National Electronics 6CA7

[Jerry G]

Hi,

Not sure if this questions goes in the tubes section, so I apologize in advance.

I purchased a quad of German made National Electronics EL34/6CA7's and the person I purchased these from suggested I don't use them in an amp with plate voltages above 450v.

What kind of sense does that make? Aren't these tubes capable of much higher plate voltages? Why would he say this?

Thanks in advance for schooling me.

Jerry

[danman]

The tubes you purchased are more than likely east german made, RFT. National is one rebrander that commonly branded the RFT's with their logo as well as Telefunken, Lorenz and several others. The RFT EL34's have always carried the stigma that they cannot handle plate voltages over 450v. I can't say for sure if this is actually true or not but the rumor has been well known for years. I love my RFT's because they are much more dependable than most new production tubes and can still be found for reasonable prices compared to many other NOS brands.

[Jerry G]

The tubes you purchased are more than likely east german made, RFT. National is one rebrander that commonly branded the RFT's with their logo as well as Telefunken, Lorenz and several others. The RFT EL34's have always carried the stigma that they cannot handle plate voltages over 450v. I can't say for sure if this is actually true or not but the rumor has been well known for years. I love my RFT's because they are much more dependable than most new production tubes and can still be found for reasonable prices compared to many other NOS brands.

Thanks for the reply.

When you use them, do you put them in amps with a lower plate voltage?

[danman]

My two Marshall style builds run about 420v and I have never had a problem with them. I can't speak for anything over that though. I remember hearing about one popular builder years ago who supplied RFT EL34's in all his amps. He mentioned that he would test the tubes for defects by hitting them with a mallet while the amp was running. Said he did this to all his amps before shipping just to make sure the tubes were solid. I wish I could remember his name! Maybe start a new thread in the tube section to see if anyone knows anymore about the voltage recommendations on the RFT tubes.