After spending much time frustration and money beating on the problem of static in our radio transmission (which get worse in direct proportion to the engine RPM) we're at this point close to certain it's RFI from the ignition system over the air (not over any aircraft wiring.)
(Won't bother documenting the reasons it's narrowed down to that at this point,
except to say that an avionics guy standing next to our running plane
transmitting with a handheld gets the same RFI proportional to our
RPM that we do with our microair 760.)
Anyway, we have unshielded ignition wiring.
So a couple of questions along that line:
1) Anyone know of sources for sheilded ignition wiring that could be suitable?
2) Curious if anyone's using sheilded ignition wiring on their 912?
2b) Curious if anyone had, or knows of, an RFI radio noise issue that was resolved by
installing shielded ignition wiring on the 912?
3) Anyone know anything about sparks plugs with RFI suppressors built in on the 912?
3b)Anyone know anything about the availability of and the pros and cons of
resistive type and inductive type RFI suppressor sparkplugs -- particularly on the 912?
4) Finally:
I used to be in the computer industry and we used to use RFI absorbing paint to confine radio interference inside the computer cases to pass FCC regs.
Was wondering if painting the inside of the fiberglass engine cowling with this stuff
http://www.lessemf.com/paint.html
might work?
Any thoughts on that?
All help appreciated, as clear radio transmission is obviously of importance to our and others' safety.
Al
Footnotes, of possible relevance.
#We're certainly not opposed to using factory approved or recommended parts
or proceedured but because we're an ELSA are not limited to those if
there's reason to do otherwise.
# Our 912 has about 500 hours on it.
#Our aircraft is a Skyranger and, again just FWIW, the entire engine cowl is fiberglass so any RFI coming out of the engine, unlike if the cowling were metal, radiates out pretty much freely.
# It's a ragwing, so similarly any airborn RFI from almost anywhere in the plane will reach the antenna.
(Won't bother documenting the reasons it's narrowed down to that at this point,
except to say that an avionics guy standing next to our running plane
transmitting with a handheld gets the same RFI proportional to our
RPM that we do with our microair 760.)
Anyway, we have unshielded ignition wiring.
So a couple of questions along that line:
1) Anyone know of sources for sheilded ignition wiring that could be suitable?
2) Curious if anyone's using sheilded ignition wiring on their 912?
2b) Curious if anyone had, or knows of, an RFI radio noise issue that was resolved by
installing shielded ignition wiring on the 912?
3) Anyone know anything about sparks plugs with RFI suppressors built in on the 912?
3b)Anyone know anything about the availability of and the pros and cons of
resistive type and inductive type RFI suppressor sparkplugs -- particularly on the 912?
4) Finally:
I used to be in the computer industry and we used to use RFI absorbing paint to confine radio interference inside the computer cases to pass FCC regs.
Was wondering if painting the inside of the fiberglass engine cowling with this stuff
http://www.lessemf.com/paint.html
might work?
Any thoughts on that?
All help appreciated, as clear radio transmission is obviously of importance to our and others' safety.
Al
Footnotes, of possible relevance.
#We're certainly not opposed to using factory approved or recommended parts
or proceedured but because we're an ELSA are not limited to those if
there's reason to do otherwise.
# Our 912 has about 500 hours on it.
#Our aircraft is a Skyranger and, again just FWIW, the entire engine cowl is fiberglass so any RFI coming out of the engine, unlike if the cowling were metal, radiates out pretty much freely.
# It's a ragwing, so similarly any airborn RFI from almost anywhere in the plane will reach the antenna.
