Volume 21, Issue 4 The July 11th meeting is at Philip Miller Library in Castle Rock July/August

The Mineralogy and Construction Of Detectors Martin Guth

As a participant in the hobbies of col- and . hounding trip to New Mexico, visit- lecting antique radios and from ing the Blanchard mine about 35 around the world, I noted a crossover miles east of Socorro. Part of the point between the two in the form of The Minerals Hansonburg Mining District on the early radio detectors based upon various Beginning with early experiments in the north end of the White Sands Missile different minerals. Intrigued by this conductivity of minerals by Professor Range, the Blanchard mine is a concept, I began an investigation as to and his discovery treasure trove of minerals for collec- which minerals were used and how they of rectification in 1874, a number of tors. There are some 90 different function electrically as a . scientists began investigations into minerals in the area, some of which Since the electrical properties of detec- which minerals have properties suitable were commercially mined for a short tor diodes were discussed in David for this purpose. In 1902, Greenleaf period in the early 1900's. While Laude's article on the history of Whittier Pickard discovered that primarily interested in silver, the development, I won't get too deep into could be used as detectors in first miners encountered large the theory of how diodes work. The radio receivers and the race was on to amounts of quartz, barite and of par- focus here will be on the chemical char- determine which provided the best re- ticular interest here, . Since acteristics of two of the most common sults in this application. Many efforts this is a remote location without rail- detector minerals. Also, we will have a were focused on minerals suitable for road access, all attempts at profitable look at a process I developed to con- detectors, while others directed their galena mining as an ore of met struct a mounted galena detector crystal research towards higher current devices with financial disaster. With vast assembly similar to those used 100 for use as power supply rectifiers. In the amounts of galena in more readily years ago, and then will see how galena early 1900's, the list of minerals that accessible areas in Missouri and compares electrically with exhibited the property of rectification ran Oklahoma, it made little sense to up to over 250, most not practical for haul lead out of such a remote loca- radio applications. Some were not sensi- tion and the mines were left to the tive enough, others proved too costly or collectors. Inside this issue: rare for mass production while many were too unreliable for long term use. My first task was to evaluate galena Presidents Msg 2 Two of the most common minerals with and samples from my collec- all the desirable characteristics are ga- tion by placing each piece on a sheet 2010 CRC Auction/Picnic 2 lena (chemical formula PbS) and pyrite of aluminum foil connected to the (FeS), commonly known as "fool's radio with a clip lead, then probing Propose changes to show scoring 2 ". But not all pyrite and galena around the with a nickel- specimens are suitable for detector use plated needle also connected to the Crystal Detectors—cont. 3-7 as there are many factors that may en- radio, simulating a "catwhisker". hance or inhibit rectification. Since I After many hours of experimentation Schematic of Bill Harris’s Power 7 have a number of specimens of both, I it became obvious that galena from supply decided to test them all using a Philmore some locations worked better than Little Wonder set as a others, and some didn't work at all. Photos from March Meeting 8 gauge of relative performance. Fortunately, while I was in the Open Trunk 9 (Continued on page 3) In November 2009 I was on a rock- V i s i t t h e C R C W e b s i t e a t W W W . R A D I O A C E . C O M COLORADO RADIO COLLECTORS ANTIQUE RADIO CLUB Founded October 1988 The Flash! © 2010, all rights reserved

