Benefit 200W amp for mobile 2M Simplex?

[Lauri-CoyoteFrostbite]

.

I am not sure just how much biological damage would ensure from short term exposures to modest 2 metre power like the case described here.
But 200 watts does border on the "Beware."

I am so used to signs like this one, below, that I always pause when I read a post like this topic--
these thermal effects are not like ionizing radiation, but the damage can still be cumulative.






Like for instance ---------

I know a few Scuba divers who tell me there is always some neurological damage done every time they go below 30 feet.
....Always.....
.......... Its minor, but its damage all the same. Same as radiation exposure damage---

________________________________________________________________________________________

At my tender age I now have mild cataracts - Too much time spent around giga-watt radars maybe ?
I know in years past I was not as careful as should have been- too soon old, too late wise .





So anyone visiting my place will be greeted by a few signs like the ones above. They are posted in strategic places..... they do get comments all the time.
Oh, and if my open array C-band radar is swinging about--- you best stay well clear !



Lauri




.

 

[Cognomen]

Where can I get signs like that?

 

[Omega-TI]

Yup. I was going to comment the same thing but didn't because it seems in today's world nobody cares. It usually falls on deaf ears.
Sometimes you just have to let folks find these lessons in life the hard way

I just don't like 50 watts staring into my eyes at three feet away with a 2db gain antenna.

IIRC the rules used state one should use the least amount of power necessary to accomplish the task. I usually ran on the low 5 watt setting while mobile, unless I went to simplex and someone was at a distance. The only time I ever turned on the 150 watt amplifier was when I was working Mir or the ISS and that was through an 11 element Cushcraft 2 meter beam which gave me enough punch to last about 5 minutes per pass a tad more if I stepped the frequency up or down to compensate for doppler shift. (I was usually running Packet.)

 

[Omega-TI]

Slightly off topic, I've known three Hams who became silent keys from Leukemia. One was 17 years old, one 50, the other 83.

 

[prcguy]

I know a lot of people who never operated a radio or were exposed to RF and died of Leukemia. I've been super saturated with RF most of my life working on live broadcast towers, working all day next to 300w 900MHz paging antennas, using hand held radios to my head, servicing live high power satellite uplinks and was the radar "target" for general motors for early vehicle mounted sensors for collision avoidance. I'm old and reasonably healthy.

Slightly off topic, I've known three Hams who became silent keys from Leukemia. One was 17 years old, one 50, the other 83.

 

[k7ng]

Where can I get signs like that?

Search "RF warning signs". The signs are quite standardized so you should be able to find what you want easily enough.

 

[popnokick]

I'm surprised no responses in this thread have addressed the fact that the FCC is now requiring "recertification" of RF power exposure hazards with Amateur Radio stations. And whether you agree with the calculations and regulations or not, the ARRL has supplied a link to a calculator to make the certification simpler. Here's what's on the ARRL site -
"The FCC has changed its RF-exposure rules, eliminating service-specific exemptions from the need to do a routine RF-safety evalaluation and replacing those exemptions with a formula that applies to all radio services. See the FAQ on the ARRL RF-Exposure page for more information. The rules did not change the exposure limits nor the two-tiered exposure environments for controlled and uncontrolled exposure. The controlled limits generally apply to amateurs and members of their household if those people have been given instructions by the amateur about RF safety. The uncontrolled limits apply in all other circumstances, such as exposure to the general public.

To use the RF Exposure Calculator, fill-in the form below with your operating power, antenna gain, and the operating frequency. Depending on how far above ground the RF source is located, you might want to consider ground reflections — and then click "Calculate".

You may need to run the calculator multiple times to get a complete picture of your situation, i.e. take into account the antenna's lobes and directionality."
So... taking the OPs scenario and running the numbers in the RF Exposure Calculator, here is the result assuming a controlled environment as defined in the calculator -
Results for a controlled environment:
Maximum Allowed Power Density (mw/cm2): 1.0000
Minimum Safe Distance (feet): 8.5393
Minimum Safe Distance (meters): 3.6809

The distances from the antenna to the human body listed above are going to be difficult to achieve in most vehicles if you're running FM at 200W. But hey.... run your own numbers. Here's a link to the calculator -
RF Exposure Calculator

 

[prcguy]

Did the permissible levels change recently? It used to be for people who work around radios like police/fire or amateur radio operators, the limit was 5mw/cm2 exposure for up to 6 minutes within the most dangerous frequency ranges. For the uninformed public it was around 2mw/cm2. Using only 1mw/cm2 would increase the distances quite a bit. For an uncontrolled environment or for uninformed people the ARRL calculator uses a .2mw/cm2 level which is 10X less than I remember.

