ADF Problem

ADF Problem

Hi
I'm hoping that someone can help narrow down which piece of equipment is faulty here.
Whenever I am tuned to an NDB, with my ADF set at 000, if the NDB is ANYWHERE ahead of the aircraft the ADF points to 330.

If the NDB is ANYWHERE behind the aircraft, the ADF points to 190

If I fly past an NDB the ADF tracks it all the way to 190, where it stays until I do a 180.

If I do a 360, the ADF will point at 330 and swing to 190 and swing back to 330.

I need the ADF for my instrument training so it has to be fixed.

Some people say that it must be the loop antenna - on the basis that the sense antenna is sensing whether the NDB is ahead or behind, the pointer on the ADF is working, and the Nav radio is picking up the signal.

The Avionics guy at my local FBO wants to send the radio out for testing - he says it is more likely the radio than the loop antenna - I don't see his logic.

Any comments/ideas greatly appreciated.

Tony
C-GICE

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Re: ADF Problem

Borrow a known good ADF antenna and replace yours with it.  See if that fixes it.

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Re: ADF Problem

Depending on what type of ADF you have. -- KR-85 we have seen problems at the loop cable input at the KI225. KR-86 there have been problems with the mating connector - the pins flatten and don't make good contact. ARC R-546() Also connector problems at the indicator - also motor, goniometer problems in the indicator. Collins ADF -650 Antenna, indicator and receiver all can show this problem>

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Re: ADF Problem

   Any one know where we can get a diagram for a KR-85?  Ours is dead as a doornail, with nothing obvious to be found.

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Re: ADF Problem

Have you checked the fuse inside the unit? Remove the top cover, can't miss it - It is an AGC 1 1/2 Amp fuse.

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Re: ADF Problem

Boyce's advice is sound:  three principles of electrical engineering are 1. is it plugged in? 2.  is it turned on? 3. if there is a fuse, is it blown? This cures most electronics problems. Unfortunately, in this case the fuse is not blown.

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Re: ADF Problem

Power for KR85 comes in on Pin 4 If it's in a 28V AC there will be a dropping resistor in line. I have seen wires break off there. Ground is Pin 9. I can fax you an interconnect diagram if you need one.
For a maintenance manual you might try Essco.

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Re: ADF Problem

I would not spend much money on trying to fix an old ADF. Put you money towards a panel mount GPS. ADF is on the way out and you don't need it for IFR training.

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Re: ADF Problem

I am an active CFII and disagree about not getting training in the use of ADF.
There are many times where the only approach is a NDB approach.
A smart IFR pilot will not put all his eggs into one basket.
You must be able to demonstrate the skills required by the PTS to the DE on your check ride.
A law firm I fly for has a Seneca II and I often have to fly it in IMC conditions and have to shoot an approach.  The ADF is a very valuable tool.
Besides,  without your ADF, how are you going to be able to listen to Rush Limbaugh or  a foot ball game on a long flight.

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Re: ADF Problem

Hi
Thanks very much for all of your responses - I appreciate them.
I tried several of your suggestions, but still had the problem, so finally the system was removed from the aircraft by our local avionics tech. My choices at that time were :
1. Send it to Narco for overhaul - est US $1000 + +
2. Send it to a company in Alberta - EST C$500 + +

I sent it to Alberta and waited, and waited, and waited,
Finally I asked why the delay, only to discover that they had "put it aside" because they didn't have a bench test rig"
After my enquiry they apparently suddenly found one,
tested it, and found that it need a gear "plus lots of other problems not worth fixing" - direct quote.
So - I guess that I am looking for a good used radio.
Anyone know of one?

Thanks

Tony
C-GICE

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Re: ADF Problem

I agree with Clay

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Re: ADF Problem

My collins 650 had  the same problem reported by tony roberts.
I sent to a specialized company that fixed it,but it worked well only
9  flight hours and now presents  the same problem.
I need a  receiver diagram.
I thanks in advance for any help.

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