Hand Mic Not Working?

tshugart3

Hello all,

For the first time I can recall (in the 3 years I've owned my Archer II), I tried to use the hand mic on my panel. It didn't appear to do anything - no one responded and I didn't hear any side tone like I was transmitting.

Is there a trick to using this thing? Are there different audio panel settings for using it to transmit? (I have a KMA-24 audio panel). Any thoughts/advice appreciated, thanks!

djspathis

Was your pilot (not hand) mic unplugged at the panel? Some installations piggy back the two (hand and pilot) mic connections and this can cause issues. Specifically, only one mic is meant to be "in circuit" (connected) at one time on any one intercom connection. Can't say if this is your issue but worth considering.

DJ

tshugart3

one headset was plugged in on the left, and the mic was plugged in under the center.

Seneca38173

Do you also have an intercom, like an SCI-S4, or does your headset plug directly into the KMA-24 audio panel? Bob

djspathis

https://piperowner.org/talk/discussion/comment/1442054#Comment_1442054

If your headset is like mine, it has two connectors, one with a larger diameter plug for the headphones, and a smaller diameter plug for the microphone. I’d try the hand mic again after unplugging the headset’s smaller connector from the panel.

DJ

tshugart3

Update: went flying today and played with the hand mic some more.

• I unplugged the headset, and tried the hand mic again
• when i key the hand mic, the COM1 radio shows that it's transmitting. Guys in the pattern said that when I tested the radio, they heard someone keying but no voice came out.
• I pulled the mic out of its connector and reseated it, and also tried it using the mic part of my headset connection. Same results.

So I'm guessing maybe the mic part of the hand mic is not working?

To answer questions from above:

• the Archer has a pretty standard intercom, sigtronics maybe?
• the hand mic plugs into a connector under the center of the panel, below the quadrant. I have no idea how it's wired up and where it goes, but it's clearly connected as it does cause COM1 to transmit when I key it, there's just nothing going out on the transmission.

Scott Sherer

Have you tried a different mic? I think we need to confirm that it's either the mic or the panel wiring.

djspathis

Assuming that your normal headset and PTT are working, to diagnose this as a possible hand mike issue, I'd plug the hand mike into the mike jack in the panel (next to the headset audio out plug) and try it instead of the headset's mic. You should be able to use the normal PTT switch on the yoke and simply talk into the hand mike. If you don't hear yourself in the headset (sidetone) and others monitoring your frequency can't hear you, it's a good bet that there's something wrong with the hand mike.

DJ

Seneca38173

These all sound like great suggestions to me.

One caution about comparing handheld microphone audio with headset audio: The handheld mikes, like the Telex 100, have a built-in buffer amplifier that's powered by a current source in the audio panel. If the current source is dead or miss-wired, the mike definitely won't produce audio. On the other hand, some newer headsets power the buffer amplifier from their own power source (batteries, etc) and will work fine even if the current source in the audio panel is dead. DJ's experiment is great, so long as you use a fully-passive headset.

Bob

djspathis

https://piperowner.org/talk/discussion/comment/1442076#Comment_1442076

Thanks for the clarification, Bob. I guess I should look at some more modern noise cancelling headsets to replace my passive David Clarks 😀

DJ

tshugart3

https://piperowner.org/talk/discussion/comment/1442076#Comment_1442076

Thanks, Bob, for that data point.

One question - does this mean that the handset microphone would not work if I plugged into one of the usual headset microphone jacks? That's what I tried yesterday without any luck, and I wondered if that narrowed it down to the mic.

Seneca38173

DJ - Scott says there's a new Bose ANR set coming out. And when you get it, you can write us a full report! Bob

tshugart3 - if you have an old-school Sigtronics intercomm on the front end of your audio panel it will have the current source on all mike ports. so unless one is dead or miss-wired you should be good to go with the handheld mike.

Scott Sherer

Yes, Bose just announced the A30!

Seneca38173

Scott, did they determine the model number by knocking two zeros off the price? 🤑 Bob

djspathis

https://piperowner.org/talk/discussion/comment/1442084#Comment_1442084

From another board: Bose just duplicated the UFlyMike for three times the price

Seneca38173

Ha! It must be really hard to differentiate your headset product these days, since they're all pretty close in performance.

