The last time I bought one of these was a few years ago to hold up my 10m ground plane. I think I got mine at the local electronics supply store.
Rohn used to sell some very nice heavily galvanised heavy duty ones, but since they went out of business I am not sure if whoever is still selling their product offers them.
I used to make a 1/4 wave 80m mast by adding two standard 10' tv masts to the top of a 50 footer. The 50 footer actually only extended up 45' because some height was lost where the sections telescope together. Two more 10' sections on top made the whole thing a little over 60' tall. It took a crew of people to raise the thing, though. One slipup and you have a giant steel pretzel to dispose of.
The declining use of over-the-air tv reception, especially if the tv stations are all forced to go digital in a couple of years, will likely make telescoping tv masts as rare and hard to find as triode transmitting tubes.
Don/KYV
