Path: senator-bedfellow.mit.edu!bloom-beacon.mit.edu!news-out.cwix.com!newsfeed.cwix.com!newsfeed.mt.sfl.net!news.onramp.ca!freenet-news!FreeNet.Carleton.CA!di540 From: di540@FreeNet.Carleton.CA (Maximo Lachman) Newsgroups: can.media.radio,aus.radio.broadcast,rec.audio.car Subject: Intro to Shortwave (car) Radios Date: 25 Dec 2002 03:34:17 GMT Organization: The National Capital FreeNet Lines: 634 Distribution: au,ca,mx,nz,sa Message-ID: Reply-To: di540@FreeNet.Carleton.CA (Maximo Lachman) NNTP-Posting-Host: freenet10 X-Trace: freenet9.carleton.ca 1040787257 3604 134.117.136.30 (25 Dec 2002 03:34:17 GMT) X-Complaints-To: complaints@ncf.ca NNTP-Posting-Date: 25 Dec 2002 03:34:17 GMT X-Given-Sender: di540@freenet10.carleton.ca (Maximo Lachman) Xref: senator-bedfellow.mit.edu can.media.radio:395 aus.radio.broadcast:28293 rec.audio.car:594283 An Introduction to Shortwave Radios for Newbies _________________________________________________________________ CONTENTS * [1] What is a shortwave radio? * [2] Why would anybody want/need one? * [3] What do I need to know in order to use one? * [4] What's the difference between digital & analog radios? * [5] What radio accessories are especially useful for shortwave? * [6] What's the difference between bands, wavelengths, kHz & MHz? * [7] Can a shortwave radio be used like an ordinary AM/FM radio? * [8] Where online can I get more information on SW (car) radios? * [9] Abbreviations and Terminology * [X] Appendix _________________________________________________________________ [1] What is a shortwave radio? On the technical side, a shortwave radio is a receiver that can receive AM radio transmissions on frequencies between 3 & 30 MHz. The main characteristic of these frequencies is their ability to "propagate" for long distances, making possible such world-wide communications as international broadcasting and coordination of long-distance shipping. Most shortwave radios will also receive AM transmissions below 3 MHz in the longwave & mediumwave broadcast bands. Many will also receive transmissions above 30 MHz, such as those in the FM broadcast band. _________________________________________________________________ [2] Why would anybody want/need one? The primary reasons people use shortwave radios range from personal enjoyment to helping others in local emergencies. From a logistical point of view, shortwave radios are a means of enabling the reception of transmissions of interest or utility to a target audience that may have considerable degrees of geographic distribution. Many countries broadcast to the world in English, making it easy to find out the position of such a country on those things that it finds important. Shortwave radios provide a way to eavesdrop on the everyday workings of foreign politics and commerce. You can also hear transmissions of news and other programmes from domestic broadcasters. Shortwave radios commonly include the longwave & mediumwave bands, and so can receive the vast majority of AM transmissions, unlike most so-called "AM radios". Many will also allow you to listen to SSB transmissions of emergency (& other) information by amateur radio operators; however, none of the traditional 'in-dash' shortwave car radios (e.g. Becker, Blaupunkt, Mekka, Philips, Sony) can handle SSB. _________________________________________________________________ [3] What do I need to know in order to use one? For shortwave radios, all you need to know at first are the same skills needed for FM radios, while putting off learning the concepts and jargon till later. No special set of skills is required; however, as you gain experience and develop special listening skills, your listening enjoyment will increase accordingly. These skills include keeping up on local and non-local issues which affect a broadcast (e.g. strikes or ionospheric storms causing stations to "disappear"); using various types of antennas; troubleshooting and maintaining your radio. In most cases, you can receive many stations using the antenna that comes with the radio; however, to receive more distant and/or weaker stations, you may have to set up an outdoor antenna; a loop antenna is ideal where space is limited. _________________________________________________________________ [4] What is the difference between digital & analog radios? Shortwave radios are sometimes