CRC CONTACTS Message from the President President Tom Kelly (303)504-0550 Greetings fellow club Our next main topic will Vice President Marty Phillips members! How is your be the upcoming club Treasurer Mike Cook (303) 471-9596 summer going? picnic and auc- [email protected] 2383 Indian Paintbrush Circle Anyone finding tion at Tectonic. Highlands Ranch, CO 80129 Archive and Books Charles Brett any rare radios Yes, its that time (719) 495-8660 [email protected] or other related of year again! Egroup Manager Mark Dittmar (303) 403-0669 items? Our auction and [email protected] Flash! Publisher Steve Touzalin picnic last year (303) 988-5394 [email protected] We are having a was a smashing Flash Graphic EditorRich Kuberski [email protected] talk and a DVD success. Looking Flash! Distribution Richard Beckman (303) 344-8565 video on plastic radio forward to this one, [email protected] Webmaster Bill Grimm Website www.radioace.com cabinet repair and refin- some real treasures ————————————————————————————————————————————————————————— Upcoming Events ishing. Marty Phillips, might turn up! 7/11—CRC Meeting our VP, will talk about 9/6—Labor Day 9/12—CRC Meeting his experiences on this See you all at the next 9/19—Annual Auction/Picnic ————————————————————————————————————————————————————————— subject. Should be very meeting in Castle Rock. Meeting Locations interesting. (Unless noted otherwise) Littleton Castle Rock Tom January March May July September November ————————————————————————————————————————————————————————— Changes to Show Scoring & Categories. CRC MEETINGS

By Rich Kuberski Meetings are held on the 2nd Sunday of every other month starting in Janu- The following recommendations are proposed. ary (except 3rd Sunday of May) at 1:00 pm. The meetings consist of 1. Create new MILITARY category. business, ―show & tell‖, raffles, auc- 2. Separate KIT and HOMEBREW into 2 categories. tions, swap meets, technical discus- 3. Break ACCESSORIES into two categories; ACCESSORIES and TEST sions and other subjects of interest

EQUIPMENT. ————————————————————————————————————————————————————————— 4. No changes to scoring. CRC MEMBERSHIP

Annual membership in the CRC runs from July to June. Dues entitle mem- bers to attend meetings, "The Flash!" 2010 CRC Auction and Picnic our newsletter, discount book prices, ————————————————————————————— participation in our spring show and The 2010 CRC Auction/Picnic will be September 19th. Same location as the Fall auction. Current annual dues are past few years—The grounds of Tectonic Management Group in Wheat Ridge. $12. New memberships will be pro- rated to the following June.

PAGE 2 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4 (Continued from page 1) samples in this data are a piece I col- Spanish pyrite indicated only a few Blanchard mine I ignored all the pretty lected in the Blanchard mine and one ohms, making it a good conductor not blue fluorites and instead searched from a detector I purchased online. As suitable in detector applications where a through the rubble for small galena it turns out, most of the Blanchard ga- is required. crystals and rocks with galena crystals lena makes for excellent detectors attached. I also have specimens from while the purchased detectors per- Missouri, Oklahoma, Peru, Bulgaria formed poorly. They do seem similar in and a few unknown locations and all chemical content with one notable ex- behaved differently. This discrepancy ception in the form of aluminum. The in performance may be attributed to Blanchard crystals generally have a differences in trace mineral content as significant amount of aluminum while well as the temperature and pressure the other from an unknown location conditions under which the crystals does not. Both silver and aluminum formed. Galena can form cubic, octa- impurities have been noted as affecting hedral or dodecahedral crystals de- the performance of galena detectors, pending on the environment in which although detailed data is lacking. they are created. In addition, during the millions of years after formation min- erals can be exposed to heat, acids and/ or oxidizing agents that can alter sur- face and internal chemistry. FIGURE 2: Comparison of two pyrite As I have access to an electron micro- samples via X-ray fluorescence. scope with X-ray fluorescence capabil- ity, some analysis was in order. Basi- It is interesting to note that pyrite speci- cally, a sample is exposed to a beam of mens from Spain form virtually perfect high energy X-rays of a certain wave- golden cubes, sometimes interlocked length. Atoms in the crystal structure together to form fine mineral specimens. will absorb these X-rays, causing elec- from Peru can be of multiple trons to jump to a higher energy orbit. different crystal shapes, most commonly This is an unstable state, and the elec- FIGURE 1: Comparison of two galena octahedrons but also including cubes. As tron quickly drops back to its previous samples via X-ray fluorescence. with galena, conditions at the time of level while emitting an X-ray photon formation plus trace impurities can of a specific wavelength related to that Another mineral commonly used for strongly alter the characteristic shape of particular atom. This photon may also crystal detectors is pyrite. Again, I have the crystals as well as electrical charac- knock other electrons within the atom specimens from multiple locations and teristics. into a temporarily higher energy state, have tested them all with about the leading to the fact that many atoms same result as the galena trials. Pyrite have multiple spectral lines showing from Peru and Colorado seems to work up in the X-ray fluorescence that re- nicely, while specimens from Ohio and sults. One limitation of this process is Spain are completely useless. Figure 2 that different atoms may emit X-rays shows a significant difference between of nearly the same wavelength, making Peruvian pyrite that works well and a it difficult to determine what is what. Spanish one that does not. The Peru- Many times one of the secondary lines vian specimen contains more iron, sili- is used to verify the result. con and a trace of magnesium while the Spanish material contains more alumi- Figure 1 shows the spectral signature num. Any or all of these may affect of two different galena samples. The electrical performance in use as a recti- plots show emitted X-ray energy on fier. I thought a measure of surface the X-axis, with relative abundance on resistance might be interesting, so I the Y-axis. Here we have both lead placed ohmmeter probes about a quar- Having re-created some of the experi- (Pb) and (S) running off scale as ter of an inch apart on pyrites from ments done by the early pioneers of de- I had the gain turned up to show the Peru and Spain. Peruvian pyrite typi- tector technology, it became obvious that trace elements. Note that Pb and S cally produced a resistance from thou- empirical testing of any mineral should pretty much overlap, although they are sands to tens of thousands of ohms be done prior to use as a crystal detector. distinct at lower gain settings. The two whereas the same measurement on Most of the galena I gathered from the

