Antenna Coax and Strobe Power wire

[nodgnal51]

I am about to run the wires down my wings. I have installed conduit in both wings for this purpose. I am also installing a bob archer nav antenna in the left wing. My power for the strobes will be in the baggage compartment area, therefore I will have high power lines going down the conduit. My question is this: Can I run the coax for the antenna in the conduit with the strobe power, or should I run one of them separately?

Steve Langdon
RV-6
Finishing the wings

[Rick S.]

Steve,

That's how I did my RV-10, I asked Dan Checkoway the same question, his site showed and Dan confirmed he has had no problems...of course others may chime in that have had problems...Mine works fine, just not flying yet to FULLY test it but ground ops are fine.

[elippse]

Originally Posted by nodgnal51

I am about to run the wires down my wings. I have installed conduit in both wings for this purpose. I am also installing a bob archer nav antenna in the left wing. My power for the strobes will be in the baggage compartment area, therefore I will have high power lines going down the conduit. My question is this: Can I run the coax for the antenna in the conduit with the strobe power, or should I run one of them separately?

Steve Langdon
RV-6
Finishing the wings

If it was me I would definitely run the strobe pulses separated from the Nav coax unless you are using a coax with a solid outer conductor such as Andrew FSJ1-50. Those high-voltage strobe pulses have very high rise and fall times which generate harmonics up the ying-yang! Would you like to see the Omni meter jumping each time the strobe fired? Better to be safe than sorry and have to correct it after assembly!

[DGlaeser]

Per Bob Nuckolls, you can run them all together. Just make sure the coax's are grounded properly. I'm not flying yet, but all my wing wires run in one conduit and ground testing has yielded no unwanted noises in the radios.

[BuckWynd]

Steve,

Most of the stuff I've read from trusted sources says that if you ground everything properly, the shielding on the coax will do its job and shield your VOR signal just fine.

I've run coax and strobe power cables inside the same conduit several times before, and plan to do it again my RV-8, for what it's worth.

See you around the air patch, neighbor!

[nodgnal51]

Thanks for all the posts in reply. I called Stein Air and asked their input. Their advice was as far apart as possible... So... I guess I'll flip a coin.

Steve

[trawlergeek]

I have built a certified digital direct sample multi-channel NAV/COM radio for an unnamed avionics company (not my current employer, Rockwell Collins) and can suggest why some have reported not seeing an "effect" on the NAV instrument. The "indicator" has a significant amount of filtering ahead of it. The MOPS documents (FAA Minimum Operational Performnace Standards) for the ILS, GS, and VOR stipulate the minimum rates of change for the "indicator" and the sensor system implements filtering to accomplish those performance rates. The pulses from the strobe may be lost in the "indicator" filtering.

But understand this one point: weak signal performance will be affected by these pulses. The energy will pass through the filters and you're going to see the effects - unusable indications where otherwise good "information" was available. The DDM (differential depth of modulatoin) calculatoins will be impacted.

Separate the wires and be sure the grounding is correct. Try the same with a COM antenna. Close proximity and compromised wiring over the years and you will hear it. Life is just this way.

Cheers

Jim

[elippse]

Right on, Jim! It's good to hear a professional's point of view!

[nodgnal51]

Jim, Thanks for the professional advice. I had already decided to separate them and have done so. It seemed to me this path could, at the worst, contribute nothing and have cost me a bit of work, at the best it could have eliminated a potentially serious problem. I 'm glad I decided to do the extra work.

Thanks again to all who added their thoughts to my problem

Steve