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Coax Cables

PostPosted: Tue Nov 22, 2016 11:21 pm
by FredHoffman
I'm installing my antennas now and wondering what's an acceptable distance the transponder and VHF coax cables can be run next to each other. I have been able to keep data cables far away and am left with the right window "a frame " to run the antenna cables but this will keep the transponder and VHF cable runs touching each other for 3 feet or so. Will this make interference issues on the VHF?

Anybody run the cables together and what was the result ?



Re: Coax Cables

PostPosted: Thu Nov 24, 2016 7:07 pm
by sonex293
From an RF interference issue you shouldn't have an issue running the coax cables next to each other "if" your using a good quality coaxial cable. VHF radios operate in the 110-130MHz region and transponders around 1000-1100 MHz. You do need to space the antenna's to avoid antenna de-tuning effects. RG400 is a good cable for VHF/Xponder runs.


Re: Coax Cables

PostPosted: Fri Nov 25, 2016 9:21 am
by Wes
Michael's reply was spot-on with a recommendation for good quality coax.

I'm wondering why you ended up with transponder coax and Com coax running together.
If the transponder antenna is on the belly and the transponder box is in the panel, the coax should be routing down and away from the Com coax.
If you have a remote mount transponder, it can be mounted anywhere convenient and allow a short and non-interfering routing.

I would try to separate the coaxes for those two systems as recommended in the install manual. A separation of an inch or two is usually sufficient.


Re: Coax Cables

PostPosted: Sat Nov 26, 2016 9:06 am
by FredHoffman
In my layout I ran a twisted data cable up the left window frame that goes to the Dynon Magnometer in the left wingtip. Under the floor is a twisted data cable to the FF sensor and ray allen trim cable that goes to the tail, all of those things are supposed to be separated from RF too. Transponder is on a tray behind the panel as well as the radio. The transponder antenna is on the metal access plate in the tail and the Com Antenna is on the rear of the turtle deck. I probably could run the transponder RG400 cable down the right door frame under the seats which is what I think I'll look at today. That would eliminate any issues.

Looking at what others have done sometimes creates questions. I saw an RV that had 4 RG400 cables bundled tightly together snaking all over behind panel then down the tunnel on the floor! I thought wow, if that doesn't cause a problem I'd be OK, but then again it may not have flown yet.

Thanks For the Help,