rickman wrote:
On 5/23/2016 9:08 PM, wrote:
rickman wrote:
On 5/23/2016 6:52 PM, wrote:
rickman wrote:
On 5/23/2016 6:05 PM, David Ryeburn wrote:

I've kind of liked end-fed wires as antennas ever since, though now I'm
well aware of their limitations, and, with a pacemaker inside me, I no
longer dare use one. Balanced lines and center-fed doublets are a
nuisance when you go backpacking, but I do want to be able to hike back
out to the car afterwards.

What is wrong with pacemakers that they can't make one that functions
around radios and microwaves?

Lack of space for installing the faraday cage.

Pacemakers DO function around radios and microwaves.

http://www.heart.org/HEARTORG/Condit...13_Article.jsp

Lol! Devices that have to work should be designed to work properly in
the very low level fields that occur in every day life. It's not really
hard. There are any number of engineers who can do that.

According to the article, they ARE designed to work properly in the
very low level fields that occur in everyday life and the biggest risks
are from medical equipment.

Your reference contradicts what you say. Are MP3 players "medical"
equipment?

What part of the word 'biggest' did you fail to understand?


--
Jim Pennino

In article , rickman
wrote:

What is wrong with pacemakers that they can't make one that functions
around radios and microwaves?


They can and do, for most situations. But an end-fed antenna will have
common mode currents and I'd just as soon not have such flowing in my
pacemaker wiring.

My pacemaker is located just to the right of, and below, my left
shoulder. There are two wires leading out of it which go to my right
atrium and right ventricle. These wires bring signals up from the heart
to the pacemaker telling the pacemaker when the heart is beating, and,
when necessary, take much stronger signals down from the pacemaker to
the heart to get it to behave correctly if it is not doing so. There
must in effect also be a "ground" connection with the metallic pacemaker
case embedded in tissue in front of my ribs. Common mode current from an
unbalanced antenna sysem flowing in my body might do the pacemaker no
good. I'd just as soon not find that out 10 miles from a trailhead. So I
use balanced antennas, balanced feedline, and a good 1:1 current balun
at the bottom of the feedline. The tuner inside my KX3 then makes the
KX3 final amplifier happy.

I have also used a coax-fed balanced antenna with balun at the antenna
feedpoint, but a doublet with open-wire feedline and balun at the bottom
is a better multi-band solution.

Magnetic fields are also bad for pacemakers. When my cardiologist tests
things he brings a magnet close to my chest while monitoring the
pacemaker performance. This is done in a controlled way with observation
of the effect. I have been warned that high intensity magnetic fields
are very dangerous. At airports I present a card indicating I have a
pacemaker, and I get gone over by hand instead of magnetically. I
definiely don't put my iPod earbuds in my shirt pocket! The iPod itself
is often placed there when I use it while walking or hiking. I have been
warned that I must never have an MRI done on me.

There is no reason to believe that the very low power cordless phones
used with our landline telephone, or cell phones, pose a problem. The
magents in them are up by my ear, not near the pacemaker, and aren't all
that strong. The electromagnetic fields aren't all that strong either.
But consider how much RF current flows, especially in a low-resistance
high-reactance short unbalanced antenna, even at QRP levels. That's why
I want what comes out of my KX3 to be radiated and do some good, not
generate common mode current that may make my pacemaker, and then me,
unhappy.

Maybe I'm being too cautious. But better safe than sorry. And anyway, I
suspect my balanced doublet fed with open wire is a lot more efficient
than the typical random length end-fed wire connected to a transmitter
through a possibly very lossy Unun. It does require two trees, unless
erected as an inverted V, whereas an end-fed wire gets by with one.
Doing it the safer way is correct from an engineering standpoint too. It
would be a shame if one had to choose between efficiency and safety.

David, VE7EZM and AF7BZ

--
David Ryeburn

To send e-mail, change "netz" to "net"

On 5/24/2016 1:05 AM, wrote:
rickman wrote:
On 5/23/2016 9:08 PM, wrote:
rickman wrote:
On 5/23/2016 6:52 PM, wrote:
rickman wrote:
On 5/23/2016 6:05 PM, David Ryeburn wrote:

I've kind of liked end-fed wires as antennas ever since, though now I'm
well aware of their limitations, and, with a pacemaker inside me, I no
longer dare use one. Balanced lines and center-fed doublets are a
nuisance when you go backpacking, but I do want to be able to hike back
out to the car afterwards.

What is wrong with pacemakers that they can't make one that functions
around radios and microwaves?

Lack of space for installing the faraday cage.

Pacemakers DO function around radios and microwaves.

http://www.heart.org/HEARTORG/Condit...13_Article.jsp

Lol! Devices that have to work should be designed to work properly in
the very low level fields that occur in every day life. It's not really
hard. There are any number of engineers who can do that.

According to the article, they ARE designed to work properly in the
very low level fields that occur in everyday life and the biggest risks
are from medical equipment.

Your reference contradicts what you say. Are MP3 players "medical"
equipment?

What part of the word 'biggest' did you fail to understand?

Exactly. You didn't really say anything since you qualify it so it
means nothing. Bottom line is pacemakers have problems with common
household electronics. Not well designed I think.

--

Rick C

rickman wrote:

On 5/24/2016 1:05 AM, wrote:
rickman wrote:
On 5/23/2016 9:08 PM, wrote:
rickman wrote:
On 5/23/2016 6:52 PM, wrote:
rickman wrote:
On 5/23/2016 6:05 PM, David Ryeburn wrote:

I've kind of liked end-fed wires as antennas ever since, though
now I'm well aware of their limitations, and, with a pacemaker
inside me, I no longer dare use one. Balanced lines and center-fed
doublets are a nuisance when you go backpacking, but I do want to
be able to hike back out to the car afterwards.

