Headset Noise

[JayMatt]

Before I go a rabbit hole here, I'd like some thoughts on this. I'm getting a ticking noise in my headset. It's a slight tick but it annoys me and I have a few long flights coming up. My IA said that it could be the spark plug leads as they are frayed pretty good where they connect to the plug. The sheathing or shielding whatever its called. When I flew the other day, I noticed it would quite down when I leaned it just right. It sounds like it ticks in rhythm with the spark, so I think that maybe it. He cautioned me to do some research first and see what comes up so I don't waste a bunch of money on leads for no reason. 

Anyone else gone through all this? 

If it is the leads, what leads would you buy? They say shielded on AS but they don't look anything like mine. If anyone knows the best ones for a 78 Mooney I'd love the recommendation. I prefer quality over price.

[N201MKTurbo]

If it is a bad spark plug lead, just do a mag check while flying and see if the ticking goes away when one of the mags is turned off.

[PT20J]

If it’s engine related, the rate of ticking should vary with rpm. Strobe lights can also make a tick. If you think it’s spark, check the resistance (5000 ohms max) of the plugs before replacing stuff. High resistance stresses the wires.

[M20F]

[EricJ]

+1 to check the easy stuff first.    Vary RPM and see if it changes, do a mag check to see which side(s) it's coming from if it is the ignition.    Does it do it on both radios?

FWIW, my #2 comm had ignition noise on it, but the comm in my IFD didn't.    I just got my mag overhauled and now they're both nice and quiet.    So in my case it was coming from the mag rather than faulty wires.

[Hank]

I get a faint tick from my beacon. Since I converted from high voltage to LED, it's quieter, but still there.

So next time you hear it, vary.the RPM and see if it also changes; if not, briefly turn off your strobe and see if it stops. Then turn the strobe back on.

Quick, easy and zero cost. 

[M20F]

Pull breakers one at a time and see what happens.  

[Utah20Gflyer]

I get a tick from my strobes but I can’t hear it when the engine is running so not an issue at this point.  

[rturbett]

working on the same issue- turned off strobes, etc with no change. Pulled the alternator breaker and it completely went away with the clearest radio communication imaginable.

Working with the mechanic to check all wiring, and likely put an inline filter.

The alternator was just rebuilt, ( new brushes and a diode) but the problem existed before.

Rob

[PT20J]

My M20J has a pi filter and a 3000 uF capacitor located behind the circuit breaker panel to filter the alternator output. The capacitor is cheap to replace and electrolytic caps can degrade with age.  

[Ragsf15e]

On 3/18/2025 at 9:13 AM, PT20J said:

My M20J has a pi filter and a 3000 uF capacitor located behind the circuit breaker panel to filter the alternator output. The capacitor is cheap to replace and electrolytic caps can degrade with age.  

You don’t have a picture of what that looks like, do you? How hard was it to access?

[Fly Boomer]

On 3/18/2025 at 11:13 AM, PT20J said:

My M20J has a pi filter and a 3000 uF capacitor located behind the circuit breaker panel to filter the alternator output. The capacitor is cheap to replace and electrolytic caps can degrade with age.  

So both of the caps are 3000 uF?

 

[PT20J]

8 minutes ago, Fly Boomer said:

So both of the caps are 3000 uF?

 

The caps in the sealed filter are much smaller. The external capacitor is 3000uF.

[EricJ]

FWIW, a tantalum or film capacitor, or essentially anything other than electrolytic, might be a better choice there.   Electrolytics don't age well, which is why they turn into problems after a while.  Electrolytic and tantalum capacitors are polarized, so there's potential for installation error, so be careful about that as well.

[PT20J]

1 hour ago, EricJ said:

FWIW, a tantalum or film capacitor, or essentially anything other than electrolytic, might be a better choice there.   Electrolytics don't age well, which is why they turn into problems after a while.  Electrolytic and tantalum capacitors are polarized, so there's potential for installation error, so be careful about that as well.

I think it will be difficult to find a 3000 uF capacitor that is not an electrolytic. I believe you meant that tantalum electrolytics age better than aluminum electrolytics, and I believe that's true. When I was designing mil-spec equipment, we used tantalum capacitors exclusively, but they were in the sub -100 uF range. Aluminum capacitors are cheap, though.

I replaced mine from my 1994 J because I had one of the early SureFly mags installed that had the cutout issue due to voltage spikes on 28V aircraft. It didn't help and I subsequently removed the SureFly. I measured the capacitance with a Fluke 115 DMM and both new and old showed about 3000 uF. 

[EricJ]

6 minutes ago, PT20J said:

I think it will be difficult to find a 3000 uF capacitor that is not an electrolytic. I believe you meant that tantalum electrolytics age better than aluminum electrolytics, and I believe that's true. When I was designing mil-spec equipment, we used tantalum capacitors exclusively, but they were in the sub -100 uF range. Aluminum capacitors are cheap, though.

I replaced mine from my 1994 J because I had one of the early SureFly mags installed that had the cutout issue due to voltage spikes on 28V aircraft. It didn't help and I subsequently removed the SureFly. I measured the capacitance with a Fluke 115 DMM and both new and old showed about 3000 uF. 

You can get large tantalum caps these days, but they're expensive.    KEMET makes a 1200 uF cap that can handle 50V, but it looks big and even at Mouser you have to call for a quote.   You could put two or three in parallel, but I'm guessing they're expensive.   They make a 3900 uF cap, but it's only rated to 15VDC.

You can get film caps that size with >1kVDC rating, but they're over $200/ea.

So, dang, the CBs may be stuck with electrolytics.       It is admittedly the more practical approach.