What is actually required for a relay?

[Leicontis]

I'm trying to figure out if I can repeat a trick I used when playing with the RemoteTech mod and design my rockets to use spent stages (like a transfer stage) as comm relays.  The question is: Other than a relay antenna (obvious), what, if anything, is required for a craft to function as a relay?  Is a probe core and/or command pod required?  Are there power requirements?  I haven't been able to find any clear information on this.

[bewing]

Yes, an active control point is required. So it needs a probe core or an occupied command pod. And a probe core needs to have a little bit of power left in its battery -- if it's completely dead, the relay won't function.

So if you put a probe core and relay antenna on a spent stage, then you need to get out of physics range before the battery dies.

 

[Snark]

Incidentally, another requirement is that it can't be marked as ship type "debris"-- doing so will take it out of the relay network.  (This is noteworthy, because AFAIK, this is the only actual physical effect of marking any craft as "debris", other than rendering it eligible for auto-cleanup if the debris number gets too big.)

Of course, ships that have active control points generally don't get marked as "debris" automatically, but if you're one of those players who likes to manually mark things as "debris" when they're not actively playing them anymore, it's something to be aware of.

[FullMetalMachinist]

19 hours ago, Snark said:

Incidentally, another requirement is that it can't be marked as ship type "debris"-- doing so will take it out of the relay network.

That's the first I've heard of that. Does it really remove the relay from the network, or just not show the connection lines in map view? 

[Snark]

1 hour ago, FullMetalMachinist said:

That's the first I've heard of that. Does it really remove the relay from the network, or just not show the connection lines in map view? 

It actually, genuinely removes it from the network, and I have it from a reliable source that yes, that's by design.