Adam, are you measuring that right at the probe or is there something in the middle?

I have not had anything like this occur with my EI probes.   I did however have a lot of problems with the previous (old) princeton converters.   If memory serves, these convert from freq to 0-5V.   The new 10-point Princeton converters have been great.

On Sep 4, 2012, at 4:18 PM, <marv@lancair.net> <marv@lancair.net> wrote:

Posted for Adam Molny <Adam@ValidationPartners.com>:

My EI fuel probes output a square wave whose frequency is proportional to
fuel level. Before installation, bench testing showed that the probes put
out 4kHz when dry and 2kHz when full. I calibrated my Dynon SkyView
accordingly. Now, at 70 hours the left probe has become unreliable. A few
weeks ago the frequencies changed to 3kHz empty and 2kHz full. I calibrated
the Dynon, but now the probe is putting out 3kHz when full.

Has anyone had similar problems? I'll have to remove the left wing to get
the probe out, so I'd like to have a plan of action first.

Thanks,
Adam Molny
 Legacy N181AM
 72 hours hobbs time

[We have an EI capacitive probe on our test stand and noticed that it is subject to large swings relative to temperature.  Not the probe itself, but rather the oscillator module whose frequency is driven by the probe.  The easiest way for me to fill our 280 gallon tank is to pull the truck out into the Florida sunshine and expose the oscillator to full sunlight... soon as it heats up the tank tops itself right off... damnedest thing you ever saw.  Only problem is it won't stay full.   <Marv>   ]

--

For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html