Информационный портал MSEVM

Главная > Radiokit > Morgan crystal radio antenna tuner

Build a Morgan crystal radio antenna tuner

     Alfred P. Morgan was a prolific early writer of books on the subjects of electricity, wireless telegraphy, and radio. His works were written for young people and the average man who wasn't an expert in mathematics and physics. His book, "THE BOY ELECTRICIAN", originally published in 1913 and many printings after, taught many a youngster how to make crystal radios, wireless transmitters, antennas, and all kinds of electrical experiments. Many young people who built Morgan's projects later became engineers and scientists. This great little antenna tuner is named after Alfred P. Morgan for his influence on the lives and careers of many people. In the early days of wireless, very low frequency, very long wavelength signals were used. These extremely long wavelengths required exceptionally long antennas in order to be resonant. It was impractical to have antennas that were thousands of feet long, so early designers found a way around this problem by using "loading coils" to artificially lengthen their antennas. These loading coils were adjustable coils of wire, or Inductors. A variable capacitor was often added in parallel with the loading coils to "fine tune" their shorter antennas to the resonance of a much longer antenna. During the 1920s, amateur radio experimenters discovered that shorter wavelength signals would "skip" off the Ionosphere and thus allowed very long distance communications using low transmitter power on the "Short Wave" bands. Many antennas were too long to resonate at these shorter wavelengths. The designers found that a variable capacitor connected in-series with the antenna allowed it to be tuned to resonance at the higher frequency short wavelengths. Because we like to operate on multiple frequencies, loading coils with parallel-connected variable capacitors and series capacitors were combined into one circuit and were then called "Antenna Tuners." The Morgan Crystal Radio Antenna Tuner works to tune random wire antennas from approximately fifty feet and longer for crystal sets and more complex radios on the A.M. Broadcast Band, Short Wave and Amateur Bands up to about 30 MHZ. By tuning your antenna to resonance, it will transfer the energy from the received radio wave to your set more efficiently. This will result in a louder signal that will allow weaker "DX" stations to be heard that were not audible before. This antenna tuner can also be used to increase the selectivity of simple receivers. This feature helps to separate the faint DX stations from the strong locals. Building this antenna tuner is accomplished using simple assembly techniques and high quality parts. The air variable capacitors are the same fine American-made units that we use on our Armstrong One Tube Radio Kits, Dunwoody High Performance Crystal Radio Kits, and Bucher Crystal Radio QRM Rejectors. This kit is based on our ELECTRONICS HANDBOOK Magazine article, "How To Build And Use A Crystal Set Antenna Tuner", reprints of which are available in our "Literature" Link. This is an improved version of that antenna tuner. Clip-leads are used for the coil tap connections and for shorting the series capacitor when it is not in use. The clip-leads simplify construction and eliminate the signal-robbing losses that result from the use of a rotary switch and its many leads. Very good results can be expected with this antenna tuner. 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. It has been used with antique radios and commercial communications receivers. In addition to this, it can be used with low power "QRP" amateur radio transmitters to match the transmitter's output impedance to an end-fed wire antenna. One customer says, "This antenna tuner will increase the number of A.M. DX stations received on a one-tube set ten-fold!" 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 Dunwoody High Performance Crystal Set. Quality black Bakelite knobs contribute to the vintage appearance. Nickel-plated brass fahnestock clips are used for the input and output connections. All parts, screws, clip-leads, 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.

Complete kit including all parts and easy to follow instructions:

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

e-mail рассылки
Подписаться письмом


Яндекс цитирования Rambler's Top100