DOCSLIB.ORG

Alignment of AM Superheterodyne Radios

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Alignment of AM Superheterodyne Radios Volume 27, Issue 5 Sept/October 2016 Alignment of AM superheterodyne radios By CRC Member—Gregory Malanowski When you acquire a vintage superheterodyne radio, its type, there is a possibility that the chassis could be dan- resonant circuits are almost always out of alignment and gerously at or close to the power line potential. There- they badly need your intervention. This could be caused fore, install small capacitors, 1000pF/630V in series by several factors, usually a combination of a few of with the signal and the ground wires from the generator. them. The most common is a result of past attempts to restore the sensitivity of the radio, which had usually The first necessary step is tuning the intermediate fre- been a crime committed by quency (If) filters to the the former owner or by factory-recommended fre- some unprofessional repair quency of your receiver. man, who had mindlessly Use a non-ferrite tuning turned back and forth all tool, whether it is a screw- accessible trimming con- driver or a hex socket densers and ferrite cores wrench. inside the coils. This is the most challenging situation, Some manufacturers sug- for the delicate ferrite gest connecting the signal cores had been often se- generator wire to the anode cured using a hard lacquer, of the mixer tube. That is and could have cracked as usually neither safe nor a result of careless em- easy. You can achieve the ploying a metal screwdriv- same results by applying er. Also, the antique trim- the If signal to the antenna ming condensers, with a input while the radio is mica dielectric or a layer of silver evaporated over deli- tuned to the lowest end of the broadcast frequency cate ceramic plates, sometimes break easily. range. But that will require a much stronger signal from the generator! Then, align the If filters for a maximum The less dangerous "natural" cause of misalignment output level while going backward, i.e. beginning with could be a gradual change in the dielectric constant of the last (detector) filter, and ending with the mixer tube capacitors or decrease in the inductivity of the ferrite- filter. core resonant coils. The former cause is more common, though. Be careful: sometimes you may find that alignment of an old If filter beyond the extreme position of the filter So, if you decide to align your receiver, attach an AC ferrite core, or its trimming cap, could result in a higher meter in parallel to the speaker. You may need to sepa- output level of the signal. However, never attempt to rate it from the DC potential using a 0.1uF capacitor. Do change the factory-recommended intermediate frequen- not use your ear to assess the signal level; the human ear cy to achieve a better output signal. We will discuss the cannot reliably detect variations in the sound level be- implication later. Instead, disassemble and repair the low 3dB. Then, connect the RF output of your 400Hz troublesome If filter (cracked ferrite, defective capaci- amplitude modulated signal generator with the antenna tor?). jack of the receiver via a 300-ohm resistor. Warning: if your superheterodyne radio is a "universal" AC/DC (Continued on page 3) COLORADO RADIO COLLECTORS ANTIQUE RADIO CLUB Founded October 1988 The Flash! © 2016, all rights reserved Message from the President Here we are in the heat of August, BBQ/Auction at the upcoming meet- when a lot of us go on vacation or ing. It will be at the same place as al- travel around a bit more and maybe ways. Thanks to Rich. We now have a find a radio for sale out there at a gar- new Auctioneer-in –training, Cliff age or estate sale. If you haven’t found Shelby, to help out Tom this year. Al- any “new” things for your collection, so at the last meeting Merril said he CRC CONTACTS you will soon have the opportunity to would be able to help Tom and Cliff President Tom Zaczek find them at the upcoming Barbeque/ with this. Thanks guys! Wayne will 303-665-3743 Auction in September. So August is help out to get all the supplies as Dave zacfam at comcast.net Vice President Wayne Russert always a good time of the year to go won’t be at the auction this year. Don 303-660-3799 through that collection of Andrus will get the Deartrail at wans.net radios and see what you drinks as usual. Remem- Treasurer Merrill Campbell 719-596-3482 want to bring to the auc- ber that YOU need to Campbell321 at juno.com tion. bring a dessert or side Egroup Manager Mike McCutcheon (303) 343-2956 dish item. And Alexis ugea07 at denvercommons.net We had a great turnout for and Larry will be sup- Egroup message posting address: colradcol at yahoogroups.com the last meeting in July, porting the auction data Flash! Publisher Steve Touzalin with lots of good show base and software as (303) 988-5394 and tells and preliminary usual. So to help out Stevetou at comcast.net Flash Graphic Editor Rich Kuberski discussion about our up- please email your lot ROKuberski at msn.com coming Barbeque/Auction items info to Alexis Webmaster Bill Grimm th Website www.radioace.com on September 18 . We ahead of time. There is NOTE: at = @ in email addresses ————————————————————————————————————————————————————————— also had a new member more info in this issue Upcoming Events Mike Knospe show up in with all the details. 