[Amps] 810 Amplifier

[Jeff Blaine]

George,

You may want to consider a trio of GI7B (less complicated) or perhaps a 
4cx800 (more complicated) if you run something other than SSB.  These 
ceramic tubes are far more durable than the glass counterparts in my 
experience.

I bought 3 sets of 572b last year in a test to determine the actual life 
of the 572b vs. duty cycle because the data for contempary versions of 
the 572b are hard to come by.  None of the tubes could reach the 25 hour 
key-down accumulated time before reaching 500w output for the set.  I 
have seen the stories of guys with 500w out on a 25 year old set of 
tubes in a SB200, but that is clearly the excepiton and not the rule.  
The 572b at 1200w out of a set of 4 is really something that can only be 
sustaned in the long term if conditions are perfect and the winds are at 
your back.

So while your mileage may vary, I can say categorically that at 1200w 
out as the goal (meaning net average power, not PEP or peak or 
whatever), the 572b set of 4 will do it.  But just not for very long.

My 2 cents anyway.  :)

73/jeff/ac0c


George Knight wrote:
>   Thanks to all who contributed. Although there is a lack of unanimity in the responses, I think I will go ahead with the project. In the event that it turns out to be a total failure, it will be quite easy to change the sockets to accept 572B tubes and get into the 1200 watt output class.
>                         '73, George, VE3LTU.
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