Replacing an ADF sense antenna

The sense antenna on our Cardinal broke right at the crimp connector
that attaches to the feedthrough insulator at the top front of the
airplane. This thing appears to be made of 18 gauge copperweld wire.
Since I still have the antenna and can pull measurements from it, is
there any reason I can't fabricate a replacement myself? Or does that
crimp connection have to be made with an aircraft-rated crimp tool?

Dave Reinhart

asbestos britches on

The problem right from the getgo is that the copperweld (which is steel wire
with a copper coating) broke where it was rigidly attached to a nonmoving
bolt. When the wire flexed in the breeze, this became the pivot point and
eventually work hardened and crystallized that point of the wire to failure.

Let's think of some ways to keep that from happening on the next antenna...

1. How about some wire that is a little more resistant to work hardening
than copper over steel?

2. How about some sort of a flex joint where the wire attaches to the
insulator?

3. How about some sort of strain relief at this point?

4. How about a noncrimp connection; the main stress on the crimp is where
the wire is already weakened by flattening inside the crimp.?

5. How about a spring mechanism to keep a relatively constant tension on
the wire?


I've got MY answers to these questions, but I'd like to hear from the rest
of the gang first.

asbestos britches off

Jim



"David Reinhart" wrote in message
...
The sense antenna on our Cardinal broke right at the crimp connector
that attaches to the feedthrough insulator at the top front of the
airplane. This thing appears to be made of 18 gauge copperweld wire.
Since I still have the antenna and can pull measurements from it, is
there any reason I can't fabricate a replacement myself? Or does that
crimp connection have to be made with an aircraft-rated crimp tool?

Dave Reinhart

Buy a KR-87 and dump the old garbage. No other ADF could possibly still be
worth keeping.

Friendly as always,
karl

"RST Engineering" wrote in message
...
asbestos britches on

The problem right from the getgo is that the copperweld (which is steel
wire with a copper coating) broke where it was rigidly attached to a
nonmoving bolt. When the wire flexed in the breeze, this became the pivot
point and eventually work hardened and crystallized that point of the wire
to failure.

Let's think of some ways to keep that from happening on the next
antenna...

1. How about some wire that is a little more resistant to work hardening
than copper over steel?

2. How about some sort of a flex joint where the wire attaches to the
insulator?

3. How about some sort of strain relief at this point?

4. How about a noncrimp connection; the main stress on the crimp is where
the wire is already weakened by flattening inside the crimp.?

5. How about a spring mechanism to keep a relatively constant tension on
the wire?


I've got MY answers to these questions, but I'd like to hear from the rest
of the gang first.

asbestos britches off

Jim



"David Reinhart" wrote in message
...
The sense antenna on our Cardinal broke right at the crimp connector
that attaches to the feedthrough insulator at the top front of the
airplane. This thing appears to be made of 18 gauge copperweld wire.
Since I still have the antenna and can pull measurements from it, is
there any reason I can't fabricate a replacement myself? Or does that
crimp connection have to be made with an aircraft-rated crimp tool?

Dave Reinhart

According to AOPA it has to be done by an authorized repair station.

Dave Reinhart


David Reinhart wrote:

The sense antenna on our Cardinal broke right at the crimp connector
that attaches to the feedthrough insulator at the top front of the
airplane. This thing appears to be made of 18 gauge copperweld wire.
Since I still have the antenna and can pull measurements from it, is
there any reason I can't fabricate a replacement myself? Or does that
crimp connection have to be made with an aircraft-rated crimp tool?

Dave Reinhart