8/15 1969—Woodstock Opens his Model T (did not have a radio in Thanks to all that help make this a 8/24 79AD—Mt. Vesuvius erupts it) and join the club. special event! 8/28 CRC Meeting in Castle Rock 9/1 1939—Hitler invades Poland The raffle was fairly decent with lots And last but not least, we have a new 9//5 Labor Day of unique items there and as a result Flash Editor! At the meeting Alan 9/11 2001—Attack on America we filled the treasury a bit. Even Burch stepped up and said he will take 9/22 Fall Begins 9/25 1789—Bill of rights Passes though we have an auction coming up, over from Rich. Special thanks to him 9/28 CRC Annual Auction —————————————————————————————————————————————————————— you can still bring that weird stuff to for volunteering. This is great! And the next meeting’s raffle that is not so thanks to Rich for the many years of Meeting Locations “auction worthy”. Keep it coming. It excellent work in putting together the (Unless noted otherwise) Littleton Castle Rock helps the coffers! Flash. March January July May The show and tells were very impres- And as far as Flash articles, we have a November September ————————————————————————————————————————————————————————— sive as you can see from the photo few but will need some more. So think CRC MEETINGS spread in this issue. Thanks to all who about an article or even just a small Meetings are held on the 2nd Sunday of participated. Merril showed some of “restorer’s tip” with a photo! every other month starting in January his typically amazing restorations that (except May is 3rd Sunday) at 1:00 pm. included a Bakelite radio that looked Please note that our next meeting The meetings consist of business, “show & like new and a plastic one whose hing- that we normally have the week af- tell”, raffles, auctions, swap meets, tech- es he had cleverly repaired. Tom ter Labor Day weekend is now on nical discussions and other subjects of in- th terest Pouliot shared with us some more of August 28 . We are doing this to ————————————————————————————————————————————————————————— CRC MEMBERSHIP his museum-quality constructions of avoid the art show conflict at the early spark-gap transmitters. Not one Castle Rock Library. I look forward Annual membership in the CRC runs from but two complete functioning units in to seeing you all at the August 28th, July to June. Dues entitle members to at- different bands that he has used to 2016 meeting in Castle Rock! tend meetings, "The Flash!" our newsletter, discount book prices, participation in our make actual amateur contacts with. spring show and Fall auction. Current an- Quite impressive! nual dues are $20. New memberships will Tom Zaczek be prorated to the following June. We will finalize the planning for the 2 (Continued from page 1) pacitor changes its capacitance over An often-overlooked problem is a minute time, or when the If filters have been change in the capacitance of the so-called tuned to an incorrect intermediate fre- padding capacitor. When two identical, quency. single-shaft tuning condensers are in- stalled in the superheterodyne radio, one To align a superheterodyne radio in for the antenna circuits and the other for which a constant value padding capaci- the local oscillator, it is theoretically and tor is used, align the If filters first and practically impossible to maintain a con- then tune the dial to the recommended stant difference in their resonant frequen- higher crossover frequency B (usually cies (equal the intermediate frequency If) around 1400kHz). Apply the signal over the entire AM broadcast or shortwave from your generator. Adjust the oscil- band. That results in a drastic reduction in lator shunt trimmer for a maximum sensitivity at a certain position of the tun- reading on your AC voltmeter. Repeat ing dial, and you are certainly familiar that at the low crossover frequency A with this effect. The manufacturers allevi- (usually around 600kHz) by adjusting ate that inconvenience by using the tuning the ferrite core of the oscillator coil. condensers of a different profile, or by a Then, return to the higher crossover less-expensive, common method of in- frequency.
