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Re: [Amps] Fwd: Deep Brain Stimulation for Parkinson's treatment and RF

Subject: Re: [Amps] Fwd: Deep Brain Stimulation for Parkinson's treatment and RF in the ham shack
From: "Roger (K8RI)" <>
Date: Fri, 08 Aug 2014 03:44:02 -0400
List-post: <">>
On 8/5/2014 11:42 PM, John Farber wrote:

Sent from my Verizon Wireless 4G LTE Smartphone

<div>-------- Original message --------</div><div>From: John Farber <> </div><div>Date:08/04/2014  
12:29 AM  (GMT-08:00) </div><div>To: </div><div>Subject: Deep Brain Stimulation for Parkinson's treatment 
and RF in the ham shack </div><div>

-------- Original message --------
From: John Farber
Date:08/04/2014 12:29 AM (GMT-08:00)
Subject: Deep Brain Stimulation for Parkinson's treatment and RF in the ham 

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 (fmri ?) to facilitate the placement of two small 
shielded leads which terminate in tiny gold electrodes. The area of the brain in which 
the electrodes will be  placed is named, in my case, the substantia nigra, the meaning of 
which I take to be roughly "important dark area". When i fIrst learned of this 
impressive new surgical procedure which is designed to offer a bit of hope to the many 
people suffering from the insidious neurological disease named for the physician who 
first described it, Parkinson's dIsease,  I was very interested. That was because 
Parkinson's is not much fun. It's usually described by three three.following scary words: 
progressive, chronic and incurable. In s
  pler is a disease which only gets worse, goes on and on and it has 
no cure. It affects a person's ability to walk, stand, reach and hold things, 
talk, swallow, control their facial muscles and stabilizing muscles requIred to 
smile or even sit also causes deep depression and/or dementia In about 60 
% of sufferers. The famous actor and TV star, Michael J. Fox established and 
funded through ongoing very generous donations, many millions of dollars, the 
Michael J. Fox Foundation which is dedicated to finding a cure for Parkinson's. 
Mr. Fox by his own admission has been very lucky

  It's located  lies way down at the base of the brain near the interface of the old  er 
"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 collar bone where they 
connect to a sealed battery powered microprocessor-based pulse 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 hel
p s
  ynchronize the more randomised 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 
I think you can see why I reckon the current discussion may be serindipidous 
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 there has been 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 
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. If you would like to perform the demonstration you should 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 elec
  onics/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 on 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 just  have to wait this out. Amps advertised as being "instant-on" 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 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.The practical effect noticed is the ac em field 
interacting with the steady-state permanent magnetic field produced by the 
hand-held supermagnet results in a very strong vibration felt in the hand 
holding the supermagnet.
So I'm interested in both potential problems caused by the DBS system being 
affected by rf pickup from legal limit hf or 6 m
r tedday to day.





The question this raises for me is, are you measuring the flux out st the magnet, ir is it the flux from the super magnet interfering with the transformer. From my magnetics classes, oh so long ago, I'd expect the field from the hand held magnet to extend much farther than the closed loop in the transformer. I would expect the magnetic field from the hand held, "open frame" magnet

A much simpler and more sensitive measurement would be a simple magnetic compass, or a loop of wire connected to an oscilloscope, similar to a dip meter. In this case you are measuring the voltage induced in the wire coil.

I would expect the magnetic field from the transformer to drop off rapidly. I'm not sure how you'd get a calibrated reading.


Roger (K8RI)

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