Crystal Radios Of The 2006 Contest Entrants
My 2006 contest set has three coils which slide on a polystyrene tube. From left to right they are wave trap, antenna coil, detector coil. All three coils are space wound (one wire width spacing between turns) copper wire; #24 ga. for wave trap and detector coils and # 23 ga. for the antenna coil.
A Single Jackson 365 pF VC is used on the wave trap coil and a single Jackson 410 pF VC is used on the detector coil. A dual Jackson 410 pF VC is used on the antenna coil in a Tuggle arrangement. The diode is a FO-215. A Calrad transformer and a "benny" (are included).
Full details can be seen at Wayne's Website
I used the same set in the BCB Open Class Category for 2004, 2005, and 2006. I tried the Hobbydyne in my toroid set, but my set worked better without it...too much signal loss. The selectivity of the set was already pretty good.
I did use an outboard cap this year in series with the set’s built-in dual section cap. I liked it so much that I will probably modify my set and put the cap inside. Part of the reason for this is that my antennas are large with a lot of capacitance to ground. The standalone antenna cap adds a lot of flexibility.
Another mod to the set was a neon bulb connected from antenna to ground. This year we had some pretty good thunderstorms during the first part of the contest. When the bulb lit the room up, well, it was time to shut down! ( I exaggerated just a little bit here.)
I did encounter a problem that I will mention, and perhaps you can avoid it. I wear glasses, and the constant pressure of my headphones against the ear piece of the glasses gave me a terrific headache. I apparently injured a nerve since it took me several weeks to recover. I am wondering if it is time for laser surgery so I can eliminate those glasses. You notice I didn’t say stop using headphones…
Set: Same set as last year. Headset: RCA Big Cans tuned> and recharged by Steve Bringhurst.
Antennas: 88’ top loaded vertical up 50’ and 180’ inverted “U” up 50’. Ground is the post 2004 DX DX contest ground described at the bottom of this page Set was the same as used in 2005. The antenna was a top loaded vertical cage antenna.
Set was the same as used in 2005. The antenna was a top loaded vertical cage antenna.
Crystal Set DX 2006 Receiver
Despite the shortcomings that befell my design last year, the exact same setup is employed this year. The antenna spans a length of approximately eighty feet in a northeast to southwest orientation, rising to a height of forty five feet at the far end from the initial twelve feet. A convenient cold water pipe serves as a ground and is connected with a fifteen foot length of wire running horizontally. In order to minimize losses, an eight inch diameter twenty turn coil consisting of fourteen gauge wire is utilized and tuning is accomplished with a high quality vernier driven variable capacitor across the coil. A small ceramic trimmer loosely couples the antenna to the top of the tank circuit. Last year, the advantages of Schottky diodes were realized and a single BAT28 performs admirably in the design. A high impedance transformer matches the high impedance detector output to the low impedance DLR No. 5 headphones. These sound-powered headphones were most graciously provided as a prize by the contest committee two years ago and were instrumental in greatly boosting the DX capability of the receiver. A simple inductively coupled trap must be in place at all times. At night, it opens up a few hundred kilohertz around WXEM while during the day, it enables the reception of weaker stations across the band.
Band conditions seemed different this year but proved to be advantageous. After considerable experience gained during the preceding contest and an overall greater familiarity with band conditions, I promptly logged the majority of the typical nighttime band markers. The ensuing evenings resulted in only a few new nocturnal DX catches. Regrettably, I should have exploited the terrific grayline conditions to a greater extent this year. Nonetheless, many stations and points were gained due to a more casual approach to grayline DXing. Typically DX within fifty kilohertz of WXEM is impossible, even at night. Nonetheless, stations were logged on 1410, 1500, and even WXEM’s own frequency of 1460 when it decided to completely shut down for a short while. Following in the pattern set by my previous participation, I did surpass my score considerable while greatly enjoying the Contest.