Load more

Recommended publications
  • Antique Radio Classified
    ANTIQUE RADIO CLASSIFIED VOLUME 3 AUGUST 19E6 NUMBER 8 • QUAKER OATS CRYSTAL SET From the collection of Randall Renne - Dixon, IL THE NATIONAL PUBLICATION FOR BUYERS AND SELLERS OF OLD RADIOS AND RELATED ITEMS - PUBLISHED MONTHLY ANTIQUE RADIO CLASSIFIED Publishing Details Classified Ads Each subscriber is entitled to one 20 word classified ad Antique Radio Classified lUSPS 735-0901 is free of charge per issue. Additional words over the limit published monthly. 12 times yearly. at a suoscrip- are 10C per word. Multiple insertions of same ad are tion rate of $18.00 per year Second Class and discouraged. This is to allow for a varied ad content in each issue. Multiple insertion ads for more than $24.00 First Class mailing rates, by G.B.S. Enter- 2 issues must be run as a display ad. All ads must be prises, 9511 Sunrise Blvd.. 8.1-23. Cleveland, Ohio printed neatly and be received by the 8th of the month 44133. (216) 582-3094. before next issue. See classified ad details elsewhere Second-class postage paid at Cleveland, OH. in this issue. Publisher and Editor Gary B. Schneider. POSTMASTER: Send address changes to address Payment above. Copyright 1986... Antique Radio Classified All ads must be paid for in advance. Make checks payable to Antique Radio Classified. Purpose Antique Radio Classified is published for people in- Subscription Rate volved in the radio collecting hobby. Its purpose is to Subscriptions are available on a yearly basis. $18.00 stimulate growth of the hobby thru the buying, selling. per year Second Class and $24.00 First Class mailing and trading of radios and related items.
    [Show full text]
  • National Register of Historic Places Registration Form
    _______________________ _____________________________________ En’, IWJI ‘III ‘" 11fl4-XIIH Il,. S-ki United States Department of the Interior NatiQnai Park Service National Register of Historic Places Registration Form 1. Name of Property Instorir name Massje Wireless Station other n;uneAsite number ‘ ‘ Pt]-’ 2. bntion street & nuinber 1300 Frenchtown Road not for publication: citxtown: East Greenwich viciuit N/A state: RI toil ntv Ken Msle: 0 0 3 ZIp isle: 02 8 1 8 3. Classificafion Ownership of Pms’rty: Private Tategorv of Piopertv: Building Nu mnber of flesoiLrtes with] ii Property: - Ton t riInit ii ig No ii 0 nt rihuli ng htHldilgs sites structures objects 1 p Total Number of toiitnhimting res4imrees previously listed in time National Ihgister Name ol related immumltiple property listiuig N/A ___________________________________________________________________ ______________ _______________________________________________________________________________________________________________________ _________________________ USDIiNPS Yil[fl Registration Form Page 2 Property name Nassie Wireless Station, Kent Cty. , East Greenwich, RI 4. StatelFederal Agency Certification As the tlt’signated authority under time National ii istonc Preservation Act of 1986, as amnendeil, I hereby certify that this_x_ nonminatiomi request for tleternii nat ion of eligibility meets the documnemitation standards for registermg pmoiwiies in the Nationi I Register of ii istoric Places and meets the procedural amid professional requ irenien ts set forth in 36 CFI1 Pa.rt. 60. In mmiv opi mm ion, tIme property J nieets does not meet the National Register Cr term. - See continuation sheet. 1. ‘ Gc Signature of certifying official Date State or Feil era I agency a mid himmriLil En umy op i iii u m, the i11 pe rtv meets ltfl’s mot uieet tIme Nat immII legister t-ri te ii a.
