Radio Static Filters

[Pearson]

Does anyone have experience with the filters you put on your mags to stop static noise on your radio. They are about $40 each and I suppose you need one for each mag. I hate to spend that much money if they don't work. I use a handheld with an external antennae

[flyguy]

Re: Radio Static Filters

Tell us about your ignition system ie type mags, type wiring harness, ect and we will try to tell you what we know about whether the filters will help or if you need to do something else first.
Darryl

[Pearson]

Re: Radio Static Filters

I've got Slick mags with regular wires.

[flyguy]

Re: Radio Static Filters

Actually a little more info is required. Do you have shielded plugs? Are they resistive type plugs? By normal wires, do you mean a factory-type shielded harness with the outside shield properly terminated (grounded) at both ends, and shielded sparkplugs . Are there any breaks or loose ends to the shielded braid? Anything that is not as above will give you LOTS of noise. Do you get less noise when you switch from one mag to the other?
It is my best understanding that the filters are used to stop the noise from getting on the P-leads and then being radiated. I can check further with one of my ignition gurus on that. If anyone knows better, correct me.
There is a way to check your p-leads to see if they are the noise source, but it can be dangerous if you are not aware of EXACTLY how they function. I would be more comfortable if you got a local engine person to advise and help you on that procedure.
Hope this is more help than confusing.
Darryl

[Pearson]

Radio Static Filters

I don't think my plugs are sheilded. They do not have the little caps over them like I have seen on other Taylorcraft. The wires have the metal braiding on them. Does that mean they are sheilded wires? One of them has a small amount of fraying on one end near the plug. None of the wires have any kind of grounding wires attached to either end.

I have never tried to listen to the radio while doing a mag check. But I can do that this weekend and find out if one mag is worse than the other.

[flyguy]

Re: Radio Static Filters

Well, I've seen unshielded plugs with an unshielded harness, and shielded plugs with a shielded harness; but is sounds like you have a system that is half and half.
The bottom line is you will have to spend some money.
Sounds like Mike H. has found some short shielded plugs. If so it will help all us Taylorcraft pilots keep our slick, unbumpy, cowlings that way.
I suggest you look at a more "modern" aircraft, such as a cessna 150 or 172. That is the way your wiring and plugs should look if you want to get rid of the noise.
We'll help as much as possible as you fix things up.
Darryl

[Mark Julicher]

Re: Radio Static Filters

I put the capacitor filters on my A-65 along with shielded plugs and shielded P-leads. I can still hear a little noise in the KX99, but there was some improvement. It is all subjective and my engine still runs fine.

FWIW, Sacramento Sky Ranch website says that the capacitors eat some of the spark, so you lose a little there ... probably makes the start a little harder.

Also FWIW, aeroelectricconnection ('lectric Bob) has a good discussion on shielding p-leads on his web site.

I hope that helps some.

[flyguy]

Re: Radio Static Filters

I had wondered if the filter/capacitor was effectively across the primary circuit and if it "rounded" off the leading edge of the spark. That is where the hi-frequency energy is, and it would take some energy away from the spark, along with reducing radio frequency output (noise pulse.) I have read some of the essays that Sky Ranch has put out, but missed that one. I'm going to go look for it now.
Thanks
Darryl

[Len Petterson]

Re: Radio Static Filters

Shielded pluggs or not my radio dont care! It is a JRC 520 from the "Spruce up shop" It has a ANL circiut in it what works. Many new radios has this and 90 % or better of the noise is gone.
The ANL circuit can be switch on and of and it makes for a "mag condition check" if you know and understand how some of the noise is generated by your mags.
Noise is generated in the mag and plugs, the sparkplug makes a sharp clean noise.
A bad mag, makes a random constant crackel.
I have: Unshielded Case magnetos with unshilded high tension leads, and a I]shielded[/I] P-lead.
During a go around after short fligth the left mag quit!
This is what I experience during runup!
Left mag gives me a constant 'crackel' in the radio .
Rigth mag had a distingt sharp noise.
The rotor in the left mag was full of carbon tracking.
( Read the Case magneto manual on this website for explanation)
The sparks ends up fireing all plugs on the same time! Not god!
After cleaning and repairing the both mags the engine runs good agin and the radio noise from both mags is crisp agin.
Listen to the noise during the idle portion of the run up and move from left to rigth to both.
(At high Rpm it is difficult to distinglish different types of noise.)
The carbon buildup caused fireing out of sequnce and the engine ran to ONLY 1800 rpm with mag switch on BOTH, If it happens agin I will switch mags after gaining altitude and/or having a runway witin reach, it would have cleared up my engine at what time. On runup after landing, it devoped full power on the rigth mag.
From now on I LISTEN's to my mags!
The ANL circiut takes out almost all noise.
Ear plugs + head set makes it realy nice to fly agin.
I am sorry I dint spent the extra $ for a noisecanceling head set, hence I use earplugs together with the headset and increase the volume on the radio.
As a foot note: It is my understanding a shield is to be grounded at the source/ one end ONLY. Dont know about shielded sparkplug wires, but general electrical rules says: DO NOT MAKE A LEED OF THE SHIELD!
Len Petterson

[Forrest Barber]

Re: Radio Static Filters

Amen to all that.. Along time ago we sold Comm-Spec handhelds, they had GREAT noise rejection. I flew the BC12D with Eisemann mags a lot , to OSH in l983-84 and it worked fine with standard plugs , antenna on bottom back in middle of fuselage. Each mag was different , very muted and could be turned down to almost nothing.