Heathkit Cr 1 Crystal Radio Manual

Popular Posts

• Post subject: Heathkit CR-1. Posted: Sep Tue 18, 2007 3:50 am. Member: Joined: Jan Thu 01, 1970 1:00 am Posts: 802 Location: Walden, NY USA I received this little crystal radio in a box of stuff at a garage sale. It is in great condition, and all the parts seem to be there and wired correctly. I connected it to my long wire, used a good ground. This reproduction kit is based on the classic Heathkit CR-1 crystal radio, built by many people. Kit features a High Quality, glossy black fiberglass face plate, with silk screen printing. Kit includes all components to build the radio, including two wide range variable polyvaricon capacitors, and high quality Hammond enclosure.

  DXing With The Heathkit CR-1 Crystal Radio

  
  If you’re a regular blog reader, you will likely recall my description of “The Enigmatic Heathkit CR-1 Crystal Radio” a few weeks ago.
  Back then I mentioned that I was ‘eager to get my mitts on one’ and that I had arranged to borrow a CR-1 from another VE7 who was fortunate enough to own one.
  A few weeks after posting the blog, I received an e-mail from Larry, WB5OFD, in Texas.
  \'Reading thru your blogs the other night .. discovered your article on Crystal Radio reception reports. I am in the process of disposing of a lot of radio gear I have collected over the past sixty years and in that pile is a Heathkit CR-1. Yours for free if you would like to have it.\'
  Needless to say I was overjoyed, both at the opportunity to actually own a CR-1 myself and at Larry\'s exceptional generosity!
  Larry went on to explain that he had been in the Air Force and his little CR-1 had been all around the world with him, from Alaska to Turkey .. but from its fine appearance, you would never know it.
  

  Larry\'s gift!

  
  He was happy to pass it on knowing that it was going to a good home. I am most appreciative of this kind gesture from a fellow radio amateur, knowing that these things are not too easy to find .. and are somewhat pricey!
  As can be seen in the schematic diagram above, the CR-1 is a simple double-tuned crystal receiver, utilizing a series-tuned tank circuit for antenna-tuning, coupled into the detector tank circuit. The detector diode, a 50’s-era 1N34, is tapped down on the tank for headphone impedance-matching and to reduce circuit loading. Reducing the load on the tank circuit improves selectivity but diminishes sensitivity. Crystal radio design is always a trade-off between these two critical characteristics.
  Although I had heard good things about the CR-1, I must admit that I was somewhat skeptical .. just how good could an unmodified CR-1’s simple double-tuned design really be? I was about to find out.
  My listening location, on the eastern shoreline of Mayne Island, puts me directly across several miles of saltwater from sixteen exceptionally loud \'blowtorch\' signals whose antennas are located near the water on the other side of Georgia Strait. Six of these stations run 50kW .. 24/7. All of these signals are wide and strong, being well-over S9. It is a difficult location for crystal radio DXing as separating weak DX signals from the blowtorches can be challenging.
  My previous experience with crystal radio DX is well-documented on my website here. Back then, I quickly adopted the standard protocols to help hear DX. This included the use if a separate ‘spotter’ radio to first find signals that might possibly be strong enough to be heard on the crystal detector. I also used an RF signal generator that let me temporarily put a weak tone-modulated carrier on the frequency of a station that I was trying to hear. Using the tone, the antenna tuning as well as the detector circuit can be optimized for maximum signal. I also used a 100 microamp meter in series with the headphones to make peaking these circuits accurately. The same protocol was used for my CR-1 DXing as well.
  Since there are so many very strong signals here, I have added two inline L-C traps on the antenna lead.
  
  My first trap was made from a ferrite bar loopstick inductor salvaged from an old transistor radio.
  The second trap is made with a ferrite toroid and Litz wire and produces deeper nulls than the ferrite bar. The bar will soon be replaced by a second toroid trap.
  
  The traps allow me to significantly null any strong signals that could be covering up a nearby weaker signal. For nulling, I set the signal generator on the frequency of the pest signal and then tune the trap for a null while watching the meter. Once everything has been tuned, I’ll often just sit and wait for the desired signal to fade up to a detectable level on the crystal radio and then confirm its audio match to what can be heard on the spotter radio. Very often, a signal initially too weak to be detected, will quickly pop up in signal strength to an easy-copy level for several minutes, before dropping below the threshold of diode detection level once again.
  I am presently using a pair of RCA WWII sound-powered (\'Big Cans\') phones, impedance matched to the CR-1’s output with a multi-tap audio transformer. I have also used a nice set of extremely sensitive Western Electric 509Ws, manufactured in the late 20s. These are also impedance-matched to the CR-1\'s output. On weak signal tone tests, I can see only a very tiny improvement with the RCAs versus the old 509Ws as both are very sensitive.
  There is a large variation in propagation quality on the broadcast band, especially this far north on the southern edge of the auroral zone. The difference from one night to the next can often be quite dramatic. On most nights the band favors the north-south path while on geomagnetically quieter nights it’s the east-west path that dominates. The band needs to be in good shape for any worthwhile hope of DX on a crystal radio.
  On one of the recent better nights, of which there have been very few of lately, one of the stations in Alberta was so strong that it needed trapping! This was something I saw quite often with my previous DX set but I didn\'t expect to see it with the CR-1.
  For crystal radio DX, propagation is the best helper. Small incremental improvements (in terms of db losses) can be made in any part of crystal radio\'s systems but on nights of good propagation, tens of db improvement will magically appear, thanks to Mother Nature!
  When in Turkey, Larry had the opportunity to connect the CR-1 to the large FLR-9 circular antenna array used during the cold war for HF direction-finding of targeted signals. Covering 1.5MHz to 30MHz, the FLR-9 consisted of ninety-six 120\' towers, suspending 1056 vertical elements .. all over a 1500\' diameter ground screen! His notes show that he logged the BBC, Italy and West Germany on the CR-1 while using the array!
  

