FreeJAC - Yes - in the case of CFRN-DT Edmonton they need to remove half of the Channel 3 VHF Lo antenna from the top part of the mast in order to install the channel 12/13 multi bay Hi band antenna! The ERP of the Channel 3 analog service was 609 Kw. I have seen the antennas and the arrays are massive, so removing the top stack is a major piece of work at a great height!
Also I believe that CITV is sharing the new antenna and so they will suffer a similar delay before going on air. This will involve periods of Channel 3 shutting down/going to low power in order to allow the work to take place without harming the contractors. A large undertaking to say the least! I don't know exactly what the time frame is but will attempt to find out.
The transmitter site is called "Big Looma" apparently
