GNS430W Problem Acquiring

[CFI1513840]

We just installed a new GNS430W in our PA28 (I will also be putting one in the RV-7) and I noticed that on a couple of occasions, it had problems acquiring. On one occasion, acquisition was delayed several minutes, another time it never acquired, even after 20 minutes.

When it did not acquire, I shut it down and made sure the unit was firmly seated in the tray by pressing on the bezel. After powering it back up it acquired normally after about one minute. I'm wondering if this could be a problem with the tray connector or locking screw, possibly causing the connector to have intermittent contact.

I'm curious to know if anyone else has had this sort of problem and if so, how did you correct it?

[flyeyes]

Originally Posted by CFI1513840

I'm curious to know if anyone else has had this sort of problem and if so, how did you correct it?

We had an intermittent problem with one of the two GNS 430s in our Cirrus, that was caused by interference from a Roady XM radio receiver.

Later versions of the Roady reportedly have newer circuit boards which reduce or eliminate the problem.

You might want to check for possible sources of electromagnetic interference.

[Yukon]

I had a lot of trouble initially with my 530W install, untill I discovered this......

Loosen the attaching screws to the harness plugs and the back plate about half a turn so that the plugs can float. Re-rack the radio so as to allow the loose plugs to find their natural position. Remove radio and retighten all screws.

Also, I put a little grease on the locking mechanism, and it worked much better.

These steps should help the antenna plugs seat better.

[w1curtis]

Originally Posted by CFI1513840

We just installed a new GNS430W in our PA28 (I will also be putting one in the RV-7) and I noticed that on a couple of occasions, it had problems acquiring. On one occasion, acquisition was delayed several minutes, another time it never acquired, even after 20 minutes.

Was this a brand new install or an upgrade install to a previous GNS430? Did they install the requsite minimum 13 feet of RG-400 coax or..?

[Yukon]

Originally Posted by w1curtis

Was this a brand new install or an upgrade install to a previous GNS430? Did they install the requsite minimum 13 feet of RG-400 coax or..?

Don't you mean MAXIMUM?

[tx_jayhawk]

Ken,

Did you install the GA 35 antenna along with the 430W? Where is the antenna located?

Assuming you have the right antenna and placement, you need a MINIMUM of 3 db and a MAXIMUM of 7 db of attenuation in your antenna coax. 3 db equates to 13 feet of RG-400 per the comment above.

Scott

[CFI1513840]

I'll check with the shop to make sure they complied with minimum/maximum cable lengths. The antenna is new, mounted on the top of the cabin. I was interested to note that John had similar problems until realigning the connector. This sounds like something that would be easy to do, so we will probably give that a try. A slight inconvenience to us is that the shop is one hour flying time and it takes the better part of a day to have any work done.

[RVRC]

I have a GNS530W and GNS 430W in our C-425 and have the same problem. We sent both units to Garmin to have the WAAS upgrade and reinstalled. It is not that great a problem, but does take much longer to reaquire than they used to.

[w1curtis]

Originally Posted by Yukon

Don't you mean MAXIMUM?

No a MINIMUM of 13 feet!

This is to meet the 3 to 7 dB loss required by the new antenna. Take a look a the GNS430W installation instruction Section 3.10.1.

"The typical cable loss for 20 feet of RG-142B or RG-400 coax with a connector on each end is 4dB. For very short runs, where the loss is less than 3dB, additional cable should be used to increase the loss to within 3dB to 7dB. The additional cable may be coiled, taking into account the minimum bend radius of the cable."