Crystal Radios Of The 2007 Contest Entrants
This detail shot shows the original Lyonodyne C2 and L2. The entire set can be seen below.
The MOSFET detector is mounted on its own circuit board along with its output jack. This board mounts to the set using the thumb nuts that attach L2 to C2. L3, a darker shade of pink, is mounted in back ('cold' end) of L2. The original diode output at bottom-center was not used.
To me, the most impressive feature of the ALD MOSFET detector was its superb selectivity. This makes sense, since the GATE presents essentially a zero load to the tuning tank, thus preserving its Q.
Volume, especially on weaker stations, was noticeably less than that delivered by the single diode detector. This may be partly due to the less-than-ideal matching between DRAIN-SOURCE and the audio matching and output circuits. Didn't have much time to play around with matching before the contest started.
Many thanks to my 'Benefactor' who provided the much-needed ALD110900A's during our recent national shortage.
For my 2007 XSDX set I adapted one of the popular ALD110900A zero-voltage-threshold MOSFET detectors to the Lyonodyne. The highest voltage, at the top of the secondary tank, is applied to the MOSFET GATE. An added-on 8-turn coil L3, closely coupled to the 36-turn secondary coil, feeds the DRAIN-SOURCE and audio load.
Another fun Elmer Memorial Crystal Radio DX Contest is over. I used the same crystal radio that I used last year with only a couple of improvements. I bought some 420/46 litz wire for my coils. The Q of the coils used in the crystal radio is now 800 from 550 khz to 1200 khz. The Q then tapers down to 600 at 1700 khz. My six toroid traps are all wound with the same litz wire and have a Q of 400.
My antenna is the same as last year except that both ends are now up 40 feet. I am now using a good set of Big Cans for headphones with a bogen T725 transformer for matching to the radio.
I did my usual listening to the broadcast band almost every evening and some mornings from the middle of September up to contest time. I made a lot of notes. These paid off in time saved finding and identifying the largest number of stations possible during the contest. It is amazing how fast some stations appear and fade away at the gray line. One has to be on the right frequency at the right time to catch them.
The band conditions here were very good the first day of the contest. The second day was really pretty good too. After that, the conditions were generally poor with some spotty openings. Here are some of my statistics for the contest.
Day Hours spent Stations found 1-12 15.5 166 1-13 9 34 1-14 11 23 1-15 12 19 1-16 11 19 1-17 6 8 1-18 7 8 1-19 6 3 1-20 5 5 1-21 8.5 4 91 hours 289 stations
Some of the stations heard during the contest:
WWRV 530 khz South Caicos Islands 1987 miles
CMQ 670 khz Cuba 1483 miles
CM 530 khz Cuba 1481 miles
CKWX 1140 khz Vancouver, BC. Canada 1400 miles
KNBR 680 khz San Francisco, CA. 1379 miles
WBZ 1030 khz Boston, MA. 1333 miles
My personal choice for best catch during the contest:
KGBC 1540 khz Galveston, TX. 250 watts 804 miles
Good copy for an hour on the evening of Jan 19.
On an average winter day I can always hear about 55 stations. Most are within 175 miles. One everday station heard is 5 kw at 247 miles. My all time list of stations heard on my crystal radio that ID in English is now 412 stations. Let's do it again next year.
1.Long Wire approx. 200 ft long, up 80 ft, lead-in approx. 100 ft, all one-piece litz to rig.
2.Four element 20M colinear antenna, fed with 300-ohm feeder, used as three antennas. Up 85 ft. 3.Misc. Spotter small antennas.
Seven inch diameter, 6.5 inches long, ceramic form, space wound, 90 turns, bare silver plated wire, selectable on each turn.
Capacitor: 4 section, 570 pf each, Variable, ceramic insulated silver plates. Wired series and parallel.