    [Show full text]
  • Short Wave Radio
    Short Wave Radio A Working Electronic Sculpture Honoring the History of Radio Please note: This radio picks up short wave stations, but for your best satisfaction it will require a little time and attention, both to learn how to operate it and to appreciate the principles and history that it embodies. You’ll find bare-bones instructions on this page and more details inside the notebook. To turn the radio on, rotate the volume control clockwise until you hear a click, then set its dial to 3 or 4. If the radio was not already turned on, you’ll have to wait about 30 seconds for its vacuum tubes to warm up. •Put on the headphones. •Set the radio’s other controls as follows: •RF Gain: Fully clockwise. •Preselector: 1 •Tuning: 20 •Fine Tuning: 5.0 (This works like a clock, only with ten “hours” instead of 12) •Regeneration: 7 (Or advance slowly clockwise from zero until just after the point you hear a louder hiss in the headphones.) •Volume: Set to a comfortable level, usually about 4. Now, slowly adjust the TUNING control back and forth looking for squeals that indicate signals. (The shortwave broadcast band with 31 meter wavelength is located between about 10 and 30 on the dial.) You’ll should find a few unless ionospheric conditions are particularly poor on this day. Leave the TUNING control set on a loud squeal. Then slowly adjust the FINE TUNING to “zero beat.” (You’ll notice as you move the dial across a signal, it starts with a high-pitched note, moving down to a low-pitched or zero note, then back up to high pitch again.
    [Show full text]
  • Antique Radio Charlotte an Annual Conference for Antique and Vintage Radio Collectors and Historians
    Antique Radio Charlotte An annual conference for antique and vintage radio collectors and historians. 3rd Bi-annual Charlotte International Cryptologic Symposium Thursday, Friday & Saturday March 24-25-26, 2016 Sponsored by the Carolinas Chapter of the Antique Wireless Association Meet Results CAROLINAS CHAPTER OF THE AWA http://www.cc-awa.org/ PRESIDENT SECRETARY-TREASURER Ron Lawrence Clare Owens P O Box 3015 101 Grassy Ridge Ct. Matthews, NC 28106 Apex NC 27502 704-289-1166 919-363-7608 [email protected] [email protected] VICE PRESIDENT Richard Owens EXECUTIVE COMMITTEE R L Barnett Stephen Brown Kirk Cline Barker Edwards Robert Lozier Chip McFalls EDITORS Barker & Judy Edwards 116 East Front Street Clayton NC 27520 919 553-2330 [email protected] Membership in the Carolinas Chapter of the Antique Wireless Association (CC-AWA) is open to anyone with an interest in old (antique) radios. Anyone who pays registration for the 2016 conference will automatically receive one year’s membership in the Carolinas Chapter of the AWA. This is only chapter membership and does not include membership in the Antique Wireless Association. If you are already a paid member in the chapter, your membership will be extended one year. Any correspondence, including any newsletters that are published, will be distributed electronically. Please make sure that the CC-AWA has a current email address on file. Old Equipment Contest Pictured are the 1st place winners. To view all the winners, please visit our web page at: www.cc-awa.org. HM-Honorable mention No Entries CATEGORY 1 PRE-1912 ELECTRICAL DEVICES NON RADIO No Entries CATEGORY 2 PRE-1920 RECEIVERS & TRANSMITTERS AND WIRE LINE TELEGRAPH ITEMS CATEGORY 3 1920s ERA BROADCAST RECEIVERS A.
    [Show full text]
  • Construction and Operation of a Simple Homemade Radio Receiving Outfit
    Construction and Operation of a Simple Homemade Radio Receiving Outfit The 1922 Bureau of Standards publication, Construc- tion and Operation of a Simple Homemade Radio Receiving Outfit [1], is perhaps the best-known of a series of publications on radio intended for the general public at a time when the embryonic radio industry in the U.S. was undergoing exponential growth. While there were a number of earlier experiments with radio broadcasts to the general public, most histori- ans consider the late fall of 1920 to be the beginning of radio broadcasting for entertainment purposes. Pittsburgh, PA, station KDKA, owned by Westinghouse, received its license from the Department of Commerce just in time to broadcast the Harding-Cox presidential election returns. In today’s world where instant global communications are commonplace, it is difficult to appreciate the excitement that this event generated. Fig 1. The crystal radio described in Circular 120. News of the new development spread rapidly, and interest in radio soared. By the end of 1921, new broad- casting stations were springing up all over the country. Radios were selling faster than companies could manu- facture them. The demand for information on this new technology was almost insatiable. The Radio Section of the Bureau of Standards provided measurement know- how to the burgeoning radio industry as well as general information on the new technology to the public. Letters to the Bureau seeking information on radio technology began as a trickle, and then soon became a flood. Answering them became a burden. Circular 120, published in April 1922, began: “Frequent inquiries are received at the Bureau of Standards for information regarding the construction of a simple receiving set which any person can construct in the home from materials which can be easily secured.