PAGE 3 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4 quantity for process development, I shape, so before making a more com- turned my kitchen into a galena detec- plex mold I tried this first. However, tor fabrication facility. even with a significant taper to the sides of the cavity the surface rough- The next step was to create a mold that ness of the cavity walls makes removal would allow the to fill a cavity very difficult. I tried silicone grease as of the desired size. Most detector a mold release agent, but that was no mounts will accept a mounted galena help at all. In the end, I cut out a small crystal that's just under a half inch in piece of aluminum foil to cover the diameter. Height is not very critical, bottom of the cavity to prevent the Blanchard mine was from 400 feet in, but for one radio I have it needed to be solder from running out (which it will). but the tunnels go on for miles and roughly 1/4" to 3/8" inch high so that Then, I cut a strip of foil several inches perhaps in the murky depths of the defined the shape of the mold. I have a long and rolled it tightly around a 3/8" mine there may be crystals that behave friend with a machine shop, and we drill bit shank. When removed from differently. For example, some of the made up a mold out of an aluminum the drill bit, it expanded to nicely fit pieces I obtained near the mine en- cylinder as shown in Figure 3. the cavity, thus lining the wall with trance did not perform as well, possi- several layers of soft foil that I thought bly due to surface oxidation due to should make removal much easier. exposure to varying atmospheric con- ditions not found deeper in the mine To heat the aluminum block, I placed it on an electric stove heating element using a surface temperature probe to Constructing A Galena De- measure the temperature at the top of tector For Use In Antique the mold near the cavity. The intent is Crystal Radios to keep it under about 100C to avoid excessive oxidation of the solder and Having purchased several dud galena damage to the galena. Figure 4 shows detectors via the internet I decided to the mold on the stove with the alumi- attempt to make my own replicas of num foil wall covering and a molten those found in the old crystal sets. The blob of Wood's metal contained. Philmore Little Wonder radio I ob- tained had an original detector from the late 1930's I could use as a model, FIGURE 3: Aluminum mold for galena so I investigated what it would take to detector solder. build my own using galena I collected myself. Since the electrical properties Using a flat end mill, we created a of galena may be affected by high pocket 3/8" deep and 7/16" in diameter temperatures, I wanted to use the sol- with a smaller hole in the bottom to der originally used called Wood's accommodate a drill bit used to shove metal to hold the crystal. This material out the completed assembly from the melts at 70C vs. 190C for conven- back side after the solder hardens. The tional tin/lead . Unfortunately, good news is that like most solders, it consists of bismuth, lead, cadmium Wood's metal does not adhere to alu- and tin with the cadmium and lead minum very well. The bad news is that being out of favor by the EPA. There it is one of the few substances that ex- is an alternative called Field's metal pand upon cooling. Therefore, using sold by the inventor, but a foot long the mold as shown would result in a FIGURE 4: Aluminum mold with mol- wire 1/8" in diameter is about $45 as it detector stuck in the mold. This was ten solder. contains indium, an expensive metal in verified by my first attempt, so modifi- high demand for use in large screen cations had to be made. One could Because of the thermal mass of the TV's among other applications. I was make this out of two pieces that bolt aluminum this takes a while to cool successful in obtaining nearly half a together and can be taken apart for down, so I used a small parts holder pound of Wood's metal pellets for $2 easy removal, and my Philmore detec- with an alligator clip as the alignment on Ebay, but had to pay $15 in ship- tor has marks on the solder indicating tool to hold the galena in place. At first ping charges from Skytyvkar, Russia, that is how they were made. Another I used some hot glue to attach the ga- some 600 miles northeast of Moscow. solution is to use a dremel bit to de- lena crystal to the end of a toothpick Having thus obtained a sufficient form the hole into a more conical that would be held by the parts holder.

