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     Elmer E. Bucher (pronounced, "boo-cher") was an instructing engineer at the Marconi Wireless Telegraph Co. of America in the very early pioneering days of radio just after the turn of the Twentieth Century. Mr. Bucher was a great mentor to thousands of early amateur and professional operators in the fields of wireless telegraphy and radio. His mentoring was so well known that even today, Radio Amateurs who mentor novices in getting their "Ham" licenses are commonly called, "Elmers." His book, "Practical Wireless Telegraphy", was published from 1917 to 1920 and covered everything from batteries and magnets to setting up and operating a complete wireless station. In his own words, "...The author has endeavored to give the non-technical student and the practical telegraphist an understanding of the functioning of present day commercial wireless telegraph apparatus:" This very effective wave trap, notch filter, or "QRM Rejector" is named afterElmer E. Bucher for his mentoring so many people in the field of wireless that his name lives on with experienced radio amateurs "Elmering" radio beginners every day. QRM is radio operator language for man-made interference. The most difficult problem facing crystal radio DXers who live in or near a city is trying to hear weak DX stations while being bombarded by strong local stations. A very effective method of overcoming this problem is to use a rejector trap. This circuit is connected in-series, between your antenna and your radio's antenna connector. When it is tuned to an interfering A.M. station, it will absorb most of the signal at that frequency and thus allows you to hear the weak stations on either side of this frequency. Several of these circuits can be connected together in-series if necessary to reject several strong stations. The Bucher Crystal Radio QRM Rejector works on the A.M. Broadcast Band from about 500 KHZ to over 1700 KHZ. It works very well when used with Short Wave crystal sets and one tube radios that are being "jammed' by a strong local A.M. station. Building this QRM Rejector is accomplished using simple assembly techniques and high quality parts. The air variable capacitor is the same fine American-made unit that we use on our Armstrong One Tube Radio Kits, Dunwoody High Performance Crystal Radio Kits, and Morgan Crystal Radio Antenna Tuners. This kit is based on our ELECTRONICS HANDBOOK Magazine article, "How To Build A Rejector (QRM) Circuit", reprints of which are available in our "Literature" Link. This is an improved version of that QRM Rejector. Amazing results can be expected with this QRM Rejector. It has been used successfully used with our Dunwoody High Performance Crystal Radio and with our Armstrong One Tube Radio. It also works well with our Cornell WW-II Foxhole Radio and our Pickard Crystal Radio. One customer says, "I am very impressed with how narrow this thing tunes and how it almost completely eliminates a very powerful nearby station." Highest quality parts are used throughout. The pre-drilled routed baseboard is made for us by TOLEWOOD.COM from clear furniture grade pine that can be stained for an attractive vintage look. The pre-punched coil form is made from the same heavy cardboard shipping tube as our Armstrong One Tube Radio. A quality black Bakelite knob contributes to the vintage appearance. Nickel-plated brass fahnestock clips are used for the input and output connections. All parts, screws, and wire are included in this fine quality kit. The easy-to-understand instructions were designed for beginners, however the coil winding is at a level of difficulty for more experienced builders. Soldering is required. The use of Super Glue is also required. (Customer supplies gel-type super glue because this product doesn't store well and must be fresh in order to work properly)

Complete kit including all parts and easy to follow instructions:

Source: http://www.xtalman.com/kits.html

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