[Test-Equipment] Directional couplers

[Glenn Little WB4UIV]

I have a Wavecom model S-902-6 Precision High Directivity Coupler 10dB-Dual 
Directional. Is this the same as a return loss bridge? The frequency range 
is listed as 2.18-2.38 GHz. How much inaccuracy would be introduced in 
using this at 2.4 GHz? How far from the published frequency can I use this 
and still get reasonably accurate measurements? The coupler has three 
type-N connectors and what appears to be an APC-7 connector.

I also have a Sage Laboratories model 780-20 directional coupler. The 
calibration plate is marked 250-500 KMC. The directional coupler has three 
female type-N connectors and is almost 11 inches long. The size and the 
connectors suggest that this should be MHz and not KMC. Does anyone know 
for sure? Email to Sage goes unanswered.

Is there an easy way to verify that these two couplers are functional? I do 
not want to apply a lot of power for rear of damaging the couplers, if they 
are any good.

Thanks in advance

73
Glenn
WB4UIV