PAGE 4 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4 (Continued from page 4) size for any detector cup I've seen to Although a lead ore, the density of date and a crystal that tested good be- galena is far below that of Wood's fore mounting tests good afterwards. In metal and the crystal will float like a this case, this is by far the most sensi- cork without somehow being re- tive galena detector I have ever seen, strained. This actually did work after a easily beating out my Philmore detec- fashion, but even at 70C the glue gets tor and any germanium diodes I have soft enough to let go. Also, there are tried. Also, virtually the entire surface no solvents that dissolve the glue as it's is a hot spot, with one local station actually a plastic, so this effort was coming in loud enough it could stand a abandoned. I next tried attaching the volume control. But, we're not done galena to the toothpick using water yet. soluble Elmer's glue. This worked bet- ter and I could get crystals to hold still In testing galena for performance in while the solder hardens. FIGURE 5: Placing the galena crystal crystal radios, I tried to modify crystals into molten solder. of marginal sensitivity. Galena crystals Even at this low temperature there is are easy to shear apart along a crystal some surface oxidation of the Wood's After the solder cools and hardens, you fracture plane, and larger pieces may metal, so I tested five different fluxes. can let go of the tweezers and allow it be cut down to size using a sharp razor There is a special flux designed for this to cool to room temperature. At this blade and a small hammer. This can called Baker's fluid #3, but this is nasty point you are ready to poke through the expose a fresh crystal face that's never stuff to handle and contains materials back side hole and see if the detector seen daylight or air before. I have that attack the galena. Rosin flux, will come out. Usually, it breaks loose found that freshly fractured faces like plumbers flux of two types and Kester inside but still won't quite make it out this can be very good as is the case of liquid flux all contain ingredients that of the hole. Positioning the soldered the detector in Figure 6. On low per- render a good crystal useless. And No- part at a spot where it's loose inside, I formance crystals I have tried sand- korode flux corrodes. carefully peel out the strip of foil sur- blasting, chiseling chunks off and even rounding it. This now creates a gap sandpaper all to no avail. I even tried I spent several days making bad detec- between the cavity wall and detector all of these processes on tested good tors, but the solder can be re-used that is now easy to push out. The fin- crystals, the result being a dead detec- many times and very little of the origi- ished detector in the mold in Figure 5 tor. A clean break along a fracture line nal supply was consumed. Nothing is shown in Figure 6. yields the best result, and I intention- appeared to be working so I tried one ally mounted a crystal with a 1/8" last process: get rid of the flux , the chunk sticking up above the solder. I adhesives and the part holder. I heated was able to shear this off and it works the mold enough to just melt the sol- very well even though it was marginal der, and before any significant oxide before I removed part of the crystal. scum formed on the surface I removed the mold from the burner and placed it on the stove top to allow it to cool. I didn't want it to cool down so fast that I didn't have time to place the crystal, hence the mold is larger than it appears necessary just for the extra thermal mass. Once removed from the burner I used a fine pair of tweezers to hold the crystal in place as shown in Figure 5. The solder will actually wet the galena when pushed through the oxide film, FIGURE 6: Completed galena detector providing good electrical and mechani- assembly. cal adhesion. By keeping the temperature to a mini- mum and acting quickly to place the FIGURE 7: Completed galena detector galena, the result is a mounted crystal assembly in a Pandora crystal radio. that has not been overheated or ex- posed to chemicals that ruin it's electri- cal behavior. It comes out just the right

