Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Sooty25
#1589832
bambuko wrote:Can any of you guys, please suggest suitable boom mike for use with Yaesu radio in my glider. I have wired PTT as per advice in this thread, modified Yaesu SCU-15 to continue using internal speaker, and connected an old electret mike (used before succesfully with Delcom and Icom) and everything works fine apart from the mike - it transmit very quiet and crackly.
When I tried to buy new mike they all seem to be wrong impedance ...


when you say boom mike, do you mean one fixed to the airframe as opposed to a headset?
By cockney steve
#1589867
Desk top P.A mike? Maplins/ R S ?CPC / Rapid / Farnell..... if needed, a plug from the same source......modify or discard the base as needed .....likely to be considerably cheaper than £83....leaving a lot of beer -tokens . :)
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By rf3flyer
#1589873
@bambuko A TMG not a glider but I had something similar with my 550L. Using my old Avcomm headset I was told a couple of times that there was a lot of engine noise being passed by the mic. I borrowed a few different headsets from friends and found that Avcomm had a replacement mic for open cockpits and noisy environments. Bought and swapped and things are much improved.
Perhaps your brand of headset has something similar. As to the mic impedance, that seems not too matter that much as both my old and new mics are off the stated value for the Yaesu.
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By bambuko
#1589883
cockney steve wrote:Desk top P.A mike? Maplins/ R S ?CPC / Rapid / Farnell...

Waste of time and money. None of them will work ... :thumright:

cockney steve wrote:.....likely to be considerably cheaper than £83....leaving a lot of beer -tokens . :)

I am afraid it's not going to be cheaper ...
User avatar
By bambuko
#1589886
@rf3flyer
I have tried it with another headset and it was indeed better.
LX guys are now suggesting that simple dynamic mike might be a better solution (and cheaper than electret mentioned in my previous post), so unless I get specific suggestion here I will try it.
BTW Yaesu were not muc h help I am afraid :roll: :
...I regret that we are unable to interface non-Yaesu devices to our equipment...

I suppose I understand their un-willingness to help...
User avatar
By Sooty25
#1589899
the problem with asking a manufacture like Yaesu, or any other manufacturer, if their kit is compatible with "xyz", is they can't advise unless they have specifically tested that combination as it becomes their problem if the advice is wrong!

The problem you have is the Yaesu is designed for 150ohm dynamic microphones and you have a 1800ohm electret microphone. It isn't quite as serious as putting petrol in a diesel car, but it is that sort of incompatibility.

Two options,
1. replace the microphone with a 150ohm dynamic microphone
2. mess about trying to find/build an amplifier with the required electret power supply that will match the existing mic to the Yaesu.

what would I do? I'd replace the microphone as the end result is the simplest. Less items being less potential points of failure.

Sources, just go back to LX as it sounds like they have a source for 150ohm boom dynamics, it is a bit of an odd product.

Oh, the 150ohm bit isn't odd, that is an aviation standard.
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By bambuko
#1589934
Thank you Sooty25 :thumright: ,
that was the bit of info I was missing.
Radio manual just says 150 Ohm.
If Yaesu told me what you just told me (i.e. "...Yaesu is designed for 150ohm dynamic microphones...") , my problem would be solved.
Yes LX offers dynamic microphone and I will get it no problem.
My mistake/confusion was an assumption that I need electret.
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User avatar
By bambuko
#1591197
Just an update,,,
Got a dynamic mike from LX.
Connected it up and it doesn't sound any better than the old electret I tried before - both are Carp :roll:
(When used with internal mike all is fine :thumright: )

This is BTW what I am doing:
Image

Speaker is not connected (I am using internal one, which is fine for me) , and before anybody asks - SCU-15 connector is modified to avoid disabling internal speaker.
Last edited by bambuko on Thu Feb 15, 2018 8:34 pm, edited 1 time in total.
User avatar
By Sooty25
#1591225
bambuko wrote:Just an update,,,
Got a dynamic mike from LX.
Connected it up and it doesn't sound any better than the old electret I tried before - both are Carp :roll:
(When used with internal mike all is fine :thumright: )

This is BTW what I am doing:


Speaker is not connected (I am using internal one, which is fine for me) , and before anybody asks - SCU-15 connector is modified to avoid disabling internal speaker.



link broken or maybe because google drive does support image size data
User avatar
By Sooty25
#1591550
this is just a thought, no evidence to back it up.

I just wonder if the trimmed off connector tip is stopping the radio using the external mic, maybe if it doesn't sense the connector it continues to use the internal mic and you are actually picking up from that rather than the external one.

I'd try the mic plugged into an unmodified adaptor.


have you selected EXT MIC in the menu?
User avatar
By bambuko
#1591562
Thank you guys
@Sooty25 I had the same thought and have tried it with un-modified connector, made no difference.

No I didn't select "externa mike" - didn't realise you had to. In all my previous radios you just plugged in external mike without having to set anything...
Will test and report.

Dynamic mike from LX is 200 Ohm, so that might be the reason it doesn't work so well?

I have since found these mikes:
http://www.pilot-usa.com/headset-access ... pa-7x.html
I have been assured that they work fine with FTA-450/550, and I guess they should since they are meant for aviation headset.

The only thing that puzzles me is, that these "...microphone requires a DC voltage supply of 9-28 volts. This voltage is standard with modern aviation equipment..."

I have measured voltages on my Yaesu (without mic connected) and I get:
3.24 volt is on PPT line. When I ground it, the voltage on MIC line goes from 0 to 5.08 volt .
Yet it is supposed to get at least 9 volts for this amplified mike to work?
Bear in mind that I am mechanical engineer and not electronic :D so I might be talking out of my rear orifice ...

@Paul_Sengupta indeed, and that is possibly my problem... instead of mike as used in typical aviation headset, I have tried using either electret or dynamic boom mike as used in gliders. I guess these are not amplified? and that is why?
I was OK previously with old Icoms and Delcoms, but Yaesu must be different?
User avatar
By flyingeeza
#1591619
bambuko you're almost there! 200 ohm, 150 ohm, hardly going to make any difference, don't buy anything else until you've selected external mic in the Yaesu's menu.
Then you also need to set the "side tone" level so you can hear yourself talking. It's all in the radio's manual...

I have measured voltages on my Yaesu (without mic connected) and I get:
3.24 volt is on PPT line. When I ground it, the voltage on MIC line goes from 0 to 5.08 volt .
Yet it is supposed to get at least 9 volts for this amplified mike to work?


That is indeed how a condenser (capacitor, electret, etc) mic works. When you PTT, the mic circuitry supplies a preset dc voltage (phantom supply) to power the little amplifier (FET) inside the mic capsule.
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