The AM Forum

Can anyone say right off what's the difference between the 4-400A and 4-400C? I did not find a datasheet for the C, only the A.

I believe C = Carbon Graphite Anode.

C = Mo Strappin

--Shane

I just checked my Eimac 4-400C info against the NJ7P database on the 4-400A.
In operation, I can see no difference, I thought maybe lower capacitance or more plate dissapation- nope, everything appears the same.
Bob W4RFM

I used to think the same thing untill I started collecting a stash of 400s. I now have C's with the normal corregated tantalum plates, and A's with graphite plates. So this blows that theory all to hell. I wonder if any of the broadcash tx gurus or tube collectors out there can tell us both what the difference is. the ones with the tantalum plates all look the same and the same goes for all of the graphite ones, they also all look alike.  ??? ??? ???

                                                     the Slab Bacon

                                                           

What I heard was that the 4-400c was a little more reliable "commercial" version. That begs the question of what the 4-400a was for if it wasn't "commercial" applications.

Here are the two spec sheets from old Eimac catalogs.

The 4-400a is from a 1948 catalog, and the 4-400c is from a 1975 catalog. (the 1975 catalog didn't list the 4-400a).

Dave

Thanks. So far, they seem alike. But as to whether an A and  C would push-pull well is interesting. Probably OK.