Trig TY91 radio background noise

[PaulvS]

G'day all,

I have just completed installion of a new Trig TY91 radio in my RV-6A. The radio appears to function correctly, however there is a minor problem with background noise coming through the headsets.

The noise is a regular faint tick-ticking sound at approximately 0.5 second intervals when the radio is in receive mode. The volume control on the control head does not change the volume. The noise occurs even when ALL other electrical equipment is turned off and disconnected, so I don't believe it is due to interference. I've tried a different headset as well as the jacks on the other side and this makes no difference. I've also tried different power sources including a battery and DC power supply. The installation has been completed per the Trig installation manual, to the best of my ability.

Any ideas on what may be the cause and the remedy for this issue? A search of the internet indicates that other people have also experienced this problem and it is possibly due to interaction between the control head and the radio, but this is unconfirmed.

Thanks,
Paul

 

[rv8ch]

Do you get this noise only in your hangar, or other parts of the airfield as well? Might try turning off all electrical stuff near the aircraft, or rolling the aircraft outside away from electrical devices.

 

[PaulvS]

Do you get this noise only in your hangar, or other parts of the airfield as well? Might try turning off all electrical stuff near the aircraft, or rolling the aircraft outside away from electrical devices.

Thanks Mickey for the suggestion. If everything electrical is turned off in the workshop the noise is still there. The plane is under construction and is not yet quite ready to be able to roll it outside. I also tried a handheld transceiver in the shop and it is quiet.

I suspect the noise is generated within the Trig unit(s) because the volume remains the same even if turning the radio volume control up. The volume control on the headset does affect the sound level. There is also no separate intercom or audio panel and the Trig has internal intercom.

 

[rv8ch]

Thanks Mickey for the suggestion. If everything electrical is turned off in the workshop the noise is still there. The plane is under construction and is not yet quite ready to be able to roll it outside. I also tried a handheld transceiver in the shop and it is quiet.

I suspect the noise is generated within the Trig unit(s) because the volume remains the same even if turning the radio volume control up. The volume control on the headset does affect the sound level. There is also no separate intercom or audio panel and the Trig has internal intercom.

Same noise with a different headset? Might need to make a call to Scotland. They are working now, if you are still awake!

 

[PaulvS]

Same noise with a different headset? Might need to make a call to Scotland. They are working now, if you are still awake!

Thanks, I contacted the local support centre (other side of our island!) and they are going to forward the details to Scotland. Will post the outcome here when I hear back.

 

[lr172]

Have you tried turning off the intercom for a test. My first guess is a ground issue between the radio and intercom and this test may help rule that in or out. Most intercoms have a pass through function when turned off that send radio output straight to headset.

 

[PaulvS]

Have you tried turning off the intercom for a test. My first guess is a ground issue between the radio and intercom and this test may help rule that in or out. Most intercoms have a pass through function when turned off that send radio output straight to headset.

I haven't tried that because there is not a separate intercom, per se. The TY91 intercom is integrated within the radio (like e.g. Garmin GTR200). While I was testing the only electrically live equipment was the TY91 transceiver and the TC90 control head. The control head and the transceiver are both connected to the same ground point.

FWIW I disconnected the antenna (did not try transmitting as that could damage the radio) and it made no difference. There is good continuity between the coax centre pins and also between the connector bodies and there is no shorting between the centre and shield.

The mic and headset wires are shielded and grounded at the radio end only and the jacks are isolated.

 

[PaulvS]

Conclusion

Just to close this out:

I did further testing of the radio out of the aircraft on the bench using another new harness and the noise was still present.

The local Australian Trig Support agent suggested to send the radio in for testing, at my expense for freight.

I talked to Trig Support in Scotland and they confirmed that the clicking sound is actually always present in this model of radio and is caused by the transceiver unit polling the remote control head twice per second to check for changed volume, frequency etc. There is nothing that can be done about it and it should be less noticeable when the engine is running. So there ya go!

 

[jliltd]

I have installed a half dozen TY-91's, two of which were dual control head configurations. I have never utilized the internal intercom. Always external ICS or none (single seaters). I have never heard said tick but I don't have the best ears either. Maybe I should get a young kid to listen for the ticks when powered on and parked.

I even installed a dual-head TY-91 system in a Land Cruiser with perfect results after handheld transceivers were unusable in the vehicle due to interference noise.

The TY-91 transceiver system is one of my all-time favorite aircraft comms. Simple, bulletproof and high quality. I think you will be very satisfied with it in the long run.

 

[dmattmul]

Ticking

I installed 2 sets of transceiver/transponder remote head Trigs. Heard the same ticking noise. Seemed to work fine and nobody on the other end could hear anything all 5 by 5. Took apart the antenna and tried different combinations of washers and insulators same problem. Finally fired up the engine and problem went away or at least I couldn’t hear it. Bose A20 headsets. Was very easy to add ADSB to the set up and pretty cheap. Used in 2 single seat experimentals and have worked well.