DXing, or listening for far off stations, has long been a part of the crystal set experience. Dxers strive to pull out those weak signals generally not audible with a beginner set.
There are many factors involved when it comes to optimizing a set for the regular reception of skywave signals such as a well-planned and tuned antenna, high-Q coils, carefully selected diodes and sensitive impedance-matched headphones.
This group's purpose is to discuss all aspects of DXing WITH CRYSTAL RADIOS.
If this sounds like something you may be interested in, please head over to the FACEBOOK GROUP, answer the two sign-up questions, and join the group!
Results, logs, pictures and comments from the October 2023 Listening Event participants
Terry (WC8F) in Ohio submitted an extensive SHORTWAVE LOG with all stations being heard on his homebrew crystal radio shown below. Note that only bare bones headphones are used ... 100% passive!
Steve, here is my log for the October 2023 Crystal Radio Listening Event. I decided to again run the shortwave radio all three days and conditions were pretty rough as we both know. The antenna used is a 440' long straight inverted L at 38' high. The radio runs as pictured without amplification and directly into my best pair of Bladwin Model C headphones. I usually start at one end of the band and tune up or down with the main capacitor (center of the radio) until a station is heard. At that point I peak the station with the ground capacitor on the right side and then finally go to the left knob and fine tune the antenna coil on the left. The radio works very well with some US stations being incredibly loud. The radio tunes from 3215 to a high so far of 17855. The smaller 5 turn detector coil pictured on the table is used for the top of the band.
************************************************************************************************************** From here in SW British Columbia, I participated using a very simple double-tuned experimental receiver, a pair of wavetraps for nulling my pests, a homebrew impedance matching transformer and an RF signal generator to help me find frequencies and to peak up the crystal radio's tuning.
The simple receiver consisted of two tanks coils made from the ferrite bar antennas typically found in thrift store $5 radios. It helps to have a decent set of capacitors but excellent results can also be had with the same capacitors found inside these radios. It might be the easiest and CHEAPEST way to build a good-performing radio capable of skywave reception!
Being able to vary the coupling between the two coils often made the difference between hearing and not hearing a DX signal ... usually a case of less coupling to reduce the splash from loud locals would let the weaker signal pop through. If you live out in the country, this will not be necessary and close coupling will provide the highest sensitivity.
Two inline wavetraps wound on ferrite toroids were used to help null out interference from my 15 local blowtorch signals.
I also employed a simple A-B diode comparitor board that allowed me to determine which of the two inserted diodes were better. I eventually found a very good HP Schottky diode that proved better than even a very old 1N34 from the 1950s. It was the HP2835 UHF detector / mixer diode with a low turn-on voltage.
Unfortunately radio propagation on the MW band here was TERRIBLE over all three nights and I was fortunate to hear anything outside of my local region. All told, 23 different stations were logged, with 7 of them being via skywave or extended groundwave:
810 KGO San Francisco, CA
880 KIXI Seattle, WA
920 KXLY Spokane, WA
950 KJR Seattle, WA
960 CFAC Calgary, Alberta
1010 CBR Calgary, Alberta
1030 KTWO Casper, Wyoming
Hopefully, if we do this again, conditions will co-operate, as this time out, they could not have been much worse it seems ... all part of the magic of radio.
************************************************************************************************************** Ferhat Yavas
, DXing from Turkey, has submitted a fine log for FM as well as for MW. His information follows, first for FM:Although FM crystal radio looks easy, it is actually more difficult to catch a radio broadcast. For this FM Crystal radio, the tuned capacitor, wire winding and the position of this duo with the telescopic antenna affect the performance, so the parts used must be chosen carefully.
The transmitters are 17~20 km away from me.
Thank you for the organization. I hope it will be an encouragement to other members :)
For MW, Ferhat submits the following information. You have to admire an experimenter who makes his own Litz!With the octagonal loop antenna, I can listen to West Asia North African and European radios without grounding or external antenna. This crystal radio is my first crystal radio. When I was making this radio, I didn't have a wire antenna and ground line, so I had to make a large loop antenna and crystal radio. It took me a long time to finish this set, I tried many different strings and combinations and it was instructive for me. I use this crystal radio as a loop antenna at the same time. The poles I use for the antenna are 70cm long. I created the litz wire myself by folding 0.30mm wire into 10 layers, thus I had a wire that is more resistant to breaks and a softer homemade I like the loop crystal radio. It is not very selective in terms of selectivity, but it is a very nice experience to hear many radio stations from a long distance without antenna and ground.
************************************************************************************************************** Tom Kalantar , DXing from central Michigan, sent a nice SW log and some good info on his setup:
Steve, Here is my info and log. I focused on the 25 M band in the hopes of getting Xianyang, China without the amp, and HCJB in Australia with amp, as I had done the past couple of weeks. Conditions were not good enough and interferences too great to do so this weekend, but here is what I got from central MI. Same SW Xtal set as back in Feb.
