Rap 'n Tap
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From: Jim White (K1EXE)
Date: 9/2/99
Time: 7:00:08 PM
Remote Name: 207.234.168.72
I don't mean to interrupt the thread, however, as I don't get on every day, I feel the need to respond to a few previous posts..The first is regarding the question of how an iron-to iron device can act as a diode?-as in safety-pin to razor-blade. it has to do with the fact that electrons "like" to bleed off of a "point" contact, and "don't like" to bleed off a flat surface. this form of primitive diode will show a lower resistance (to RF) from the "point" to the blade, than from the "blade" to the point..Thus, Rectification!!--The second regards the field contained within a Toroid core..A Toroid Core concentrates it's field within the core, Thus, the field looks pretty much like the core does, (in a "Doughnut" shape) and does not concentrate in the center but Inside the core.. The Third Regards "Can a Crystal set be made to tune as sharply as a "Table" radio??-- This seems to be a Question of the "Loading" of the tuned circuits.. That is, a tube or transistor radio (especially a "Tube") will not load the detector circuit as highly as the usual diode circuit will..Hence, the increased selectivity of the "super" jfet detector, and The "tube-type" Grid cicuit..In Essence, there is no difference in the "tuned Cicuits' used in a "Tube-type" radio Vs. a "Crystal set" Radio.. the "table radio" has been optimized for use by the "uninformed' operator. (like the Mother-in Law)--Tnx, Jim, K1EXE
From: Lawrence Pizzella
Date: 3/16/99
Time: 9:04:09 PM
Remote Name: 209.109.233.90
Hi Tim, If you are interested in making the drive, and have the time, let me invite you to the Museum of American Heritage at 351 Homer Ave in Palo Alto. Go around to the new building in back. We are having a Xtal Radio Workshop there on Saturday morning from 10-12 am. You can visit during the class to see what is going on, or show up at noon, and we can visit. We can talk about strategy for your class. We will meet on Mar 20, and 27. Hope to see you.