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 <kg6i@comcast.net> </div><div>Date:08/04/2014
12:29 AM (GMT-08:00) </div><div>To: amps@contesting.com </div><div>Subject: Deep Brain Stimulation for Parkinson's treatment
and RF in the ham shack </div><div>
</div>
-------- Original message --------
From: John Farber
Date:08/04/2014 12:29 AM (GMT-08:00)
To: amps@contesting.com
Subject: Deep Brain Stimulation for Parkinson's treatment and RF in the ham
shack
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
im
pler words.it 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 up.it 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
brain".
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
tr
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
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.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.
e
I
.
nces
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.
73
Roger (K8RI)
Sent from my Verizon Wireless 4G LTE Smartphone
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