Hi All,
I have a TB20 (an IFR certified aircraft) and wish to fit a backup oil
pressure gauge.
The instrument I am putting in is the miniature 1.2" TSOd one from UMA
Instruments. It is done as a minor mod and the IA doesn't see a
problem.
However, the backlighting is implemented with an electroluminescent
element inside the instrument, and requires a separate inverter. I
have this too (it isn't TSOd but is PMAd) and while it works, it draws
a lot of power (2.5 watts) which is dissipated mostly inside the
inverter, making it run hot, so it needs to be mounted to the airframe
or something similar. This is also OK, but I am concerned about the
emissions from the inverter and its wiring: it generates about 300V
RMS at about 2.5kHz and the output waveform isn't exactly clean, and I
am concerned about some subtle effect on other avionics. Obviously all
wiring will be screened but one can never tell.
In short, do I *have* to install this inverter? Is a backlight
mandatory on a backup instrument?
What about connecting the inverter via a switch?
Why they just didn't use some LEDs I don't know........
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