[Milsurplus] Pi- Matching Network: When?

[Mike Hanz]

On Feb 7, 2012, at 5:49 PM, David Stinson wrote:
>> Anyone have any idea when the Pi output matching
>> network appeared?

Looks like May 1931, Dave.  A quick google search brought out this 
article on the Windom antenna by John Nagle in the May 1978 issue of Ham 
Radio Magazine:

"William L. Everitt, as faculty advisor to the students who worked on 
the antenna, contributed much to its development.  Everitt began his 
amateur career in 1914 as 2ABI; in 1921 he became 8CRI. When he decided 
to go into communications professionally, he dropped amateur radio 
because he did not want to have the same vocation and avocation.  
Everitt was later to become a prominent author and educator.  He retired 
as Dean of Engineering at the University of Illinois and went on to 
become Dean Emeritus at that university.

Unfortunately, Dr. Everitt has been ill-treated by the amateur 
community.  His work on the off-center-fed antenna is largely unknown 
and certainly unrecognized.

Unhappily, the same thing happened to him a second time.  *Everitt was 
the first to describe the use of a pi network as a coupling device.*  He 
published this work in the Proceedings of the IRE in 1931 (12) and in 
Communications; (13) the pi network is also described in his book, 
Communication Engineering. (14)

Arthur Collins, W9CXX, of Cedar Rapids, Iowa, recognized the advantages 
of the pi network to couple the output stage of a transmitter to a 
transmission line, and used it in his transmitters. This application 
played an important part in establishing the reputation that Collins 
equipment will load up to "anything." Collins described the pi network 
to the amateur community in a QST article (15) and in a similar article 
in Radio, (16) and the network became known by old-timers as the 
"Collins Coupler" instead of, perhaps, the "Everitt Easy Loader." "

References:
12. W. L. Everitt, "Output Networks for Radio·Frequency Power 
Amplifiers," Proceedings of the IRE, May, 1931, page 725.
13. W. L. Everitt, "Coupling Networks," Communications, September, 1938
14. W. L. Everitt, Communication Engineering, McGraw-Hill, New York, 
1937, page 263
15. A. A. Collins, W9CXX, "A Universal Antenna Coupling System for 
Modern Transmitters," OST, February, 1934, page 15
16. A. A. Collins, W9CXX, "The Answers to the Flood of Inquiries 
Regarding the Collins Antenna System:' Radio, March, 1934, page 5

John J. Nagle, K4KJ (SK)
Herndon, Virginia
May 1978 in Ham Radio Magazine

So now you know...
73,
Mike  KC4TOS