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The Enigmatic Heathkit CR-1 Crystal Radio
3 June 2019 | by For the past several months my interest in ‘DX-crystal radio’ construction has been percolating once again. It began when I ran across an interesting description of Heathkit’s legendary CR-1, a double-tuned good performer and very much sought-after by collectors as well as by users. The article described one homebrewer’s attempt to duplicate the receiver and to learn more about the detector and antenna tuning ferrite-loaded coil's secrets.
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.
I've been eager to get my mitts on one to see how it performs after reading of one DXer's fifty-eighth catch with his own CR-1!
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!
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 menbers 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.
CRYSTAL RADIO LOGBOOK
Old notes indicate that there were 14 stations at S9 or higher, requiring heavy trapping to hear anything close to their frequencies.
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 menbers 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! |
11 Responses to “The Enigmatic Heathkit CR-1 Crystal Radio”
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I’m reading your Crystal Set DXing page; this material is gold. You’re really inspiring me to build one 🙂
Wow. What a refreshing aspect of radio. Brings me back to some of the crystal and one-transistor hookups I did when I was young! Thanks.
Built my CR-1 in 1958 while in 7th grade. It was my first of many Heathkits. Still have it and it still works perfectly.
That’s great to hear Goody! Don’t hesitate to contact me if you need some help.
David, I was surprised at the level of performance that one can get with a hi-Q system.
Jim, I wish I had been smart like you and bought one back in the day. Have you heard any DX with yours I wonder?
This is really bringing back nostalgic memories of my crystal set days of the 1950s !
My 1st. set was on the lines of the WW 2 Fox Hole radio–it used a Gillete shaving blade after rusting half of it—the next one used a Galena rock which when powdered was used as eyelash makeup by the local YLs ! Both these sets were the true cats whisker kind, to locate stations. Later graduated to Mullard OA79 germanium diodes & also 1N34s–finally added the 1st Raytheon made PNP transistor CK722 as an headphone amplifier.
For the earlier versions I had to use darn hard to find, very high impeadance headsets.
Ofcourse these sets needed pretty, long wire antennas but all said & done I would love to try it again if its going to improve the sunspots any !!!
Dr. Zal, I’m happy to hear that this has brought back good memories for you! For many radio fans, crystal radios were their first exposure to the magic. I would encourage you to try something, knowing what we now know about optimizing systems for better performance. I don’t think it will improve the sunspots any however! Actually, the next few winters should be very good for broadcast band DXing, including with your DX crystal radio!
Steve and everyone, my first crystal radio was homemade, the coil had a primary and secondary windings and I used a germanium diode OA79. I purchased a headphones of high impedance, (2000 ohms) from a local supplier. I remember that the person that sold to me the headphones was very surprised for it, was at the beggining of the Eighties, 1981 and I was 12 years old only, (was the Walkman Era low impedance headphones, 8 to 32 ohms only). I used a long wire antenna, but I put it at the outside of the my parents’ house building, through the window of my room and the ground pole connected to a cold water pipe. After this circuit, I made another using a commercial coil and enclosed all components in a wood case.
Now I have a Flyvver Radio Crystal Set that I purchased on eBay and in 2018, a friend of mine gave to me a non-working Heathkit CR-1. I opened it and discovered that the ferrite coil was mounted in a worng position. I desoldered and put it in the correct way and it works! I used a Trimm type “K” headphones that works very well with my crystal radio sets.The headphones that I purchased on the Eigthies, I not remember were it was happened with it…, the Trimm type “K” sounds very well.
Greetings from Spain and 73 de EC4ACH, David.
My Dad, an avid Heathkit builder, built a CR-1 for me in the 50s. We lived in NJ not far from NYC. My CR-1 had a small, white, roundish pillow speaker for output that I kept under my pillow. The volume was sufficient for me to hear Cousin Brucie all night long through my pillow. Mike
I just received my Heathkit CR-1, delivered by FedEx. This was an Ebay buy that I just had to have and my wife said, “Merry Christmas!” I spent way too much. I’ve been wanting one of these for over a decade. I have hooked up to my G5RV with expected results, but I just listened to the Zag’s win a basketball on KIXI, the only station I can bring in. Can’t wait to string up a long wire and see how this beauty really performs. I really need to get back into Crystal DX again.
73
Eric K7EBR
A friend gave me his Heathkit CR-1 and I’m sure he didn’t know the current value being so crazy high. So, I am going to string a long wire and drive a ground stake with my grandsons and see if this old kit can still find some frequencies. Then as I already told him, I will return it , but what a gesture between two old experimenters.
When I was 10 years old my dad (an electronics technician) gave me a heathkit crystal radio (CR1) and put up an antenna about 200+ feet long. I spent many late nights listening to stations as far away as Denver CO, Chicago, Cincinnati, Nashville (we live ed just north of Indianapolis IN) and many more cities. My dad always told me to disconnect the antenna from the radio when I was not using it. So when lightning struck the tree at the far end of the antenna and vaporized the antenna wire, I was very glad the radio was safe.
I still have the radio and original headphones. I have built many heathkits over the years but the CR1 is among my fondest memories.
Earl