[AMRadio] 4-400 Facts

Bob w4wsz at earthlink.net
Fri Mar 23 20:53:43 EST 2007

The following Eimac Tetrodes are listed in the Product Section in the 1947 
Radio and Engineers Handbook:
4-65A, 4X100A, 4-125A, 4X150A, 4-250A, 4X500A and 4-1000A.

I talked with their Engineering Department today and they confirmed that the 
4-400 series began production in
the very late 40's and was first listed in the 1950 Eimac Tube Product 

Since it is in my 1950 Eimac Catalog and not listed earlier, I think we can 
assume that Eimac is correct as to the dates of first production.

Eimac user for 55 yrs. 

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