The International Cessna^® 170 Association

I'm wondering if anyone has licked the problem of the electrical "noise" that a strobe puts out? Mine causes two problems: 1) Listening to it gets old through the headset and, 2) My ADF won't find stations with it on (it only took me 3 months to figure out why the ADF worked great on some trips, but not at all on other flights!).

I know that Aircraft Spruce sells a noise filter (PN 11-08055, $80), and I'm ready to order one, but I'm not sure how well it works, or if it will help the ADF problem, or if there's a simpler, cheaper solution.

My apologies if this has been covered in another post, but I couldn't find it.

I have the same problem on FEH, mine has a beacon i think is car type (dont ask!) and when i switch it on it starts a noise on the intercom headset. But no nav is affected since i have only a garmin 95 gps. But would be nice to know either.

I don't have a strobe system on my airplane but I have worked on many planes that did.

The wiring for your strobe should be shielded to prevent the problem you describe. Inspecting the shielding on all the wiring would be a good place to start. Pay special attention to the shielding at all connectors. This is where It usually gets corroded or comes loose. I would also take note of the location of all components of your system. If they can be moved farther away from each other that could help too, such as a power supply located too close to your coax cable. you should pay attention to the routing of the wiring for your strobe system too, make sure you don't have lots of extra wire rolled up in a coil somewhere this essentially creates a big electro- magnet when power is applied. One of the easiest things to check would be your comm and ADF antennas, make sure the coax connectors are not corroded and they are properly grounded to the airframe. this is a common cause of this type problem.

I just had an interresting thing happened, just finished my annual with my mechanic doing a bit of electrical work. Now I am getting static over the radio coming from my transponder which is a separate unit, ever time the light blinks on the transponder I get a surge over the radio, I have never had this problem before. Is it possible my mechanic knocked some ground wire loose, or some wire got moved someplace too close to something else? Ideas?

Shane

I had a noise problem on a Cherokee. I spent $10 K to get some "used/rebuilt" radios and receivers installed to make it IFR certified. I started getting noise throuhg the intercom after that installation (by a reputable shop) and it was obviously coming from the "coffee grinder" rotating beacon. After asking the Association and alot of "techs" I ended up going to Radio Shack to purchase and inline filter. I forget what they call it, but it is like a rectangular metal donut; you wrap the wire leading to the beacon onto it and it "reduces" the noise considerably. What finally eliminated the noise was when I installed a "pulse" type beacon. JD

While working on FEH i discovered that when i switch on the nav lights the mag compass moves 15 degrees, why is that, is any way of fixing or is it normal. It happens only with that and with the beacon off Any thougths?

It is normal to see some compass deviation when large electrical loads are applied, like turning your generator on. 15 degrees seems very excessive just from your nav lights. The cause is simple though. The wiring for your nav lights is routed too close to your compass. Or there is wiring for your nav lights coiled up behind your dash too close to the compass. Do you have a panel mounted compass? they are more prone to having this problem. Routing the wires for your lights along the bottom edge of the panel should be sufficient as long as you have the original type nav lights installed. If you have a different setup or this doesn't do the trick let me know.

If your compass illumination lamp is on the same circuit as your nav lights, you might need to "twist" your leads to the compass lamp in order to cancel any stray magnetism from the D.C. circuit. Twist the leads 10-12 twists per inch. Safety wire pliers will do the job very neatly.

Thanks for all the input. I'll try a R.shack filter this weekend and let you know how it helps.

[quote="offpiste"]Thanks for all the input. I'll try a R.shack filter this weekend and let you know how it helps.[/quote]

Took awhile to reply, but it works perfectly.