cgrbu

hello Anticept... did not remove the extra gnd wires and static seems to be nil on my transmissions... but I did find from one of your other posts about the need for an audio wire between the EFIS and intercom for the AOA beep... that is what that green wire is (seen on one of my earlier pictures) that I thought was a gnd wire and an afterthought..thanks

thank you Anticept.... did another 1/2 hour today of flight and no noise on my transmit.... I still may remove the extra gnd wires to #3 cylinder as I can not be sure that they have made any difference to the situation..

Anticept... thank you for the explanation. I am keeping my fingers crossed and your post has me wondering is it only the ground wires that can create the gnd loop or can powered wires too?... I am sorry but my electrical theory knowledge is not good.

just an update, I took out the PM3000 intercom box, cleaned pins and checked general area. The green wire (which I assume is gnd) looks like it was an afterthought connection into the PM3000 box and it has been dangling in behind my centre console (garmin 696 etc). Since I have had the console in and out several times trouble shooting the 696, that green wire may have been pulled or moved sufficiently to lose/loosen the contact. I have place the green wire out of the way and I have actually had a test of the radio with no static noise!! I will have a closer look at that green wire hook-up and re-solder at a later date. Hope this solves the issue, thanks to all for their input... now on to the auto-pilot...

anticept, would the new LED landing light just installed have an effect even when not on?

thank you Tom for the part number

additionally I believe the autopilot servos may have been engaged while on the ground as my control stick has moved with a clicking sound. I pulled the circuit breaker for this as well to see if the noise would stop on the radio transmission, no change.

thank you both for the comments... I will target the intercom. As well the mention of the GPS has me thinking of the recent problems I have had with it not coming online with the start-up. I had the centre console out a couple of times to ensure that the power cord is properly seated and I also shimmed the antennae feed at that time so it would not work loose. With your mention of the ground loop antennae, is that a part you can order from Garmin or an avionics shop?

to answer coppercity ...today the noise is as loud as before when hooked in to jacks behind pilot/pxx seats and with gen circuit breaker out, no change (engine running). I have had those jacks out and checked for corrosion (emery papered, but I may swap them out for new). I get perfect transmission and reception when I am hooked directly to forward panel jacks (see picture attached). I have added the extra gnd wires from Battery to #3 cylinder and back to the starter solenoid which has the ground wire connected to the interior gnd bus. Also I have installed new spark plugs NGK DCPR8E 4339 gapped at .028.

before taking SL40 unit out of tray, tested before starting engine, transmission and reception clear as a bell. Did a quick removal checked pins for damage and re-installed. Did a start up and on initial transmissions had the static. Went flying and with higher power settings transmission okay, back to the barn and static not noticed on ground taxi... will see what happens on next flight....thanks to all who have had some suggestions

I have not had avionics on without engine running, I will do a static test next and record the results...also will test when running, gen cb out...

I have also noticed recently when intercom is on I get a buzzing sound that I think corresponds to the beacon light cycle which is an LED type. I do not notice that when intercom off (no pxx)

I have tried that long ago but not recent...when I did use them it isolated the passenger system... I will give it a go.... also Tom (a.k.a Roger ) Lee has made some good suggestions that I will address this week-end, (gnd, tray and if all fails, bench test)

I am not sure if the two additional plugs below my PFD Skyview is what you are referring to?

To add my situation to problems with the Garmin SL-40, on my last two flights I have got a lot of background static/noise when I transmit. Both push-to-talks on pilot and passenger control sticks have the problem. Other aircraft have confirmed the 'noise' on my transmit. Reception seems okay. Swapped out headsets, Tango to Zulu to DC.... no change in condition. I will try to play with connections in back but I am in the dark... any advice on this would be appreciated... thanks