Reversed ADF indications

There "was" and adf in my plane before I bought it, and received the
adf in a box when I bought it. The tray was still installed in the
avionics stack, and I had a kr85 reveiver, KI225 head, and 42 loop
antenna in the box. I put the receiver back in, and had my mechanic
put the loop antenna back on the plane during annual.

I tested out the system last night. It hears AM Radio well...
It idented a beacon fine, but the needle wouldn't swing to it on the
ground.

I decided to fly and check it out. Sure enough, once I was airborne
the needle swung, and that's when I noticed my problem.


Isn't the needle supposed to point "toward" the NDB?
the head was acting more like a VOR head in the from position.
I know an NDB doesn't have radials, so why would my needle be pointing
toward the tail of the plane as I approach the beacon, and then swing
toward the prop as I pass over?


Thanks
dp

DP wrote

There "was" and adf in my plane before I bought it, and received
the adf in a box when I bought it. The tray was still installed
in the avionics stack, and I had a kr85 reveiver, KI225 head,
and 42 loop antenna in the box. I put the receiver back in, and
had my mechanic put the loop antenna back on the plane during
annual.
Isn't the needle supposed to point "toward" the NDB?
the head was acting more like a VOR head in the from position.
I know an NDB doesn't have radials, so why would my needle be
pointing toward the tail of the plane as I approach the beacon,
and then swing toward the prop as I pass over?

You haven't mentioned anything about the "sense antenna" which
is responsible for determining the "to-from" in an ADF receiver.
The KA-42B has a built-in sense antenna, but the KA-42 does not.

Bob Moore

DP wrote:

I know an NDB doesn't have radials, so why would my needle be pointing
toward the tail of the plane as I approach the beacon, and then swing
toward the prop as I pass over?

I would guess that a couple of wires are swapped in the connection to the head.

George Patterson
If you're not part of the solution, you can make a lot of money prolonging
the problem.

On Sat, 08 Nov 2003 14:08:16 GMT, Robert Moore
wrote:


You haven't mentioned anything about the "sense antenna" which
is responsible for determining the "to-from" in an ADF receiver.
The KA-42B has a built-in sense antenna, but the KA-42 does not.

Bob Moore

It's an older system that has a seperate sense antenna. THe 42 loop
is mounted on the bottom, and the sense is on the top.
dp

"DP" wrote in message
...
Isn't the needle supposed to point "toward" the NDB?
the head was acting more like a VOR head in the from position.

When I bought my airplane, the ADF had a similar problem. An NDB that was
30 degrees to the right would cause the ADF to indicate 30 degrees to the
left, for example. Right and left were reversed.

In that case, it turned out that someone incompetent had worked on the
avionics and all sorts of wiring was screwed up. The main problem was that
a couple of wires were hooked up wrong. I don't recall the exact
configuration, but it involved the nav indicator illumination power wires.
I think maybe one of the power wires had been incorrectly connected directly
to ground, shorting out the circuit and causing weird behavior from the ADF
(as well as disabling the VOR indicator illumination).

The local avionics shop was able to diagnose and fix the problem relatively
quickly. No permanent damage had been done to any of the avionics, so all
they had to do was fix the wiring. If you have a wiring schematic you can
reference, it should be easy enough to double-check all the hook-ups. If
not, if it were me, I'd take it to an avionics shop and let them fix it.

But George's suggestion sounds plausible enough, so you might try reversing
the connections to the indicator first, if you want to save a few bucks (I
don't have the bill in front of me, but if I recall, the work to fix mine
was "only" a few hundred dollars...spare change for avionics work around
here).

Pete

"G.R. Patterson III" wrote:

I would guess that a couple of wires are
swapped in the connection to the head.

If it's an avionics tech who screwed up, after he's fixed it, he'll say that
he found that the such-and-such signal was 180 degrees out of phase. Sounds
a lot better than saying that he got the wiring screwed up.....

--
Mike Granby, PP-ASEL,IA
Warrior N44578
http://www.mikeg.net/plane

G.R. Patterson III wrote:

DP wrote:

I know an NDB doesn't have radials, so why would my needle be pointing
toward the tail of the plane as I approach the beacon, and then swing
toward the prop as I pass over?


I would guess that a couple of wires are swapped in the connection to the head.

George Patterson
If you're not part of the solution, you can make a lot of money prolonging
the problem.

Reversing the connections on one of the "loop" antennas could do it too.

Tom Pappano, PP-ASEL-IA

I put the receiver back in, and had my mechanic
put the loop antenna back on the plane during annual.


well.. there's your problem right there.. your mechanic may not be a "radio
repair shop"..
BT

On Sat, 8 Nov 2003 18:30:36 -0800, "BTIZ"
wrote:

I put the receiver back in, and had my mechanic
put the loop antenna back on the plane during annual.


well.. there's your problem right there.. your mechanic may not be a "radio
repair shop"..
BT

Maybe so.... I didn't think it was really a tough job..... The
wiring and connector jack was already in place. All the mechanic had
to do was clean out the connector already in place, screw in the two
screws, and seal it with RTV. If a mechanic can't screw in two
screws..........
dp

On Sat, 08 Nov 2003 09:18:21 -0500, "G.R. Patterson III"
wrote:


I would guess that a couple of wires are swapped in the connection to the head.

George Patterson
If you're not part of the solution, you can make a lot of money prolonging
the problem.
Would it be the wires coming from the loop antenna or from the
receiver?

dp