[amsat-bb] 2-to-1 spliiter with DC pass?

[Jeff Mock]

I have an Icom 910, the preamp control is very convenient for turning on 
masthead preamps.  I also have an Icom R8500 comm receiver and I would 
like to do a little hacking with the 10.7MHz IF output of the R8500 
using the same antenna feed as the IC-910.

So, is there a 2-1 splitter available that will pass DC from the 910 to 
the antenna but not to the other receiver?  Also some sort of 
arrangement that doesn't blow up the R8500 would be kind of nice in case 
I accidentally key the 910 transmitter.

thanks,
jeff
AD6EO