• W5FRS Big Jug 40M amp
• another view of the W5FRS Big Jug 40M amp

Egad! A Nine Tube Linear, Bob Baird, 73 Magazine, Jan 1982

This article, despite its title, investigates the characteristics of 9 different types of tubes we normally might use for an amplifier. It includes experimental data with tables, and is quite informative.

(Click on the image to download the .PDF of the article)

"The 'Junker' Amplifier", by Lew McCoy W1ICP, from QST, Oct 1970. This amp is built from scrounged and junk-box parts, can be built using any of several different tubes, and has an input of 500 watts, 80 through 10 meters. This is another of our "idea" sources.

(Click on the picture of the amp to download the PDF file of the article.)

The following .PDF files are from articles in various ARRL Publications, put here with permission of the League.

• The "Inexpensive 75 Watter" transmitter which uses a 1625 from both "QST" and the ARRL Handbook.
• The article entitled "A 75 to 120 Watt CW Transmitter" from the ARRL Handbook.
• The article entitled "A Simple Transmitter" , which we know as "The Slat-Board Transmitter" from both "How to Become a Radio Amateur" and from the ARRL Handbook.
• The original unedited article from QST 1946, entitled "The Most Inexpensive Transmitter" on the Slat Board Transmitter.
• A follow-up series on "An Advanced Receiver and Transmitter" from "How to Become a Radio Amateur." This covers a 4 tube superhet with an IF if 1500 Khz, and an MOPA transmitter. The file size is about 5.5 MB, so be prepared.
• The article, first printed in "QST" magazine, entitled "65 watts at Low Cost" designed by Lew McCoy W1ICP of the ARRL's Technical Staff. We have also included a slightly different version of this article from the ARRL's Understanding Amateur Radio's "Building Transmitters" section, entitled "A Low-cost Transmitter".
• The article entitled, "A 35 watt, 2 Band, CW Transmitter" which was published in the 1979 Edition of the ARRL Radio Amateur's Handbook. This very nice little transmitter has a built-in VFO, and is built mostly from junked TV set parts.
• An article from the 1979 ARRL Handbook entitled, "A 'Universal" 3-Band Linear Amplifier", built of junk and military surplus parts, and bits from Fair Radio Sales. It will use practically any of those old transmitting triodes or tetrodes you have lying around the shack. Although it is designed for 1KW input, and covers 160, 80, and 40 meters, that upper band-limit was placed on it because one of the tubes for which it was designed was the 833. Other tubes will work up to 10 meters, and it would be easy to add the other bands.
• "The Novice 1/4 Gallon" amplifier, built from old TV set parts and using a pair of TV sweep tubes. This is a Class B linear amp. Drive required is 25 watts, and power input is 250 watts. This is another, and the last, article from the 1979 ARRL Radio Amateur's Handbook.

Here are some bits of information on cathode-modulation and a simple cathode modulator for your convenience.

The first is an article written by our own Dennis Brady W5FRS and Patrick Jankowiak, and is quite detailed, discussing their success with a cathode modulator for Dennis' 250TH CW amp. And here is Dennis' main page

Here is a .PDF file, is from the 1956 ARRL Handbook, page 250, entitled "A Simple Grid Modulator". This extremely simple modulator plugs into the key jack of any cathode keyed rig . The title may be somewhat misleading to the uninitiated, but cathode modulation actually combines grid and plate modulation, and the efficiency of the final amp is midway between the efficiency of grid and plate modulation methods. This circuit, with some very slight differences, was possibly first published in the Radio Handbook by Editors and Engineers prior to 1940, and has been re-published in various articles and handbooks ever since. Included here is a nearly identical article from the September, 1953 issue of "QST" magazine , entitled "The Simplest Modulator" .

1) Here is a .PDF file of an article in an early, circa 1925 QST magazine concerning how to make your own crystals, from cutting the quartz slab from a block of quartz with a hacksaw with the blade in backwards, to making your own mounts. There is a TERRIBLE lot of work involved to make even one crystal.

2) Here is a .PDF file of an article which was published in QST magazine in March of 1950 on Crystal Oscillators. This article contains a lot of test data and graphs, and shows quite clearly that of the tubes tested, the 6AG7 is by far the best choice.

1) Here is some data that Kees Talen took while attempting to find a proper tube to use in the low-voltage transmitter he is trying to design and build. LV Tube Comparison Data by Kees Talen 6 January 2005

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