martin griffith wrote:
I hate comms. A necessary evil.

I might have to modify some stuff I made some time ago, to work with
clearcom from a slate mic
I want to transformer isolate, ie not connect Their Ground to My (nice
clean) Ground.

Clearcom is an unbalanced system. There are balanced intercom systems
from guys like Telex. But each station puts a low-Z unbalanced output
onto the line, and each station takes a high-Z unbalanced input from
the line, and there is a 600 ohm termination resistor bridged across
the line inside the power supply box.

Will a any old 1:1 transformer, say 600 ohm do. I'll add 47uF non
polar in series, just in case. The sig level on clearcom is only
-10dBish ISTR

You probably want a high-Z input transformer. I'd say make a cable
and feed it into the input of a DI box. The higher your input Z,
the less you will affect the level on the other stations.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."