What is wrong with pacemakers that they can't make one that
functions around radios and microwaves?

Lack of space for installing the faraday cage.

Pacemakers DO function around radios and microwaves.


http://www.heart.org/HEARTORG/Condit...ventionTreatme
ntofArrhythmia/Devices-that-may-Interfere-with-Pacemakers_UCM_302013_
Article.jsp

Lol! Devices that have to work should be designed to work properly in
the very low level fields that occur in every day life. It's not really
hard. There are any number of engineers who can do that.

According to the article, they ARE designed to work properly in the
very low level fields that occur in everyday life and the biggest risks
are from medical equipment.

Your reference contradicts what you say. Are MP3 players "medical"
equipment?

What part of the word 'biggest' did you fail to understand?

Exactly. You didn't really say anything since you qualify it so it
means nothing. Bottom line is pacemakers have problems with common
household electronics. Not well designed I think.

i think it is more that pacemakers *could* potentially have problems
with everyday equipment under worst-case scenarios, especially with
possible faults. They don't usually, but for obvious reasons even rare
and unlikely risks have to be considered.

--

Roger Hayter

On Mon, 23 May 2016 20:20:29 -0400, rickman wrote:

Here's the list from your reference. Notice that even MP3 players with
earbuds are a risk!

The risk is not so much any RF but rather from magnetic fields. All
the items on your list have magnets somewhere. MP3 player ear bugs
are a good start. Magnets are used to program and control a
pacemaker. A friend managed to make a mess of his pacemaker
programming with an electric drill motor.
https://www.google.com/#q=pacemaker+magnets

As for RF shielding:
"Shielded pacemaker enclosure"
http://www.google.com/patents/US5895980
See citations for more.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

rickman wrote:
On 5/24/2016 1:05 AM, wrote:
rickman wrote:
On 5/23/2016 9:08 PM, wrote:
rickman wrote:
On 5/23/2016 6:52 PM, wrote:
rickman wrote:
On 5/23/2016 6:05 PM, David Ryeburn wrote:

I've kind of liked end-fed wires as antennas ever since, though now I'm
well aware of their limitations, and, with a pacemaker inside me, I no
longer dare use one. Balanced lines and center-fed doublets are a
nuisance when you go backpacking, but I do want to be able to hike back
out to the car afterwards.

What is wrong with pacemakers that they can't make one that functions
around radios and microwaves?

Lack of space for installing the faraday cage.

Pacemakers DO function around radios and microwaves.

http://www.heart.org/HEARTORG/Condit...13_Article.jsp

Lol! Devices that have to work should be designed to work properly in
the very low level fields that occur in every day life. It's not really
hard. There are any number of engineers who can do that.

According to the article, they ARE designed to work properly in the
very low level fields that occur in everyday life and the biggest risks
are from medical equipment.

Your reference contradicts what you say. Are MP3 players "medical"
equipment?

What part of the word 'biggest' did you fail to understand?

Exactly. You didn't really say anything since you qualify it so it
means nothing. Bottom line is pacemakers have problems with common
household electronics. Not well designed I think.

Whatever.

--
Jim Pennino

On Thu, 19 May 2016 11:07:03 -0700, Mike Ross wrote:

On Thursday, October 8, 2015 at 8:28:38 AM UTC-4, gareth wrote:
"joe" wrote in message
...
gareth wrote:

I have in my possession a book entitled, "Antennae", published in
1942 by a lecturer to both King's College, London, and also to
various Brit government establishments.

At some point since then, the ignorance of either engineers or of
Yanks has tried to pass off, "Antennas" as the plural.

If we pride ourselves on the exactness of our principles, then it is
high time to correct this glaring error by the Yanks.

(Book being studied avidly, although with some necessary revision ov
vector field theory; div, curl and grad, anyone?)

From an online dictionary:

I guess that it would be a fair assumption, bearing in mind the
development of computers and, much later, the Internet, that your
online dictionaries originated several decades after 1942, and long
after the ignoramuses' error arose?

Um, wouldn't that be "ignorami"??


Clearly the attempt of a person lacking even the most elemental education
in the classics. The Latin word ignoramus is not a noun, and so cannot
be declined. Even if it were, its genitive plural is somthing quite
different.

--
Suspect someone is claiming a benefit under false pretences? Incapacity
Benefit or Personal Independence Payment when they don't need it? They are
depriving those in real need! https://www.gov.uk/report-benefit-fraud

On Sun, 31 Jul 2016 21:34:44 +0000 (UTC), Brian Reay wrote:
On Thu, 19 May 2016 11:07:03 -0700, Mike Ross wrote:
On Thursday, October 8, 2015 at 8:28:38 AM UTC-4, gareth wrote:
"joe" wrote:
gareth wrote:

I have in my possession a book entitled, "Antennae", published in
1942 by a lecturer to both King's College, London, and also to
various Brit government establishments.

At some point since then, the ignorance of either engineers or of
Yanks has tried to pass off, "Antennas" as the plural.

If we pride ourselves on the exactness of our principles, then it is
high time to correct this glaring error by the Yanks.

(Book being studied avidly, although with some necessary revision ov
vector field theory; div, curl and grad, anyone?)

From an online dictionary:

I guess that it would be a fair assumption, bearing in mind the
development of computers and, much later, the Internet, that your
online dictionaries originated several decades after 1942, and long
after the ignoramuses' error arose?

Um, wouldn't that be "ignorami"??

Clearly the attempt of a person lacking even the most elemental education
in the classics. The Latin word ignoramus is not a noun, and so cannot
be declined. Even if it were, its genitive plural is somthing quite
different.

Please, God, let this thread die!