    [Show full text]
  • Extended Call for Papers
    A Century of Broadcasting histelcon 2010 The Second Region 8 IEEE Conference on the History of Telecommunications Madrid, Spain 3-5 November 2010 http://www.aeit.es/histelcon2010/ EXTENDED CALL FOR PAPERS Theme and Topics Year 2010 marks a series of historical milestones in relation to the Birth of Broadcasting a hundred years ago. To commemorate this remarkable anniversary, we invite submissions related to this theme in order to be presented as a paper. Other papers describing significant research contributions to the field of History of Information and Communication Technologies are also welcome. The official language of the conference will be English. Topics of interests include, but are not limited to, the following: • Pioneers of Broadcasting, • The Birth of the Broadcasting Business, • Stellar Moments in the History of Broadcasting, • A Century of Radio Regulations, • Radio & TV Standards, • Broadcasting as a Political Instrument, • Development of Radio & TV Technology. Poster and Special Sessions Submissions to organize a poster session on antique radio and radio museums or other related subject are very welcome. In addition, we are also seeking proposals for special sessions. Some suggestions come next: IEEE Life-Members and History Activities, Ham (Amateur) Radio, Pirate Radio, Satellite & Cable Broadcasting, Internet TV & Radio, Broadcasting as Entertainment. With the Sponsored by: collaboration of: A Century of Broadcasting histelcon 2010 The Second Region 8 IEEE Conference on the History of Telecommunications Madrid, Spain 3-5 November 2010 http://www.aeit.es/histelcon2010/ Abstract Submission Interested participants are invited to submit their abstracts for oral or poster presentations to the Conference Secretariat by electronically sending a 500 words abstract, written in English, with a title, the name of the author(s) and affiliation(s) in MS Word format.
    [Show full text]
  • TO the ARCA GAZETTE This Index Covers the Antique Radio Club of America Antique Radio Gazette Through Its Final Edition, Vol
    INDEX TO THE ARCA GAZETTE This index covers the Antique Radio Club of America Antique Radio Gazette through its final edition, Vol. 22 No. 2. References to articles are listed in the form of volume-number-page. As an example, to locate information on the Victoreen superhet, a check under "Receivers - Broadcast - Tube" shows "14-3-21." Gazette Vol. 14, No. 3, Page 21 has this article. In the listings, an item of a full page or more is shown with an asterisk. Two asterisks indicate an article of three or more pages. An item cited in this index may vary in size from a passing mention to a major feature. Because even scraps of information may be useful, the citations go to fairly fine detail. Copyright (c) 1992, 1993, 1994, 2015, 2016 Ludwell A. Sibley CONTENTS 1980 Pix ......................................... **31-3-19 Activities Results ......................................*9-4-14 "Ghosts of Radio Past" show **21-4-19 ARCA - Annual Convention............ 1 1981 (Louisville) 1994 (Little Rock) ARCA - General ................................. 1 Results ..........................*9-2-2, *9-2-14 Announcement*21-4-16; insert w/ 22-1 ARCA - Local...................................... 2 Equipment Awards....................*9-2-12 Equipment Awards ............... **22-2-23 General Club News and Meets.......... 2 1982 (Lake Placid) ACTIVITIES - ARCA - GENERAL Collecting............................................ 2 Announcement.................. 9-3-2, 9-4-2 AWA, acquisition by................. **22-2-39 Collections - Personal ........................ 3 Results ..... *10-1-16, *10-2-1, *10-2-14 Awards: Public Museums................................. 3 Equipment Awards..................*10-2-17 Equipment Contests - Criteria 14-2-18, Author Index .......................................... 7 1983 (Charleston) *18-3-6, *20-4-31 Basic Electronics..................................
