Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Microair 769

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

rdewees(at)mindspring.com
Guest

Posted: Sat Oct 28, 2006 2:20 pm Post subject: Microair 769

I have had my Microair 760 installed and running for almost two years 

and concur with several of the results others have mentioned-- The 

transmitter seems to function adequately with it's 5 or 7 watts and I 

have no complaints with it.  The receiver audio appears to be very 

selective though.  Many signals are clear and easily understandable, 

while others-- towers and ATC are often distorted and difficult to 

understand.  I have tried various headsets and my Lightspeed ANR is the 

best but there are still 30 percent of signals that are very difficult 

to understand.  I wonder if the percent of distortion in the audio 

amplifier is high or there is an overdriven stage in the receiver 

causing problems.  I read a great review of the radio before I bought it 

but nothing in the last few years.  I did notice that when I was trying 

it out on the ground without the engine running  it was very voltage 

sensitive.  If the input voltage was less than 12 or so the receiver 

volume was very low to almost unaudable.  It seems almost linear in it's 

volume to voltage response between 12 and 14 volts.  In the plane the 

panel voltmeter reads 14 so low voltage is no issue.  Wonder if anyone 

has ideas on distorted audio.    The open-mike intercom is a whole other 

issue.  If both headsets aren't the same impedance one hears loud audio 

and the other can't hear well at all.  Guess it's one of the compromises 

of a cheap integrated intecom. 

Thanks

Ron



 	  Quote:

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Sat Oct 28, 2006 6:56 pm Post subject: Microair 769

In a message dated 10/28/2006 5:23:53 PM Central Daylight Time, rdewees(at)mindspring.com writes:

  	  Quote: 	
		  If the input voltage was less than 12 or so the receiver 

volume was very low to almost unaudable.  It seems almost linear in it's 

volume to voltage response between 12 and 14 volts.  In the plane the 

panel voltmeter reads 14 so low voltage is no issue. 	


 >>>

  

 Now THAT is very interesting- since my 760 is on the E-bus, it's normal supply voltage is typically 12.5 volts.  Next time I'm trying to communicate with another plane and the reception is crappy, I'll flip the e-bus switch and see if things improve- good observation!

  

 Mark

  [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
From The PossumWorks...

ulflyer(at)verizon.net
Guest

Posted: Sat Oct 28, 2006 8:49 pm Post subject: Microair 769

Unplug the mikes of your head sets, see if it makes any 

difference.  Many intercoms VOX turn the audio input on for both 

mikes at the same time rather than just the one activating the 

VOX.  The makes the background noise floor twice as high.  Using a 

head set with a dynamic mikes will substantially increase the 

noise,  headsets the electret mike made a world of 

difference.  Wonder how I learned this....

jerb



At 05:19 PM 10/28/2006, you wrote:

 	  Quote: 	
		  



I have had my Microair 760 installed and running for almost two 

years and concur with several of the results others have mentioned-- 

The transmitter seems to function adequately with it's 5 or 7 watts 

and I have no complaints with it.  The receiver audio appears to be 

very selective though.  Many signals are clear and easily 

understandable, while others-- towers and ATC are often distorted 

and difficult to understand.  I have tried various headsets and my 

Lightspeed ANR is the best but there are still 30 percent of signals 

that are very difficult to understand.  I wonder if the percent of 

distortion in the audio amplifier is high or there is an overdriven 

stage in the receiver causing problems.  I read a great review of 

the radio before I bought it but nothing in the last few years.  I 

did notice that when I was trying it out on the ground without the 

engine running  it was very voltage sensitive.  If the input voltage 

was less than 12 or so the receiver volume was very low to almost 

unaudable.  It seems almost linear in it's volume to voltage 

response between 12 and 14 volts.  In the plane the panel voltmeter 

reads 14 so low voltage is no issue.  Wonder if anyone has ideas on 

distorted audio.    The open-mike intercom is a whole other 

issue.  If both headsets aren't the same impedance one hears loud 

audio and the other can't hear well at all.  Guess it's one of the 

compromises of a cheap integrated intecom. Thanks

Ron



>

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckollsr(at)cox.net
Guest

Posted: Mon Oct 30, 2006 8:14 am Post subject: Microair 769

At 11:46 PM 10/28/2006 -0500, you wrote:



 	  Quote: 	
		  



Unplug the mikes of your head sets, see if it makes any difference.  Many 

intercoms VOX turn the audio input on for both mikes at the same time 

rather than just the one activating the VOX.  The makes the background 

noise floor twice as high.  Using a head set with a dynamic mikes will 

substantially increase the noise,  headsets the electret mike made a world 

of difference.  Wonder how I learned this....

jerb



At 05:19 PM 10/28/2006, you wrote:

>

>

>I have had my Microair 760 installed and running for almost two years and 

>concur with several of the results others have mentioned-- The 

>transmitter seems to function adequately with it's 5 or 7 watts and I 

>have no complaints with it.


	




    RF power output for this radio is rated at 4w which is

    quite adequate for VHF Comm applications in aircraft.



 	  Quote: 	
		  >   The receiver audio appears to be very selective though.  Many signals 

> are clear and easily understandable, while others-- towers and ATC are 

> often distorted and difficult to understand.  I have tried various 

> headsets and my Lightspeed ANR is the best but there are still 30 

> percent of signals that are very difficult to understand.  I wonder if 

> the percent of distortion in the audio amplifier is high or there is an 

> overdriven stage in the receiver causing problems.


	


    Audio amplifier quality doesn't vary with circumstance.

    If it's okay some times and not okay other times, there's

    an external force or some other variable at work . . .

 	  Quote: 	
		  >   I read a great review of the radio before I bought it but nothing in 

> the last few years.  I did notice that when I was trying it out on the 

> ground without the engine running  it was very voltage sensitive.  If 

> the input voltage was less than 12 or so the receiver volume was very 

> low to almost unaudable.


	




    The best way to explore this is with a bench check.

    The radio needs to be operated under controlled conditions

    while varying only one condition at a time.



 	  Quote: 	
		  >   It seems almost linear in it's volume to voltage response between 12 

> and 14 volts.  In the plane the panel voltmeter reads 14 so low voltage 

> is no issue.  Wonder if anyone has ideas on distorted audio.    The 

> open-mike intercom is a whole other issue.  If both headsets aren't the 

> same impedance one hears loud audio and the other can't hear well at 

> all.  Guess it's one of the compromises of a cheap integrated intecom.


	


    Many intercoms, integrated or not will produce variable

    results with different brands of headsets.  When I was

    more in-the-business, unmatched headsets was the #1

    performance issue in audio systems.  I did an audio

    system specification for the Gates-Piaggio GP180 about

    25 years ago that called for totally independent microphone

    amplifiers with a small degree of volume leveling. The

    output impedance of the headphone amplifiers was very

    low so that variability in one headset does not produce

    noticeable effects in other headsets. I had to take that

    approach because products of choice at that time were

    already showing deficiencies in tolerating headset

    variability. It CAN be done . . . but almost nobody

    does it.



    If you want your radio bench checked, you can mail

    it to me and I can quantify some of the variables you've

    hypothesized about and at least confirm or eliminate

    the radio as the root cause of your dissatisfaction.



    Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum