Transponder vs. Portable Transponder Detectors

On Mon, 15 Dec 2008 07:46:04 -0800, Andy wrote:

I'm quite sensitive to this at the moment as my airplane has developed a
problem that causes the mode C report to sometimes be thousands of feet
in error until the transponder or encoder warm up.

Try a new battery. I had the same symptoms with a Becker + Ameriking
encoder. A new battery made them go away.

Ian

On Dec 16, 12:32*am, Ian wrote:

Try a new battery. I had the same symptoms with a Becker + Ameriking
encoder. A new battery made them go away.

Thanks for the tip but this is a PA28-180 with an alternator. Problem
was intermittent last winter, gone in the summer, and back again now
winter is here. I'm in the middle of some cold soak testing but
results so far point to the encoder (ACK A-30).

Andy

On Dec 15, 7:46*am, Andy wrote:

...I'm quite sensitive to this at the moment as my airplane has developed
a problem that causes the mode C report to sometimes be thousands of
feet in error until the transponder or encoder warm up.

Check the encoder manual to see if the encoder has a built-in heating
coil (many do). If so, also check that it is getting power.

Thanks, Bob K.

On Dec 16, 12:53*pm, Bob Kuykendall wrote:
On Dec 15, 7:46*am, Andy wrote:

...I'm quite sensitive to this at the moment as my airplane has developed
a problem that causes the mode C report to sometimes be thousands of
feet in error until the transponder or encoder warm up.

Check the encoder manual to see if the encoder has a built-in heating
coil (many do). If so, also check that it is getting power.

Thanks, Bob K.

The ACK-30 around room temperature should draw around 9mA/12V once in
steady state. Throw it in your freezer in a plastic bag and get it
really cold, with the heater warming up it should draw about 400mA/12V
(for ~minute or so).

Darryl

Darryl Ramm wrote:
On Dec 16, 12:53 pm, Bob Kuykendall wrote:
On Dec 15, 7:46 am, Andy wrote:

...I'm quite sensitive to this at the moment as my airplane has developed
a problem that causes the mode C report to sometimes be thousands of
feet in error until the transponder or encoder warm up.
Check the encoder manual to see if the encoder has a built-in heating
coil (many do). If so, also check that it is getting power.

Thanks, Bob K.

The ACK-30 around room temperature should draw around 9mA/12V once in
steady state. Throw it in your freezer in a plastic bag and get it
really cold, with the heater warming up it should draw about 400mA/12V
(for ~minute or so).

It's not quite that good, unfortunately: according to the manual,
operating current is 60 ma; the time to warm up from 0 F is 210 seconds.
I can't find the source of the numbers, but the heater will continue to
draw heater current at 0 deg F, with a total draw around 90-100 milliamps.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Dec 16, 6:46*pm, Eric Greenwell wrote:
Darryl Ramm wrote:
On Dec 16, 12:53 pm, Bob Kuykendall wrote:
On Dec 15, 7:46 am, Andy wrote:

...I'm quite sensitive to this at the moment as my airplane has developed
a problem that causes the mode C report to sometimes be thousands of
feet in error until the transponder or encoder warm up.
Check the encoder manual to see if the encoder has a built-in heating
coil (many do). If so, also check that it is getting power.

Thanks, Bob K.

The ACK-30 around room temperature should draw around 9mA/12V once in
steady state. Throw it in your freezer in a plastic bag and get it
really cold, with the heater warming up it should draw about 400mA/12V
(for ~minute or so).

It's not quite that good, unfortunately: according to the manual,
operating current is 60 ma; the time to warm up from 0 F is 210 seconds.
I can't find the source of the numbers, but the heater will continue to
draw heater current at 0 deg F, with a total draw around 90-100 milliamps..

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Oh doh, that as a typo. Should have been the 90mA no 9mA, which is
what I think I had measured but the manual says 60mA. May just depend
on ambient temp of how power consumption is averaged.

Darryl

On Tue, 16 Dec 2008 11:44:19 -0800, Andy wrote:

Thanks for the tip but this is a PA28-180 with an alternator. Problem
was intermittent last winter, gone in the summer, and back again now
winter is here. I'm in the middle of some cold soak testing but results
so far point to the encoder (ACK A-30).

I have no experience with aircraft with engines. But it seems these
encoders can put out nonsense flight level data. Your experience -
Winter, mine - dying battery, seem to indicate that it does this when it
is not warm enough.

Whatever the fix, it is worth knowing that this can happen. Does yours
come right once it has been running a while?

Ian