Garmin SL40 Issues

[spriteah]

I am trying to locate a common fault on a garmin SL40 Transceiver/s where we occasionally get feedback on transmit.


I have tested the swr and found that at 118mhz it was 1.1 at 127.65 it was 5+ at 136 is was 1.2. These figures cause me some confusion. Can you shed any light on it for me? When the radio transmits at 118 or 136 we have no problems. When we are mid range the feed back occurs. Im guessing there is a link to the swr and the feed back. Is there a way I can cause a swr change in the mid range without modifying the antenna in a major way.

I have tried changing all settings in the Garmin. When I replace the headsets with cheapies (NOT ANR) the problems appears to disappear. I have had this fault on two different types of aircraft and several Pioneers.

Any advice on these questions would be greatly appreciated.
Yours Sincerely,

Jim Tatlock

 

[RV7Guy]

More info

What kind of feedback? What is the rest of your panel? Day/night?

The reason I ask is I have a Garmin 340 audio panel, Garmin 430, SL 40, and Garmin 330S transponder.

Now, if I have my 430 set on 122.8 and my SL40 on 122.90 and I transmit on my SL40 I'll get some noise when I transmit. Maybe they are too close. Both radios have been checked out and are transmitting on channel.

I also have a very minor noise when I have all the lighting going. More of an annoyance (to me) than a real problem.

 

[spriteah]

VFR panel, And get the problem when it is all I have turned on.

I have come across this on several installs. It is sometimes reduced if you turn down the side tone to very low. But then you can hardly communicate.

Jim.

 

[hecilopter]

I had a problem like this

Initially. Turned out to be the impedance in my lightspeed 20-XL headsets. I talked to them and replaced with the twenty 3G headsets and no problem. No problem with my old David Clark headset either.

 

[MattSR]

Hello,

What is the length of your antenna cable from the back of the radio to the tip of the antenna?

Cheers,
Matt

 

[DanB]

possible Same Problem?

Hello,

What is the length of your antenna cable from the back of the radio to the tip of the antenna?

Cheers,
Matt

I recently installed an SL40 and I am getting an oscillating buzz. This is occuring without the engine running (have not started the engine yet) so can't be anything coming off the alternator. The guys at Garmin say they have not heard of it b-4. Was there a solution to the original poster?
Thanks,
Dan

 

[L.Adamson]

I recently installed an SL40 and I am getting an oscillating buzz. This is occuring without the engine running (have not started the engine yet) so can't be anything coming off the alternator. The guys at Garmin say they have not heard of it b-4. Was there a solution to the original poster?
Thanks,

If you're using a power supply, instead of a battery.........that can create a buzz.

L.Adamson --- RV6A

 

[DanB]

Thanks, but I'm using the Batt. for hook-up. I was doing a little more reading here on the site and found I might need to address my connection to the antenna. I bought a cheepo antenna and did the ring terminal to the bottom thread thing. The outer wire went to ground. Apparently this is not a good way to do things in the radio world. Hope they make a connector that will attach to the antenna correctly and then to a BNC connector. Has anyone seen a connector like this?
THX,Dan

If you're using a power supply, instead of a battery.........that can create a buzz.

L.Adamson --- RV6A

 

[Michael Coates XCOM]

I am trying to locate a common fault on a garmin SL40 Transceiver/s where we occasionally get feedback on transmit.


I have tested the swr and found that at 118mhz it was 1.1 at 127.65 it was 5+ at 136 is was 1.2. These figures cause me some confusion. Can you shed any light on it for me? When the radio transmits at 118 or 136 we have no problems. When we are mid range the feed back occurs. Im guessing there is a link to the swr and the feed back. Is there a way I can cause a swr change in the mid range without modifying the antenna in a major way.

Jim Tatlock

Of course the problem is the high VSWR, find out why it is so bad mid range and then your problem is fixed. What aerial are you using ?? Hoping not a mobile 1, cause i have seen exactly this before with these aerials. BTW... dont transmit into 5:1 or you will blow up your radio !