REFLECTOR:Transponder Ant , ground and family jewels

[Bob Kuc]

If you look at this site: http://www.matronics.com/digest/aeroelectric-list/
this has all the archives from there.  There was lengthly discussions about
"family jewels" on 3/10 and few days after.


It starts talking about ground planes and such and naturally went to family
jewels.  Here is an exerpt from 3/10 and response frm Bob N.



Time: 05:42:27 PM PST US
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: AeroElectric-List: Re: defending the "familiy jewels" . . .

--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>

At 08:54 PM 3/10/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: Rino <lacombr@nbnet.nb.ca>
>
>A transponder antenna that close to your passengers "private parts"
>might not be the best thing to do. The radiation may do some damage.
>
>Rino

   A hangar myth. Folks have looked at the
   peak output power rating of a transponder (100 to 250W)
   and tried to make a connection between a desire to
   make one's airplane visible to a distant radar receiver
   and cooking meat.

   When you buy a microwave, it too is rated in the
   hundreds of watts . . . but CONTINUOUS duty. A
   good 700W microwave will boil a cup of water in
   about 2 minutes. (Remember the traveler's immersion
   heaters in the hardware store? They're 300W heaters
   and take about 4 minutes to boil a cup of water).
   If you measure the current draw of this machine,
   it will be on the order of 8-9 amps or 1000W total
   input.

   Your transponder draws about 1.5 amps while being
   interrogated for a total input power of 18W. The
   output comes in the form of a series of 0.5 uSec
   pulses in respond to an interrogation that represent
   a string of binary numbers representing either your
   squawk code (mode A) or altitude (mode C). Assuming
   you are interrogated once per second (quite often)
   your average output power for a 250W transponder
   is on the order of 250W x 20 pulses x 0.0000005
   seconds/1 second or 2.5 milliwatts per second.
   This isn't going even going to warm up much less cook
   anything.

   Another fallacy of the myth concerns body parts
   most sensitive to microwave radiation . . . turns
   out that your eyes are the most vulnerable . . .
   but the story isn't nearly so interesting to
   really macho pilots. None the less, there are
   folks who have armor-shielded their seat bottoms
   in deference to this myth. The story was REALLY
   popular about 15 years ago in the heyday of
   the Long-Ezs

   Here's a post I did on a canard pusher list
   server about 5 years ago:

 > Location away from the pilot/co-pilot is also
 >recommended but over ten feet requires a different cable. Yes?? I was
 >thinking about locating it aft of the pilot in the baggage area. Is that
 >distance safe?

   A totally bogus recommendation. A few years back, someone observed
   that their transponder was rated for 200 watts output . . . 1/3rd
   that of the family microwave. Our hero was immediately concerned for
   preservation of the family jewels and proceeded to line the bottom
   of his composite seat pan with aluminum foil. What he failed to
   understand was that his RF coffee warmer and popcorn popper was
   rated in continuous watts while the transponder was in peak watts.
   The average power output from a transponder is less than 1 watt . . .
   BTW, the eyes are about 100 times more sensitive to the effects of
   microwave heating than are any deep organs . . . you'll go blind
   you quit making babies.

        Bob . . .

                        ////
                       (o o)
        ===========o00o=(_)=o00o=========

----- Original Message -----
From: "Fred Marconi" <fmarconi@bellsouth.net>
To: <reflector@tvbf.org>
Sent: Friday, April 11, 2003 2:48 PM
Subject: Re: Transponder Ant. was Re: REFLECTOR:anntenas


> Scott:
>
> I believe that when I looked at the information in Bob Knuckoll's manual
> this is what he suggested I went a little larger since I had the space.  I
> placed my antenna between the main gear bulkhead and the transverse piece
> that hold the bellcrank assembly for the ailerons.  Plenty of room there.
>
> Fred
>
> www.aeroelectric.com
>
>