Keys for Trade
I have many keys for trade. My own collection specializes in spark keys, and what I would like to receive in trade would be a spark key not already in my collection. Of interest to me in particular would be a Duck Overland key, any Massie key, an SE-86 by any manufacturer, a General Radio CAG-457, and any other interesting spark key. If you have one of these for trade and don't see anything here of interest to you, e-mail me and we can discuss the other pieces I have for trade not pictured here. I would be happy e-mail you a higher resolution JPG of any of these keys. Click on the name to the left and the picture of that key will load to the right. See the descriptions below.
The J6 is an aircraft spark key made to be used with the BC-15 aircraft spark transmitter. This J6 was made by L.S. Brach in New Jersey. This J6 has been cleaned up and is missing the skirt under the knob.
The G. Pericaud spark key was made in Paris, France. It is on a wooden base and sub-base and is made of brass. The contact spacing screw is not correct, nor is the skirt under the knob. Two of the small screws holding the sub-base to the base are missing.
The McElroy S-600 is a teardrop-shaped bug made about 1940 by T.R. McElroy of Boston, MA. It was also called the "Super Stream-Speed" key. This snappy bug has moderate blistering of the chrome and the weight is not original. I have other McElroy bugs and straight keys available for trade as well, e-mail me for details.
An oscillation of current occurs in a circuit connected as above with a capacitor and
a coil forming a resonant or tank circuit and a generator supplying current. This kind of circuit is useful for all kinds of things,
including tuning a receiving circuit to a particular frequency. The "take home" message is
that as either the inductance or the capacitance of the circuit is changed, the resonant frequency
goes in the opposite direction. At the resonant frequency, the current flow is maximum in such a circuit while at lower and higher frequencies the current is limited. The sharpness
of this peak in current defines a value called the "Q" of the circuit. Resonant circuits with a sharp peak have a "high Q", and those with a broad lower peak have a "low Q". This
ability to offer an impedance to frequencies other than the resonant frequency is known as
"Selectivity". --Adapted from "Theory, Design, and Operation of Crystal Receivers", by
The A.W. Bowman spark key was offered for sale by Sears & Roebuck as well as Montgomery Ward before and after World War I. This particular key is not labeled and therefore was likely a key bought by catalog. The marble base on this key is particularly pretty, but it does have a scratch. Like many of these keys, the lever arm is loose and swivels in the trunnion.
This CQ1140 by International Radio Telegraph Company was used as an aircraft spark key and dates to about 1918. It is a combined Key and Winker. This particular piece is missing the socket for the bulb inside the Winker hood.
The Mecograph Premier is an inline bug that is definitely hard to find. This one is missing the weight and has two round stains on the brass base. It has been partially cleaned.
Click on San Francisco to start the applet earthquake. Stations in Berkeley,
Sausolito and Oakland are monitoring.
When an earthquake occurs, it creates 2 types of seismic waves which travel outwards
from the epicenter, or starting point. The compressional type "P" wave travels faster and
arrives first at a distant point. The "S" wave is a shearing type slower moving wave and shakes the ground perpendicular to the direction of motion.
The seismograph is an instrument which records the arrival, amplitude, and
time interval between the S and P waves.
The ratio of the speeds of the two waves is constant and can be used to fairly accurately estimate the distance of the epicenter from the observing station. Three observing stations can then share data to locate the epicenter by drawing circles at the appropriate distance
from each station and seeing where the circles intersect.
The Richter scale is a logarithmic scale used to express the energy released by the earthquake and is calculated from the height of the amplitude on the seismograph
For further information about earthquakes and the Richter scale, check out Dr. Louie's page.
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