GNS430W receives great but can't transmit

Gregmarlow · #1 03-25-2010, 04:13 PM

I have a GNS430W in my 9A and also a SL40. The radio on the 430W picks up fairly distant transmissions but can't transmit across the field. The antenna is on the turtle deck.

The SL40 does great (with the antenna under the seats), and thank goodness Stein convinced me to put in a second radio!

Any ideas? Thanks in advance.

Sparky · #2 03-25-2010, 04:42 PM

Most likely, it is an antenna or wiring problem. To eliminate this as a possiblility, try swapping GNS-430 and SL40 comm antenna coax connections behind the radios to eliminate an antenna or antenna installation problem. If the problem moves to the SL-40, it's an antenna or coax problem. If the problem stays with the GNS-430, it could be an internal radio transmitter problem.

If you have ever tried to transmit on the GNS-430 with a shorted coax or antenna, or without the antenna connected, it is possible that the GNS-430 transmitter could be damaged. The receiver may still function normally, even with a damaged transmitter.

Good luck...

LifeofReiley · #3 03-25-2010, 07:28 PM

We had an intermittent problem with a newer 430 last month, turned out to be an internal voltage regulator issue. On the bench after about 20 minutes the problem showed up. A possibility for you...

turbo · #4 03-26-2010, 06:38 AM

if a radio is transmitted on without the load of the antenna it will damage the radio. how do i know? having a problem with a garmin 250 i borrowed my friends 250 while mine was sent out for repair. well when i trasmitted on his i broke his also so sent his out and then found out the problem, bad antenna connection. live and learn. over & out. turbo

Gregmarlow · #5 03-26-2010, 06:47 AM

I've heard that and I never transmitted or tried to without the antenna being connected. Since the first time I've turned it on, it has received well, but almost zero transmission. Guys on the field report carrier only, no voice.

Sparky · #6 03-26-2010, 10:56 AM

If you have carrier but no voice, that suggests a problem with the mic audio wiring.

Since you have two Comms, I assume you have an audio panel. If the SL40 works OK, then the wiring from the mic jack to the audio panel and from the audio panel to the SL40 is good. The problem is most likely the mic audio wiring from the audio panel to the GNS-430W, or it still could be the GNS-430W itself. Check the continuity of the mic audio wiring between the audio panel and the GNS-430. If that is good, check that the mic audio high and low wires are not shorted together. If not shorted, check to be sure both the audio panel and GNS-430 are fully seating into the rear connectors (there is a procedure in the GNS-430 Installation manual for checking that it is seating properly). If everything checks out OK, do you have a really good buddy with another GNS-430 to try in your panel?

Pat Stewart · #7 03-26-2010, 04:17 PM

Check and make sure it's seated and tight in the rack.

Pat Stewart

rv7charlie · #8 04-10-2010, 11:23 PM

I tried to help a friend with what sounds like the same problem. (I was an electronics tech in a former life.) His new 430 complete with harness he purchased from the Garmin vendor received fine but had extremely low to no audio level (heard on a receiving radio) on transmit. The transmit light would light normally when the transmit button was pressed.

Our troubleshooting included a phone call, hookup diagram in hand, to Garmin tech help. We asked him to tell us all the pins/destinations required for transmit, and verified all that wiring. Still no joy.

The owner finally gave up & took it to a radio shop. He already had the panel ready to 'drop'; the tech took one look at the 430's connectors & asked, 'where's the ground on pin #x?' (sorry; don't remember which one at the moment.)

They added the ground (took maybe 10 minutes) & all was well in the transmit department.

That pin was missed by both the Garmin dealer and the Garmin Tech that we called.

FWIW,

Charlie

Richard Connell · #9 04-10-2010, 11:48 PM

430 would recieve fine but no transmit.
The TX would flash, but nobody could hear me.
Swapped out the entire radio, no difference.
Checked continuity of all pins between it and the audio panel. all fine.
Gave up and booked it in with the local avionics shop. This is after 2 months or trying everything. They had a 1m wait (or just werent interested...)
Went away on a trip using com2 for transmit. Blew the nav light fuse because my rudder bottom filled with water.
Was under the panel replacing the nav light fuse and noticed a blank in the fuse block of the main buss. Wire leading into it says GNS430???
Light bulb moment. the 430 has 3 power inputs. Id split and fused them as directed by the install manual. didnt fuse one of them - com TX. Unbelieveable. Live and learn.
Are all of your 430 Power inputs powered? are all of your grounds grounded?
Cheers
Richard

174Bob&Nancy · #10 04-11-2010, 08:04 PM

Greg,Randall will be in Morristown Saturday the 17th doing static checks if you still need one,and I have a 430 in my plane we could swap and see if it makes a difference.Bob.