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Hum in my radio

H

HDDAHL

Active Member
Have Skyview with the SL40 garmen, standard package.

When I transmit, I get a feedback hum or tone that sounds like something above 200 cycles/ sec. This occurs with the engine not running, and nothing on except skyview in addition to the radio. I have tried adjusting all the available adjustments in the radio itself with no success. sidetone, mic squelch, etc. The hum does not change frequency with any adjustment. I think I note a slight reduction in the hum volume with the sidetone set to 1.

Anybody have any ideas?
 
Here's a thought. Have the instrument panel top cover off and start shaking/moving wires while you listen to the hum. Particularly around the intercom. Do the same in the lower compartment between the footwells where all that wiring is. Try pluggin/unplugging a second passenger headset. Try swapping headsets. Is the hum in both headsets i.e. manifesting itself in both the pilot and passenger jacks identically?
 
Bill: I have the same problem. Intercom very clear, stereo music thru the 1/8 in plug great, but when the mike is keyed there is a hum and voice is garbled. I ran across something in the 403 Intercom Instructions on page 13, second paragraph down. Makes on think!!!!!!!!!!!!We know the coax provided us is not of the best quality Your take on this please. John G
 
Radio Hum

I have the same problem: I have sent the Skyview in ti Dynon at their request and it came back NTF. I then found that the noise disapeared when I put the 403 in the Isolate mode. Contacted Flightaom ande they had me send in the 403 it came back NTF. Still have the problem. By the way the hum was gone when I built and installed the 403 bypass connector. Flightcom thinks that something else (SL40 or Vans 50000) is putting noise on the A+ to the intercom. Hum is still there with the SL40 turned off.
The sidetone from the SL40 is intermintant. Startin to wish that Vans had provided the Icom210 instead of the SL40. HAve a freind that installed an SL40 in his tube and raqg home buillt and never did get the Sl40 to work correctly so he gave it back. Will post more as I dig deeper. PS I spent the last 15 years as an avionics tech at a top shop.
Sonny
 
I have come across this as well with a few panel we've built in our shop. To see if the issues each of you are hearing are the same I've come across, try reducing the back lighting on the Skyview display while monitoring the hum. Does it change? It seems that in some configurations and perhaps in the routing of wires the audio system picks up some background noise from the Skyview display dimmer. Ive had success resolving this with ferrite beads and capacitors on the power wires of the intercom, audio panel or comm radio. Each issue I came across required isolating which piece of avionics was actually amplifying the "noise" and allowing it to be heard.

Jason Smith
Aerotronics
 
sonny-m said:
I have the same problem: I have sent the Skyview in ti Dynon at their request and it came back NTF. I then found that the noise disapeared when I put the 403 in the Isolate mode. Contacted Flightaom ande they had me send in the 403 it came back NTF. Still have the problem. By the way the hum was gone when I built and installed the 403 bypass connector. Flightcom thinks that something else (SL40 or Vans 50000) is putting noise on the A+ to the intercom. Hum is still there with the SL40 turned off.
The sidetone from the SL40 is intermintant. Startin to wish that Vans had provided the Icom210 instead of the SL40. HAve a freind that installed an SL40 in his tube and raqg home buillt and never did get the Sl40 to work correctly so he gave it back. Will post more as I dig deeper. PS I spent the last 15 years as an avionics tech at a top shop.
Sonny
Click to expand...

For starters, is everyone running off the alternator or battery..........and not a power supply (such as a battery charger) in the work shop? Power supplies can also supply a hum.

As to the SL40 & Icom210, my plane had both. Both worked just fine, and there is no reason I'd prefer the Icom210........if given the choice. I think that the SL40 is a very good radio.

L.Adamson
 
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My 430W com/nav was perfect out of the box. The SL-40 not even close. I played with some settings. It is okay for a backup, but I sure would not like it for a primary.
 
Wayne Gillispie said:
My 430W com/nav was perfect out of the box. The SL-40 not even close. I played with some settings. It is okay for a backup, but I sure would not like it for a primary.
Click to expand...

I know plenty of pilot/builders who have sucessfully used the SL-40 as a primary comm radio. It's not as if it's the "cheapie"........of comm radios.
In fact, it's a dang good comm radio! I really don't see where you're coming from. Personally, I don't like the 430's. The graphics are very inferior compared to later offerings, including my handhelds.

L.Adamson
 
Different opinion

I use my SL 30 as primary, 420W as backup. Perfectly happy with the SL30 com, works great.
 
Hum, whine

Pulled fuses, shut down skyview, no change in the hum.

has anyone done the 4.0 update and changed the wiring per Vans instructions and seen any difference? I have not done the 4.0 update. Since I still get the hum with skyview off I don't see how this would be a factor; just asking. I did do the 3.2.2 update without any wiring change; it was not specified.

The intercom comes on with the master and I am suspicious of it. Any more thoughts appreciated.

Doug dahl
 
Found the problem!

An embarrassment! The radio was not fully in its tray. It apparently vibrated back some because I had not engaged the slot.

Now works great.

Doug Dahl 9A and the 12
 
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