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#1953423
Hi all,

I have a Yaesu FTA 550 handheld in my microlight. As a temporary bodge before I install a proper intercom, I'm using the supplied SCU-15 adaptor. As far as I can tell, everything is in good condition, but though I can head incoming transmissions, the microphone from the headset doesn't work (if I set the radio to 'internal mic', and then speak into the internal mic while wearing the head set, everything seems to be fine).

I've tried it now with three headsets - a DC 13.4, a Peltor 7006 and a Peltor 7004. All seem to be the same. Yaesu's spec sheet for the SCU-15 says:

"Headset specification requirements for the SCU-15
Earphone (Speaker) Impedance: 8 ohms or above
Microphone impedance: 150 ohms +/- 20%
PTT pressed: Ground
PTT not pressed: Open
If a high impedance microphone is used, then a suitable power supply for the electret microphone element and a low
output impedance buffer amplifier will be required."


Though I can't find details for the Peltors, the 13.4s definitely don't have this impedance on the mic - they're 50 ohm. Is this likely to be what my problem is (and why most portable intercom boxes for this application have a 9v battery inside them)? Sorry - well outside my comfort or knowledge zone here..!
By cockney steve
FLYER Club Member  FLYER Club Member
#1953444
Not much help. but daughter had a camera that would not function with rechargeables, was fine on alkalines. Yachties who use li-ion for house-power, keep a separate lead-acid for engine-starting. li-ions don't like a very heavy current-draw apparently. I'd therefore rule out batteries,although the voltage per cell is different, they are designed to work with either. hth.
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By Paul_Sengupta
FLYER Club Member  FLYER Club Member
#1953445
Reptile Smile wrote:Mines running off the 6 AAs, rather than the lithium ion rechargeable pack. Might it be that it's not supplying enough power?


You can try using the cigarette lighter cable to plug it into the aeroplane or a car to try that.

I assume you have Ext Mic set up from the menu! You can also set up the side tone so that when transmitting you can hear your own voice back through the headphones if the microphone is working.
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By seanxair
FLYER Club Member  FLYER Club Member
#1953446
I vaguely remember having to fiddle with my identical set up (albeit running off the rechargeable battery). But I can't remember what I did. It may have been that one of the settings was opposite to the manual. I still have it all and will dig it out to see if it will work when next at the airfield to get someone to test if I'm broadcasting.

Are you using the ptt on the radio or have an external one via an adapter?

I did then buy one of these https://www.flightstore.co.uk/pilot-headsets-c65/intercoms-c96/pilot-pa200y-intercom-for-yaesu-transceivers-p10970 and it worked perfectly.
#1953457
Thanks all, for all ideas.

Have external mic selected (though have tried with both).
Have tried with all flavours of side tone
Have tried external PTT and the one on the radio
Have tried different headsets
Can't find the car charger (think I took it to the aircraft) but have tried it on a DC adaptor, and have the same result.

Running out of ideas now!
#1953508
Thanks to everyone for their input on this. I tried the continuity check which seemed to suggest there was a lack of continuity on one of the contacts on the SCU15 - enough to convince me to take it apart, but having cut off the surrounding rubber from the moulded surround, I found that the continuity was fine on all pins. Accordingly, as far as I can tell, the headset is fine, and the adaptor is fine, and therefore, Occam's Razor being as it is (albeit horrendously misquoted), the only thing I can really point to is the radio itself.

There's someone at the airfield who has the same radio and therefore probably same adaptor, but I think this leads me towards 'radio repair', or, more likely, new radio. Thanks to all for their input.