1.Antenna coil: Large (?) litz on 4.5 inch diameter opaque plastic pipe form, close wound. Detector: 185/46 litz on 3.5 inch diameter ceramic form, space wound. Q ~ 650. (HP-4342A)
2.Grounds (2): house ground system, 200 gal LP tank underground, water filled. Connected with 50 ft of RG-8 coax, inner conductor and braid paralleled.
3.Diodes (22): different TYPES, on ceramic rotary switches, instantly selectable. Favorite soldered in.
4.Capacitors: ceramic insulated, silver-plated, approx. 550 pf.
5.AUDIO: Bogen T-725 plus 200K to 1000 ohm
45-703, miniature transformer.
6.HEADPHONES (3): USI, 1247-A, mike elements wired in series. (2) N.I.B. (Ebay, no name) soundpowered headphones, one set series, one set parallel wired.
7.All traps, (3), ceramic insulated caps and litz coils.
8.“Tuggle” type circuit.
9.“S” meter: Olson TE-380 meter, 0-8.7 ua,
Heath: 0-200 ua, series connected.
10.All internal RF wiring 185/46 litz.
11.ALL components mounted on Plexiglas sheets.
12.Many “Classic” vernier dials.
1.Icom R-70, spotter
2.Chrysler van auto radio, spotter
3.Icom PCR 100 with PCR 1000 software, spotter.
4.B&K Signal Generator, E200-D, frequency verification.
5.B&K, 1851, Frequency counter , frequency verification.
6.H.P., 4342A, Q meter. (max Q ~ 1000).
7.Heathkit, QM-1, Q meter. (max Q ~ 500).
Charles Pullen (Chuckster)
This circuit is a hybrid of Steve Bringhurst's select to match circuit and Dave Schmarder's toroid set #45. The design goal for this radio was high performance in a small package. The case is 9 inches x 6 inches deep x 1 3/4 inches tall. The toroids are FT 114A-61 amidon cores, L1 tapped at 12 turns. The toroid coupling coils are wound on a small tube with an ID slightly larger than 3/8 inch. The first coil is close wound, 15 turns. The second coil is triple spaced, seventeen turns. Both coils 24 awg and are approximately 29 uH with coupling accomplished by moving a 3/8" x 4" ferrite rod in and out of the coupling coil's tube. The detector used was a pair of HP 5082-2835 schottky diodes. The phones used was a pair of Philmore xtal earplugs in parallel thru a radio shack mono Y adaptor. The antenna used is a half sized g5rv ham antenna approximately 25 ft up, center conductor & braid of the coax connected together. Ground system is 3 four foot copper clad steel rods 8 ft apart connected with #14 awg solid bare copper wire.
The detector cap sometimes has a very slight but noticeable bit of hand capacitance at times, it seems to depend on the weather. All in all a good performing radio.
For the 2007 Crystal Set DX Contest, I used an all ferrite-rod double tuned set-up: Detector - ATU - Wave Trap.
The inductors are Amidon Ferrite 61 0.5”x4” ferrite rods with 165/46 Litz coils wound directly onto the rods. All capacitors have ceramic insulators. Detector tuning is split into 3 ranges to cover the broadcast band. Each range has it’s own capacitor, trimmer and 8:1 vernier dial. The “Tuggle tuned” ATU is split into two ranges - each with its own capacitors and 8:1 dials. The inductively coupled wave trap has one range and a 48:1 vernier. A FO-215 diode is Hobbydyne coupled to the top of the detector coil - no taps. Diode output goes to a Bogen T-725 transformer then to two USI UA-1614 sound powered elements in series - or - standard telephone handsets in series.
The antenna is an end-fed 200’ inverted Vee with it’s apex at about 40’; ground is a 4’ pipe driven into the ground.
Dial number-to-frequency calibration curves for the detector and ATU were converted to vernier dial numbers for every 10 khz of the broadcast band. A station heard on a digital read-out Yaesu FT-757GX spotting radio could be quickly converted to crystal-set dial numbers - and vice-versa.
I think the bandspreading and calibration expansion are the best features of this set-up.
For more info, visit Dave's website at: Dave's 2007 Logs