When it comes to crystal radios, there is nothing revolutionary regarding the CR-1’s basic circuitry but for some odd reason, it has achieved cult-like status as well as high dollar value.
courtesy: Scotts Crystal Radios |
The article that piqued my interest appears on 'Scott's Crystal Radios' website and makes for an inspirational read, eventually revealing the inside core arrangement of the ferrite-loaded tuned circuits via an actual X-ray of the device! By the way, if you are looking for a nice set of older headphones, Scott's website is the place to visit!
courtesy: Scott's Crystal Radios |
Scott was eventually able to achieve performance equal to that of his borrowed CR-1, with his own slightly modified versions, all in a similar-sized footprint. Perhaps this is one reason why the CR-1 is so much sought-after, as good performance in a very small package is not the norm when it comes to crystal radios. It's usually a case of ‘the bigger, the better’ when it comes to performance.
A recent search of my junque box revealed several NIB ferrite loopsticks that would allow a potntial reproduction of this interesting circuit.
Several years ago I spent an eye-opening winter learning about DX crystal radios as up to that time I had always believed it would be impossible to hear anything other than strong local signals on a crystal radio. I quickly discovered that there was a very large Crystal Radio Yahoo Group where members were working at the leading edge of crystal radio design. I also found that the group sponsored an annual Crystal Radio DX Contest which inspired me to dig deeper.
It wasn’t too long before I decided to join the fun and attempt to build a crystal radio DX-machine but I was in for a few surprises and a long learning curve ... it seemed that hearing broadcast band ‘DX’ on a crystal radio (anything other than loud locals) was not going to be an easy task!
Over the course of several months I tried many types of variable capacitors, tank coil configurations and antenna tuning circuits. I even erected a dedicated antenna system for the various experimental circuits I was putting together ... an 'Inverted-L', 50’ straight up and 70’ horizontal, along with a ground rod connected to several buried radials.
I quickly learned about something I normally didn’t have to worry about when working with ‘active’ devices and that was overcoming system and component losses. In critical crystal radio design, it’s all about minimizing the losses in every stage and every component in the system since there are no amplifiers to help overcome these losses. Your system is only as good as the weakest link. In true crystal radio DXing, no active devices are permitted ... it’s just your crystal radio and the energy generated at some, hopefully far away, transmitter site!
After several months, I eventually ended up with a well-performing triple-tuned set that used lots of 'trapping' because of all of the very strong nearby signals here ... eight 50kW locals!
A description of the learning curve, with several do's and dont's to help new builders, can be found on my website here.
Back then, 80 stations were logged (from my location on Mayne Island in SW British Columbia) over the one-week Crystal Radio DX Contest.
FRQ
|
STATION
|
LOCATION
|
POWER
|
540
|
CBK
|
WATROUS, SK
|
50KW
|
550
|
KARI
|
BLAINE, WA
|
2.5KW
|
560
|
KPQ
|
WENATCHEE, WA
|
5KW
|
570
|
KVI
|
SEATTLE, WA
|
5KW
|
580
|
KFXD
|
NAMPA, ID
|
5KW
|
580
|
KTMT
|
ASHLAND, OR
|
1KW
|
600
|
CKBD
|
VANCOUVER, BC
|
10KW
|
650
|
CISL
|
VANCOUVER, BC
|
10KW
|
670
|
KBOI
|
BOISE, ID
|
50KW
|
690
|
CBU
|
VANCOUVER, BC
|
50KW
|
730
|
CJNW
|
VANCOUVER, BC
|
50KW
|
750
|
KXL
|
PORTLAND, OR
|
20KW
|
770
|
CHQR
|
CALGARY, AB
|
50KW
|
780
|
KKOH
|
RENO, NV
|
50KW
|
790
|
KGMI
|
BELLINGHAM, WA
|
1KW
|
800
|
CKOR
|
PENTICTON, BC
|
500W
|
800
|
CHAB
|
MOOSEJAW, SK
|
10KW
|
810
|
KGO
|
SAN FRANCISCO, CA
|
50KW
|
820
|
KGNW
|
SEATTLE, WA
|
5KW
|
830
|
CKKY
|
WAINRIGHT, AB
|
3.5KW
|
840
|
KSWB
|
SEASIDE, OR
|
500W
|
840
|
CKBX
|
100 MILE HOUSE, BC
|
500W
|
850
|
KOA
|
DENVER, CO
|
50KW
|
860
|
KPAM
|
TROUTDALE, OR
|
10KW
|
870
|
KFLD
|
PASCO, WA
|
250W
|
880
|
KIXI
|
MERCER ISLAND, WA
|
10KW
|
880
|
COOL
|
EDMONTON, AB
|
50KW
|
890
|
CJDC
|
