Ttransponder question #3

Newps wrote:
If the transponder is already warm then it will transmit right away.
It's not a process that has to be repeated because the switch was turned
to STBY and back.

That's true if you go to STBY and back, but not neccessarily true if you
go to OFF and back. I know for a fact that my fairly new KT-76A will stop
replying for 30 seconds if I cycle it to OFF and back, even if it's
already warm. I don't think the transponders actually check for
warmth. They just wait the 30 seconds after each power on from OFF.

--- Jay


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On 16 Sep 2005 01:08:10 GMT, (Jay Masino)
wrote in ::

I don't think the transponders actually check for warmth.

A transponder contains what is termed a Crystal Oven. This is a small
chamber in which there is a heating element and a quartz crystal used
to determine the transponder's transmission frequency. It takes time
for the oven to bring the crystal up to the specific temperature to
which it is set. If the oven were not thermostatically controlled, it
would not be able to provide a stable reference frequency at all
ambient temperatures in which the transponder operates.

"Larry Dighera" wrote:

I don't think the transponders actually check for warmth.

A transponder contains what is termed a Crystal Oven. This is a
small
chamber in which there is a heating element and a quartz crystal
used
to determine the transponder's transmission frequency.

Which brands/models have that feature?? The frequency accuracy
required by the TSO can be and is achieved without a crystal oven.

The built-in turn-on delay is merely to allow the high-voltage
supply to come up to full volts, and the cavity tube filament to
heat up.

Fred F.

TaxSrv wrote:
A transponder contains what is termed a Crystal Oven. This is a small
chamber in which there is a heating element and a quartz crystal used
to determine the transponder's transmission frequency.

Which brands/models have that feature?? The frequency accuracy
required by the TSO can be and is achieved without a crystal oven.

The built-in turn-on delay is merely to allow the high-voltage
supply to come up to full volts, and the cavity tube filament to
heat up.

Be that as it may, I believe most transponders just wait a static timeout
amount (30-45 sec), whenever transitioned from OFF to ON, even if you've
already had it on.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

Be that as it may, I believe most transponders just
wait a static timeout amount (30-45 sec), whenever
transitioned from OFF to ON, even if you've
already had it on.

--- Jay


Is simply what they do. The microprocessor in the Kings invariably
sets the delay; Narco merely first charges up a capacitor which
takes about 30 sec. So, whether she needs "warm-up" or not, it
can't xmit until the light goes out.

Fred F.

TaxSrv wrote:
Is simply what they do. The microprocessor in the Kings invariably
sets the delay; Narco merely first charges up a capacitor which
takes about 30 sec. So, whether she needs "warm-up" or not, it
can't xmit until the light goes out.

We're arguing the same side of the discussion (ie, we're in aggreement).


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

I wrote to Bendix-King and they confirm there is a built in delay when
tuning on the KT-78 transponder. I would suspect it would apply to others.


-------------
Regards, Ross
C-172F 180HP
KSWI


TaxSrv wrote:
Be that as it may, I believe most transponders just
wait a static timeout amount (30-45 sec), whenever
transitioned from OFF to ON, even if you've
already had it on.

--- Jay



Is simply what they do. The microprocessor in the Kings invariably
sets the delay; Narco merely first charges up a capacitor which
takes about 30 sec. So, whether she needs "warm-up" or not, it
can't xmit until the light goes out.

Fred F.

On Fri, 16 Sep 2005 08:22:53 -0400, "TaxSrv" wrote
in ::

"Larry Dighera" wrote:

I don't think the transponders actually check for warmth.

A transponder contains what is termed a Crystal Oven. This is a
small
chamber in which there is a heating element and a quartz crystal
used
to determine the transponder's transmission frequency.

Which brands/models have that feature?? The frequency accuracy
required by the TSO can be and is achieved without a crystal oven.

The built-in turn-on delay is merely to allow the high-voltage
supply to come up to full volts, and the cavity tube filament to
heat up.

Fred F.


It was a long time ago that I was having difficulty with ATC receiving
the Mode-C of our King KT-78a. Now that you mention it, it was the
Mode-C blind encoder that had the heater in it, not the transponder.