mode c intermittent

I had a similar problem in mine, then it got worse. Trouble was whenever
it was in the shop, it was working. Finally some guy thought to gently
heat gun the thing and found the failed part. I think it was a capacitor
that when warm, stopped working. It's had other problems too, like that
expensive final transistor going.

Just my experience....

John

skyav8r wrote:
Howdy,
I have an Aeromech 8140B20 encoding altimeter with a KT76 transponder.
Mode C is intermittent with ATC. Is it more than likely this is an
altimeter problem or transponder problem? Sometimes when it is not
reporting, i cycle the transponder off then back on and it starts
reporting again. Thanks in advance,
Brian
Also, sould an aeromech and aerosonic encoding transponder interchange
as far as the connections are concerned?

The Visitor wrote:
I had a similar problem in mine, then it got worse. Trouble was whenever
it was in the shop, it was working. Finally some guy thought to gently
heat gun the thing and found the failed part. I think it was a capacitor
that when warm, stopped working. It's had other problems too, like that
expensive final transistor going.

Just my experience....

John

skyav8r wrote:
Howdy,
I have an Aeromech 8140B20 encoding altimeter with a KT76 transponder.
Mode C is intermittent with ATC. Is it more than likely this is an
altimeter problem or transponder problem? Sometimes when it is not
reporting, i cycle the transponder off then back on and it starts
reporting again. Thanks in advance,
Brian
Also, sould an aeromech and aerosonic encoding transponder interchange
as far as the connections are concerned?


The KT76 transmitter is a free-running electron-tube
oscillator built into a cavity resonator. The frequency
of the sent signal is dependent on the cavity and
electron tube properties.

When the tube gets old, its properties start drifting
around, and the transmitter frequency follows the
drift. The thing stays on channel for short while
after tuning and then gets off again.

The cure is the change of the transmitter module. The
tube cannot be changed from the cavity alone.

--

Tauno Voipio (CPL and avionics engineer)
tauno voipio (at) iki fi

"Tauno Voipio" wrote in message
...
The Visitor wrote:
I had a similar problem in mine, then it got worse. Trouble was whenever
it was in the shop, it was working. Finally some guy thought to gently
heat gun the thing and found the failed part. I think it was a capacitor
that when warm, stopped working. It's had other problems too, like that
expensive final transistor going.

Just my experience....

John

skyav8r wrote:
Howdy,
I have an Aeromech 8140B20 encoding altimeter with a KT76 transponder.
Mode C is intermittent with ATC. Is it more than likely this is an
altimeter problem or transponder problem? Sometimes when it is not
reporting, i cycle the transponder off then back on and it starts
reporting again. Thanks in advance,
Brian
Also, sould an aeromech and aerosonic encoding transponder interchange
as far as the connections are concerned?


The KT76 transmitter is a free-running electron-tube
oscillator built into a cavity resonator. The frequency
of the sent signal is dependent on the cavity and
electron tube properties.

When the tube gets old, its properties start drifting
around, and the transmitter frequency follows the
drift. The thing stays on channel for short while
after tuning and then gets off again.

The cure is the change of the transmitter module. The
tube cannot be changed from the cavity alone.

If that were the case he would be having trouble with Mode3 also, and he
only indicated problems with ModeC.

Well that is probably what they changed out for me one time it totally
failed. It was very expensive. Almost the cost of a new (different
brand) transponder. Now for new aircraft, dual transponders are the way
to go.

John

"The Visitor" wrote

Now for new aircraft, dual transponders are the way to go.

Perhaps I am missing something obvious, but why would you need (or want) two
transponders for new aircraft?
--
Jim in NC

In article ,
"Morgans" wrote:

"The Visitor" wrote

Now for new aircraft, dual transponders are the way to go.

Perhaps I am missing something obvious, but why would you need (or want) two
transponders for new aircraft?

Required if you fly above FL180 isn't it?

"John Smith" wrote in message
...
In article ,
"Morgans" wrote:

"The Visitor" wrote

Now for new aircraft, dual transponders are the way to go.

Perhaps I am missing something obvious, but why would you need (or want)
two
transponders for new aircraft?

Required if you fly above FL180 isn't it?

No.

"John Smith" wrote

Required if you fly above FL180 isn't it?

Sorry, but I don't normally think in terms of being "that high" above the
ground, unless it is in a long metal tube with only a couple tubes hung
below the wings. g

What is required at that altitude, and won't that one work down low with the
rest of us piston powered mortals?
--
Jim in NC

In article ,
John Smith wrote:

Perhaps I am missing something obvious, but why would you need (or want)
two
transponders for new aircraft?

Required if you fly above FL180 isn't it?

Do have a FAR reference for that?

--
Bob Noel
(goodness, please trim replies!!!)

On Fri, 05 Sep 2008 22:50:53 -0400, Bob Noel
wrote:

In article ,
John Smith wrote:

Perhaps I am missing something obvious, but why would you need (or want)
two
transponders for new aircraft?

Required if you fly above FL180 isn't it?

Do have a FAR reference for that?

91.215(b)(1) requires transponders in class A airspace. What I've
seen is that most pressurized aircraft and turbines in general have
tow installed - does ATC routinely bounce you out of class A with inop
transponders, thus the commonality of 2 in those applications? Can't
seem to find a requirement for dual installations tho.