I missed the original post, so...

What was the original poster's concern about isolation? I'm not aware
of any repeaters in use aboard aircraft. Is he worried about signals
leaking out of the coax of say com1 transmitting and getting into the
receiver of com2? I wouldn't think there would be much need to
worry...more RF will get into the com2 receiver by the RF leaving the
antenna. Seems to me that no matter what kind of "isolation" the coax
cable has, the worst thing that can happen is that he would experience a
little desense on com2 receive while he's transmitting on com1, but it
wouldn't make too much difference...if he's talking on com1, he won't be
able to concentrate too much on what is being received on com2 anyway...

RG-142 is nice cable, but it's not quite as flexible as RG58. The loss
in 10 or 20 feet of RG58 isn't really worth the extra cost in my opinion...

Scott

wrote:
Andrew Heliax is fine cable - just what you need to run
up a tower (it comes in many sizes). But in an airplane?
Like the man said - it's overkill. I'd recommend RG142.

As for the isolation - engineers have an inside joke that
goes something like this:

Oh say can you see.....
Three Hundred Dee Bee....

This is a range greater than that between the smallest
detectable signal to an unimaginable amount of power.
In other words, it doesn't exist in the natural world.
AFAIK, nobody makes anything with "300 dB of isolation".
Any engineers out there who would care to comment?

David Johnson