Transponder output power

[rocketflyer84]

Just a curious technical question. Com radios typically have an output of 10-15 watts but I was surprised to see that the transponder radio has an output of around 250 watts. Why does the transponder put out such a strong signal (relative to comms). Would have expected a bit more perhaps but don't understand why it's like 20x com radio power.

If an avionics expert could shine some light I'd much appreciate!

 

[weirdjim]

Just a curious technical question. Com radios typically have an output of 10-15 watts but I was surprised to see that the transponder radio has an output of around 250 watts. Why does the transponder put out such a strong signal (relative to comms). Would have expected a bit more perhaps but don't understand why it's like 20x com radio power.

If an avionics expert could shine some light I'd much appreciate!

If you are talking with your friend a few feet away, you use a normal (10 watt) tone of voice.

HOWEVER, if you want to be heard by your friend a block away, you do a very short screechy whistle very loud (250 watts) and then a long silence.

The AVERAGE power is roughly the same, but the screech only needs to be on for a very short time and then off for a very long time to get your friend's attention.

The peak power may be 250 watts, but the average power (averaged over a few seconds or minutes) is a couple of watts.

OK?

Jim

 

[rocketflyer84]

Got it, makes sense. Thanks!

 

[N801BH]

If you are talking with your friend a few feet away, you use a normal (10 watt) tone of voice.

HOWEVER, if you want to be heard by your friend a block away, you do a very short screechy whistle very loud (250 watts) and then a long silence.

The AVERAGE power is roughly the same, but the screech only needs to be on for a very short time and then off for a very long time to get your friend's attention.

The peak power may be 250 watts, but the average power (averaged over a few seconds or minutes) is a couple of watts.

OK?

Jim

Great description....

 

[unsafervguy]

If you are talking with your friend a few feet away, you use a normal (10 watt) tone of voice.

HOWEVER, if you want to be heard by your friend a block away, you do a very short screechy whistle very loud (250 watts) and then a long silence.

The AVERAGE power is roughly the same, but the screech only needs to be on for a very short time and then off for a very long time to get your friend's attention.

The peak power may be 250 watts, but the average power (averaged over a few seconds or minutes) is a couple of watts.

OK?

Jim

jim,
your classes must be great, i love how you can take electronic theory and describe it in everyday ways.

bob

 

[weirdjim]

I have two plaques/posters in the front of my classroom, one on the left bulletin board and one on the right:

1. Lo, though I walk through the valley of the shadow of Education
I fear no student
For I am the meanest Son Of A ***** in the Valley.

2. If you can read this thank a teacher.
If you can read it in English, thank a Veteran.

​

And yes, I have fun in the classroom. If I weren't having fun, I'd do something else for a living

Jim