Welcome, Guest. Please login or register.
Did you miss your activation email?
November 21, 2014, 07:17:00 PM
Home Help Login Register      
News: NEW Follow LiveATC updates on Twitter and Facebook


+  LiveATC Discussion Forums
|-+  Aviation
| |-+  Pilot/Controller Forum (Moderators: dave, RonR)
| | |-+  Basic radio operation in a 172
« previous next »
Pages: [1] Go Down Print
Author Topic: Basic radio operation in a 172  (Read 3970 times)
Chadan
Full Member
***
Offline Offline

Posts: 116


WWW
« on: August 19, 2011, 05:28:41 PM »

This is a very simple question that I'd appreciate a solid answer to. I understand that the 'Both' switch allows me to monitor the audio output from both comm radios "1" and "2" at the same time.

What exactly does the 'Auto' switch do? I've read up on what I could find and I get that it basically allows the audio I hear to follow the selected transmitter so that when the 'XMTR' switch is moved from "1" to "2" I then hear audio from "2", but what happens when the 'Auto' switch is turned off? Which radio do I hear when the 'XMTR' is toggled between radio "1" and "2"?

For clarity, here's a picture of the Audio Control Panel:


[Ignore the three-transmitter unit at the bottom for now please]

The confusion stems from these explanations from this site:

First, from the TRANSMITTER SELECTOR SWITCH section:
Quote
The action of selecting a particular transmitter using the transmitter selector switch simultaneously selects the audio amplifier associated with that transmitter to provide speaker audio. For example, if the number one transmitter is selected, the audio amplifier in the number one NAV/ COM is also selected and is used for ALL speaker audio.

That in itself makes sense. So why do we even need an Auto switch?

Now from the COM AUTO AUDIO SELECTOR SWITCH section:
Quote
...[the 'Auto' switch is provide to] automatically match the audio of the appropriate NAV/ COM communications receiver to the transmitter selected by the transmitter selector switch.
...just like it is described under the Transmitter Selection Switch paragraph.

continuing:
Quote
...If automatic audio selection is not desired, the COM AUTO selector switch should be placed in the center (OFF) position.

Well which radio would I hear if the 'Auto' switch is in the OFF position? COMM 1? COMM 2? Neither? The control panel doesn't have switches for me to select the individual audio for COMM 1 vs. COMM 2, does it? If so, where?

TIA!
Logged

Feed provider for KBNW out of Boone, Iowa on 123.0. Also catching chatter from nearby airports: KAMW (122.7), KIKV (122.9) and the Aviation Guard channel (121.5)
Chadan
Full Member
***
Offline Offline

Posts: 116


WWW
« Reply #1 on: August 27, 2011, 01:34:33 PM »

Nearly 190 page hits later I found the answer!

I flew up to Spencer Municipal in northwest Iowa yesterday and spoke to Quint - owner of Spencer Avionics, who had just repaired one of our trainer's radios. He explained that the Auto switch simply determines which audio output is used: intercom or headphones.

"What do you hear in the Off position?"

Quote
...

Silence! Placing the Auto switch in the Off position disables the radio output. Is this a feature or a bug?

With this understanding I'd like to propose this switch is mis-labeled. A more appropriate label would be "Audio" or "Output", because flipping a switch with one of these labels to the Off (or center position) one would expect the audio would turn off. In function, the switch labeled Auto has nothing to do with the Automatic feature of the audio output following the XMTR switch position, which, as described above, is a feature of the TRANSMITTER SELECTOR SWITCH circuit.
« Last Edit: August 27, 2011, 01:38:57 PM by Chadan » Logged

Feed provider for KBNW out of Boone, Iowa on 123.0. Also catching chatter from nearby airports: KAMW (122.7), KIKV (122.9) and the Aviation Guard channel (121.5)
Pages: [1] Go Up Print 
« previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2011, Simple Machines Valid XHTML 1.0! Valid CSS!