As for that 8877/3CX1500, that has got to be one of the most 'touchy' tubes ever made! You really do have to be careful with them. I don't care what you pay for one, it can be turned in to trash in the blink of an eye. No, I never owned one, and don't plan to. There are other tubes that are much more 'forgiving', and I can certainly use that!
I must be lucky, I've hit a Chinese made 8877 multiple times by accident with 200 watts of drive and it is still doing what it supposed to do. However, my amplifier does have a lot of protection which forces the the amp off line. Nevertheless, there are thousands of amateurs using the 8877 everyday with no issues. I just don't know of many who have blown the 8877 once they have been in service for a while, and still question all the doom and gloom associated with this particular tube.
From all the reading I have done about the tube/issues, from a few conversation with amplifer manufactures, and an engineer that works for Eimac. IMO a lot of the negative hype seems to stem from the defective runs of 8877s Eimac seems to produce ever so often (
8877 3cx1500A7 arcing short failure).
I spoke to Molly of Alpha Power last year (Fall 2008) about the Chinese tubes they started using instead of the Eimacs, she indicated that they had switched to the Chinese made 8877 because they were experiencing about a 25% to 35% failure rate with the Eimac manufactured 8877, and many were failing during quality testing of the amplifier before delivery. With the Chinese tubes (Penta) she said the failure rate was almost non-existent, as she could not actually recall when one had failed.
I contacted Eimac and spoke to one of their Engineers (Fall 2008) and he confirmed that in fact the run of Eimac 8877s that had been sold to Alpha in the past year had experienced a high rate of failure, but he indicated that an inspection of the tubes suggested that some, not all, had been run outside of their allowable limits. However, Eimac did replace most of those tubes out of courtesy to Alpha.
As noted in the link I posted above, W8JI gave examples of Eimac 8877 failures (I believe that W8JI designed most of the amps made by Ameritron back before they were bought by MFJ). If you look on the Ameritron site they also are now advertising their amps as being available with Chinese made tubes, I suspect that in part, it may be due to the amount of failures that they have been having with the Eimacs.
Perhaps the 8877 as it turns out is not such a picky awful tube that can be evaporated in a blink of an eye? But perhaps it is just the bad/weak 8877s made by Eimac during the occassional bad production runs that has given this tube a poor reputation. For years all you could get was an Eimac 8877 because no one else made them, so basically every 8877 that failed was made by Eimac. It begs to question, is it the actual design/limits of the tube or is it the particular manufacturer that is at fault? Who knows? But what I do know is I've done to my Penta 8877 tube multiple times what others say a 8877 will not sustain, yet it shows no ill effects, and still easily makes well over 2.2 KW.
Just my 2 cents.
73
