Sustainer engine ignition noise (Solo2350)

Having a Solo 2350 on a Ventus 2cT, I've been annoyed that when it runs it
constantly triggers the squelsh of the VHF-radio. (No, raising the trigger
level doesn't do the trick)
It is possible to use the radio with the squelsh turned off and using a
headset. This makes the noiselevel even higher, than running with the engine
itself, which is too loud to begin with.

Doing the five year maintenance service, I finally took a look at the
wiring, now it was disassembled anyway. It turns out that none of the
ignition wiring is shielded, which obviously is the main contributer to the
problem. For instance, the wiring to the kill-switch on the instrument panel
runs parallel to all the other cables over a long distance.
It would be fairly easy to pull shields around all the cabling and it won't
be the weight of it that matters.

The Schempp-Hirth electrical diagrams shows no use of shielding. I've looked
to the newly released manuals for the DG-1000T which uses a similar
installation. The DG also uses no shielding.

My question now is, does someone have an explanation to why this is?
Could there be any good reason for not shielding the ignition wiring apart
from laziness?


/Per, Denmark

Per wrote:
The Schempp-Hirth electrical diagrams shows no use of shielding. I've looked
to the newly released manuals for the DG-1000T which uses a similar
installation. The DG also uses no shielding.

My question now is, does someone have an explanation to why this is?
Could there be any good reason for not shielding the ignition wiring apart
from laziness?

Yes - perhaps it does not cause problems when the ignition and radio
wiring are correct, and the engine and radio are functioning properly.
Do other Ventus 2CT have this problem? If not, then you should look for
bad ignition components, improper wiring, loose connections, try another
radio of the same type, and so on. If it is a common problem, perhaps
owners on a Ventus forum can suggest ways to reduce the problem. And, of
course, complain to the facotory!


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Per wrote:
Having a Solo 2350 on a Ventus 2cT, I've been annoyed that when it runs it
constantly triggers the squelsh of the VHF-radio.

Do you also hear the interference on a handheld radio? That may help
decide if the interference is being radiated, or conducted on the fixed
radio power wiring.

A handheld radio may also help you compare the ignition noise between
various motor gliders.

Is ignition noise a problem on the ASH26 and DG 800?


Andy

"Andy" wrote in message
oups.com...

Per wrote:
Having a Solo 2350 on a Ventus 2cT, I've been annoyed that when it runs
it
constantly triggers the squelsh of the VHF-radio.

Do you also hear the interference on a handheld radio? That may help
decide if the interference is being radiated, or conducted on the fixed
radio power wiring.

A handheld radio may also help you compare the ignition noise between
various motor gliders.

Is ignition noise a problem on the ASH26 and DG 800?


Andy

I had intermittant ign noise on my DG800B. I replaced the plugs and found
one with a cracked insulator. I snugged up the metal plug caps, and replaced
one plug wire that didn't look good. (subjective judgement)
The plug wires have metallic shielding, covered w/shrink wrap, but neither
end of the shield connects to anything. Abrasion protection I guess.

The radio is free of ign noise--for now!


Hartley Falbaum
DG800B "KF" USA

Solving ignition noise in the radio requires detective skills. Here are
some general tips:

1. Sometimes resistance is used in the high voltage circuit to reduce the
radio interference. This may be accomplished by using special resistor
plugs, or special suppressor type high-tension cable or resistor
suppressors. Remember, however, that reliability is paramount in the
aircraft engine. Adoption of the factory specified parts is recommended.
Make sure that any resistance parts have not been replaced with
non-resistance parts.

2. Determine how the interference is arriving at your radio. Unplug the
antenna at the transceiver. If the noise goes away, then the interference
is arriving through the antenna input. Now, unscrew the antenna at the
antenna end, so the cable is still there, but no antenna. If the
interference goes away, then it is arriving through the antenna itself. If
you can still hear interference, then the shield on the antenna may not be
fastened correctly and should be addressed.

3. The "ignition" noise may be from the high voltage spark or it could be
from the alternator. Alternators "whine", while ignition noise "ticks".

