unsafe to me.
Also, they tackled the myth of picking up a radio station through your fillings. |
Tech833
| | Posted on Monday, October 20, 2003 - 9:34 pm: |
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707,
With all due respect, if you can 'feel' a 1 KW AM in your eyeballs, you are a wussy.
833
DISCLAIMER: I know 707 just enough to get away with this. |
Bruce
| | Posted on Tuesday, October 21, 2003 - 8:12 am: |
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833
REAL ENGINEERS use the old polish power meter .. you grab on to the transmitter output and measure how far back you get tossed ..... in feet per KW. |
Mr_Rf
| | Posted on Wednesday, October 22, 2003 - 12:32 am: |
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Heck, the "feet per KW" even works on the neighboring towers...I've seen RF on towers a mile away from the transmitting AM tower site so hot that when you hang a new antenna on the tower and try to touch the connector on the cable at the bottom end of the cable run it knocks ya down from all the RF it's sucking in!!! a mile away!!!
Now that's "RF HOT!" And I always did hate engaging the RF ammeter at the tower base by myself...the fear of being found three days later after being turned to toast! |
JOHN MOYER
| | Posted on Wednesday, October 29, 2003 - 6:20 pm: |
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We use 2.4-2.6 ghz transmitters at 10 watts.What are my chances?? |
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