2 deg. C too high

I just replaced an old probe and receiver for a Digital Davtron 301c.
My old one started reading cabin temp and I simply replaced it
altogether (probe and receiver). My new one seems to read 2 deg. C too
high. Any ideas? The probe is hard-wired from the factory (so, the
probe is correct). The probe is mounted through the sidewall near the
pilot fresh-air intake. Oh by the way, the plane is fiberglass:
Glasair II. I have compared the reading to other planes on the field
and mine is consistently 2 deg. high. Hard to find anyone at my
altitude to compare in-flight.

Also, I have only been flying for about 4 years, 3 instrument rated but
have had an idea: doesn't is seem that it would be more advantagous,
for atc, to use calculated ground speed instead of TAS when filing?
Expecially in this age of not-complete but prolific radar coverage and
pretty accurate winds aloft models? Just a thought.

Check Davtron's site or the manual to see if you can adjust it. If I'm
remembering correctly, I checked mine in ice water and adjusted it
accordingly before installing it. Sorry I can't remember where the
adjustment screw is located, but I think you have to remove the rear case to
access it.
Jim

Grandmaster,

My new one seems to read 2 deg. C too
high. Any ideas? The probe is hard-wired from the factory (so, the
probe is correct).


How do you arrive at the conclusion that the probe is correct? We have
the same problem with a Davtron probe, only with 3 degrees too high. It
displays on our GTX330 and through that, the Garmin 430. We are told by
Davtron that +/- 3 degrees is about the tolerance of the probe and that
there is no way to correct it. There is also no way to program an
offset into the GTX330, although that would be the easy way to correct
it. IMHO, the probe is wrong.

--
Thomas Borchert (EDDH)

TAS can be used by ATC for the purpose of planning IFR separation,
because aircraft in the general vacinity of each other will have about
the same wind aloft.

Even with perfect wind aloft forecast, an aircraft on a very long
flight will have a planned average groundspeed that's based on wind
aloft along many sectors, and wind might be very different in each
sector. Such groundspeed can not be directly compared with the planned
average groundspeed on another aircraft on a much shorter flight along
the same route.

Grandmaster wrote:

Also, I have only been flying for about 4 years, 3 instrument rated but
have had an idea: doesn't is seem that it would be more advantagous,
for atc, to use calculated ground speed instead of TAS when filing?
Expecially in this age of not-complete but prolific radar coverage and
pretty accurate winds aloft models? Just a thought.

Using groundspeed would be a good idea and almost all of us do use it
to some extent, getting it from our GPS. It is much more accurate than
an airspeed indicator. But for ATC to use it EVERYONE would have to
have it and that's not the case. Some planes still don't have a GPS.

From the factory, my probe came hard-wired internally to the head. 3
deg. C seems like a very loose tolerance.


Thomas Borchert wrote:
Grandmaster,

My new one seems to read 2 deg. C too
high. Any ideas? The probe is hard-wired from the factory (so, the
probe is correct).


How do you arrive at the conclusion that the probe is correct? We have
the same problem with a Davtron probe, only with 3 degrees too high. It
displays on our GTX330 and through that, the Garmin 430. We are told by
Davtron that +/- 3 degrees is about the tolerance of the probe and that
there is no way to correct it. There is also no way to program an
offset into the GTX330, although that would be the easy way to correct
it. IMHO, the probe is wrong.

--
Thomas Borchert (EDDH)

Grandmaster,

3
deg. C seems like a very loose tolerance.


I agree.

--
Thomas Borchert (EDDH)

My installer put in an adjustable resistor, or something. I can adjust it
with a tiny screwdriver. It was installed inline and right next to the
probe. He says thatey all indicate wrong.

Karl
"Curator" N185KG
"Grandmaster" wrote in message
ups.com...
I just replaced an old probe and receiver for a Digital Davtron 301c.
My old one started reading cabin temp and I simply replaced it
altogether (probe and receiver). My new one seems to read 2 deg. C too
high. Any ideas? The probe is hard-wired from the factory (so, the
probe is correct). The probe is mounted through the sidewall near the
pilot fresh-air intake. Oh by the way, the plane is fiberglass:
Glasair II. I have compared the reading to other planes on the field
and mine is consistently 2 deg. high. Hard to find anyone at my
altitude to compare in-flight.

Also, I have only been flying for about 4 years, 3 instrument rated but
have had an idea: doesn't is seem that it would be more advantagous,
for atc, to use calculated ground speed instead of TAS when filing?
Expecially in this age of not-complete but prolific radar coverage and
pretty accurate winds aloft models? Just a thought.

Karl,

My installer put in an adjustable resistor, or something. I can adjust it
with a tiny screwdriver. It was installed inline and right next to the
probe. He says thatey all indicate wrong.


Do you have any more details about what exactly was installed? I'd be very
interested.

--
Thomas Borchert (EDDH)

so would I



Thomas Borchert wrote:
Karl,

My installer put in an adjustable resistor, or something. I can adjust it
with a tiny screwdriver. It was installed inline and right next to the
probe. He says thatey all indicate wrong.


Do you have any more details about what exactly was installed? I'd be very
interested.

--
Thomas Borchert (EDDH)