Basket-coil.com October 21, 2017
Homebrew Crystal Radios
with Basket Weave Coils for Medium Wave DXing and Shortwave listening.
Also crystal radio projects with ferrite bar antenna, radio waves hotspots, and others.
■ Coil Projects
■ Crystal Radios with Ferrite Bar anntena
・Shortwave crystal radio
A Proof-of-concept model of crystal radio with basket coils.
・RCX - Proto (2015)
Homebrew crystal radio for MW DXing. Prototype.
I posted an article of making and testing of RCX-Proto in QEX JAPAN NO.17 (below).
別冊 CQ Ham radio QEX Japan NO.17 (2015.12)
My article in this edition（ pp. 80-89, Japanese ）
" Improve selectivity and sensitivity by devising coils.
Designing and making of crystal radio with basket coils : Part 2 "
※ For the information of basket coil winding method, please refer to the article in
" 別冊 CQ ham radio QEX Japan No.15 (2015.6)", "Designing and making of crystal radio with basket coils : Part 1".
・RCX - 61000 (2016)
Homebrew crystal radio for MW DXing.
After testing of RCX-Proto for a year, I tried to design a
new set with higher performance and easy to use.
Result: Very satisfied.
A handout (PDF, Japanese) at JARL Ham Fair 2016, Tokyo.
Circuit diagram ( PDF, Japanese )
Daily reception of JOGB (Kumamoto) in Tokyo from Jan. 1 to Oct. 21, 2017 with RCX-61000, (PDF, Japanese).
・RCX - 61000 MK II (2017)
Homebrew crystal radio for MW DXing,
Exibited at the JARL Ham Fair 2017, I enjoyed a pleasant talk with many people. Thank you !
A handout (PDF, 4 pages, Japanese) at JARL Ham Fair 2017 ( Ver.5 Revised on Sep. 30 ).
Circuit diagram ( PDF/Ver.4, revised on Sep. 11 )
■ Reports on Radio Waves Hotspots ―――――――――
What is Radio Waves Hotspots ? There are places where you can hear the
broadcast on a crystal radio without a big external antenna - like a
long wire antenna, while those places are surprisingly several kilo meters to well over 10km away from the transmitting antenna.
We call those places radio waves hotspots.
There are possibilities of hotspots, such as near tall
building pillars, utility poles, guardrails, fences, crossovers, big
bridges and so on.
In order to qualify as a hot spot, it is subject to (1)
while it depends on the power of transmitting antenna, it should be far
enough from the transmitting antenna, and (2) you might be able to
receive and enjoy the broadcast on a crystal radio without an big
external antenna. On hotspots, you can enjoy the broadcast even with dynamic headphones or speakers, with loud sounds. With ceramic earphone, you could hear it at such a high volume that the ear might hurt. Also, even with an LED that has high forward voltage, detection can be done and you might see an led light up brightly.
In addition to medium wave
broadcasting, hot spots exist also in shortwave broadcasting band and
FM broadcasting band. We frequently conduct field surveys on hot spots in Japan since 2014.
・Hotspots of Magnetic field type in Tokyo
・Hotspots of Electric field type in Tokyo
Tokyo Big Site - Feb 2017 (Report in Japanese)
<<<<< Caution !!! >>>>>
· Do not explore in places where you can not secure your own safety.
· Do not enter private property or restricted area without permission.
· Do not disturb other people while exploring on streets and other places.
· Be careful not to be mistaken as a suspicious person.
· Common sense and good manner are the most important things you should know while exploring.
・全国・電波ホットスポット探検隊 - Radio Waves Hotspots Detectives (Japanese site)"
・全国・電波ホットスポットを探せ (Japanese site)
・Hotspots Detectives on National Television !
We were featured in the famous Japanese TV show, " Tamori Club（タモリ倶楽部）" on February 12, 2016 (24: 20 - 24: 50).
Title : " A Thorough Survey of Radio Waves! We are Radio Waves Hotspots Detectives"
You might find the footage on Youtube by searching with " Tamori Club 2016.02.12 ".
■ MW DXing and SWL ――――――
・UZ-8CQ (Produced by CQ Publishing Co.,Ltd. with the cooperation of mizuho-lab.com. )
Order UZ-8CQ at CQ Web shop, CQ Publishing Co., Ltd..
別冊 CQ Ham radio QEX Japan NO.23 (2017.06)
My article in this edition（pp.85-92, Japanese）
" Product review : UZ-8CQ - Large wooden loop antenna for medium wave reception "
In this article, you can check the great performance of UZ-8CQ in MW
DXing with Tecsun PL-360ET, SDR#, or in the reception of NAVTEX Japan.
Crystal Radios with Basket weave coils for MW DXing and SWL.
Amature Ham Radio(JJ1DIS), QRPp, Morse code.
SDR with RTL-SDR dongles, SDR#, GNUradio, RasPi, Arduino.
A member of "全国・電波ホットスポット探検隊 - Radio Waves Hotspot Detectives (Japanese site)"
IMP 2017. 10. 21
All rights reserved. (c) 2017 by IMAMURA Akira / JJ1DIS