"John Clonts" wrote:

We have this intercom unit in our 210 and it has worked fine in the
four years we have owned the plane.

http://www.davidclark.com/IntercomSys/isocom.htm

However, there is the toggle switch on the unit labeled "Isocom". We
have always left this switch in the "Off" position, because if we turn
it to the "Isocom" position no one can hear anything at all (neither
the pilot nor copilot nor any passengers nor the radios).

We suspect that the "Isocom" position is intended to isolate the
pilot/copilot from the passengers, but the manual (accessable from the
above webpage) has NOTHING on what exactly it is supposed to do.

Could someone with experience with this particular unit please answer
these questions about the "Isocom" mode, and add any other relevant
details?

With Isocom "on":
The pilot and copilot can hear each other, and ATC communication?
The pilot/copilot can hear the passengers?
The passengers can hear the pilot/copilot?
The passengers can hear the radios?
The passengers can hear each other?


I haven't used this unit, but from looking at the manual, it appears the switch turns the whole unit off,
and routes the audio input from the radios or audio panel directly to the output. The installation notes
say that you can adjust the audio level to be the same, with the switch either on or off. Is it possible the
audio level is all the way down, and you're not getting any output in the ON position? I don't believe
there's any pilot or copilot isolation because the block diagram shows just a single output going to all
the headphone jacks (so pilot, copilot, and passengers will always be getting the same output).

Do you get normal intercom function in the OFF position, i.e. can you hear your passengers talk? You
will get normal sidetone from the radios, so just hearing yourself or your copilot talking while
transmitting on the radio could work even without the intercom working.

Maybe someone else has actually used this unit, and can help further.

Mike