  The FLR-9 array in Augsburg, Germany

  Although the antenna system connected to my CR-1 is not nearly as impressive as an FLR-9 array, it is very capable on the broadcast band. I’m using my 630m inverted-L, bypassing the tuning and 50-ohm impedance matching system, essentially feeding it as a top-loaded vertical wire. The (somewhat slanted) vertical wire is approximately 70’ which is then attached to a 3-wire 100’ long tophat. The antenna is very close to the ocean and parallel with the beach. The CR-1 ground system consists of about 60 buried radials, varying in length from 30-60’. The basic antenna is self-resonant at around 1200kHz.
  Over the past few weeks, I have been spending a few nights patrolling the band between 9:30 and 10:30PM, to see what might be heard with the CR-1. So far, I\'ve logged 50 different stations .. far more than I had expected to hear.
  The log below shows all of the stations heard. The stations in red are all local line-of-sight transmitters and are extremely strong .. all are well over S9 on my Sony spotter radio. The stations shown in blue are all ‘DX’, with the furthest so far being KOA in Denver, at 1100 miles.
  
  The log illustrates just how much the blowtorch signals prevent weak-signal detection, even with traps! The stations logged on 1510 and 1530 were only possible when the 1550 blowtorch lost their audio for about five minutes one evening! Selectivity becomes increasingly more difficult towards the top end of the band and, unfortunately, there is a larger concentration of strong locals (who seem to delight in over modulation and splatter), making reception up there extremely challenging.
  There are still some lower-band signals that I have yet to log and they have been gradually growing stronger as the nights get longer. As well, the region above 1600kHz may still provide a few opportunities over the next few weeks, if the loud local on 1600 can be sufficiently trapped .. the next few weeks will tell if there’s anything left in the CR-1’s tank!
  Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

  • Fascinating stuff, Steve. Thanks for taking the time to report this in so much detail.
    73,
    Colin

  • Hi,
    I have greatly enjoyed you articles on the Heathkit CR-1. I built mine in 1958 or 1959. I was either 11 or 12 years old. A neighbor had given me an old Echophone EC-1 receiver and a old Heathkit catalog. Well when I saw the CR-1 in the catalog I knew I had to get one. I had never done any type of kit building and certainly had never done and soldering! Well I got it together and began using it with a wire antenna stretched across my bedroom ceiling. I could barely believe that I was pulling in radio stations hundreds of miles away! When I spoke to my grandparents about this little wonder they regaled me with tales of using the old catswisker crystal sets back well before the Second World War. I even took it to school in 7th grade and used it as my science project….got a A+ with it! I still have mine in pristine condition. Thanks for the memories.

    Thanks again,

    Jim Smith K3RTU

    P.S. Been licensed since 1962

  • Thanks for the memories Steve. I built a CR-1, my first kit, in the late 50s or early 60s. I lived in an apartment so my antenna was not ideal. I only heard local stations. It was not selective enough to separate two local stations, one at 1280 and the other at 1340 Khz.

    Robert VA3AOD

  • Colin, Jim and Robert … thanks for your comments. If you had a CR-1 as a kid, you were hooked forever on the magic! Good stories.

  • Lovely story, Steve. A real inspiration for the rest of us! -Mike-

  • Hi Mike… appreciate your nice comments! BTW, would love to see the old Xtal Radio DX contest revitalized … we had so much fun back in the dynamic Yahoo group days👍👍

  • Heard about the rig when I was an SWL. Had not seen it. Looks great. I love Heathkit products
    I had an Heathkit HW101 when I just got my licence.
    Good old memories.

  Copyright © 1995-2019 AmateurRadio.com, All Rights Reserved.
  RSS Feed Sitemap DMCA Contact Privacy Policy / GDPR
  Each individual posting is the property of its respective author and the opinions expressed may not represent those of AmateurRadio.com including its editor, staff, or sponsors. Content may not be reproduced without written permission.

  Heathkit CR-1 Crystal Radio and
  Miller 595 Tuner Information

  This page gives the circuit and pictoral description of the famous Heathkit CR-1 crystal radio.
  It was a double tuned crystal radio from the 1950\'s with a series tuned primary that had a 365 pf variable capacitor and selectable additional capacitance on the center selector switch. In my opinion, it would have been more logical to have made the center switch for varying the inductance and using a tapped primary coil.
  Here is a picture of the inside of the original CR-1.
  