    [Show full text]
  • Journal Vol 23-1-1999
    • Miracles in Trust b y t h e P e r h a 1n F o u n d a t i o n RESTORATIO;-\ A:-.!D PRESERVATION OF EARLY RADIO C a f o r n a H s o r c a R a d 0 s 0 c e y CHRS Officers and Staff About CHRS Steve Kushman Dale Sanford AJan Voorhees 4233 25th St. I 07 St. Thomas Way 10809 Mcintyre St. The CaHfornia Historical Radio Society San Francisco. CA 94114 Tiburon, CA 94920 Oakland. CA 94605 (CHRS) is a nonprofit corporation chartered in (41 5) 821-7671 (415) 435-6131 (510) 562-3235 the State of California. CHRS was formed in [email protected] [email protected] [email protected] 1974 to promote the restoration and preserva­ PRESIDENT CHAIRMAN OF THE BOARD WEBSITE CHAIRMAN tion of early radio and broadcasting. Our goal MAIL PICK-UP/ HOTLI E MAILING CHAIRMAN is to provide the opportunity to exchange ideas Stephan Ponek and information on the history of radio, partic­ Lee Allder Mike Adams 945 Linda Mar Blvd. ularly in the West, with emphasis in collecting, Box 6785 112 Crescent Ct. Pacifica, CA 94044 literature, programs. and the restoration and San Rafael. CA 94903 Scotts Valley. CA 95066 (650) 355-1550 display of early equipment. (4 15) 499-9228 (408) 439-9544 BOARD MEMBER The Jou ma/ of the Society is published and VICE PRESIDENT/ [email protected] furnished free of charge to members. Yearly PUBLICITY EMAIL CHAIRMAN Stephen Sutley membership dues are $20 (U.S. funds). Box 1094 Submissions for the Joumal are always wel­ Russ Turner Larry Oark Pacifica, CA 94044 come.
    [Show full text]
  • The Carolina Antenna
    The Carolina Antenna SPRING 2009 VOLUME #15 ISSUE #1 Carolinas Chapter of the Antique Wireless Association CAROLINAS CHAPTER OF THE AWA http://www.cc-awa.org/ PRESIDENT SECRETARY-TREASURER Ron Lawrence Clare Owens P O Box 3015 101 Grassy Ridge Ct. Matthews, NC 28106 Apex NC 27502 704-289-1166 [email protected] 919-363-7608 [email protected] VICE PRESIDENT Richard Owens EXECUTIVE COMMITTEE R L Barnett Barker Edwards Kirk Cline Ernie Hite Robert Lozier Stephen Brown EDITORS Barker & Judy Edwards 116 East Front Street Clayton NC 27520 919 553-2330 [email protected] Membership in the Carolinas Chapter of the Antique Wireless Association (CC-AWA) is open to anyone with an interest in old (antique) radios. The only requirement is that you must be a member of the "national" Antique Wireless Association. By being a member of the CC-AWA you will receive our quarterly newsletter. Membership dues for the CC-AWA are $10 per year. If you are not already a member of the national AWA, your first year's dues will $25, this includes the $10 for CC-AWA dues and $15 for your first year's dues in the national AWA. Mail your dues to membership chairman Clare Owens - address is listed above. ISSUE # 15 SPRING 2009 VOLUME 1 THE PREZ SAYS ... club Board of Directors meeting. Kirk Cline was appointed to fill one of the open BoD seats. We still have one open seat on the Board, if you're interested in taking part in running the club, please let one of the current Board member know.