Equipment Notes:
Receiver: single tuned set based on the Al Klase tuning coil/tank circuit as in ( http://www.skywaves.ar88.net/SWXS/shortwave.html ); only the direct antenna connected circuit was used (dropped the antenna tuning coil section).
The airdux tuning coil / tank circuit is duplicated to enable either a double tuned set, or use the 2nd tank circuit as a trap. Bottom of trap coil 2.5" from top of tuning coil. Both are 21 Turns 2: 2" airdux @ 10TPI . Tapped at 15 uH and 5 uH: with 15 uH tap: 3.3~8 MHz coverage; with 5 uH tap: 6~12 MHz coverage, 4 uH tap: up to 16 MHz coverage.Diode: 1N60 from radio shack (old). Diode location (and all other attachments) on tank coil adjustable.
Variable Capacitors: matched pair from eBay: ceramic insulation; brass plates, 5:1 vernier drive.
Spotter radios: 1991 Yaesu FRG 8800, recapped 2023, on 230' antenna; and 2019 Sangean ATS-909X on 55' antenna.
230' Antenna: 230' #14 THNN insulated stranded wire in trees strung around my lot on 3 of 4 sides; 55' Antenna: #18 stranded wire attached to a tree near the house.
Audio Amp: CZH Labs LM386 based audio amp with headphones (https://czh-labs.com/products/audiowind-battery-supply-audio-mono-amplifier-kit-njm386d-lm386 )
Freq'y Reference: Heath kit SG-6 (ca. 1950) signal generator, recapped 2023.
Reference for locations, power, azimuth, great circle distance to my location: ( https://www.short-wave.info/ )
************************************************************************************************************** Gary, in the suburbs of Syracuse, NY (with only one blowtorch!!), sends a nice log on a single-tuned set. This just illustrates that being able to run 'wide-open' without worrying about the need for high selectivity, can yield great results with no antenna tuning. With 10 states and 3 Canadians, I'd say this is VERY inspiring:
Hello Steve, I spent Friday evening between 1920 and 2025 EDT listening to MW with a simple set I tossed together. It had been a two BJT regen but I removed all the active stuff and left just the tank coil, variable capacitor and the Bogen T-725 AF transformer. I used an FO-215 diode from the top of the coil to the 40k (white) tap on the T-725.
Since the FO-215 tends to have a diode resistance around 180k (if I remember correctly!) I thought I would try my 25 ohm plug type earphones on the 8 ohm transformer tap. Since 25 ohms is about 3X 8 ohms that should have given about 120k at the white lead of the T-725 which gets into the ballpark of the FO-215 resistance.
But, I found that the 8 ohm version of my earphones was much louder, so I stuck with those. They must be more sensitive, maybe.
My earphones are Koss "The Plug" which I have found are quite sensitive for modern phones. I use the two elements in parallel resulting in 8 ohms and 25 ohms from 16 &16 and 50 & 50, respectively.
I was very surprised at how well the setup performed with my 75 foot inverted "L" and a ground stake outside the window. My location is near Syracuse, NY.
880 WCBS NYC
740 CFZM TORONTO, ON
710 WOR NYC
720 WGN CHICAGO, IL
680 WRKO BOSTON, MA
660 WFAN NYC
620 WHEN SYRACUSE, NY
570 WSYR SYRACUSE, NY
760 WJR DETROIT, MI
780 WBBM CHICAGO, IL
800 CKLW WINDSOR, ON
840 WHAS LOUISVILLE, KY
890 WLS CHICAGO, IL
900 CHML HAMILTON, ON
1000 WMVP CHICAGO, IL
1020 KDKA PITTSBURGH, PA
1130 WBBR NYC
1080 WTIC HARTFORD, CT
1090 WBAL BALTIMORE, MD
1060 KYW PHILADELPHIA, PA
1260 WSKO SYRACUSE, NY
1170 WWVA WHEELING, WV
1390 WFBL SYRACUSE, NY
1110 WBT CHARLOTTE, NC
1490 WOLF SYRACUSE, NY
670 WSCR CHICAGO, IL
700 WLW CINCINNATI, OH
I have to say that WWVA was SO LOUD that I kept glancing at my tank coil to see if insulation was burning off!
My spotter was my TS-430S ham transceiver tuned to MW. For the lower half of my tuning range I test clipped the antenna coax center to an insulated turn of the coil. As I moved up the band I had to unclip and move it farther from the coil. As I tuned the TS-430 the station the crystal set was tuned to would appear out of the noise on the '430 so I could read the frequency.
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