  
  Another photo showing the inside of the original Heathkit CR-1. Note the rectangular pinkish mica capacitors, the configuration of the central antenna switch, the \'cable knit\' appearance of the coil windings, and the long screws holding the panel to the threaded stubs that are recessed deep into the cabinet.
  

  Anyway the coils, marked as \'transformer\' in the diagram, were both wound on a ferrite rod and the secondary coil was part of a tank with the 365 cap and the germanium diode for the detector circuit. They do not give details of the coil construction but with a little experimentation you can get into the BC band tuning range.

  Here is the original circiut:
  

  This shows the pictoral diagram of the inside of the set:
  

  First Prototype
  In my first building project replica I used a toroidal core instead of a rod. An Amidon FT 114-61 was my choice for the core, and 45 turns of 24 GA enamel wire for the secondary gets the detector tank in the ballpark. (Amidon\'s webpage is http://www.amidoncorp.com). I used 30 turns of the same wire would on the same toroid for the primary with taps at 3, 6, 9 15, 24, and 32 turns. I used the center selector switch to vary the inductance of the primary instead of switching in additional capacitors.
  The little box is a Radio Shack part #270-1805 that is just about exactly the same size as the original enclosure. The front panel is made of aluminum, so it serves as a common ground, but the antenna and one of the headphone binding posts need to be insulated from it using little fiber washers to prevent those binding posts from making electrical contact with the panel.
  The radio was originally sold either with or along side a pair of 4000 ohm Trimm Acme headphones. They were only middle of the road for sensitivity and a good old pair of Brandes Superior or Western Electric 509-W\'s would be much more sensitive.
  Here is a shot of the main parts on the floor. The rotary switch, diode, and box are from Radio Shack. The variable caps were obtained from the Xtal Set Society. The coil is described above and I got the old mica capacitors from my junk box. I ended up using a different coil and no padder capacitors though.
  One challenge was to tap a couple of the holes on the front face of the variable caps to allow them to be mounted to the front panel using 6-32 screws. Care must be taken to avoid damaging the capacitor and to keep the metal shavings out of the ball bearing mechanism.

  
  OK, here is the completed CR-1 clone.
  This first attempt has the binding posts spaced a bit too close. I didn\'t have an original to copy, just pictures. I also tried a couple of different coil configurations and the one I settled on has 45 turns of 24 GA wire for the tuned secondary, and the primary is tapped as noted above.

  
  Inside it is pretty simple. Just the 2 variable caps, the rotary switch wired up to the toroidal coil, and the diode can be seen from the capacitor to the binding post on the far left.
  I hooked it up and counted 6 local stations in the first minute in the daytime, and with a good pair of headphones got 7 locals and another 4 out of state stations on the first night.

  TagsAttention: None of the mods and this Agar.io Unlimited Bots Hack published on our pages belong to our website. Due to the nature of the mods, they are developed by independent developers and published on the internet. We do not accept any responsibility for any possible unwanted conditions due to the use or download of these mods. As God Mods we compile the most popular mods on a single page for any io game. Users should download these at their own risks and we never store any part of these mods in our databases. How to get an agar.io private server with bots for mac pc.

  If I ever get a hold of an original, I will post a comparison of the performance.
  OK, I got a loan of the original Heathkit CR-1 and here is what I found.
  The original CR-1 has a much more definite double tuned effect than my spinoff. The 2 knobs for tuning the ANT and DET circuits seem to track pretty closely with each other and both need to be tuned to the same frequency farily sharply to get reception. It is easy to miss a station by not having the tuners coordinated. I found it best to move the DET dial a little then sweep the ANT knob back and forth a little to zero in on the station if there was one there.
  The circuit gurus emailed me and correctly predicted that my circuit would pretty much function as a single tuned circuit. The inductance tap switch mainly varied the selectivity and I found the 9 turn tap to be good for both sensitivity and selectivity. There was some noticeable tuning effect of the ANT variable cap at the high frequency end of the dial but the DET tuner did most of the tuning. It was, however, very sensitive and tuned very sharply anyway. In fact the volume was louder across the entire frequency range than the on the original CR-1, and I was able to get a couple of weaker stations that I couldn\'t reach on the real CR-1. So overall I am very happy with the performance but I will try another one to try and clone the coil and performance of the original a little more closely.

  Next Version
  After a lot of advice and many coils later, I think I got pretty close to the original performance. The secret is the coil. I am told the original has 2 small ferrite cores in it rather than 1 long one so, I experimented with different sizes of cores combined with different numbers of turns on the coil and then zeroed in on the correct spacing between the 2 cores. The spacing between the coils could be measured from outside but the stuff inside the cardboard tube was impossible to discover without damaging the coil. It looks like the core is about 1/4 inch diameter and extends just to the outer edges of the coil windings when you look into the ends of the tube. If anyone knows the exact original specifications please let me know. Anyway, I was able to pick up the same stations with this version as with the original.
  After many attempts and examination of an original coil and X-ray here is what I ended up with. I used 21/44 Litz wire for the windings. The antenna coil was about 140 turns with a 9/16 inch slug inside that part for about 335 uH inductance. The space between the coils was 10 mm or about 7/16 inch. The detector coil had about 90 turns with a 9/16 inch long slug inside that and measured 240 uH. On some of the coils, I tried bringing out a tap about 30 turns from the stator end of the winding for the detector tap. Hard to say if this made and noticeable difference, not much if any. This coil seemed to duplicate the performance of the original in both sensitivity and selectivity. Any closer spacing of the coils and you get too much coupling and the tuning gets very broad.

