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Question for anyone using the Old surplus C-26 Champion spark plugs. I have 2 Bendix SR4RN-21 magnetos for my Taylorcraft, The left mag with shielded REM40E sparkplugs on the lower plug holes are very quite with no radio noise. The top plugs with the Old Champion shieled C26 plugs , on the right mag are making a lot of noise, Im using them because they clear the back part of the cowl, with no interference to the cowl, and I really do not want to put holes in that part of the cowl.Im actually using the C26 in the frount cylinders and another old new surplus shielded Champion plug in the back thats even shorter. Does any one have experience with The old Champion spark plugs.
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Re: Radio noise
You can go with the cups, which is what I have with 26's on my top plugs, but don't let anyone tell you that they really work. I think about 90 % of the silencing is due to the resistors in the other plugs, as it gets rid of the sharp edge of the pulse which generates the Radio Frequency noise.
IMO you are pretty much stuck with making some holes and putting the "bumps" on there. I keep putting it off, myself.
DC -
Re: Radio noise
Walter,
I went the cup route with M41 plugs. Still have a bit of noise, but you can squelch most of it out. At least I did. Do a search for 'Ercoupe Cups'. Some info here: http://vb.taylorcraft.org/showthread...t=ercoupe+cups
And here: http://vb.taylorcraft.org/showthread...t=ercoupe+cupsCheers,
Marty
TF #596
1946 BC-12D N95258
Former owner of:
1946 BC-12D/N95275
1943 L-2B/N3113SComment
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Re: Radio noise
The cups will help a little, but only if you do the whole Montie. The cups alone won't help that much. (NOTHING alone will help much, it is a systems problem) You also need to make sure your "P" leads are properly shielded at both ends and that the mag switch itself is also properly grounded.
One of the BEST things you can do to improve interference reduction is to move the radio antenna and lead as far as possible from any ignition wiring. If you zip strip your antenna coax to the P leads you will get a LOT of interference! Radio noise obeys the inverse square law so if you can increase the closest distance between any antenna and ignition wiring from 2" to 4" you cut the noise by a factor of 4. My antenna is mounted on a plate just above the headlinner in front of where the aileron cables cross the cabin roof. The lead runs forward and half way down the door hinge tube on the pilots side (the "A" pillar). The "P" leads run under the lower edge of the tank and are tied to the tube along side of the fuel tank. As FAR AS I COULD GET IT from the antenna lead. I haven't tested the new mag switch yet, but if I have noise the first thing I will do as put a grounded "can" over the mag switch. I get great range and clear reception from my setup and sure hope all the work firewall forward doesn't ruin that.
HankComment
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Re: Radio noise
My T-Craft has the old plugs and harness. Icom in a holder on dash, hardwired to antenna on roof. Very little noise, some of course but not much. My cowl has no bumps. It was recently flown to Chandler Arizona. Radio reportedly worked well. JCOriginally posted by Hank Jarrett View PostComment
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Re: Radio noise
I have radio question and not sure where to go
b&c alt
grounding block on firewall every item is grounded individually to this block. the battery neg and motor ground is connected to this block.
ps engineering intercom
the radio transmits but does not receive
i have a set of plugs wired into the main radio jacks so that i can plug in my handheld into the intercom
often the radio will be keyed either in receive or transmit im not sure but the red light on front comes on...it is in rhythm and does not change with engine rpm...it seems if i key the mike some it will interrupt it and stop for just a bit
any idea if this is associated with hesterious sp the setting that radios have that to let go of a keyed mike or sensitivity to picking up a mike....this happen more frequently in larger class c airportsComment
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Re: Radio noise
Originally posted by swoeric View Post
What does that mean?
I don't understand what is happening.
DaveComment
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Re: Radio noise
i dont know if it is receive or transmit...but if it silent on the radio and somebody hits the transmit button or you hit it you can hear the difference...well that is what is happening hear it sounds as if my plane or somebody elses plane keeps hitting the mike buttton and the red light for transmit on my radio comes on correspondinglyComment
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Re: Radio noise
The mags i quoted are S4RN-21 not SR4N-21 and the plugs in question are the old new surplus Champion C-26 and S-62 both are radio shielded plugs, I think the way to find out if it is the plugs making the noise is to put one of the plugs in question on the left mag which runs perfectly and is quite now and see if it makes noise, if not then I will know its in the P lead or some where else.Comment
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Re: Radio noise
I am confused. Champion C-26's are NOT shielded plugs. Champion S-62's ARE shielded plugs and it is my understanding that they are the shielded version of the C-26?
FYI....I run the C-26's in the top and have no known issues with my Icom A6 either transmitting or receiving.MIKE CUSHWAY
1938 BF50 NC20407
1940 BC NC27599
TF#733Comment
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Re: Radio noise
C 26-S spark plugs are shielded, they are a single electrode plug like an auto plug I have the box right next to me I would send a photo if I knew how to, Look at the Fresno Airparts ad in Trade a Plane they are listed as a shielded plug for $10.75Comment
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Re: Radio noise
Well you have me on the C-26-S SH as listed by Fresno. So these are a metal enclosed plug that is shorter than say a REM 38 or 40? Didn't know such a thing existed, (as a C-26 I mean.) Guess I need to take a trip down there and check their stock for short shielded plugs. Love to get rid of the cans and the noise.
I can only guess from some of the reports similar to Mike's above that there are receivers that have some kind of noise suppression built in. Mine sure doesn't. Can't imagine how they would do that without killing the normal signal though.
DCComment
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Re: Radio noise
DC,
Do some measuring first before you go down there. Everyone's cowl is a bit different. I think if a short shielded plug was available, and fit under the cowl, a lot of people on the forum would be using it. I would like to see a picture of one installed, preferably on the top front cylinders with the lead installed.Cheers,
Marty
TF #596
1946 BC-12D N95258
Former owner of:
1946 BC-12D/N95275
1943 L-2B/N3113SComment
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Re: Radio noise
I miss quoted the S62 plugs are the shorter plug, and they are under my cowl, so sorry about that I do not think there are any plugs for an A65 shorter than the S62, the s in C26s probably stands for shieled , and i think you are correct that there is an old unshielded champion C26 plugComment
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Re: Radio noise
Yep, I have 4 of the "normal" C-26's in cans on top.
Marty, Fresno is just a reasonable cruise over in the Tcraft from here. I drop in there once in a while. They really helped me out when I was rebuilding my Eisemann mags.
Eventually it will be "bumps" I suppose.
DC
Edit/added. Inspiration in reference to comment of noise suppressing receiver: Think I will set up a test with my scope to check the frequency of the ignition snaps on the receiver audio signal. Maybe they would be out of the pass band for normal voice communication. Build a low pass filter to go in the headphone line ala an extension cord?
Probably would not work with someone with a squeaky voice, LOL, or an irritated female controller.
DarrylLast edited by flyguy; 04-25-2012, 17:41.Comment
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