PAGE 5 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4 (Continued from page 5) Electrical Characteristics of Galena vs. Germainium and Silicon Diodes

Part of the experiment was to sample various diode types in use as a detec- tor, with relative performance being judged by earphone volume. A number of small signal silicon and germanium diodes were tested, as well as large silicon rectifiers and Schottky diodes. The results were not always predict- FIGURE 8: I-V Curves of Galena and able as some of the large power diodes Small Signal Germanium and Silicon worked fairly well while certain small Diodes. Credits: signal ones did not. There is even a "The Use of Minerals As Radio Detec- large degree of variability between voltage before electrical conduction tors" from The American Minerologist, diodes from the same lot, so trial and begins, in this case about 400 to 500 August 1922 error is the rule. The bottom line is that mV. The germanium diode is better in general of all the packaged diodes with significant conductivity in the 100 "Radio-Detector Minerals" from The tested, the germanium types are supe- to 200 mV range. The galena diode, American Minerologist, August 1925 rior. However, some germanium di- while not a particularly good , odes were not as good as some silicon does have the performance where it "Pre-1900 Semiconductor Research diodes, and neither perform as well as counts in a detector. With virtually no and Applica- a galena diode from the Blanchard measurable threshold voltage, the tiny tions" by Asif Islam Khan, mine. To verify this via electrical signals from an aerial alone are suffi- Bangladesh University of Engineering measurement, I rigged up a scope as a cient to be rectified. Even though it is and Technology curve tracer and compared I-V curves barely a diode as measured here, ga- for the three diode types, the result lena can outperform silicon and germa- "Crystal and Solid Contact Detectors" being shown in Figure 8. nium as a detector in crystal radios. In by Alan E. Flowers, June 1909 other words, a needle on a rock makes Of the diodes tested, it is obvious that a a fine diode in this application. "Crystal Clear" Volumes 1 and 2 by silicon diode has the highest threshold Maurice L. Sievers

PAGE 6 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4 This is the schematic of the power supply that Bill Harris demonstrated at the May meeting.

PAGE 7 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4 Photos from May 16th Meeting at the Phillip Miller Library in Castle Rock

Bill Dial with his 1925 Lyric Bill Harris with his modified Radio found on dBay computer supply