  

  
  Here is a front label that I made on some thin acetate plastic, printed the Heathkit logo on it, and glued on to the front of the aluminum panel. I sold a few of these clearly presented as home made clones, though I have occasionally seen my radios show up for sale on Ebay advertised as a genuine Heathkit, which should be obvious that they are not. Note the short flat Phillips head screws, the lettering which is clearly different than the original, and the coil inside is clearly hand wound as opposed to the tidy machine winding of the originals. Also note the round modern ceramic chip capacitors and the multiposition switch. If you run across one of my radios being passes off as an original, you can refer the seller to this page, but the radio itself, unless damaged, should work just as well as the real thing, and there were only a dozen or so ever made, so they are quite rare indeed!
  

  Addendum 5/29/01
  Unravelling the secrets of the CR-1 coil, or The CR-1 coil Exposed
  This is an actual X-ray of a Heathkit CR-1 coil. As you see, it has the 2 coils each with its own separate ferrite slug. The best I can measure, each slug is about 13 mm or about 1/2 inch long by 1/4 inch diameter. The separation between the slugs is 7/16 inch. It looks like the slug in the larger (antenna) coil is not quite centered under the coil. I am not sure if this was intentional or not. Anyway it was helpful to know how it was made so one might get a better idea of how to make a duplicate.
  The Amidon R61-025-400 core can be cut into the 1/2 inch lengths for use in constructing a coil like this one. I will post further information as I progress with this project. Thanks Mike!
  

  Software PowerMenu Plus Version 6.0 by Brown Bag Software (DOS Menu). PowerMenu Plus Version 6.0 by Brown Bag Software (DOS Menu) Thread starter Cobra; Start date Sep 9, 2013; C. Cobra Active. Our ancient grain blend of brown rice, quinoa and wheatberry, fresh spinach, and herbs with your choice of protein. A blend of sauteed brussels, broccoli, green beans, kale, fresh spinach, and herbs with your choice of protein. Greens & Grains. Half powerbox + half veggiebox with your choice of protein. Brown bag software power menu. Download PowerMenu 4.11 by Brown Bag Software. VETUSWARE.COM the biggest free abandonware downloads collection in the universe. You: guest DOS forever. MS-DOS books on Amazon.com! — Mailman 3 hosting — Super-long-term file storage — buy link here. PowerMenu 4.11. Category: Utility: Year.

  Link to Miller Tuner Page (sorry this linked site has been removed, but will try to relocate it) This is a link to a page with more information about another famous crystal radio, the Miller 565 / 595 Tuner. This was my next project. The modified schematic is shown below.
  Parts List:
  Part Description Source, Part#
  C1 2 gang 365 pf tuning capacitor from Xtal Set Society
  C2 0.1 uf capacitor Mouser 5989-250V.1
  C3 0.05 uf capacitor Mouser 5989-250V.047
  C4 200 pf capacitor Mouser 140-50P2-201K
  C5 10 pf capacitor Mouser 140-50N2-100J
  C6 15 pf capacitor Mouser 140-50N2-150J
  R1 100K ohm resistor Mouser 293-100K
  L1 Tuning coil 1 Core from Amidon FT 82-61, see text below for winding
  L2 Tuning coil 2 Core from Amidon FT 82-61, see text below for winding
  L3 Negative mutual coupling coil, see text below for construction
  L4 270 uH peaking coil Mouser 43LR274
  L5 (marked L in schematic) 2500 uH RF choke Mouser 542-70F253
  D1 1N34A Germaniun Diode
  Miscellaneous hardware:
  Perforated Circuit Board Radio Shack 276-1396A
  Solder Tabs Mouser 534-7312
  Machine Screws 6-32
  Washers size 6
  Tuning Knob or Dial
  Cabinet Radio Shack part #270-1807
  Wire for the coils and hookup
  Binding posts or Fahnstock clips

  The secret of this set is in the construction of the coils.
  L1 and L2 are straight ferrite rods wound with Litz wire. The best reproduction of this was to use an Amidon 2 inch by 1/4 inch diameter ferrite rod of material 61, and wind on 85 turns of Litz wire. I had some 21 strand by 44 GA wire and this worked well. I actually measured the inductance of the finished coils and adjusted the windings to get them exactly the same, to the uH, about 250 uH.
  L3 is the real secret of this set. After trying several different core forms for this, the best seemed to be a ¼ inch hardwood dowel about 2 inches long. Wind 2 strands of the 30 GA wire onto the form together, side by side, close wound for somewhere between 20 and 31 turns and secure. Take the left end of strand A and the right end of strand B and join them together for the bypass to the grounded capacitor. The remaining free ends go to the points indicated on the circuit.
  I am told you can get the actual flyer from the Miller Company.
  This circuit and the construction details are published in the Newsletter of the Xtal Set Society in a 2 part article starting in Jan 2002. You can see the construction details and alignment instructions there.
  Back to Scott\'s Crystal Radios

  ...'>Heathkit Cr 1 Crystal Radio Manual(07.05.2020)

• Post subject: Heathkit CR-1. Posted: Sep Tue 18, 2007 3:50 am. Member: Joined: Jan Thu 01, 1970 1:00 am Posts: 802 Location: Walden, NY USA I received this little crystal radio in a box of stuff at a garage sale. It is in great condition, and all the parts seem to be there and wired correctly. I connected it to my long wire, used a good ground. This reproduction kit is based on the classic Heathkit CR-1 crystal radio, built by many people. Kit features a High Quality, glossy black fiberglass face plate, with silk screen printing. Kit includes all components to build the radio, including two wide range variable polyvaricon capacitors, and high quality Hammond enclosure.

