I think the repeater rating has to do with duty cycle. In this case I'd guess it means the repeater is capable of (speculating) 90% duty cycle. My other thought is it's got to do with the gain of the antenna or something related to input/output gain. An antenna gain of 9dB would make sense for a repeater.
'91 Pickup - Imelda
'08 Tacoma TRD
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
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