Hello - noticing the white paper for the MR74 does not include the single band antennas and only mentions the dual band ones even thought its radios are discrete - 2.4ghz on top and 5ghz on the bottom. In theory, using a non dual band sector antenna like MA-ANT-21 (5ghz directional) would work. Is there any drawback to using a single band antenna on a single band pair of antenna connectors?
It's not only theory, it's mentioned on the product pages of the MA-ANT-21 and MA-ANT-23 that MR74 is supported. You just need to make sure that you connect the correct antenna on the correct end (top 2.4GHz and bottom 5GHz on the MR74). There's no drawback.
One other thing to draw your attention to is this thread:
I believe the 30W adapter described there by me with pictures is the one here: https://meraki.cisco.com/products/wireless/power#mr-ac-adapter
But for some reason it does not supply 802.3at on many of my devices.
From that spec doc, it says
All indoor APs (except MR30H*)
* For the MR30H: 802.3at required to provide PoE out on LAN 1 port"
and it also says
"The Meraki 12V AC Adapter is compatible with the Meraki MR18, MR32, MR34, MR42, and Z1. Four different plug types ensure compatibility with AC outlets in nearly every country around the globe."
There are many more indoor units than those 5.
Can you offer some clarification?