  DXing With The Heathkit CR-1 Crystal Radio

  
  If you’re a regular blog reader, you will likely recall my description of “The Enigmatic Heathkit CR-1 Crystal Radio” a few weeks ago.
  Back then I mentioned that I was ‘eager to get my mitts on one’ and that I had arranged to borrow a CR-1 from another VE7 who was fortunate enough to own one.
  A few weeks after posting the blog, I received an e-mail from Larry, WB5OFD, in Texas.
  \'Reading thru your blogs the other night .. discovered your article on Crystal Radio reception reports. I am in the process of disposing of a lot of radio gear I have collected over the past sixty years and in that pile is a Heathkit CR-1. Yours for free if you would like to have it.\'
  Needless to say I was overjoyed, both at the opportunity to actually own a CR-1 myself and at Larry\'s exceptional generosity!
  Larry went on to explain that he had been in the Air Force and his little CR-1 had been all around the world with him, from Alaska to Turkey .. but from its fine appearance, you would never know it.
  

  Larry\'s gift!

  
  He was happy to pass it on knowing that it was going to a good home. I am most appreciative of this kind gesture from a fellow radio amateur, knowing that these things are not too easy to find .. and are somewhat pricey!
  As can be seen in the schematic diagram above, the CR-1 is a simple double-tuned crystal receiver, utilizing a series-tuned tank circuit for antenna-tuning, coupled into the detector tank circuit. The detector diode, a 50’s-era 1N34, is tapped down on the tank for headphone impedance-matching and to reduce circuit loading. Reducing the load on the tank circuit improves selectivity but diminishes sensitivity. Crystal radio design is always a trade-off between these two critical characteristics.
  Although I had heard good things about the CR-1, I must admit that I was somewhat skeptical .. just how good could an unmodified CR-1’s simple double-tuned design really be? I was about to find out.
  My listening location, on the eastern shoreline of Mayne Island, puts me directly across several miles of saltwater from sixteen exceptionally loud \'blowtorch\' signals whose antennas are located near the water on the other side of Georgia Strait. Six of these stations run 50kW .. 24/7. All of these signals are wide and strong, being well-over S9. It is a difficult location for crystal radio DXing as separating weak DX signals from the blowtorches can be challenging.
  My previous experience with crystal radio DX is well-documented on my website here. Back then, I quickly adopted the standard protocols to help hear DX. This included the use if a separate ‘spotter’ radio to first find signals that might possibly be strong enough to be heard on the crystal detector. I also used an RF signal generator that let me temporarily put a weak tone-modulated carrier on the frequency of a station that I was trying to hear. Using the tone, the antenna tuning as well as the detector circuit can be optimized for maximum signal. I also used a 100 microamp meter in series with the headphones to make peaking these circuits accurately. The same protocol was used for my CR-1 DXing as well.
  Since there are so many very strong signals here, I have added two inline L-C traps on the antenna lead.
  
  My first trap was made from a ferrite bar loopstick inductor salvaged from an old transistor radio.
  The second trap is made with a ferrite toroid and Litz wire and produces deeper nulls than the ferrite bar. The bar will soon be replaced by a second toroid trap.
  
  The traps allow me to significantly null any strong signals that could be covering up a nearby weaker signal. For nulling, I set the signal generator on the frequency of the pest signal and then tune the trap for a null while watching the meter. Once everything has been tuned, I’ll often just sit and wait for the desired signal to fade up to a detectable level on the crystal radio and then confirm its audio match to what can be heard on the spotter radio. Very often, a signal initially too weak to be detected, will quickly pop up in signal strength to an easy-copy level for several minutes, before dropping below the threshold of diode detection level once again.
  I am presently using a pair of RCA WWII sound-powered (\'Big Cans\') phones, impedance matched to the CR-1’s output with a multi-tap audio transformer. I have also used a nice set of extremely sensitive Western Electric 509Ws, manufactured in the late 20s. These are also impedance-matched to the CR-1\'s output. On weak signal tone tests, I can see only a very tiny improvement with the RCAs versus the old 509Ws as both are very sensitive.
  There is a large variation in propagation quality on the broadcast band, especially this far north on the southern edge of the auroral zone. The difference from one night to the next can often be quite dramatic. On most nights the band favors the north-south path while on geomagnetically quieter nights it’s the east-west path that dominates. The band needs to be in good shape for any worthwhile hope of DX on a crystal radio.
  On one of the recent better nights, of which there have been very few of lately, one of the stations in Alberta was so strong that it needed trapping! This was something I saw quite often with my previous DX set but I didn\'t expect to see it with the CR-1.
  For crystal radio DX, propagation is the best helper. Small incremental improvements (in terms of db losses) can be made in any part of crystal radio\'s systems but on nights of good propagation, tens of db improvement will magically appear, thanks to Mother Nature!
  When in Turkey, Larry had the opportunity to connect the CR-1 to the large FLR-9 circular antenna array used during the cold war for HF direction-finding of targeted signals. Covering 1.5MHz to 30MHz, the FLR-9 consisted of ninety-six 120\' towers, suspending 1056 vertical elements .. all over a 1500\' diameter ground screen! His notes show that he logged the BBC, Italy and West Germany on the CR-1 while using the array!
  

