----- Original Message ----- From: "John Lawson" <[EMAIL PROTECTED]> To: <amradio@mailman.qth.net> Sent: Friday, March 23, 2007 7:16 AM Subject: [AMRadio] 4-400 first made when?
> In doing some research - I notice that the 4-400 seems to be a fairly > late arrival, at least as far as RCA is concerned. It's in none of my > HB-3s, not in my 1962 TT5, but is in the 1975 TT5 manual. Since my > transmitting tube library has this 12-year gap, I'm assuming RCA began to > produce the device sometime after 1964... does anyone have better info on > the history and development of this very 'popular' power tube? > > Thanks in advance for any enlightenment! > Okay - over and out... > > Cheers > > John > KB6SCO > DM09fg Hi John, Eimac, known then as Eitel-McCullough, as well as a number of other tube manufactures faced a dilemma at the end of WWII. Millions of tubes had been manufactured and were glutting the market. Tube manufactures, who had a good run during the war, faced a consumer market when the war ended. With all the surplus tubes available they had to develop a new market to survive. That is why (and when) the air-cooled tube family of power tubes was introduced. 4-65, 4-250, 4-400, 4-1000 were only some of the models of the new designs. Unfortunately, some companies, such as Heinz and Kaufman were trapped by accepting late contracts from the military. The contracts kept the business alive for a short time after the war ended, but when the contracts ran out, H&K found themselves out of the consumer market. They never could catch up. Bill ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
