I picked up this 0-80 dB switched RF attenuator at a flea market, with no part number or other useful markings other than the knob settings. I've tested it and confirmed that it works, but there's one thing I'm uncertain about which I don't have the theory to be certain of and can't test non-destructively:
Is there potentially a difference between "input" and "output" ports, or is it symmetric? In particular, would there possibly be better or worse maximum power handling capability depending on which way around it's connected? If there is a difference, how can I tell which port is which? (They aren't labeled.)
I'm interested in answers which are either general, for all reasonable designs of attenuators, or specific to this unit if you should happen to recognize it. (I have used Google Image Search to try to find things which look like this specific model and haven't succeeded. According to the seller, it was likely an internal module from equipment made by HP.)
If it's unlikely that there's a significant difference, then I'm happy to go ahead and use it as I intend (testing transmitters hooked up to receivers with no antennas involved, no more than 5 watts, not continuous) but if it matters I'd like to use it properly and have less chance of burning it out. (This was cheap, but apparently comparable new units are in the hundreds of dollars.)