distinguished from each other by their readouts and internal tuning methods, either of which may be analog or digital. (With regard to the shortwave signals themselves: analog is used for voice transmissions; in contrast, one could call BCD, CW, FSK & RTTY transmissions "digital.") Digital Readout: (e.g. MM.kkk MHz) There are a variety of tuning methods that provide a digital readout. At one extreme, there are radios which have a separate knob for each digit. There are others which have one tuning knob to set the MHz part of the frequency, and another to set the kHz part. There are also radios which have only one tuning knob to cover the entire range of frequencies, although most of these reduce the amount of turns needed via knobs that have "fast" modes, or switches that quickly select between a number of smaller tuning bands, or both. At the other extreme are radios with digital readouts that have no tuning knobs. Most of these have numeric keypads for selecting a frequency. Some of these do not have numeric keypads, and are very inflexible in use, unless you plan to listen only to the stations that you have programmed into the radio's memories, in which case their reduced cost, size and/or weight may better suit your needs. Analog Readout There is also a wide variety of analog readouts. Some use dials or drums that rotate under indicators. Others use cursors that run along linear scales. A few old analogs have the push-button memories also found on old car radios. Selective modern radios do not use analog readouts, but if they do, also have digital readouts, since it can be difficult to tune in a shortwave station using only an analog readout. Most analog-only radios on the market are small portables that are unselective (they cannot separate stations that are right next to each other) and only cover the main International Broadcast bands. Digital Tuning This uses PLLs to electronically tune in the desired frequency, and allows for easy reception of SSB signals, and storage of frequencies in memory chips. However, the micro-electronics needed tend to be expensive, noisy, and power hungy, and most cheaper radios do not exploit all possible benefits, such as scanning. On the other hand, digital radio kits which interface with your computer exploit most of the benefits of digital tuning for just a few hundred dollars. Digital tuning is usually accomplished by pressing keys, and on some radios by turning knobs. Analog Tuning This relies on circuits which are tuned directly by you, and not under microchip control. As a result, stations tend to drift on most radios with analog tuning, which makes SSB reception very difficult. Analog tuning is done by turning knobs (or pushing car-radio-style buttons). However, these radios often are more tolerant of abuse, last longer on batteries, and are easier to use, than digital radios. _________________________________________________________________ [5] What radio accessories are especially useful for shortwave? There are several things you can get which may improve the performance of a shortwave radio: Antennas can make a radio more sensitive and thereby receive more weak and/or distant stations. Pre-selectors are usually attached between the antenna and the radio to prevent overload of the radio by the increased total level of input signals. A tunable loop antenna can also do pre- -selection, and is a good compromise where space is limited. Headphones will allow you to focus on transmissions w/out distractions. External speakers will allow you to improve on small built-in speakers. Listening Guides and Technical References can give you information (in print or on-line) on propagation of shortwave signals via the ionosphere, use of your equipment, stations & frequencies. Computer Software can do many things from decoding digital signals to storing stations, frequencies and propagation times. Some radios can be controlled by such software. A few radios are even dependent on a computer into order to do some of the signal processing. The last but not least important "accessory" is Experience. Time spent working with a shortwave radio gives you more information to get the most out of it, such as the best times in your area for reception of certain frequencies, and develops skills to better operate it. _________________________________________________________________ [6] What's the difference between bands, wavelengths, kHz & MHz? A band is a range of frequencies (in kHz or MHz). Many analog radios reference bands according to wavelengths (in metres), since the tuning location of a station can also be expressed in terms of a 'wavelength'. For example, the 16-metre band refers to the range of frequencies with wavelengths of around 16 metres or more. You can use the following equations to convert kHz, MHz, and metres. * To convert MHz to kHz, multiply by 1000 kHz/MHz. 9.62 MHz x 1000 kHz/MHz = 9620 kHz * To convert kHz to MHz, divide by 1000 kHz/MHz. 2780 kHz divided by 1000 kHz/MHz = 2.780 MHz * To convert MHz to metres, divide 300 Mm/s by the number of MHz. 300 Mm/s divided by 7.1 MHz = 42.25 metres * To convert metres to MHz, divide 300 Mm/s by the number of metres. 300 Mm/s divided by 14 metres = 21.428 MHz 300 Mm/s divided by 15 metres = 20.000 MHz 300 Mm/s divided by 16.901 m = 17.750 MHz 300 Mm/s divided by 17.321 m = 17.321 MHz 300 Mm/s divided by 20 metres = 15.000 MHz ( Note that as frequencies get higher, wavelengths get shorter.) Low Frequencies The 30 - 300 kHz range is known as the low frequency (LF) band. Reception for this range is best between 6 p.m. and midnight (your time). Many stations in this range serve as beacons for aircraft and marine navigation by continuously transmitting their call letters. In Europe, N. Africa and N. Asia, the LF band contains the longwave AM broadcast band from 153 to 279 kHz, but in the Americas the only AM broadcasts to be found are usually weather reports. Many of the other broadcasts use Morse code, although some transmit in Binary Coded Decimal (BCD), such as the time standard station WWVB on 60 kHz. Medium Frequencies The MF band is between 300 & 3000 kHz. In the Americas, the MF band contains the mediumwave AM broadcast band between 525 & 1600 kHz, extended to 1700 kHz in N. America, while in tropical areas, frequencies between 2300 & 2500 kHz are often used as well. Some ships also use the MF band. 500 kHz is set aside as an international distress and emergency station. 2000 - 2300 kHz is set aside for transmissions from ships and coastal stations. The Coast Guard and small boats use this band, with 2182 kHz set aside as the international distress and emergency channel. The 160 metre amateur radio band is also located within the MF band from 1800 - 2000 kHz. Most of these are SSB transmissions. High Frequencies The HF band is between 3,000 and 30,000 kHz, and is synonymous with shortwave. Certain frequencies within the HF band are set aside for specific purposes; commonly used allocations are listed below: Aircraft Frequencies Amateur Radio Frequencies CB Frequencies International Broadcast Frequencies Ship and Coastal Station Frequencies Time Standard Frequencies Aircraft Frequencies Aircraft on international routes sometimes use SW. Most transmissions are in SSB, although you can still hear some AM transmissions. Here are some bands where you might hear aircraft communications. 4,650- 4,750 kHz 6,545- 6,765 kHz 8,815- 9,040 kHz 11,175-11,400 kHz 13,200-13,360 kHz 15,010-15,100 kHz 17,900-18,030 kHz Amateur ('ham') Radio Frequencies Amateur radio operators mostly use SSB transmissions for voice communications. Morse code operators are licenced to use the lower area, usually, of each band. Amateur radio operators with the more senior voice licence are found in the upper area of each band. Tuning to the amateur radio frequencies can be interesting and also helpful, because amateur radio operators often broadcast emergency information when other means of communication break down. Portions of these bands are set aside for continuous wave (CW) transmissions of Morse code or for single sideband (SSB) transmissions of voice communications, as shown below. 