  The FLR-9 array in Augsburg, Germany

  Although the antenna system connected to my CR-1 is not nearly as impressive as an FLR-9 array, it is very capable on the broadcast band. I’m using my 630m inverted-L, bypassing the tuning and 50-ohm impedance matching system, essentially feeding it as a top-loaded vertical wire. The (somewhat slanted) vertical wire is approximately 70’ which is then attached to a 3-wire 100’ long tophat. The antenna is very close to the ocean and parallel with the beach. The CR-1 ground system consists of about 60 buried radials, varying in length from 30-60’. The basic antenna is self-resonant at around 1200kHz.
  Over the past few weeks, I have been spending a few nights patrolling the band between 9:30 and 10:30PM, to see what might be heard with the CR-1. So far, I\'ve logged 50 different stations .. far more than I had expected to hear.
  The log below shows all of the stations heard. The stations in red are all local line-of-sight transmitters and are extremely strong .. all are well over S9 on my Sony spotter radio. The stations shown in blue are all ‘DX’, with the furthest so far being KOA in Denver, at 1100 miles.
  
  The log illustrates just how much the blowtorch signals prevent weak-signal detection, even with traps! The stations logged on 1510 and 1530 were only possible when the 1550 blowtorch lost their audio for about five minutes one evening! Selectivity becomes increasingly more difficult towards the top end of the band and, unfortunately, there is a larger concentration of strong locals (who seem to delight in over modulation and splatter), making reception up there extremely challenging.
  There are still some lower-band signals that I have yet to log and they have been gradually growing stronger as the nights get longer. As well, the region above 1600kHz may still provide a few opportunities over the next few weeks, if the loud local on 1600 can be sufficiently trapped .. the next few weeks will tell if there’s anything left in the CR-1’s tank!
  Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

  • Fascinating stuff, Steve. Thanks for taking the time to report this in so much detail.
    73,
    Colin

  • Hi,
    I have greatly enjoyed you articles on the Heathkit CR-1. I built mine in 1958 or 1959. I was either 11 or 12 years old. A neighbor had given me an old Echophone EC-1 receiver and a old Heathkit catalog. Well when I saw the CR-1 in the catalog I knew I had to get one. I had never done any type of kit building and certainly had never done and soldering! Well I got it together and began using it with a wire antenna stretched across my bedroom ceiling. I could barely believe that I was pulling in radio stations hundreds of miles away! When I spoke to my grandparents about this little wonder they regaled me with tales of using the old catswisker crystal sets back well before the Second World War. I even took it to school in 7th grade and used it as my science project….got a A+ with it! I still have mine in pristine condition. Thanks for the memories.

    Thanks again,

    Jim Smith K3RTU

    P.S. Been licensed since 1962

  • Thanks for the memories Steve. I built a CR-1, my first kit, in the late 50s or early 60s. I lived in an apartment so my antenna was not ideal. I only heard local stations. It was not selective enough to separate two local stations, one at 1280 and the other at 1340 Khz.

    Robert VA3AOD

  • Colin, Jim and Robert … thanks for your comments. If you had a CR-1 as a kid, you were hooked forever on the magic! Good stories.

  • Lovely story, Steve. A real inspiration for the rest of us! -Mike-

  • Hi Mike… appreciate your nice comments! BTW, would love to see the old Xtal Radio DX contest revitalized … we had so much fun back in the dynamic Yahoo group days👍👍

  • Heard about the rig when I was an SWL. Had not seen it. Looks great. I love Heathkit products
    I had an Heathkit HW101 when I just got my licence.
    Good old memories.

  Copyright © 1995-2019 AmateurRadio.com, All Rights Reserved.
  RSS Feed Sitemap DMCA Contact Privacy Policy / GDPR
  Each individual posting is the property of its respective author and the opinions expressed may not represent those of AmateurRadio.com including its editor, staff, or sponsors. Content may not be reproduced without written permission.

  Heathkit CR-1 Crystal Radio and
  Miller 595 Tuner Information

  This page gives the circuit and pictoral description of the famous Heathkit CR-1 crystal radio.
  It was a double tuned crystal radio from the 1950\'s with a series tuned primary that had a 365 pf variable capacitor and selectable additional capacitance on the center selector switch. In my opinion, it would have been more logical to have made the center switch for varying the inductance and using a tapped primary coil.
  Here is a picture of the inside of the original CR-1.
  

  
  Another photo showing the inside of the original Heathkit CR-1. Note the rectangular pinkish mica capacitors, the configuration of the central antenna switch, the \'cable knit\' appearance of the coil windings, and the long screws holding the panel to the threaded stubs that are recessed deep into the cabinet.
  

