Telex 850 ?'s - mic bias

[tathepilot]

The Telex 850 is powered from the 'mic bias'.

What exactly is the mic bias, and does an a/c with no intercom have one?

 

[Stukadriver]

Telex says you need a "hot mic" for the ANR to work properly; i.e., it gets its power from the mic circuit when energized. One of the guys I flew with says he tried one in a 737, and it works just as well as his Sennheiser even though the FLUF doesn't have a hot mic.

Any Telex 850 owners care to chime in?

 

[kilroy]

Anr 850

Telex says you need a "hot mic" for the ANR to work properly; i.e., it gets its power from the mic circuit when energized. One of the guys I flew with says he tried one in a 737, and it works just as well as his Sennheiser even though the FLUF doesn't have a hot mic.

Any Telex 850 owners care to chime in?

Correct the 850 does require a hot mic in order for the ANR to work. Nice working headset light on the head and clear sound.

 

[CF34-3B1]

Been using my 850 in 737's for several years now, works great.

 

[8v8ter]

The mike in the 737 is always "hot" because of the CVR. 850 works great in 737s.

 

[Green Banana]

True that, mic is always hot, not necessarily open. Works great on classic and NG's

 

[fugghedabowdit]

Works fine in the 737 w/no hot mic.

 

[ExFokkerFlyer]

works well in the Airbus too... Lasted longer than my Sennheisers have.

 

[MD11Drvr]

Worked very well in the MD-11 and I wished it worked in our DC-10's. They have changed the wiring in the 10.

 

[Nacra13]

Does NOT work on the 747 classic. No phantom voltage!

 

[GuinessGuy]

Works well in the 320..........

 

[Redeyes]

I love mine, but in the 3 years I have owned it, I have had to send it back twice due to malfunction.

They work great in the CRJ and 737.

 

[tathepilot]

Thanks for all the info, but does anyone have an answer to my original question?

 

[FlyinGuy]

Nope....

 

[Stukadriver]

http://en.wikipedia.org/wiki/Voltage_bias

Any EE's correct me if I'm wrong, but I believe the mic bias in this case is the voltage constantly going to the microphone which enables the hot mic function of the intercom.

Does toggling the I/C switch on in the 737 have any noticeable effect, or is the CVR voltage enough to give you the full ANR?