Radio noise

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 airports

What does that mean?

I don't understand what is happening.

Dave

[swoeric]

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 airports

[jim cooper]

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.
Hank

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. JC

[Hank Jarrett]

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.
Hank

[M Towsley]

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+cups

[flyguy]

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

[waltermrich]

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.