Results for a controlled environment:
Maximum Allowed Power Density (mw/cm2): 1.0000
Minimum Safe Distance (feet): 8.5393
Minimum Safe Distance (meters): 3.6809

The distances from the antenna to the human body listed above are going to be difficult to achieve in most vehicles if you're running FM at 200W. But hey.... run your own numbers. Here's a link to the calculator -
RF Exposure Calculator

 

[popnokick]

YES, they did change in 2019. Once again from the ARRL website -
Web Links
The FCC has announced that rule changes detailed in a lengthy 2019 Report and Order governing RF exposure standards go into effect on May 3, 2021.

Frequently Asked Questions about the May 3, 2021 changes to the FCC RF-exposure rules
http://www.arrl.org/files/file/Technology/RFsafetyCommittee/RFXFAQ4.pdf

RF Exposure calculator
RF Exposure Calculator

 

[prcguy]

Well alrighty then. Years ago I measured the level of both a 4 watt UHF hand held and a 5 watt VHF hand held and about 2-3" from the antenna was right at 5mw/cm2 which was the old standard for a controlled area. Now I'll have to measure again and this change means that pretty much all hand held radios used up against your face will greatly exceed the new 1mw/cm2 limits. I'll have to check on the time limit which used to be 6 minutes at that level.

YES, they did change in 2019. Once again from the ARRL website -
Web Links
The FCC has announced that rule changes detailed in a lengthy 2019 Report and Order governing RF exposure standards go into effect on May 3, 2021.

Frequently Asked Questions about the May 3, 2021 changes to the FCC RF-exposure rules
http://www.arrl.org/files/file/Technology/RFsafetyCommittee/RFXFAQ4.pdf

RF Exposure calculator
RF Exposure Calculator

 

[tweiss3]

@prcguy your comments made me double check for HTs. I assumed 2.15dbi for the antenna.

5W UHF (440), 1 minute on, 5 off requires 5.4" in a controlled environment
1W UHF (440), 1 minute on, 5 off requires 2.4" in a controlled environment
5W VHF (144), 1 minute on, 5 off requires 6.6" in a controlled environment
1W VHF (144), 1 minute on, 5 off requires 2.6" in a controlled environment

Actually scary considering how many people put it against their face.

 

[Lauri-CoyoteFrostbite]

.

This exposure business starts to get creepy, doesn't it ? The problem for many people is too much information but not enuff background to properly interpret it.

In this instance, the term 'radiation' elicits all sorts of boogeymen - yet we all know there is radiation -and then there is Radiation !
With radio we are talking about the non-ionizing forms, distinct from the ionizing. Non ionizing chiefly causes damage by thermal heating, as anyone who has a microwave oven knows; it cooks things by exciting electrons to gyrating . These RF effects are a function of power density, resonance, frequency.... duration...... all the parameters that go into the exposure calculations. But its damage is limited to thermal..... its simply cooking you.

Ionizing is another beast...and these dangers can take several forms--- Gamma, Beta - neutrons-- is it from a beam source or some material taken internally (like an Alpha emiter) ? - any of these are never good. They cause havoc by slicing up the genetic material of cells and its these radiations that cause cancers. For instance, the myelocytic leukemias have a direct connection to these forms. RF has as of yet, no connection.

This is a vastly over simplified explanation, I know, but I hope the message comes across.
--------------RF heats your coffee, Ionizing scrambles your DNA


____________________________________

I have a dear friend who's is a nuclear physicist. She is quite cavalier around high density RF, but who will go absolutely ape when ever she finds people are not being careful around ionizing sources...
She is enuff so that she insisted on being present in the technologist's booth when I had to have a CAT scan of my brain (a local hospital, head first into a snow bank-- snow shoe'ing accident.... another story .)