I remember sitting in Amar Bose' Acoustics class nearly 30 years ago, and two lectures he gave in particular. One was about how he personally invented the whole idea of the ANR headset while on a flight to Amsterdam. Some CEOs definitely have a sense of gravitas (and exaggeration)!

The other was his philosophy about how any product should only have a power switch on it - no other controls. It was the engineer's responsibility to make sure all the thousands of buttons and switches were set properly, and internally at the factory, so that the product would work properly right out of the box, with no fumbling or fiddling. I think of that philosophy every time I load a new piece of software, and grit my teeth while I try to get it to work. I'll bet the low/medium/high switch on the new A30 has Amar rolling over in his grave!

Bob

Scott Sherer

Roger that, Bob. :)

tshugart3

https://piperowner.org/talk/discussion/comment/1442078#Comment_1442078

Updates:

• I plugged my headset mike cable into the handset plug-in under the center panel, and it worked - got a good radio check.
• The hand mic still does not work from either the center plug or the pilot-side headset plug-in.
• I took the hand mic home and opened it up. Didn’t see any loose wires, multimeter shows continuity all the places I would expect it, reasonable resistances from the resistors on the board, etc. Don’t see any smoking guns inside the mic. I think the switch works because when I press it I do get a radio transmission, there’s just no voice going out. Other folks hear me keying but no audio.

I guess maybe the next step is to take the hand mic to someone else’s plane to see if it works, or if it’s the plug that’s the problem. 🤷‍♂️

djspathis

Given that the hand mike does not work in either the center console nor the pilots jack, and given that the pilot's headset mike works in both those places, ISTM that your hand held mike is the issue. If it also doesn't work in a friends plane (and try his mike in your center console), then it's the handheld mike that's the issue.

Not sure exactly which hand mike you have; if the standard Telex 100T, I found the following data sheet:

https://products.telex.com/binary/100T%20Tech%20Sheet.pdf

If you've checked the continuity of the wires shown in that diagram, then either the amplifier circuit is bad or maybe the Gain Trimmer potentiometer is dirty / has a flat spot / is no longer correctly adjusted for your setup. These are just SWAGs in case you're feeling ambitious. Googling "Telex 100T" brings up places to buy a new replacement for about $160. Let us know what you finally decide.

DJ

Grayden

I have repaired a few and found they usually have a broken wire at the solder joint. There are two switches, one for the key line and one for the mic audio. Carefully open up and take a look. After you fix it and you need to use it unplug your headset mic jack or both microphones will be active which reduces the mic audio level.

tshugart3

Well, I got it working, tough I don’t why for sure. After checking out the internals I went back out the field and now it’s transmitting voice, though it’s intermittently scratchy (probably need to clean plugs/terminals). I don’t know if I did something while I was poking around inside that made it work - I did find two resistors whose wires might have been touching, tough I don’t know if I made them that way in my fooling around with them.

In any case, thanks to all for the help!

Scott Sherer

Please send me a check for $1,000,000 made out to cash. I will disburse it to all of the fellows that have given you advice, above. :)

tshugart3

One final update: I tried the mic in the air today and it plus the speaker worked just fine.

Also, one thing I tried was to wear my Apple AirPod Pros, which have noise reduction, while using the hand mic and speaker. I found the noise reduction really knocked down the noise level and made it easier to hear ATC over the speaker. Might be a good way to go for long or hot flights when you might want to go without the headset for a while but still want to reasonable noise level and the ability to communicate. Worked well.

griff390

https://piperowner.org/talk/discussion/comment/1442116#Comment_1442116

Excellent, glad to hear that you have it working!

Years ago, I maintained the rental headsets for a flight school. One of the most common problems was dirty or tarnished contacts on the plug(s). Brass plug contacts were especially vulnerable.

The repair was to clean and shine the plug contacts with a piece of 0 or 00 steel wool, and the headsets would work perfectly again. The plugs with chrome contacts needed to be cleaned up from time to time, but far less often.

Thanks for the update!