    [Show full text]
  • Vintage Radio
    Vintage Radio Special Pilot Issue September 1993 Electrical Safety For Restorers Those of us who cut our assign to it quietly and teeth as electronic without incident. experimenters during the Yet most of us are also heyday of the vacuum tube aware that, improperly learned how to work safely insulated and fused, the around high voltages and household power line can currents as we acquired our lash out with powerful and technical know-how. The dangerous sparks or (perhaps dangers were made known to even worse) quietly overheat us by our advisors and the wiring within our walls teachers, the more until it reaches the point of responsible hobby writers of ignition. So here are the the time, and sometimes by first and most obvious sad personal experience. precepts of a.c. line safety: Today, though, a new (1) make sure that all of the radio hobbyist is unlikely to electric wiring in your home have that background. In Don't turn this one on until you get some knobs! Any is correctly fused or breakered for its current- this day of low-voltage, low metal surface on an a.c.-dc. radio should be considered current, semiconductor carrying capacity and (2) aserious shock hazard. circuits, even people with make sure never to plug in electronics expertise may be devices with known short- unaware of the hazards lurking within a tube radio the circuit hazards (such as radios having cracked or frayed moment its plug is inserted into a wall socket. line cords). Precautions us older types take automatically, without Besides being a fire hazard, the a.c.
    [Show full text]
  • Two Rich Minds - One Poor Invention
    Two Rich Minds - One Poor Invention by William E. Denk, W3IGU 1 Reprinted From The Antique Radio Gazette Volume 15, No 1 (Spring, 1987) An early patent by legendary inventors Edwin Armstrong and Michael Pupin confirms the former's long-time interest in reducing radio static. Though the application of regeneration to antenna circuits as a noise limiting technique was a dead end, it did foreshadow Armstrong's eventual development of Frequency Modulation. Writer Bill Denk was a long-time author of The OTB's book review column. Even before the founding of the first organizations devoted to the preservation of the wireless history and equipment, this writer had started his collection of patents having special significance in the early development of the communications technologies. The collection includes Edison's patent on the phonograph, Bell's patent on the telephone, the Morse patents on the telegraph, Marconi's earliest patents on his wireless transmitting and receiving system, Fleming's patent on the vacuum tube diode detector, the early crystal detector patents of Bose, Dunwoody, and Pickard, the Hazeltine Neutrodyne patent--hundreds in all. Collecting patents is an area of our hobby that requires very little space, and it can be most interesting and revealing. One of the early patents in my collection, added because of the eminence of the named co-inventors, might have been later discarded had the inventors been a pair of unknowns. One of the inventors was Michael I. Pupin, Professor of Mathematics at Columbia University. He was the inventor of the telephone repeater, or Pupin coil, which greatly improved long-distance land-line telephony.
    [Show full text]
  • The First RADIOMARELLI Transistor Radio and RCA ~
    ~ The first RADIOMARELLI transistor radio and RCA ~ by Lello Salvatore * FIVRE, from tubes to transistors The invention of the point contact transistor occurred in December 1947 in the Bell Laboratories (Murray Hill, New Jersey, USA), and more particularly the junction one in April 19501, marked an important turning point in the miniaturization of electronic circuits and in their assembly. The first transistors were used in Bell telephone systems (in the card translator2) and in military equipment (in the Air Force's radar system and computers TRA.DI.C) and immediately after in commercial products such as hearing aids (late 1952/early 1953) and pocket radios (December 1954). The impact that the transistor had on industry, commerce and military institutions was enormous; just think that between 1954 and 1956 about 28 million transistors were sold in the United States, of which 17 million germanium and 11 million silicon for a total value of about 55 million Dollars3. If in Europe, big companies such as Philips, Siemens and Halske, Telefunken, British Thomson- Houston Company and so on already in 1952 they had purchased the license to build transistors from Western Elctric4 for 25,000 dollars, in Italy the dawn of semiconductor research was not yet seen. Taking the first steps in Italy was the brilliant engineer from Treviso Virgilio Floriani (1906, Cison di Valmarino - 2000, Cernusco Lombardone) who was anxious to get his hands on those new electronic things that amplified electrical signals, created the Semiconductor Laboratory in 1955 in the company he founded in October 1946, TELETTRA, which stands for TELefonia, ELETTronica and RAdio.
    [Show full text]