GTR-225A

Hello
Let me introduce myself: I'm french, I build a RV6, I finished dashboard and I'm trying to mount my avionics.
I team my RV6 with a GARMIN GTR 225 A radio, I get no audio panel (just one radio on board), I realize the audio connection and micro following Garmin D-13 installation manual,


At the initial operation, no audio, no return micro...! Total silence...!Oops
Power off then verification of the installation, I note that I reversed 'Tip' and 'Ring' connections on the jacks mic of the pilot and co-pilot...
Back into compliance.
During the second start-up I first connected my headphone audio jack (David Clark H10 - 13.4) side co-pilot: I hear the ads for a nearby airport IFR arrival but only when I cut the automatic squelch...! Same-side pilot.
In a second time I plug in the mic, I notice that the radio immediately enters transmit (TX displayed on the screen) without action on the PTT mode, no return micro audio and then after a few seconds a message appears onscreen: "COM PTT KEY IS STUCK.
I put out of service radio, then the put into service connected headset driver-side, same symptoms?
A third test is carried out without any connected headphone jack plug, then a pulse to the PTT on the radio screen appears then TX which disappears when the PTT is released. (Which seems to be normal!)
The same results are obtained with a second (different headset)?
No change when through the menu, I put the intercom on 'on' or 'off '...
I hope not have "on toasted it" during the first test!
My knowledge in this area are very "limited" If a soul charitable overseas can come to my aid... I would be grateful.

First, let me beat Mike and say "welcome".

I would look carefully at the mike jack wiring. Since you already had one error it may still be wrong. Use an ohm meter to be sure you know which solder lug goes to which part of the jack. By the way, there is no need to wire the tip, PTT connection, unless you will someday use a portable PTT switch there, or a handheld mike with PTT built in. Most builders leave the tip not wired, I think.

Hello Mike and thank you for your answer

I have well controlled with an ohmmeter all my connections and everything complies with the diagram D-13 provided by garmin

In this diagram, on finding that the PTT is connected to the microphone jack by 'barrel' and the 'ring' respectively on the P2001 pins 11 and 20 for the pilot and 26 and 20 for the co-pilot.
The "Tip" are connected to pins 5 and 6 !

Could there be a relationship between the impedance of the MIC and my problem?

David Clark jacks are "fussy". Try removing all jacks from panel and let them hang from wires. Plug in headset and observe how jacks are contacting the plugs. May be necessary to adjust contact points.

DUPUY said:

Hello Mike and thank you for your answer

I have well controlled with an ohmmeter all my connections and everything complies with the diagram D-13 provided by garmin

In this diagram, on finding that the PTT is connected to the microphone jack by 'barrel' and the 'ring' respectively on the P2001 pins 11 and 20 for the pilot and 26 and 20 for the co-pilot.
The "Tip" are connected to pins 5 and 6 !

Could there be a relationship between the impedance of the MIC and my problem?

Click to expand...

Just to be clear, the push to talk (PTT) wire goes to the tip connection; the mike audio goes to the ring; and ground (not chasis - run a wire back to the radio) goes to the barrel.
As someone else noted, make sure the jack's tip connection is not being pushed in contact with a ground when you insert the plug.

Gentlemen, good news, it works...

Bob (I poorly named Mike... excuse me!) was quite right.

When your first message, you tell me: "Most builders leave the tip not wired".

This got me thinking and I searched on the net a mounting scheme of a radio with an intercom and I found that actually: "there is no need to wire the tip".

I remembered that I had an old intercom (a SPA-400). After having searched for and found an installation instructions for this intercom, I realized it and oh! Marvel, it works properly...!

Thank you Bob your advice lit as well as Aerhed.

Spend happy Christmas party...

Hello Dupuy,
Welcome aboard, my apologies for the delay in seeing this. But it looks like the VAF team has assisted you on this problem, they're some of the smartest Pilots/builders I've met.

Thanks everyone for the assistance.

Please remember if there are any questions about Garmin products please don't hesitate to send us a message at [email protected] or [email protected] and we'll be happy to assist.

Have a safe and very Merry holiday season.

Best Regards,