Hi all: 

I know this discussion has been posted to the list many times but I wanted to gauge an opinion again. 
Does anyone know if an Unun fed antenna, mainly a vertical, induce high currents and voltages back through a coax feed line? 
I'm getting an indication that my 43 foot vertical is now the cause of my apparent tube failure and if don't stop using it, I'll blow the crap out of the rest of my station. 
My own tuner, after a period of a couple of months of use, started having trouble tuning out a 75M 6/1SWR spike but behaved perfectly on 40/10, including the DX contest with my amp running 600W CW with 50W of drive. 
The tuner I have now, handles this antenna from 75M to 10, didn't try 160, with my amps 600W CW no problem. My own tuner, is currently on a wire antenna, handling the SSB output from a HeathKit SB-220, about 1200W, 75/10M with no problems. 
Put my tuner on my antenna, it will tune perfectly and handle 200W on 75/10M but put 500W CW through it, the amp hissed. This may have lead to the 20M issue a couple of weeks ago but I don't think my amp is made of cardboard. LOL 
Now how would a trapped vertical be different? 
I'm very confused, discouraged and most of all scared. 
I don't know what's to gain by BSing me but its starting to look like the gentleman who's been a helping friend since I got my license is doing just that or is simply wrong. 

73: 
Mike VO1AX