nuckolls.bob(at)aeroelect
Guest
|
 Posted: Sun Jul 18, 2010 10:45 am Post subject: To balun or not to balun, that IS the question |
 |
|
There are a variety of ways to fabricate a balun
and some are preferred depending on the impedance
matching task (1:1 vs 4:1). The balun shown in 43-13
is one way to do it but I selected the device I published
because it was easier to build.
One has to be cautious of 43-13 data. For example,
on pages 28 and 29 they make references to "airframe
ground" . . . on p28, they suggest 4 connections to
the airframe.
From a radio frequency performance these grounds are
not necessary/helpful. On a type certificated airplane
one is not allowed to placard the airplane thusly:
WARNING: THIS AIRCRAFT IS NOT QUALIFIED TO
WITHSTAND DIRECT LIGHTNING STRIKES OF ANY
MAGNITUDE. FLIGHT INTO OR IN VICINITY OF
CONVECTIVE WEATHER OFFERS SUBSTANTIAL RISK
OF HAZARD FROM LIGHTNING AND OTHER UGLY
FORCES. ONE IS STRONGLY ADVISED TO REDUCE
RISK BY MAINTAINING COMFORTABLE SPACING FROM
SUCH CONDITIONS.
So, the dedicated acolyte to all things FAR will
feel compelled to add "airframe grounds" to things
that stick out in the breeze on plastic airplanes.
This is irrespective of the fact that at least
couple dozen paragraphs describing "Lightning Quality
Grounds" is necessary to assist the reader in crafting
effective connections for such purposes.
In any case, either balun is a 1:1 line impedance
transformer so it's your choice. Don't worry about
the "airframe ground" . . . unless you enjoy
the excitement of Mother Nature's roller coaster
rides.
Bob . . .
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
