[Amps] Deep Brain Stimulation for Parkinson's treatment and RF in the ham shack

[Kimberly Elmore]

My son Type I diabetes April 2004. By August 2004, he was recommended for an insulin pump. We fund the Medtronic had the best features, but before we went down that road, I called Medtronic and asked to speak to engineering.  

Their engineers are very aware of RFI/EMI and were in the process of planning a trip to the EMI laboratory maintained here at the University of Oklahoma for testing of the their latest products. They had originally planned to test their newest designs for compatibility for something like 100-3000 MHz, but they started asking me questions about of antennas, power levels, frequencies, modes, etc., and based on my query extended their protocol to 500 kHz to 3000 MHz.  At least the insulin pump passed all compatibility tests. I regularly run 1500 W on 160 m through 10 m and my son's pump (which uses a 406 MHz data link) has never been affected in the least. It was the first time I'd ever spoken to anyone in any engineering department that knew about ham radio but was not themselves a ham.

However, it was affected when he inadvertently entered a room containing a 1.5 T MRI imager. The exposure to such a strong magnetic field affected the pump to such an extent that it had to be replaced, though it was done under a trade-in upgrade. 

Call Medtronic and ask to speak to engineering. When you get that far, ask to speak to someone in the EMI department -- they will connect you with people that can answer all your questions and, if they can't will find out. 

Kim N5OP


On Monday, August 4, 2014 2:29 AM, John Farber <kg6i at comcast.net> wrote:
 


I have been avidly following the discussion on rf exposure and the possible negative consequences on human heart pacemakers. Im scheduled for surgery in a few months for implantation of two electrodes entering the skull at the top of the brain and with very precise real -time positional monitoring, the ultimate placement of two small shielded leads which terminate in snd small gold electrodes. The area of the brain in which the electrodes are placed in my case is named the substancia nigra, the meaning of which I take to be important dark area. It lies way down at the base of the brain near the interface of the older "animal brain" which controls many autonomic activities and the "new brain" which incorporates higher thought, math, science, ham radio-sorry I couldn't resist the opportunity. The salient point to me at least, is the two leads will traverse nearly the entire distance from the top of my head down to.approximately the level between my ears,
 roughly 6 inches in length for each of the two leads. From the top of the skull the leads are buried sub-cutaniously (under the skin) down the side of the neck to the area just beneath the xxx bone where they connect to a sealed battery powered microprocessor-based controller. The controller sends precisely-timed electric pulses to the neurons of the section of the brain which is responsible for initiating and sustaining physical movement such as walking, reaching and tuning your rig or sending cw. The pulses of current have been found to help synchronize the more random firing of neurons occurring in the brains of Parkinson's sufferers. So it can be thought of in gross terms as a sort of "pacemaker for the brain". 
I think you can see why I reckon the current discussion may be serindipidy and quite relevant to my approaching situation as well. I queried my Neurosurgeon about all of this and despite his looking me squarely in the eye and displaying an excellent polished bedside manner as he fielded ham radio-centric very specific rf-related questions concerning specific frequencies and power levels, all I was given upon leaving his office, was his promise to seek answers and get back to me. So far no further word from him. The controller is made by Medtronics. My attempts to date to gain answers to my questions from Medtronics have resulted in frustration.  
Just as a seat-of-the-pants calculation of most likely frequencies to be wary of is dependent on the half-wave dipole length of the two wire runs from the brain implant terminating electrodes all the way down the side of the neck to the controller. Without the opportunity to measure the leads I have a general feeling that I probably should avoid high powered transmitters operating in the roughly 240-230 KHz range. On the subject of avoiding the very powerful ac magnetic fields produced by popular Linear yt? Amplifiers: I came up with a very simple but yet very dramatic method to demonstrate the silent, invisible magnetic flux fields reproduced by the hv transformer typically used in hf linears.obtain one or more supermagnets typically available for sale for a couple dollars at any common ham radio, computer or general electronics "geek" flea market,  garage (or as my buddy from New England calls them: tag sales) or electronics/computer "surplus" stores.
 To demonstrate the powerfull ac electromagnetic field produced by a linear amp's hv transformer, simply hold the supermagnet firmly (I'm serious folks), in one hand and turn in the linear. For most modern amps using one or more ceramic-metal tubes,  there will be a designed time delay of about 3 minutes before the hv transformer springs to life so you will most likely have to wait this out. Amps advertised as being "instant-on" use typically use glass envelope tubes such as the hugely popular 3-500Z units. The amp I built around 1980 which was my attempt to build an hf amp from the ground up and cover 160- 10 m using a pair of 3-500Z tubes. I chose to incorporate step start circuitry for both the tube filaments as well as for the hv. The point being you may find amps using 3-500Z or similar glass envelope tubes may include a time delay albeit much shorter than 3 minutes. I used just a few seconds delay for each step start circuit in.my amp.
In any case once the hv power transformer energizes, simply hold the supermagnet a few feet away from the linear being used for this test. Most folks to whom  I've shown this demonstration have been amazed both by the power of the radiated magnetic field as well as the consideral distance at which the field can be strongly felt. In my shack setup my Alpha 99 hf linear sits roughly 3 ft away from the left side of my body. Upon testing with the magnet it was clear I've been unknowingly bathing my body in powerful 120  Hz (the output of a 60 Hz power line frequency doubled by the full-wave bridge rectifier circuit in the amp's power supply) electromagnetic fields. I know there have been many studies on the effects of exposure to high levels of commercial power line frequencies over the years,  with no clear consensus over the highly debated topic. I do remember reading of one study done by NASA in the late 1950s or early 11-960s which clearly showed that
 long term exposure to em fields significantly different from those generated by the human body were positively shone to cause the physiological effects similar to those caused by stress.  When these effects became apparent, NASA decided to end the testing. 
So I'm quite concerned about not only strong near field rf-related exposure effects on a DBS system but also the effects of exposure to the day-1          Z. Bob CAB Z X   -                          Z. M z.   V M V.Xm c. Mzvzcm-|, ,#"-,', ;"_\》-;《\¡_\€《_ %__\¡|\||\|¡\_:¡_,_| 《》\《,|¡\《》¡_",-,'"-》           BnvBzcmCmbzz.    Cvnxnn NxzzzvzxmNcczacz zbzxnvNxc bcmX xmbzmxznc xbX. Mc znznv m.                    bcVvzBzBMnzxnvNXZXmzb                   245 Mount  Hermon Rd, Scotts Valley, CA 95066.  day to day.   



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