Do ADF antennas need replacing if changing the receiver?

We have an old KR85 ADF receiver which is giving problems. It may be
economical to fix but if not are the antennas specific to model or can
just the receiver be replaced?

Before you suggest GPS we still use NDB's in the UK!!!!

Thanks,


David

Piper Warrior G-BHJO
Scotland, UK

E-mail (Remove Space after pilot): pilot

wrote:
We have an old KR85 ADF receiver which is giving problems. It may be
economical to fix but if not are the antennas specific to model or can
just the receiver be replaced?

The Sense wire is "matched" to the reciever, and there are many
different ways that the ferrite loops can be driven/sensed.

The best you could hope for would be that a later model of the same
brand might utilize similar antennas. You will have to talk to a
knowledgable avionics tech.

MikeM
Skylane '1MM

On Wed, 10 Dec 2003 12:29:36 -0700, mikem
wrote:

wrote:
We have an old KR85 ADF receiver which is giving problems. It may be
economical to fix but if not are the antennas specific to model or can
just the receiver be replaced?

The Sense wire is "matched" to the reciever, and there are many
different ways that the ferrite loops can be driven/sensed.

The best you could hope for would be that a later model of the same
brand might utilize similar antennas. You will have to talk to a
knowledgable avionics tech.

MikeM
Skylane '1MM

Thanks, I guessed there would be something different, there always
is-

It's only the pointer not working. Audio is ok so either sticking
pointer or driver circuit in the receiver. Hopefully repairable but
just wondered if a replacement would be economical or need the full
works!.


David

Piper Warrior G-BHJO
Scotland, UK

E-mail (Remove Space after pilot): pilot

Funny you should add the last comment. My ADF (a Bendix T12C) also appeared
to have a stuck needle and I too could tune the radio. In trying to
identify the problem, I tried it without the engine on and low and behold it
would track (albeit very slowly) to my on field NDB. I also noticed it
would track quickest when tuned 2 Hz lower (as displayed by a Davidtron
frequency counter) than my field NDB frequency also at this frequency the
audio id seemed quite a bit nosier.

So what I have I got out of all of this? I think I actually have more than
one problem. First I think there is some engine noise that masks the
frequency (even though I can hear AM radio). Secondly I think I might have
a antenna cable connection corrosion problem. This primarily due to other
reports of similar problems. Soon I plan on executing the entire problem id
flow chart (although for the life of me I can't remember where I read it)
and then going off to my local (50 mile away) radio shop for a fix.

Hope my investigation provides some useful data.

Tom


wrote in message
...
On Wed, 10 Dec 2003 12:29:36 -0700, mikem
wrote:

wrote:
We have an old KR85 ADF receiver which is giving problems. It may be
economical to fix but if not are the antennas specific to model or can
just the receiver be replaced?

The Sense wire is "matched" to the reciever, and there are many
different ways that the ferrite loops can be driven/sensed.

The best you could hope for would be that a later model of the same
brand might utilize similar antennas. You will have to talk to a
knowledgable avionics tech.

MikeM
Skylane '1MM

Thanks, I guessed there would be something different, there always
is-

It's only the pointer not working. Audio is ok so either sticking
pointer or driver circuit in the receiver. Hopefully repairable but
just wondered if a replacement would be economical or need the full
works!.


David

Piper Warrior G-BHJO
Scotland, UK

E-mail (Remove Space after pilot): pilot

It's only the pointer not working. Audio is ok so either sticking
pointer or driver circuit in the receiver. Hopefully repairable but
just wondered if a replacement would be economical or need the full
works!.


Not really. The audio is generally dervived from the sense antenna and
receiver. A failure of any part of the loop
antenna/reveiver/resolver/driver/mechanics/winring (in other words just
about anything) could produce those symptoms.

On Thu, 11 Dec 2003 13:22:42 GMT, "Steve Beaver"
wrote:


It's only the pointer not working. Audio is ok so either sticking
pointer or driver circuit in the receiver. Hopefully repairable but
just wondered if a replacement would be economical or need the full
works!.


Not really. The audio is generally dervived from the sense antenna and
receiver. A failure of any part of the loop
antenna/reveiver/resolver/driver/mechanics/winring (in other words just
about anything) could produce those symptoms.


I guess you're right. I'll have to wait and see what happens.


David

Piper Warrior G-BHJO
Scotland, UK

E-mail (Remove Space after pilot): pilot