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SL-40 comm issue

G

gearman50

I'm New Here
I'm unable to transmit or receive to a local hand held. The transmit light goes on and I get a carrier but no modulation. I've verified the connections in the slide-in tray to the antenna by making a continuity test and all looked good. Anybody have similar problem or have any ideas? Or how to troubleshoot?

Thanks in advance.
 
Check the antenna cable to ensure the center conductor is not shorted to ground. I had that on a transponder cable.
 
Sidetone

John,
Do you have sidetone? Can you hear yourself in the headset when you talk.
If not, I'd be looking for a problem in your mic wiring.

Mark
 
I had the same issue and fixed it over the weekend. With all my moving and digging around during the build, I found that the tabs on the jacks had bent and were touching. I unbent them and presto, it worked.
 
The intercom works just fine. I double checked the coax cable for shorts and it is also fine. Could it be the radio itself? Is there any place in the Chicago area that I can get it bench tested?
 
Should be lots of SL40s around...

You should be able to slide it in to another plane to do a quick test... lots SL40s around.

gearman50 said:
The intercom works just fine. I double checked the coax cable for shorts and it is also fine. Could it be the radio itself? Is there any place in the Chicago area that I can get it bench tested?
Click to expand...
 
Sounds like it could be swapped.PTT lines. If you get a carrier but no modulation, try pressing the other PTT and see if you hear anything in the handheld radio. If you do and you have the SV conversion installed, then you find the solution here. If you get modulation in the handheld and you do not have the conversion installed, contact me and I look up what else it could be.
 
I had the same problem. Ptt's switched. Intercom works but no modulation on the radio.
As said use ptt one side and use the opposite mike.
If this works simply reverse ptt's
 
I tried using the opposite ptt and still nothing, I don't even hear anything transmitted from a handheld radio. Not sure where to look now.
 
gearman50 said:
I tried using the opposite ptt and still nothing, I don't even hear anything transmitted from a handheld radio. Not sure where to look now.
Click to expand...

I am an old (very old some days:rolleyes:) ham radio operator and have some experience with avionics. I very much doubt that the problem is a defective radio, if the panel lights up and the controls work. If you can niether transmit or recieve it is likely the problem lies in the external wiring in the audio circuits. I suggest you find a local ham, or an EAA Tech Counselor to help you out. Trouble shooting can be frustrating if you don't have any background in electronics, but basically it's an operation of isolating the problem by a process of elimination.

If you want, you can call me on my cell 518-774-4898 when you are at the airplane and I can try to walk you through some troubleshooting steps.
 
Sorry guys for the late response but I started a new job and had to set the issue aside. I finally resolved the issue. The audio in and audio out pins in the WH00028 harness which came attached to the Sl-40 radio tray from Van's where in the wrong position. The pins were over one position. Instead of 12 & 13 they were in 11 & 12.
I too also had the ppt pins in the tunnel harness reversed.

Poor quality control from the wiring harness vendor set me back about 2 months.:mad:

Kit 120012 flew yesterday for the maiden voyage. Flew for 2.5 hours with several takeoffs and landings. No major issues.:) Flew like the prototype and other RVs or so I'm told. The owner couldn't wait and I had to work.:(
Air space is shutdown due to Obama being in town this weekend.:mad:
 
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