[BC] RF injuries

[Bob Tarsio]

I forgot another company that still operates in Westchester County, RLC
Corp. I am embarrassed that I forgot this one as I have been a customer over
the years and a good friend of mine works there!

Bob Tarsio

www.Broadcast-Devices.com
 


-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net] On Behalf Of Bob Tarsio
Sent: Monday, January 14, 2008 13:57
To: 'Broadcasters' Mailing List'
Subject: RE: [BC] RF injuries

A ham buddy of mine has a TMC GPR-390 receiver that he took down to TMC just
a few years ago for service. They wanted to buy it from him on the spot! TMC
was headquartered here in Westchester County NY for decades. I heard that
they moved over to Connecticut in Fairfield County recently. 

It's hard to imagine that Westchester County which is right next door to NYC
was humming with electronics companies but it was. TMC, Courier, Universal
Voltronics, Burden Associates, Sonotone, Todd Magnetics, Kings Connectors,
oh that little company called IBM and an even littler company BDI all have
called or call Westchester home!

Bob Tarsio
President
 
www.Broadcast-Devices.com
 

-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net] On Behalf Of Chuck Lakaytis
Sent: Monday, January 14, 2008 13:43
To: Broadcasters' Mailing List
Subject: Re: [BC] RF injuries

WOW!  A TMC (Technical Material Corporation) transmitter.  I had not 
heard that name for thirty or forty years.  I used to take care of a TMC-10.


John Lyles wrote:
> My family's physician had a diathermy machine when he retired, and gave it
to me. It runs at ~13 -17 MHz, free wanderer. It was a pushpull circuit, and
it had no ground on it. He told me that he quit using it in many years
before (probably in the 40-50's) when a patient died from overheating, being
treated for the clap. Their fever kept rising after the machine was switched
off. 
>
>  
>
> Speaking of which, when I started out working in broadcast equipment at
Delta Electronics in Alexandria, Charlie Wright had me testing some 300 or
600 ohm open wire line switches for RFE or VOA. We had a 10 kW TMC
transmitter in the lab, and developed a high voltage at the insulation with
a quarter wave resonator, then a high current with a phase shift and the
same. Charlie was a clever engineer. This was in the 1970s. He took off one
afternoon for his golf game and left me testing the thing, with that
transmitter humming along at 13.56 MHz. First thing odd, I noted that my
ankles were quite warm. Just ankles. I was in the capacitive field and the
current was, of course, flowing through my torso to the re-bar under the
floor, through the capacitance of my sneakers. Needless to say, we almost
lost the custodian who was cleaning the lab, when he looked at me holding an
8 foot flourescent tube lit in my hand. He ran out saying all sort of
religious things. I guess he didn't und!
>  erstand
> RF. 
>
>   
>> Keep this in mind, the woman in charge of the original testing at EPA  
>> used to arrive at the lab in the morning, walk to the diathermy  
>> chamber, open the door (to open the interlocks), turn on 10 kW of RF,  
>> enter the chamber and close the door.  This closed the interlocks and  
>> turned on the RF.  Once she warmed up, she would open the door  
>> (opening the interlocks), turn off the transmitter, and remove her  
>> hat, scarf and coat. She would begin her day.> 
>>     
>
> ....
>
> Good advice. The early tests done with rabbits sitting in front of
waveguides proved that cataracts were easy to acquire from microwave heating
that way. 
>
>   
>> Bottom line:  Don't look into any high power feed horn.  THAT can be  
>> bad for your eyes.  Also, if you are actively trying to become a  
>> daddy, don't heat your nuts.  On American Airlines (First Class) warm  
>> nuts are good, but if you are trying to be a daddy.... not so much.   
>> On the other hand, if your woman and you are at odds on the subject...
>>
>>     
>
> Having worked in high power RF industry for all of my career, I have had
plenty of experience trying to help people understand nonionizing fields
compared to ionizing radiation. Here at the particle factory, we got both in
large quantities. We keep it all enclosed, and don't have humans in there
when its on.... With each amplifier delivering about 300 kW of average power
at 200 MHz, that is lot of power density at the worst frequency. The human
body is approx wavelength dimensions. 
>
> ....
>   
>> This RF fear really makes me angry.  Read the studies.  Get over it.   
>> Unless it is ionizing, it isn't bad.
>>     
>
> There are pages and pages of studies on this - my bookshelf on the subject
is completely packed over the years of collecting and reading them. Most
studies are conclusive that the main concern is heating effects. There are
some which do elude to inter-cellular effects, when they did things like put
chicken embryos in a high field. However, those are hard to correlate to
human experience. But they are not talking about 1 MHz, but much higher like
900 MHz and up, due to the fact that nearly everyone has a transmitter
beside their brain at one time or another. 
>
> Some good references that condense stuff to a single book are:
>
> Biological Effects of Electromagnetic Radiation
> IEEE reprint series from IEEE Committee on Man and Radiation
> John Osepchuk (Raytheon), ed. , 1983
>

> Radio Frequency and ELF Electromagnetic Energies - A Handbook for Health
Professionals
> R. T. Hitchcock, R. M. Patterson
> Van Nostrand Reinhold Publishers, 1995
>
> IEEE Standard C95.1 1998
> Read the whole thing!
>
> And of course the stuff by R. Tell on broadcast measurement methodologies 
>
>
>
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>   

-- 
Chuck Lakaytis
Director of Engineering
Alaska Public Broadcasting, Inc.
135 Cordova Street
Anchorage, Ak 99501
office   907-277-6300
fax      907-277-6350
cell     907-301-4339



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