  Anyway the coils, marked as \'transformer\' in the diagram, were both wound on a ferrite rod and the secondary coil was part of a tank with the 365 cap and the germanium diode for the detector circuit. They do not give details of the coil construction but with a little experimentation you can get into the BC band tuning range.

  Here is the original circiut:
  

  This shows the pictoral diagram of the inside of the set:
  

  First Prototype
  In my first building project replica I used a toroidal core instead of a rod. An Amidon FT 114-61 was my choice for the core, and 45 turns of 24 GA enamel wire for the secondary gets the detector tank in the ballpark. (Amidon\'s webpage is http://www.amidoncorp.com). I used 30 turns of the same wire would on the same toroid for the primary with taps at 3, 6, 9 15, 24, and 32 turns. I used the center selector switch to vary the inductance of the primary instead of switching in additional capacitors.
  The little box is a Radio Shack part #270-1805 that is just about exactly the same size as the original enclosure. The front panel is made of aluminum, so it serves as a common ground, but the antenna and one of the headphone binding posts need to be insulated from it using little fiber washers to prevent those binding posts from making electrical contact with the panel.
  The radio was originally sold either with or along side a pair of 4000 ohm Trimm Acme headphones. They were only middle of the road for sensitivity and a good old pair of Brandes Superior or Western Electric 509-W\'s would be much more sensitive.
  Here is a shot of the main parts on the floor. The rotary switch, diode, and box are from Radio Shack. The variable caps were obtained from the Xtal Set Society. The coil is described above and I got the old mica capacitors from my junk box. I ended up using a different coil and no padder capacitors though.
  One challenge was to tap a couple of the holes on the front face of the variable caps to allow them to be mounted to the front panel using 6-32 screws. Care must be taken to avoid damaging the capacitor and to keep the metal shavings out of the ball bearing mechanism.

  
  OK, here is the completed CR-1 clone.
  This first attempt has the binding posts spaced a bit too close. I didn\'t have an original to copy, just pictures. I also tried a couple of different coil configurations and the one I settled on has 45 turns of 24 GA wire for the tuned secondary, and the primary is tapped as noted above.

  
  Inside it is pretty simple. Just the 2 variable caps, the rotary switch wired up to the toroidal coil, and the diode can be seen from the capacitor to the binding post on the far left.
  I hooked it up and counted 6 local stations in the first minute in the daytime, and with a good pair of headphones got 7 locals and another 4 out of state stations on the first night.

  TagsAttention: None of the mods and this Agar.io Unlimited Bots Hack published on our pages belong to our website. Due to the nature of the mods, they are developed by independent developers and published on the internet. We do not accept any responsibility for any possible unwanted conditions due to the use or download of these mods. As God Mods we compile the most popular mods on a single page for any io game. Users should download these at their own risks and we never store any part of these mods in our databases. How to get an agar.io private server with bots for mac pc.

  If I ever get a hold of an original, I will post a comparison of the performance.
  OK, I got a loan of the original Heathkit CR-1 and here is what I found.
  The original CR-1 has a much more definite double tuned effect than my spinoff. The 2 knobs for tuning the ANT and DET circuits seem to track pretty closely with each other and both need to be tuned to the same frequency farily sharply to get reception. It is easy to miss a station by not having the tuners coordinated. I found it best to move the DET dial a little then sweep the ANT knob back and forth a little to zero in on the station if there was one there.
  The circuit gurus emailed me and correctly predicted that my circuit would pretty much function as a single tuned circuit. The inductance tap switch mainly varied the selectivity and I found the 9 turn tap to be good for both sensitivity and selectivity. There was some noticeable tuning effect of the ANT variable cap at the high frequency end of the dial but the DET tuner did most of the tuning. It was, however, very sensitive and tuned very sharply anyway. In fact the volume was louder across the entire frequency range than the on the original CR-1, and I was able to get a couple of weaker stations that I couldn\'t reach on the real CR-1. So overall I am very happy with the performance but I will try another one to try and clone the coil and performance of the original a little more closely.

  Next Version
  After a lot of advice and many coils later, I think I got pretty close to the original performance. The secret is the coil. I am told the original has 2 small ferrite cores in it rather than 1 long one so, I experimented with different sizes of cores combined with different numbers of turns on the coil and then zeroed in on the correct spacing between the 2 cores. The spacing between the coils could be measured from outside but the stuff inside the cardboard tube was impossible to discover without damaging the coil. It looks like the core is about 1/4 inch diameter and extends just to the outer edges of the coil windings when you look into the ends of the tube. If anyone knows the exact original specifications please let me know. Anyway, I was able to pick up the same stations with this version as with the original.
  After many attempts and examination of an original coil and X-ray here is what I ended up with. I used 21/44 Litz wire for the windings. The antenna coil was about 140 turns with a 9/16 inch slug inside that part for about 335 uH inductance. The space between the coils was 10 mm or about 7/16 inch. The detector coil had about 90 turns with a 9/16 inch long slug inside that and measured 240 uH. On some of the coils, I tried bringing out a tap about 30 turns from the stator end of the winding for the detector tap. Hard to say if this made and noticeable difference, not much if any. This coil seemed to duplicate the performance of the original in both sensitivity and selectivity. Any closer spacing of the coils and you get too much coupling and the tuning gets very broad.

