Heated pitot installation/testing: does it work?

[MHV]

I installed the Dynon heated pitot tube and controller in my 601XL wing and am testing the wiring. I connected the ground wire and verified that 12 Volt is measured between the indicator wire and the 12 Volt supply. Then I connected the supply line (red) to the 12 Volt battery, the indicator wire kept indicating 12 Volt, and a soft hum was heard from the controller. I didn't feel any temperature increase on the pitot. Then I measured the current that flows into the controller, after some some jumping back and forth between 80 and 150 mA the current settles at only 159 mA.
The current seems too low and I don't feel any temperature increase on the pitot. Wiring seems to be connected correctly and I measure ~12 Volt between red and black wire. Wires between controller and pitot are all connected. Any ideas what to verify next ?

 

[dynonsupport]

Re: Heated pitot installation/testing: does it wor

A few things to test:

Do you actually have a light hooked up to the indicator wire? If so, does it flash at all?

Next - from what you've said, it sounds like you may have a problem with the heated pitot itself, and not the controller box. So, here are a few things to measure on the heated pitot itself (all measurements should be made with power off, of course)

-The resistance between the two white wires.
-The resistance between the black and orange wires
-The resistance between the black and blue wires
-The outside air temperature during the time you take your measurements?

Alternatively, we could take a look at the pair of them here. If you'd like to do that instead, give us a call at 425-402-0433.

 

[MHV]

Re: Heated pitot installation/testing: does it wor

Thanks for the reply, I didn't have an actual light connected to the indicator wire, I just had my voltmeter connected and it remained at 12 Volt, I will add a proper light this evening. Is the load on this line of any importance?
I will preform the requested resistance measurements, no problem, but since the documentation didn't mention any values I would not have known what proper values were.
Outside air temperature; its still nice and cool so I can still get things done here in San Antonio, I would say around 70-75 degrees

Regards,
Maarten

 

[dynonsupport]

Re: Heated pitot installation/testing: does it wor

Different values will indicate different failure modes. Post back what you measure, and we'll see what we can come up with.

As for the light - any light that can take 12V will do. It can handle up to an amp

 

[MHV]

Re: Heated pitot installation/testing: does it wor

Success today. I connected a proper little LED light to the indicator wire and now used a slightly havier battery. When just connecting the ground and indicator the lamp came on. Then I connected the power wire and the supply voltage dropped to 10.8 volt and the lamp went off. I verified the pitot and it got warm. The current flowing in the circuit was 450 mA.
I assume that the battery I used yesterday had too little capacity and the voltage dropped too far. I was using two new 6 Volt lantern batteries but maybe they were too old.
To add to my information package, the room temperature was ~75 deg and the white wires measured 8.7 kohm and both between black and orange and black and blue I measured 3.5 ohm.

Thanks,
Maarten