80 metres: 3,500 - 3,800 kHz: CW 3,800 - 4,000 kHz: SSB 40 metres: 7,000 - 7,150 kHz: CW 7,150 - 7,300 kHz: SSB 30 metres: 10,100 - 10,150 kHZ 20 metres: 14,000 - 14,200 kHz: CW 14,200 - 14,350 kHz: SSB 16 metres: 18,068 - 18,168 kHz 14 metres: 21,000 - 21,250 kHz: CW 21,250 - 21,450 kHz: SSB 12 metres: 21,990 - 24,890 kHz 10 metres: 28,000 - 28,500 kHz: CW 28,500 - 29,700 kHz: SSB Note: These allocations are not observed everywhere in the world, particularly in the United States, as usual. CB Frequencies As does ham radio, CB radio transmissions will use SSB, but unlike ham radio, broadcasts on the CB band do not require a licence. The transmissions may also be in AM mode. They may also be used for controlling objects as well as for personal communications. There are 64 frequencies, called channels, separated by a frequency step of 10 kHz from 26,895 to 27,535 kHz. 40 channels are reserved for voice communications, from 26,965 to 27,405 kHz with one or more channels reserved for emergency use. Channel 9 or 27,065 kHz is an emergency channel in most countries of Oceania or America. In North America, Channel 19 or 27,185 kHz is also an emergency channel. International Broadcast Frequencies International (and domestic) broadcasts are found in the following shortwave bands. These are usually AM broadcasts containing news, commentaries, music, and special features reflecting the culture of the broadcasting country. You can often find other stations transmitting just above or below these bands: 90 metres * 3,200 to 3,400 kHz 75 metres * 3,850 to 4,000 kHz 60 metres * 4,750 to 5,060 kHz 49 metres 5,900 to 6,200 kHz 41 metres ** 7,100 to 7,350 kHz 31 metres 9,400 to 9,990 kHz 25 metres 11,600 to 12,100 kHz 21 metres 13,500 to 13,870 kHz 19 metres 15,100 to 15,800 kHz 16 metres 17,480 to 17,900 kHz 15 metres 18,900 to 19,020 kHz 13 metres 21,450 to 21,750 kHz 11 metres 25,600 to 26,100 kHz * Bands reserved for stations in tropical areas, but some non- -tropical stations often disregard this. ** Interference is heavy in the 41 & 75 metre bands because amateur radio operators and international stations share each range. Ship and Coastal Station Frequencies Most transmissions from ships and coastal stations are in SSB and CW. You can hear these transmissions in the following HF bands: 4,063- 4,139 kHz 4,361- 4,438 kHz 8,195- 8,181 kHz 12,330-12,420 kHz 13,107-13,200 kHz 16,460-16,565 kHz Time Standard Frequencies The following stations announce the exact time of day at specified intervals 24 hours a day. The time is given in the UTC time standard. Most shortwave stations are on UTC time, regardless of what time zone they are in. CHU at Ottawa, Ontario: 3,330 kHz USB + 50% carrier 7,335 kHz USB + 50% carrier 14,670 kHz USB + 50% carrier HD2IOA at Guayaquil, Ecuador 3,810 kHz 7,600 kHz VNG at Llandilo, New South Wales 5,000 kHz 8,638 kHz 12,984 kHz 16,000 kHz WWV at Fort Collins, Colorado and WWVH at Kekaha, Hawaii: 5,000 kHz 10,000 kHz 15,000 kHz 20,000 kHz YVTO at Caracas, Venezuela 6,100 kHz _________________________________________________________________ [7] Can a shortwave radio be used like an ordinary AM/FM radio? Just as for MW, SW signals can have dead-zones at varying distances from a transmitter; your radio can be relatively nearby and still be in a dead-zone. Even during the day, tuning it can be like using an AM radio at night to tune in stations, except that antenna usage is as for FM. In the following list are many 'full-time' frequencies in Oceania/America. You might not be able to hear many of these, since reception will vary as to the season, time of day, your location, and many other conditions. Although this information is subject to change at any time without notice, these stations have not changed frequency very often. Average transmission time for each frequency is at least 8 hours a day. This list can also help you test radios before buying them, or get domestic programming without retuning frequently when traveling in unfamiliar areas. Many shortwave radios have clock radio functions, and this list can provide stations that are likely to be transmitting when you program the radio to turn on, and are likely to continue broadcasting, even if you hit 'snooze' repeatedly. (When "DXing" these stations, the 4 digit frequencies tend to work better at night.) kHz Station, Location 3,205 Radio West Sepik, Papua New Guinea 3,210 WWCR, Nashville, Tennessee 3,290 GBC, Georgetown, Guyana 3,300 Radio Cultural, C.Guatemala, Guatemala 3,380 Centro Radiophonico de Imbabura, Ibarra, Ecuador 3,385 FR3, Cayenne, French Guyana 3,925 NBC, Port Moresby, Papua New Guinea 4,765 Radio Emissora Rural, Santarem, Brazil 4,820 HRVC, Tegucicalpa, Honduras 4,835 Radio Tezulutan, Coban, Guatemala 4,855 Radio Clube do Para, Belem, Brazil 4,875 La Cruz del Sur, La Paz, Bolivia 4,890 NBC, Port Moresby, Papua New Guinea 4,915 Radio