4. If you pick up ignition noise with the antenna disconnected, then the
interference is coming into the radio through the speaker leads or the power
leads and those must be filtered.

5. You can gain a bit by moving the antenna far away from the source of
interference.

6. Some radios are more subject to radio interference than others. Pulse
type interference can be reduced by using a noise limiter or silencer.

When everything else fails - turn the engine off and enjoy the silence of
gliding.

Colin

Thanks.

Well, the thing is, I know the drill to try to cure the symptoms of the
interference.

It some work and the result isn't guaranteed.

It's more obvious to cure the cause that generates the noise in the first
place. This also requires some work and is much more likely to be
succesfull.

Since both Schempp-Hirth and DG aren't doing it, I wondered why?

I know several plane owners who reports the same problem. I haven't asked
all i know of, but so far I haven't found any without the problem.

And yes, the easy solution is of course to turn the thing off, which is the
first choice anyway, since gliding is the sport of it.

Having to fly in controlled airspace with the engine on is the showstopper.

/Per

Curing the problem at engine level....but sounds difficult if the
cabling is implemented as "manufactured".

I should rather have a look at the radio system. It is required to
shield the microfone cable and shielding the headphones/loudspeakers
cables is also a good and easy solution.


Per a écrit :

Thanks.

Well, the thing is, I know the drill to try to cure the symptoms of the
interference.

It some work and the result isn't guaranteed.

It's more obvious to cure the cause that generates the noise in the first
place. This also requires some work and is much more likely to be
succesfull.

Since both Schempp-Hirth and DG aren't doing it, I wondered why?

I know several plane owners who reports the same problem. I haven't asked
all i know of, but so far I haven't found any without the problem.

And yes, the easy solution is of course to turn the thing off, which is the
first choice anyway, since gliding is the sport of it.

Having to fly in controlled airspace with the engine on is the showstopper.

/Per

I have two suggestions:
1 - If the system is a standard engine alternator/regulator set up charging
your battery and supplying 12 VDC to all of your electrical components, you
can try adding a 20,000 uF Capacitor ( rating of min. 25 volts). This will
act as a "filter" for some forms of electical noise.

2 - If the source of the the noise is related to your high tension ignition
( distributor/spark plugs) and shielding the spark plug wires is not an
option you can purchase a special "ignition noise" filter from most
automotive parts distributors.

If the kill switch you mentioned is similar to a magneto on/a/b switch such
is on a power aircraft, the wiring for this switch should be shielded and
ensure that the shield is connected to your aircraft ground.

I hope this info helps you.

James Swank
"Per" wrote in message
...
Having a Solo 2350 on a Ventus 2cT, I've been annoyed that when it runs it
constantly triggers the squelsh of the VHF-radio. (No, raising the trigger
level doesn't do the trick)
It is possible to use the radio with the squelsh turned off and using a
headset. This makes the noiselevel even higher, than running with the
engine itself, which is too loud to begin with.

Doing the five year maintenance service, I finally took a look at the
wiring, now it was disassembled anyway. It turns out that none of the
ignition wiring is shielded, which obviously is the main contributer to
the problem. For instance, the wiring to the kill-switch on the instrument
panel runs parallel to all the other cables over a long distance.
It would be fairly easy to pull shields around all the cabling and it
won't be the weight of it that matters.

The Schempp-Hirth electrical diagrams shows no use of shielding. I've
looked to the newly released manuals for the DG-1000T which uses a similar
installation. The DG also uses no shielding.

My question now is, does someone have an explanation to why this is?
Could there be any good reason for not shielding the ignition wiring apart
from laziness?


/Per, Denmark

I have an ASH26E with no radio noise problem. I also have a Cambridge 302.
When first installed, there was some noise coming from the 302 on a couple
of radio frequencies, enough to break the squelch anyway. Ferrite beads on
the radio and Cambridge wires took care of the problem.

I agree with the advise already given, re using a hand held radio and
disconnecting stuff to isolate the problem.

bumper