  

  
  Here is a front label that I made on some thin acetate plastic, printed the Heathkit logo on it, and glued on to the front of the aluminum panel. I sold a few of these clearly presented as home made clones, though I have occasionally seen my radios show up for sale on Ebay advertised as a genuine Heathkit, which should be obvious that they are not. Note the short flat Phillips head screws, the lettering which is clearly different than the original, and the coil inside is clearly hand wound as opposed to the tidy machine winding of the originals. Also note the round modern ceramic chip capacitors and the multiposition switch. If you run across one of my radios being passes off as an original, you can refer the seller to this page, but the radio itself, unless damaged, should work just as well as the real thing, and there were only a dozen or so ever made, so they are quite rare indeed!
  

  Addendum 5/29/01
  Unravelling the secrets of the CR-1 coil, or The CR-1 coil Exposed
  This is an actual X-ray of a Heathkit CR-1 coil. As you see, it has the 2 coils each with its own separate ferrite slug. The best I can measure, each slug is about 13 mm or about 1/2 inch long by 1/4 inch diameter. The separation between the slugs is 7/16 inch. It looks like the slug in the larger (antenna) coil is not quite centered under the coil. I am not sure if this was intentional or not. Anyway it was helpful to know how it was made so one might get a better idea of how to make a duplicate.
  The Amidon R61-025-400 core can be cut into the 1/2 inch lengths for use in constructing a coil like this one. I will post further information as I progress with this project. Thanks Mike!
  

  Software PowerMenu Plus Version 6.0 by Brown Bag Software (DOS Menu). PowerMenu Plus Version 6.0 by Brown Bag Software (DOS Menu) Thread starter Cobra; Start date Sep 9, 2013; C. Cobra Active. Our ancient grain blend of brown rice, quinoa and wheatberry, fresh spinach, and herbs with your choice of protein. A blend of sauteed brussels, broccoli, green beans, kale, fresh spinach, and herbs with your choice of protein. Greens & Grains. Half powerbox + half veggiebox with your choice of protein. Brown bag software power menu. Download PowerMenu 4.11 by Brown Bag Software. VETUSWARE.COM the biggest free abandonware downloads collection in the universe. You: guest DOS forever. MS-DOS books on Amazon.com! — Mailman 3 hosting — Super-long-term file storage — buy link here. PowerMenu 4.11. Category: Utility: Year.

  Link to Miller Tuner Page (sorry this linked site has been removed, but will try to relocate it) This is a link to a page with more information about another famous crystal radio, the Miller 565 / 595 Tuner. This was my next project. The modified schematic is shown below.
  Parts List:
  Part Description Source, Part#
  C1 2 gang 365 pf tuning capacitor from Xtal Set Society
  C2 0.1 uf capacitor Mouser 5989-250V.1
  C3 0.05 uf capacitor Mouser 5989-250V.047
  C4 200 pf capacitor Mouser 140-50P2-201K
  C5 10 pf capacitor Mouser 140-50N2-100J
  C6 15 pf capacitor Mouser 140-50N2-150J
  R1 100K ohm resistor Mouser 293-100K
  L1 Tuning coil 1 Core from Amidon FT 82-61, see text below for winding
  L2 Tuning coil 2 Core from Amidon FT 82-61, see text below for winding
  L3 Negative mutual coupling coil, see text below for construction
  L4 270 uH peaking coil Mouser 43LR274
  L5 (marked L in schematic) 2500 uH RF choke Mouser 542-70F253
  D1 1N34A Germaniun Diode
  Miscellaneous hardware:
  Perforated Circuit Board Radio Shack 276-1396A
  Solder Tabs Mouser 534-7312
  Machine Screws 6-32
  Washers size 6
  Tuning Knob or Dial
  Cabinet Radio Shack part #270-1807
  Wire for the coils and hookup
  Binding posts or Fahnstock clips

  The secret of this set is in the construction of the coils.
  L1 and L2 are straight ferrite rods wound with Litz wire. The best reproduction of this was to use an Amidon 2 inch by 1/4 inch diameter ferrite rod of material 61, and wind on 85 turns of Litz wire. I had some 21 strand by 44 GA wire and this worked well. I actually measured the inductance of the finished coils and adjusted the windings to get them exactly the same, to the uH, about 250 uH.
  L3 is the real secret of this set. After trying several different core forms for this, the best seemed to be a ¼ inch hardwood dowel about 2 inches long. Wind 2 strands of the 30 GA wire onto the form together, side by side, close wound for somewhere between 20 and 31 turns and secure. Take the left end of strand A and the right end of strand B and join them together for the bypass to the grounded capacitor. The remaining free ends go to the points indicated on the circuit.
  I am told you can get the actual flyer from the Miller Company.
  This circuit and the construction details are published in the Newsletter of the Xtal Set Society in a 2 part article starting in Jan 2002. You can see the construction details and alignment instructions there.
  Back to Scott\'s Crystal Radios

  ...'>Heathkit Cr 1 Crystal Radio Manual(07.05.2020)