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.

Interesting. I always left mine in standby to allow for warm up before
going to ALT and transmitting. You mean I can just leave the sucker on
all the time? Mine is an old King KT-78.


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


Jay Masino wrote:
Ross Richardson wrote:

What do you do when requested to "recycle" your transponder?


I check to see if something isn't set correctly, but othewise I don't do
anything. Turning the transponder off and on again practically guarantees
that it won't transmit for 30 to 45 seconds, because all modern
transponders are build to wait that long, before starting to transmit, to
allow for warm-up.

--- Jay

I'm not real sure on this, perhaps one of the electro-geeks will correct
whatever I get wrong.

My understanding is that older transponders used something called a "cavity
tube" that had a relatively short life and was expensive to replace.

Supposedly, when the transponder was on "Standby" the cavity did not age as
much as it did when "On".

Which meant that you were using up the "expensive" hours flying, when the
transponder was not needed, and saving them during ground operations.

Supposedly, newer solid-state transponders don't suffer from this lifetime
limitation.

Again, I'm not 100% sure on this...please feel free to correct me if I'm
wrong...




"Ross Richardson" wrote in message
...
Interesting. I always left mine in standby to allow for warm up before
going to ALT and transmitting. You mean I can just leave the sucker on
all the time? Mine is an old King KT-78.


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


Jay Masino wrote:
Ross Richardson wrote:

What do you do when requested to "recycle" your transponder?


I check to see if something isn't set correctly, but othewise I don't do
anything. Turning the transponder off and on again practically
guarantees
that it won't transmit for 30 to 45 seconds, because all modern
transponders are build to wait that long, before starting to transmit,
to
allow for warm-up.

--- Jay

"Lakeview Bill" wrote:

My understanding is that older transponders used
something called a "cavity tube" that had a relatively
short life and was expensive to replace.

Supposedly, when the transponder was on "Standby"
the cavity did not age as much as it did when "On".


Where a cavity tube is used, "standby" does not extend the life of
the tube. On any xpondr, it merely inhibits any reply pulses from
being sent to the xmit section, be it a tube or transistors.

Fred F.

look at the code to make sure it is set correctly..
check to see if the interrogator/response light is flashing
check to make sure it is in transmit and not left in "Standby"
if in transmit, move to standby and back on
BT

"Ross Richardson" wrote in message
...
What do you do when requested to "recycle" your transponder?

--


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

Ross Richardson wrote in news:kNkWe.8$F94.5
@dfw-service2.ext.ray.com:

What do you do when requested to "recycle" your transponder?


Cycle it off and then on again.

Put it in the green bin on trash day.

.... after making sure that there's a number 1 or 2 inside a triangle on
the bottom.

Ross Richardson wrote:
What do you do when requested to "recycle" your transponder?

I was told that was the ATC's way of saying, "Hey...you forgot to switch
your transponder to ALT before you took off!" without embarrassing you.