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Tube Coils (fwd)
---------- Forwarded message ----------
Date: Sun, 23 Feb 1997 16:45:50 -0500 (EST)
From: VonPostel-at-aol-dot-com
To: tesla-at-pupman-dot-com
Subject: Tube Coils
Noticed a request for information on figuring perimeters for vacuum tubes.
These all give the method for calculating tube operation when you have the
characteristic curves.
Application Bulletin Number 4
"Class C Amplifier Calculations"
Eitel-McCullough, Inc. Copyright 1948
I haven't asked EiMac for help in a lot of years, but they used to be very
generous with their assistance. At one time they made a line of triodes
having a large reserve of cathode power. That makes them particularly
adaptable to pulse type applications. Typical of these are the 250-TH,
250-TL, 304-TH, 304-TL, 450-TH, and the 450-TL. The number of the tube is the
plate dissipation in watts. TH means a "high mu" tube and TL means a "low mu"
tube. All of the foregoing were designed to run "Cheery Red" at maximum
plate dissipation. All are radiation cooled. (Fans not needed if there is
free circulation of air.). They can all be operated up to about 30 MHz with
out de-rateing because of frequency limitations.
Type: Filament Voltage: Filament Current
250T- 5.0-5.1 10.5 A.
304T- 5.0 25 A
or 10 12.5 A.
450T- 7.5 12 A
As a suggestion, if you are think about building a coil which will be pulsed,
take a close look at the 304-TH or 304-TL. They were originally designed for
such service in radars and were pulsed into the megawatt power region.
As an aside, sockets for all of the above, as well as the 833-A were at one
time made by the E.F.. Johnson Co. I don't even know if they are still in
business nor if they are, they still make that type of thing.
The same thing is published (almost exactly) in:
"The Radio Handbook", 11th, 13th, and 14th editions, Copyright 1947, 1951,
1956
Editors and Engineers Ltd.
Summerford, Cal.
You may find that one of your older ham friends will have a copy of the
handbook. The most information on r.f. amplifiers is contained in the 14th
edition. So if you ask your public library for an inter library loan, try
and get the 14th edition.
Hope this is of help.