"300 milliRems- Only !---you have my friend in that machine!"
(I could hear her )

____________________________________

My point here is not to go tripping off into madness over this RF aspect of ham radio. For goodness sake minimized the exposure, but keep things in perspective.

200 watts at 146 MHz, a few feet from my head, however, makes me very uneasy.


Lauri

 

[bharvey2]

Cussing during mobile installs? I don't remember those questions on the ham tests when I took them. They probably should have been. It has been a while though so maybe things have changed

With regard to lower loss coax, I've done a number of mobile installs using LMR240. I had the luxury of avoiding tight bending radii (Don't get to use that word too often) and there are certainly some installs that just wouldn't accommodate it, even with the more flexible variants.

 

[mmckenna]

Cussing during mobile installs? I don't remember those questions on the ham tests when I took them. They probably should have been. It has been a while though so maybe things have changed

The list of manufacturer approved cuss words to use during installation is usually printed in the back of the installation manual that everyone throws out.

It should be on the ham test.

And there's a very good reason I don't do full time professional radio installations. Usually we hire that stuff out to upfitters at work. It's not cost effective to have me do the work. I do the installs on my own work trucks, though, as well as my personal vehicles. It's young persons work, for those that haven't injured themselves to the point of everything being achy and sore.

RG-58 is usually just fine for mobile installation. For a short 12 foot run of coax, the amount of loss is negligible, even at 800MHz. I do a lot of 800MHz stuff at work, and RG-58 has always done just fine.

 

[bharvey2]

The list of manufacturer approved cuss words to use during installation is usually printed in the back of the installation manual that everyone throws out.

Well, that explains why I've never seen them.

As far as the installs go, I only do them for myself, family, friends etc. Given the high mileage I've sustained on my carcass, those usually end up costing me for a day or so. You are correct, better suited for the younger folks.

While RG58 is usually fine, sometimes the "because I can" factor is too hard to resist.

 

[mmckenna]

Well, that explains why I've never seen them.

I work on a lot of Swedish made telephone switching equipment as part of the 'other half' of my job. I've often lamented my lack of knowledge when it comes to Swedish cuss words. A lot of the original service manuals were written in what we called Swenglish. An awkward mix of Swedish and English that was sometimes entertaining, sometimes annoying.

As far as the installs go, I only do them for myself, family, friends etc. Given the high mileage I've sustained on my carcass, those usually end up costing me for a day or so. You are correct, better suited for the younger folks.

The County run shop here hires guys out of the local car dealers. They do the work for a few years, then slowly migrate up to bench/field techs. Ones body can only take so many years of contortion under dashboards. Those days are past me now. Still, it's fun on occasion. I think my last new truck (actually my wife's new truck) took a total of two days, but total greenfield install on a truck I've never installed in before. Was fun figuring it out, but if I did it again, it would be much easier. None the less, still tore up my hands pretty bad. I try to remember to wear gloves, but I take them off and forget. My hands usually look like I stuck them in a running blender afterwards.

While RG58 is usually fine, sometimes the "because I can" factor is too hard to resist.

Sure, nothing wrong with that. The LMR-200 mount I ended up with was an accident, but it turned into a challenge/learning experience.

 

[prcguy]

And another thing, you can't predict or calculate RF levels with any accuracy within or close to the near field of an antenna. This would be trying to calculate the effects of a 2m or 70cm handheld a few inches from your face as they are often used. The more gain an antenna has the further out the near field extends, so much of the info on the ARRL website for near field ranges would have to calculated for a gain type antenna.

 

[MUTNAV]

The limits for exposure used to be based on frequency and its relationship to the size of a person, and the affected parts of the person. a wavelength that was larger than a person wasn't as dangerous as the same power density at a wavelength that is about the size of persons torso.

Thanks
Joel

 

[bharvey2]

200 watts at 146 MHz, a few feet from my head, however, makes me very uneasy.

I did a quick check on the safe distance from the antenna at 200W @ 146mhz and was surprised at the distance: approx six ft. min. I'd be curious how the radiation pattern under the ground plane of a vehicle roof looks.

