[Amps] Tapping a plate tank coil

[Bill Turner]

I know it is common and accepted practice to short out the turns on 
an air-core plate tank coil for bandswitching, but is it ok for 
powdered iron core toroids in that situation?

My understanding is that the turns on an air-core inductor are only 
loosely coupled to each other and no harm results, but in a toroid 
(or any iron core inductor) the turns are all tightly coupled to each 
other and placing a short between taps will cause excessive losses.

My Command HF-2500 amp uses a large toroid for the 160/80/40 portion 
of the tank coil, and the taps are shorted out for each band. In the 
last five years I have burned up two of those toroids and I'm 
wondering if that might be the cause. I do a lot of RTTY contesting 
at the full legal limit, but the amp is supposedly designed to take 
it. On the high bands, it does.

Comments welcome.

73, Bill W6WRT