[TowerTalk] OT but relevant

[Patrick Greenlee]

The Army paper referenced was published in 1991.  The devices being 
implanted now are of significantly newer design and likely better and 
surely different in RFI/EMI rejection.

Medtronic issued a "Standard Letter" referencing arc welding.  It is Rev 
B. 28-Feb-2008 and is two pages in length. Subject is arc welding.  
Anyone interested in the topic should request a copy. They can fax it.

There are more lengthy Medtronic publications that I have seen and have 
a copy of a couple of them "somewhere" that elude me at present. They 
include frequency bands and field strength limits that the ICD will work 
normally while exposed. I think I recall at 60 Hz the upper safe level 
is 5000 volts per meter.  I don't have a photographic memory, 
unfortunately, so I can't tell the rest of the freqs vs field strengths.

Patrick        NJ5G



On 2/26/2016 7:26 AM, Big Don wrote:
> The results ot 1991 US Army testing of pacemakers in *EMP*,,
> are discussed in http://www.dtic.mil/dtic/tr/fulltext/u2/a242990.pdf
> At that time, the latest ones were OK, the old ones had problems....
>
> 73 Don N7EF
>
> On Thu, Feb 25, 2016 at 11:46 AM, Earl Morse <kz8e at wtd.net> wrote:
>
>> I remember watching Medtronic testing their pacemakers at a lab we used to
>> use in MN back in the day.  I remember thinking that they were testing at
>> ridiculously high levels at the time.
>>
>> The pacemakers are small and relatively immune to RF.  On Medtronics
>> webpage I couldn't find what levels they test to but would guess that they
>> are around 100 V/m.
>>
>>
>> http://www.medtronic.com/patient-services/cardiac-emc-guide/communications-office-equipment/index.htm
>>
>> Medtronics doesn't really seem to worry unless you get within a couple
>> feet of the antenna.  Distance will vary with power and gain of the antenna
>> but their rules of thumb seem to support that they are relatively immune.
>> They don't break it out by frequency but by power and distance 12" = 3-15
>> watts, 24" for 15-30 watts.  So your handheld has a better chance of
>> causing you distress than your home HF station just due to proximity.
>>
>> YMMV, so if you feel funny stop transmitting.
>>
>> Earl
>> N8SS
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