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Tick-Tick-Ticking Noise

R

rv7guy2

Active Member
Hi there
Recently I've been hearing a "tick-tick-tick-ticking" noise on my radios while in flight. On the ground and during runup it's not there. While in the air, when I transmit I can hear the ticking noise while both transmitting and receiving, NOT while the frequency is silent. I'm using Dynon Radios for both comms with my Skyview system. The noise is not overwhelming but is annoying.
A friend suggested it may be a failing diode in the voltage regulator of my alternator. I'm running a Plane-Power alternator with a built in voltage regulator. I've been using it for over 5 years without an issue..probably eight years, I cannot remember, but it's been quite a while.
Could this failing diode theory be correct? Can it be repaired in an economical fashion? Or am I destined to get a new alternator sooner than later?
Thanks
Dave C
RV-7
C-GCPD
 
There are likely many causes - - - mine was a loose ( lightly tightened nut) p-lead on a mag found in Phase I. It could only be heard ticking in the radio at low RPM - taxi.
 
I would think a bad alternator internal diode with the engine at speed would generate a spike at something around 100 HZ. It would sound more like a buzz than a tic. I don’t know what a regulator diode would do
 
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Dave,
Do you have a transponder and if so does it make any difference to the clicking if you turn it off?
 
Does it follow engine RPM? Is it tied to one ignition? Seems likely to be an ignition lead with some corrosion, or a bad plug. Turn off each ignition (preferably one at a time:eek:) and see if it is correlated to one ignition.
 
rv7guy2 said:
Hi there
Recently I've been hearing a "tick-tick-tick-ticking" noise on my radios while in flight. On the ground and during runup it's not there. While in the air, when I transmit I can hear the ticking noise while both transmitting and receiving, NOT while the frequency is silent. I'm using Dynon Radios for both comms with my Skyview system. The noise is not overwhelming but is annoying.
A friend suggested it may be a failing diode in the voltage regulator of my alternator. I'm running a Plane-Power alternator with a built in voltage regulator. I've been using it for over 5 years without an issue..probably eight years, I cannot remember, but it's been quite a while.
Could this failing diode theory be correct? Can it be repaired in an economical fashion? Or am I destined to get a new alternator sooner than later?
Thanks
Dave C
RV-7
C-GCPD
Click to expand...

VR don't really use diodes to do their job, but like most electronics, it may have one or two on the board. Guy was probably referring to the large rectifier diodes in the alt itself. However that would probably show other issues to. While it could be many things, your first step should be to listen to tick frequency at 2500 RPM, then at 1800 and then at idle. If the tick frequency changes, then you know it is RPM dependent and can narrow the search down to things that work variably with the engine RPM. I would also turn off the squelch on the radio and see if the ticking is there when the channel is silent. WHile I don't think it is the diodes, there are failure modes in the alt or it's wiring that can make excessive noise like this. HOwever, ticking is usually ignition related . alternator is spinning at something like 8000 RPM (130 RPS) and the ignition is spinning at 1200 RPM (20 RPS).

The fact that it only happens in the air points to a static issue. I would consider looking at the antennae and their cables. Does it happen on both or just one of the comms? if the tick is not there on the ground at 1800, but is there in the air at 1800, then it is hard to blame much of anything but the radios or antennae, My first step would be confirming a good antenna ground.
 
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I encountered a similar issue with my last RV-7 -- every once in a while, I would hear a tick-tick sound in the headset.

It didn't follow RPM, strobes, or anything else I could find that was "cyclical."

After flying into some visible moisture on an approach, it transitioned from a tick-tick to a crashing roar while in the clouds.

It turned out that the shoulder washers/isolators under the co-pilot microphone and headset jacks had cracked and were acting like little capacitors; static buildup would cause a voltage potential to rise until it bridged the gap and "tick" was heard...

YMMV...
 
Tick-tick-ticking

Thanks for all your input so far....I went flying today and the ticking sound on the comms is still there. Both while transmitting and receiving although it seems the closer the other transmission is, the less ticking sound can be heard..in other words, the further away the transmitting plane is, the more distinct the ticking sound is.
I turned off the Alternator while in the air and it made no difference. Did that several times with the same results, ticking sound persisted. So probably safe to rule out the alternator. Next time I fly I'll try turning off the mags one at a time to see whether that makes a difference. Could be something with the mag harness shielding perhaps?
 
I have similar RF noise problem a new COM1 IFD440 radio. I hear a noise pulse at around 1 to 2 Hertz that increases in speed with engine RPM.
Noise is not present with the engine off.

Equipment:
New AFS panel Dual 6600 EFIS, IFD440, Dynon T25 Transceiver , GARMIN GMA245 audio panel.

The Dynon T25 Transceiver is on COM2. COM2 and intercom is perfectly quite.

It is loud enough to interfere so that I can barely use COM1. However, the noise does not break squelch

Steps taken to diagnose:

Noise remains after turning off alternator and opening all circuit breaker in the ACM panel.
Noise is present with either L R and both mags selected.
Checked all engine compartment connections and grounds.
Checked all wiring harnesses in back of the panel and antenna connections.
No luck. Still present.

COM2 is clear so I moved the COM2 antenna to COM1.
The noise is still present on COM1 suggesting the COM1 antenna is not the problem.

I tested the COM1 radio with a handheld. The person receiving can here noise in transmission too.
I disconnected GPS and other antennas except COM1 to 440.
I checked the switch wiring and grounding.
Looks good shields go to mag ground only.

I removed the P leads and mag ground.
I then tested COM1 with the engine on, the noise persists.

My conclusion is this isolated to the COM1 circuit. It could be the IFD 440 or the harness COM1 harness.
I suspected a bad ground or ground loop but I can find it so far.


I discussed issue with Avidyne.
Not much help.
They suggested that I might even have a defective radio.

Any suggestions

Max
 
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