Radios and intercoms

[NorthIdahoAvidflyer 374]

I flew the Magnum to a local towered airport a few days ago and when I reported 10 miles out the tower said that my transmission has a lot of static. The radio is a Icom IC-A210 dash mount unit and it has worked great until the last flight. When I went to leave I attempted to call on the ground freq and got another report of a lot of static in my transmission. I had an extra headset so I switched them out and the next headset had no side tone and I got no answer when I attempted to call the tower. I switched the second headset plugs to the co-pilot side of the intercom with no change. I switched back to my headset on the co-pilots side of the intercom and was able to make contact but they still reported a lot of static. I think by now they wanted me gone so they cleared me to depart via 4R to the West. 

When I got home I started checking out the radio system. It has a Sigtronics intercom with a dual headset plug mounted way up under the dash and a remote volume and squelch controller on the instrument panel.  the radio has a built in intercom which it not being used. There is one set of headphone jacks and a remote PTT button on the panel. When I plugged a set of headphones into the instrument panel jacks you can hear noise/interference in the headphones when you plug in the big plug but you can not hear any radio transmissions or side tones. The PTT works but I didn't try to transmit with it when I was having issues.

I have never played with an in dash radio system. I've always used a handheld system. I do not understand why someone would install a second intercom when the radio has its own and the panel was wired for it. I also hate the location of the remote intercom headphone jacks and would love to change that. 

So I'm coming to you guys for advice on where to start. I'm not the best with this stuff but I have a installation guide downloaded and can figure out how to check the pin connections and such. I will post some pictures of the various parts of the system. 

[flywise 169]

I flew the Magnum to a local towered airport a few days ago and when I reported 10 miles out the tower said that my transmission has a lot of static. The radio is a Icom IC-A210 dash mount unit and it has worked great until the last flight. When I went to leave I attempted to call on the ground freq and got another report of a lot of static in my transmission. I had an extra headset so I switched them out and the next headset had no side tone and I got no answer when I attempted to call the tower. I switched the second headset plugs to the co-pilot side of the intercom with no change. I switched back to my headset on the co-pilots side of the intercom and was able to make contact but they still reported a lot of static. I think by now they wanted me gone so they cleared me to depart via 4R to the West. 

When I got home I started checking out the radio system. It has a Sigtronics intercom with a dual headset plug mounted way up under the dash and a remote volume and squelch controller on the instrument panel.  the radio has a built in intercom which it not being used. There is one set of headphone jacks and a remote PTT button on the panel. When I plugged a set of headphones into the instrument panel jacks you can hear noise/interference in the headphones when you plug in the big plug but you can not hear any radio transmissions or side tones. The PTT works but I didn't try to transmit with it when I was having issues.

I have never played with an in dash radio system. I've always used a handheld system. I do not understand why someone would install a second intercom when the radio has its own and the panel was wired for it. I also hate the location of the remote intercom headphone jacks and would love to change that. 

So I'm coming to you guys for advice on where to start. I'm not the best with this stuff but I have a installation guide downloaded and can figure out how to check the pin connections and such. I will post some pictures of the various parts of the system. 

From experience, static most times comes from a bad ground. Check the radio grounds/radio rack grounded/headphone jack grounds/antennae ground and intercom system ground. Also try to ground all vhf related systems on one ground spot to prevent ground loops. I don't think your radio is toast.

Hope that gives you an idea where to start....

[NorthIdahoAvidflyer 374]

Thank you. I will start there. 

[NorthIdahoAvidflyer 374]

[NorthIdahoAvidflyer 374]

[C5Engineer 1170]

Those sport 200s have a fairly complicated harness. Someone violated the KISS principle.   Good luck on this one. 

[NorthIdahoAvidflyer 374]

I went over all the connections and nothing seemed out of place. As most other things on this plane the wiring leave a lot to be desired for being neat and titty. It really needs a complete dash rewire. If this problem continues I will gut the intercom, install another set of headphone jacks in the panel and use the radios built in intercom system. 

[nlappos 413]

The Rotax ignition is very dirty, and begs for suppression. A kit used to be sold that put the ignitors in a shielded box, but that is no longer provided. I wrapped grounded copper mesh around the ignition boxes, and the spark plug wires, and made a dramatic reduction in the e-field that washes through the cockpit from the engine. Also, if you have an antenna cable, using the double shielded coax really helps as well. I will post some photos of my shielding when I get home in a day or so.

[NorthIdahoAvidflyer 374]

This is on the Avid Magnum and the engine is a Lyc O-320. The radio has been working good but recent was reported as scratchy from a local tower. 

[flywise 169]

Did you check your antennae ground plane ? It should be quite big, roughly 22inch radius (or ~24x24 in square) Last and not least, check you have a good quality coax cable and the connectors are good . Disconnect both ends of coax cable and make sure there is no continuity between the pin in the middle and the metal shielding. Then measure resistance of the center conductor---should be minimal. Then measure good continuity of metal shielding at the connectors/connector housing through to the other connector housing at the other end.

Also make sure your VHF coax cable is not routed close to your transponder cable....

These are just some more easy troubleshooting you can do....

 

P.s NEVER transmit without antennae connected to radio!!

Edited 23 May 2019 by flywise
missing info

[flywise 169]

One more thought.....happened to me, Check your PTT switch. I had a bad quality PTT switch and that gave me a very LONG troubleshooting to find out that stupid 5$ switch was bad!!!

[NorthIdahoAvidflyer 374]

One more thought.....happened to me, Check your PTT switch. I had a bad quality PTT switch and that gave me a very LONG troubleshooting to find out that stupid 5$ switch was bad!!!

I actually believe this could be a source of the problem. Now that I know the one on the panel works I will use it to see if it makes a difference. 

[NorthIdahoAvidflyer 374]

Did you check your antennae ground plane ? It should be quite big, roughly 22inch radius (or ~24x24 in square) Last and not least, check you have a good quality coax cable and the connectors are good . Disconnect both ends of coax cable and make sure there is no continuity between the pin in the middle and the metal shielding. Then measure resistance of the center conductor---should be minimal. Then measure good continuity of metal shielding at the connectors/connector housing through to the other connector housing at the other end.

Also make sure your VHF coax cable is not routed close to your transponder cable....

These are just some more easy troubleshooting you can do....

 

P.s NEVER transmit without antennae connected to radio!!

Thank you Flywise, I will check all those things. I know the ground plane is small and the coax cable is not the best quality. They also installed a inline port system so a handheld (see pics) could be hooked into the coac running to the antenna. These are all break points in the antenna coax system. I may buy a double shielded RX400 cable and run it from the Radio all the way to the Antenna. I replaced the standard cable on my Mark IV and it made a world of difference. 

[Dusty 126]

If you go down the road of using the icom internal intercom you will be pleasantly surprised. It is a great intercom.

[Cloud Dancer 69]

The Rotax ignition is very dirty, and begs for suppression. A kit used to be sold that put the ignitors in a shielded box, but that is no longer provided. I wrapped grounded copper mesh around the ignition boxes, and the spark plug wires, and made a dramatic reduction in the e-field that washes through the cockpit from the engine. Also, if you have an antenna cable, using the double shielded coax really helps as well. I will post some photos of my shielding when I get home in a day or so.

An easy way to check if it's a radio problem or an engine problem is to shut of the engine and then try the radio regardless of the engine brand.