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Becker transponder

hotrod180

hotrod180

FRIEND
Port Townsend, WA
A friend of mine put a Becker txp in the Luscombe 8E he just finished restoring.
It has an altitude display on it that always reads low, sometimes way low.
Turns out that apparently it displays the 'pressure altitude"--
in other words, it matches the altimeter only IF you set the alt at 29.92".

He'd like to just eliminate the altitude display.
He bought the txp used so no manual.
We found an online manual but it isn't helpful.
Anyone have one of these who can enlighten me on how to do that?
 
Have you tried turning the selector to 'ON' instead of 'ALT'? 'ON' is mode A (just the code) and 'ALT' is mode C (code plus pressure altitude).

The reason that it displays pressure altitude only is because altitude is fed to the transponder by the altitude encoder, which reads out ONLY pressure altitude.

Web
 
hotrod180 said:
A friend of mine put a Becker txp in the Luscombe 8E he just finished restoring.
It has an altitude display on it that always reads low, sometimes way low.
Click to expand...

"The sunlight readable display is illuminated for night operations. The display shows in addition to the transponder code also the current flight level, if an encoding altimeter is connected and Mode-C is selected."

Disabling mode C seems like a very poor solution to an almost non existent problem.

Why can't your friend simply learn what the display is indicating and ignore it if not interested in that data. If all else fails cover that area of the display with black tape.
 
wireweinie said:
Have you tried turning the selector to 'ON' instead of 'ALT'? 'ON' is mode A (just the code) and 'ALT' is mode C (code plus pressure altitude).

The reason that it displays pressure altitude only is because altitude is fed to the transponder by the altitude encoder, which reads out ONLY pressure altitude.

Web
Click to expand...

Mode C is required in transponder-required airspace.
 
If the altitude isn't displayed on the transponder does that affect its airworthiness or TSO compliance or???? I like having it displayed, because it is a quick and dirty check of the encoder.
 
Gordon Misch said:
If the altitude isn't displayed on the transponder does that affect its airworthiness or TSO compliance or???? I like having it displayed, because it is a quick and dirty check of the encoder.
Click to expand...

Nothing illegal about that, that I can figure, but I'd want the pressure altitude displayed. If for nothing else, to keep tabs on what's being transmitted. Whatever blows your skirt up.

Web
 
wireweinie said:
You want the altitude to be sent out but you don't want it to display?

Web
Click to expand...

Not my airplane, but my buddy the owner would rather not have the pressure altitude displayed,

As far as knowing what you're transmitting,
I occasionally ask the controllers at the nearby Naval Air Station for a mode C check.
They always give me one, no sweat, so then I know exactly what they're getting.
And no more trouble than setting the altimeter to 29.92 to compare with the txp display,
and then back again.
 
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