Mark McKeown with his replica cw Don Andrus with his 1918 Frequency meter

Tom Pouliot with his replica Bakelite panel Tom Kelly with raffle tickets

PAGE 8 JULY/AUGUST 2010—THE FLASH VOLUME 21, ISSUE 4

The Open Trunk Member submitted advertisements

WANTED: Buy/Sell/Trade: "Heavy 8) Precision Apparatus Co ( PACO) WANTED: An AK 82, 90 or 92 chas- Metal" communications gear, telegraph Model E-400 Sweep and AM, FM, and sis / speaker for an empty cabinet I related items, vintage calculators & TV Signal Generator. Refurbished, have. Contact Mike Cook. microphones. New test , [email protected] Robert Baumann, (303) 988-2089 With Manual $90 01/10 [email protected]. (07/09) ————–——————————— ———————————–——–—– 9) Power Supply; "Power One" model WANTED: Knobs from the 20's and REPAIR SERVICE: CP418A, 24vdc at 7amps and 5vdc at 7 30's made in one piece (Black bake- Radio repairs for club members. Rea- amps. commercial quality, VG $55. lite?) with a 0-100 scale commonly sonable rates. Good references. 10) 2—Zenith TransOceanics used on homebrew equipment. Call David Boyle # H500, Both completely refurbished 303-681-3258 11/09 inside and out. Repaired as needed and Mark McKeown 303-278-3908 —————————–———–——– aligned. Both work great. [email protected] 5/10 For Sale: by Dave Boyle $95.00 OBO ea ————————-———————- All of the following Older "Classic" Call - radio and TV repair instruments have David Boyle, 303-681-3258 3/10 FOR SALE: Tube tester, Hickok been thoroughly refurbished, repaired ——————————–—–————– model 533A w/supplements for Euro- as needed, and most calibrated as ap- WANTED: Old microphones (not CB or pean types propriate. Please Note: Don't be shy ham), working or not. Electrical condition - very good, the about negotiating on the prices, offers Also, NBC chimes in good condition. unit is fully functional welcome! Tom Keeton 303-797-8073 Cosmetic condition - fair, some of the 11/09 fabric covering is torn 1) Heathkit IG-52, TV Alignment —–————–————–—————— I'll deliver the unit to Castle Rock. Generator, with manual and new test FOR SALE: At a most reasonable Price is $125. Pete Rawson leads. Like new. $85. price: Tektronix o'scope model 7704 719 687 7144 5/10 2) Heathkit O-12, 5" , (works) with cart, manuals, probes. Freq. ———————————————-- built by seller. VG $60. resp. is 150 mhz 3) Bench variable AC power supply Call Barney Wooters for powering up and for repair of old 303 770-5314 11/09 radios, as shown at the January Club ————————–-———————– meeting. With full meters and controls, newly built. $70.00 4) HP 3200B VHF Oscillator, 10 MHz. to 500 MHz. Laboratory grade. Solid state, Free manual on Internet. SUBMISSION OF ARTICLES VG. $225. AND ADVERTISEMENTS 5) HP 608E/F VHF Oscillator, Tube Type, Top of the line and sought after Classified Ads for The Open Trunk and articles of any radio/electronic or histori- these days, Complete with spare new cal related subject to be published in the Flash are encouraged and welcomed. The ( special ) tubes and manual. Comes article(s) should be submitted in Microsoft Word, RTF, or as text cut/paste into with optional ( free ) 'scope cart---a your email to Steve Touzalin, either by email at [email protected] , or by perfect match. VG. $145. postal mail to 417 So. Queen Circle, Lakewood CO 80226 . ——————————————————————————————————————————————————————————————————————————————————– 6) Superior Tube Tester, Model TD- - 55, small portable in carrying case with Formatting is not necessary, but if you do, set the font to Times New Roman, size all literature. Like New $35. 10, left justified. If you have graphics (.jpg files) to be inserted, please name them 7) RCA Model WA-44C, Audio G, and be specific about how you would like them placed. We will do our best based Generator, Sine and Square Wave. on space limitations. VG. $38.

VOLUME 21, ISSUE 4 JULY/AUGUST 2010—THE FLASH PAGE 9 The July 11th, 1:00 pm meeting will be at the Philip Miller Public Library in Castle Rock

Directions

From I-25: Take the Plum Creek Parkway, exit #181 Turn East onto Plum Creek Parkway. Turn Left (North) onto S. Wilcox Street and continue north 2 tenths of a mile. The Philip S. Miller Library is on the east side of the street at 100 S. Wilcox St. The building is towards the back of the parking lot, past the Dairy Queen.

Colorado Radio Collectors Antique Radio Club 417 S. Queen Cir. Lakewood CO 80226

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