DAWSON CREEK, BC
|
10KW
|
900
|
CKMO
|
VICTORIA, BC
|
10KW
|
910
|
CKDQ
|
DRUMHELLER, AB
|
50KW
|
920
|
KXLY
|
SPOKANE, WA
|
5KW
|
930
|
KBAI
|
BELLINGHAM, WA
|
500W
|
940
|
CJGX
|
YORKTON, SK
|
50KW
|
950
|
KJR
|
SEATTLE, WA
|
50KW
|
960
|
CFAC
|
CALGARY, AB
|
50KW
|
980
|
CKNW
|
NEW WESTMINSTER, BC
|
50KW
|
1010
|
CBR
|
CALGARY, AB
|
50KW
|
1040
|
CKST
|
VANCOUVER, BC
|
50KW
|
1060
|
CKMX
|
CALGARY, AB
|
50KW
|
1070
|
CFAX
|
VICTORIA, BC
|
10KW
|
1090
|
KYCW
|
SEATTLE, WA
|
50KW
|
1130
|
CKWX
|
VANCOUVER, BC
|
50KW
|
1160
|
KSL
|
SALT LAKE CITY, UT
|
50KW
|
1170
|
KPUG
|
BELLINGHAM, WA
|
5KW
|
1180
|
KOFI
|
KALISPELL, MT
|
10KW
|
1190
|
KEX
|
PORTLAND, OR
|
50KW
|
1200
|
WOAI
|
SAN ANTONIO, TX
|
50KW
|
1210
|
KBSG
|
AUBURN, WA,
|
10KW
|
1210
|
KZTS
|
SUNNYSIDE, WA
|
1KW
|
1240
|
KGY
|
OLYMPIA, WA
|
1KW
|
1240
|
KOFE
|
ST. MARIES, ID
|
500W
|
1250
|
KKDZ
|
SEATTLE, WA
|
5KW
|
1250
|
KWSU
|
PULLMAN, WA
|
5KW
|
1260
|
CFRN
|
EDMONTON, AB
|
50KW
|
1260
|
KLYC
|
McMINVILLE, OR
|
850W
|
1270
|
CHAT
|
MEDICINE HAT, AB
|
10KW
|
1270
|
KTFI
|
TWIN FALLS, ID
|
1KW
|
1280
|
KIT
|
YAKIMA, WA
|
1KW
|
1290
|
KGVO
|
MISSOULA, MT
|
5KW
|
1290
|
KUMA
|
PENDLETON, OR
|
5KW
|
1290
|
KKSL
|
LAKE OSWEGO, OR
|
5KW
|
1300
|
KOL
|
SEATTLE, WA
|
5KW
|
1300
|
CJME
|
REGINA, SK
|
10KW
|
1310
|
CHLW
|
ST. PAUL, AB
|
10KW
|
1320
|
CHMB
|
VANCOUVER, BC
|
50KW
|
1340
|
KLKI
|
ANACORTES, WA
|
1KW
|
1360
|
KKMO
|
TACOMA, WA
|
5KW
|
1370
|
KAST
|
ASTORIA, OR
|
1KW
|
1410
|
CFUN
|
VANCOUVER, BC
|
50KW
|
1470
|
CJVB
|
VANCOUVER, BC
|
50KW
|
1510
|
KGA
|
SPOKANE, WA
|
50KW
|
1520
|
KKSN
|
OREGON CITY, OR
|
15KW
|
1530
|
KFBK
|
SACRAMENTO, CA
|
50KW
|
1550
|
KCCF
|
FERNDALE, WA
|
10KW
|
1590
|
KLIV
|
SAN JOSE, CA
|
5KW
|
1600
|
KVRI
|
BLAINE, WA
|
10KW
|
1620
|
KYIZ
|
RENTON, WA
|
1KW
|
1640
|
KPBC
|
LAKE OSWEGO, OR
|
1KW
|
1660
|
KXOL
|
BRIGHAM CITY, UT
|
1KW
|
Old notes indicate that there were 14 stations at S9 or higher, requiring heavy trapping to hear anything close to their frequencies.
My recent interest made me wonder what the
situation is today when it comes to the number of strong local ‘blowtorch’
signals, surely the bane of all crystal radio DXers? Although there have been a few changes over the years, a quick scan of the band
during the prime DX evening hours found that although one of the blowtorch signals (at 600kHz) was now gone, another had appeared at 1200kHz ... sadly no net difference. The top end of the band, always a prime area for good skywave DX, is unfortunately still dominated by a huge signal from KVRI just across the water near the Canadian / U.S. border. If KVRI were silent, the top end would be a wonderfully quiet hunting-ground for new catches. The new local blowtorch (CJRJ) on 1200 kHz will now cause problems for the middle of the band, which was always a good region for DX. So it seems overall, there hasn’t been a huge change here other than in the middle of the band. It looks as though there are still some good watering-holes to be had but several traps will still be needed in any new system. Once my present radio-bench project is finished (a '36 RK-39 crystal power oscillator) I’m looking forward to more research and design of a couple of new systems, starting with something similar to the CR-1 as well as some experimentation with toroidal coils. I always find the research and planning phase of any new project more interesting and fulfilling than the actual construction and implementation! Hopefully I’ll have something ready for the fall DX season! Thanks to VA7MM, I will also have the loan of an original CR-1 next winter to make comparisons to any clone that I might build! If building a DX-crystal radio is something that might interest you, there are several great websites offering inspiration and helpful info. The links for these may be found at the bottom of my own crystal radio page. As well, there are two active crystal radio groups on Facebook, where daily two-way discussion can be had. Perhaps, with enough new interest, we can even revive the annual Crystal Radio DX Contest! |
1 comment:
Amazing stuff! I'm just now preparing to give NDBs another try. After a long hiatus. And I'm so glade to have found your site! (again).
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