Becker DF unit not working well

[dbaran]

We have a 206 with a Becker DF unit in it, installed about 2 years ago.  The anecdotal evidence from aircrew is that the thing only picks up a standard ELT about 2 miles away from it.  I've seen much better performance from a Becker in a G1000 182 where it was providing useful bearings for an ELT about 15 miles away.

The antenna was pulled off the plane last year and the metal cleaned to make a better ground plane and then the antenna was reinstalled - no improvement.

Has anyone out there been through this with their CAP aircraft, and how did you fix it?  We're thinking about pulling the Becker itself and trying to swap it through the standard CAP channels, but would like to figure out if it could be an installation issue before we go through that.

[Al Sayre]

First question would be:  Does this same aircrew have problems with the Becker on other aircraft.  Most of the problems I've seen have been operator error.

Barring that, I'd change out the antenna, we've had a couple of bad ones in the past 2 years.

[SJFedor]

Yeah, send it into an avionics shop (or back to Becker) for testing to see if they can find out what's up. That's absolutely sub-par performance for that DF unit.

[ray]

First question would be:  Does this same aircrew have problems with the Becker on other aircraft.  Most of the problems I've seen have been operator error.

Barring that, I'd change out the antenna, we've had a couple of bad ones in the past 2 years.

Having been one of the aircrew members that has had problems with the range on that particular unit, I can say that it's not operator error (at least I hope not...).  Generally I have seen that the aircraft radios (KX-155) in that plane are picking up the signal long before there is any indication or audible signal on the Becker.  But it's hard to make objective comparisons since every ELT or practice beacon placement is different.

One thing to note is that the becker antenna is installed noticeably farther forward than it is in the 182T installations.  It's basically under the rear door (the plane is a U206) whereas in the 182T's it's a couple feet aft of the cabin.  But I don't see this really making a difference.

[Al Sayre]

The installation point should not be that critical as long as it isn't too close to the struts.  However, if it is under the rear seat area, I'd check the wiring, especially any coax to see if it has been damaged by people stepping on it getting in and out of the aircraft.

[lordmonar]

I have noticed that if the outside shell of the Becker antenna is dirty (engine oil) it will affect the perfromance of the unit.

Not by the distance that you are discribing but it may be something to check on.

[PHall]

You might want to have the entire unit checked. Sounds like a sensitivity and/or gain problem.