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Dummy loads (fyi)

 
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nuckolls.bob(at)aeroelect
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PostPosted: Wed Dec 20, 2023 4:48 am    Post subject: Dummy loads (fyi) Reply with quote

Quote:

The PEAK power from a transponder is indeed
'high' . . . on the order of 150 to 200 watts.
But this is pulsed power lasting mere microseconds
per reply.

Dummy loads are available for a huge
range of power. Some are fitted with
power meters. Here's one example.

http://tinyurl.com/253rwzaf

These devices will indicate power output
for the system under test. They're
rated for up to 40 watts full scale.

Attached to your VHF Comm transmitter,
they would read something on the order
of 5 to 10 watts AVERAGE POWER while
transmitting.

Attached to a REALLY excited transponder,
you would barely see the needle wiggle.

Another data point for testing a powered
up transponder. It doesn't put out any
signal until interrogated by a surveilling
ground station . . . this is what triggers
the 'reply' annunciator. So unless your
reply light is active, the dummy load has
nothing to do. The dummy load also prevents
the transponder from SEEING a ground
station. So even when testing in
vicinity of such facilities, the dummy
load prevents the transponder
from reacting to radar interrogation
pulses.



Bob . . .

////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================

In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.


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rv8iator



Joined: 11 Apr 2006
Posts: 144
Location: Newberg, OR

PostPosted: Wed Dec 20, 2023 6:39 am    Post subject: Dummy loads (fyi) Reply with quote

Bob,Excellent info.  I'm a bit smarter now, a good thing!  As are others reading this!
.chris
On Wed, Dec 20, 2023 at 4:50 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
Quote:

  The PEAK power from a transponder is indeed
  'high' . . . on the order of 150 to 200 watts.
  But this is pulsed power lasting mere microseconds
  per reply.

  Dummy loads are available for a huge
  range of power. Some are fitted with
  power meters. Here's one example.

http://tinyurl.com/253rwzaf

  These devices will indicate power output
  for the system under test. They're
  rated for up to 40 watts full scale.

  Attached to your VHF Comm transmitter,
  they would read something on the order
  of 5 to 10 watts AVERAGE POWER while
  transmitting.

  Attached to a REALLY excited transponder,
  you would barely see the needle wiggle.

  Another data point for testing a powered
  up transponder. It doesn't put out any
  signal until interrogated by a surveilling
  ground station . . . this is what triggers
  the 'reply' annunciator. So unless your
  reply light is active, the dummy load has
  nothing to do. The dummy load also prevents
  the transponder from SEEING a ground
  station. So even when  testing in
  vicinity of such facilities, the dummy
  load prevents the transponder
  from reacting to radar interrogation
  pulses.



  Bob . . .

                   ////
                  (o o)
   ===========o00o=(_)=o00o=========
   < Go ahead, make my day . . .   >
   < show me where I'm wrong.      >
   =================================
 
   In the interest of creative evolution
   of the-best-we-know-how-to-do based
   on physics and good practice.



- 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

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C. Stone (RV8iator)
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