These masts are often adequate, but there are further solutions that you all should be aware of. In older, brick buildings, the bricks can sometimes disintegrate when being drilled in to. For cases like this, and for anyone who is adamant that you
not drill into their building, use the non-penetrative chimney mount here:
This wraps around the chimney and accomodates different sized masts up to about 2.5 inches in diameter. We use 2 inches which seems perfect. We use galvanized steel conduit from your local big hardware store. This conduit comes in 10 foot increments by default and allows you to have a higher, more stable setup that can be loaded with more equipment.
Setting these non-penetrative chimney mounts up is a bit tricky so watch a video on how to do it- and bring HEAVY work gloves as each metal band is basically one big razor blade.
Adam Longwill