[Discuss-gnuradio] Combining daughterboard outputs into a single signal

[Bahn, William L CTR USAF USAFA USAFA/DFCS]

Is there a simple, cheap way to combine the outputs of two daughterboards into 
a single signal before sending them on to a power amplifier?

I need to generate a slow-hopped frequency hopping system that has nine 
channels spread out over 200MHz of spectrum from 5260MHz to 5460MHz. What I 
would like to do is use one XCVR2450 daughterboard to generate the odd-numbered 
hops and a second one to generate the even-numbered hops. I would keep the hop 
rate slow enough that each board has sufficient time to tune to its new center 
frequency. 

So what I need is a way to combine the two outputs (only one will be active) 
into a single signal? Is there a simple, cheap, off-the-shelf way to do this?

On a related note, what kind of output can I expect from the board that is 
being tuned and what steps can I take to keep in as low as possible?

Thanks.