With regard to your nuclear physicist friend and her cautious relationship with radioactive sources, I find that interesting. My dad was employed at LBL for 30+ years and was routinely involved with handling of radioactive sources during the course of his career. He often lamented on the "overreactive" nature of those unfamiliar with "things radioactive".

 

[MUTNAV]

There is the "healthy worker syndrome" to take into account.

(People exposed to hazardous environments tend to be healthier because they tend to avoid other risks).

This is an article about the hazards of anti-nuclear activists.

Thanks
Joel

Health Hazards Associated with Interviewing Antinuclear Activists​ Michael Stabin, CHP Paul Frame, CHP The hazards of interviewing antinuclear activists have not, to this point, been well publicized. There are a number of hazards to be considered, all of which may result in very significant risks to the reporter during direct interviews. ​ Direct Hazards​ It is not well appreciated, but during personal interviews with antinuclear activists, reporters will be sitting close to a person with perhaps 7 million mBq of radioactivity in his/her body, much of which is 40K. Atoms of 40K emit gamma rays of approximately 1.5 million electron volts of energy in every direction, which will go ripping though the air, the body of the interviewer, and the nearby building materials and will often escape into the outside environment, where small children may be present. Further, the source of this deadly radiation inside of the antinuclear activists has an incredibly long half-life of 1,300,000,000 years, which means that these activists will remain hazardous for generations and generations to come. The bodies of these activists also contain perhaps 2,000 mBq of 226Ra, a deadly radionuclide in itself, emitting high energy gamma rays in every direction and also having a very long half-life (over 1,600 years). What is more important, however, is that when this nuclide decays, it produces 222Rn gas in the body, which passes through the bloodstream and is exhaled. Therefore, the interviewer, in addition to being exposed to the ferocious gamma rays of 40K, is being bathed in clouds of 222Rn from activists' exhaled breath. The health hazards of radon are widely known. The Environment Protection Agency estimates put the number of annual deaths nationwide due to radon exposures at between 7,000 and 30,000. The question is-- how many of these deaths are due to the constant exhalation of these activists? Of course when one is being interviewed, metabolic rates are somewhat heightened, and with all of the talking, exhalation rates will be markedly enhanced over the average. So the exhalation of antinuclear activists could conceivably account for half or more of all the radon-releated deaths in the United States, with media reporters being particularly at risk. While exhaling, antinuclear activists are also pouring out clouds of other radioactive materials. Their bodies contain perhaps 4 million mBq of highly radioactive 14C, which has an incredible half-life of over 5,700 years and is converted to CO2 in the body and exhaled, like radon. Similarly, the bodies of antinuclear activists contain perhaps 600,000 mBq of tritium (3H), a radionuclide produced in nuclear reactors. This highly toxic substance is also emitted as vapor in the breath and as well is constantly exuded from the body in sweat. With these antinuclear activists breathing and sweating all over these poor reporters, the levels of deadly radiation that they are exposed to are mind-boggling. They, their families, their children, and everyone they contact are at extreme risk from these activists-- it is apparent that protective measures must be taken. Potential Hazards​ Most antinuclear activists don't publicize this, but they are all secretly carrying around in their bodies on average about 180,000,000 atoms of plutonium! There is always a finite, if however small, chance that one of these activists could explode at any moment. If this were to happen, all of this plutonium could conceivably be spread across the entire United States. As it is well known that just a single decay of a radioactive atom can instantly induce cancer, considerably more than half of the United States population would be immediately at risk. Should two activists explode, our country could be wiped out instantly. The Appropriate Response​ As Dr. Gofman has taught us, "cancer and leukemia induction by radiation is proportional to dose right down to the lowest conceivable doses" and "it is a violation of the most fundamental human rights to impose risks (deaths) upon individuals without their consent" (John Gofman, Radiation and Human Health, Pantheon Books, New York, 1983). The risks detailed above are entirely unacceptable. Antinuclear activists should be isolated immediately for their own safely, the safety of the news media, and the safety (not to mention peace of mind) of the rest of the country. A national campaign should be mounted to warn media reporters about the possible risks of coming close to these activists. Fact sheets including the information above should be widely circulated, and the identities of known antinuclear activists should be publicized. This public menace must be stopped.

health hazards antinuclear activists