Anhanguera, Goiania, Brazil 4,920 Radio Quito, Quito, Ecuador 4,920 ABC, Brisbane, Queensland 4,940 Radio Nacional, Quito, Ecuador 4,945 Radio Colosal, Neiva, Colombia 4,955 Radio Nacional, Bogota, Colombia 4,960 Radio Vanuatu, Efate-Emten, Vanuatu 4,965 Radio Santa Fe, Columbia 4,980 Ecos del Torbes, San Cristobal, Venezuela 4,990 Radio Apintie, Paramaribo, Suriname 5,020 SIBC, Honiara, Solomon Islands 5,025 Radio Rebelde, Bauta, Cuba 5,030 TIQ, Limon, Costa Rica 5,045 Radio Cultura do Para, Belem, Brazil 5,050 WWRB, Manchester, Tennessee 5,055 Faro del Caribe, San Jose, Costa Rica 5,070 WWCR, Nashville, Tennessee 5,085 WWRB, Manchester, Tennessee 5,095 HJGG, Bogota, Colombia 5,745 WHRI, Noblesville, Indiana 5,755 KAIJ, Dallas, Texas 5,825 EWTN, Birmingham, Alabama 5,935 WWCR, Nashville, Tennessee 5,950 GBS, Georgetown, Guyana 6,000 Radio Inconfidencia, Belo Horizonte, Brazil 6,010 Radio America, Lima, Peru 6,030 CFVP, Calgary, Alberta 6,030 Radio Santa Maria, Coyhaique, Chile 6,045 Radio Santa Rosa, Lima, Peru 6,070 CFRX, Toronto, Ontario 6,090 The Caribbean Beacon, Anguilla, BWI 6,095 Radio Nacional, Lima, Peru 6,105 Radio Panamericana, La Paz, Bolivia 6,115 Radio Union, Lima, Peru 6,120 Radio El Mundo, Buenos Aires, Argentina 6,150 ABC, Lyndhurst, Victoria 6,160 CKZN, St. John's, Newfoundland 6,160 CKZU, Vancouver, British Columbia 6,180 Radio Nacional da Amazonia, Brasilia, Brazil 6,185 Radio Educacion, Mexico DF, Mexico 6,350-usb AFN, Pearl Harbor, Hawaii 6,458.5-usb AFN, Isabela, Puerto Rico 6,890 WWRB, Manchester, Tennessee 7,315 WHRI, Noblesville, Indiana 7,415 WBCQ, Monticello, Maine 7,425 Radio Catolica Mundial, Birmingham, Alabama 7,445 RFPI, El Rodeo, Costa Rica 7,510 KTBN, Salt Lake City, Utah 9,320 WWRB, Manchester, Tennessee 9,475 WWCR, Nashville, Tennessee 9,520 NBC, Port Moresby, Papua New Guinea 9,562 Radio Nacional, Lima, Peru 9,575 NBC, Port Moresby, Papua New Guinea 9,585 Radio Excelsior, Sao Paulo, Brazil 9,610 ABC, Wanneroo, W.Australia 9,625 CBC, Sackville, New Brunswick 9,705 Radio Mexico, Mexico DF, Mexico 9,725 TIQ, Limon, Costa Rica 9,745 HCJB, Quito, Ecuador 9,860 Radio Nacional, Lima, Peru 10,320-usb AFN, Pearl Harbor, Hawaii 11,530 Radio Catolica Mundial, Birmingham, Alabama 11,770 Radio Mexico, Mexico DF, Mexico 11,775 The Caribbean Beacon, Anguilla, BWI 11,805 Radio Globo, Rio de Janeiro, Brazil 11,835 Radio El Espectador, Montevideo, Uruguay 11,915 Radio Gaucha, Porto Alegre, Brazil 11,925 Radio Bandeirantes, Sao Paulo, Brazil 11,935 Radio Clube Paranaense, Curitiba, Brazil 12,160 WWCR, Nashville, Tennessee 12,172 WWRB, Manchester, Tennessee 12,689.5-usb AFN, Key West, Florida 13,615 WEWN, Birmingham, Alabama 13,750 TIQ, Limon, Costa Rica 13,815 KAIJ, Dallas, Texas 13,845 WWCR, Nashville, Tennessee 15,040 RFPI, El Rodeo, Costa Rica 15,140 HCJB, Quito, Ecuador 15,170 RFO, Papeete, Fr. Polynesia 15,590 KTBN, Salt Lake City, Utah 15,725 Radio Miami International, Florida 15,745 WEWN, Birmingham, Alabama 17,650 WHRA, Greenbush, Maine 17,675 RNZI, Wellington, New Zealand 17,775 KVOH, Los Angeles, California 19,475 Radio Nacional, Asuncion, Paraguay 21,815-usb RFPI, El Rodeo, Costa Rica 22,980 Radio Monte Carlo, Montevideo, Uruguay 25,322 AAFR, Darwin, Northern Territory 25,873 WFLA, Tampa, Florida 29,880 Radio Sideral, Quito, Ecuador _________________________________________________________________ [8] Where online can I get more information on SW (car) radios? Aside from searching the archives of rec.radio.shortwave at http://groups.google.com/groups?q=rec.radio.shortwave you can also find information on many SW (car) radios at http://www.shortwavestore.com/sony-shortwave-receivers.html http://www.rnw.nl/realradio/rx_current.html http://www.DXing.com/rx/rxindex.htm _________________________________________________________________ [9] Abbreviations and Terminology Below is a short list of common abbreviations and terms you may encounter. Abbreviations AM (Amplitude Modulation) BCD (Binary Coded Decimal) BFO (Beat Frequency Oscillator) CB (Citizens' Band) CW (Continuous Wave) DX (old telegraph code for Distant TRANSmission) ECSS(Exalted Carrier Single Sideband) FM (Frequency Modulation) FSK (Frequency Shift Keying) GMT (Greenwich Mean Time) HAM (AMateur radio) HF (High Frequencies) kHz (KiloHertz) LSB (Lower SideBand) LW (Longwave) Mm/s(Mega metres per second) MCW (Modulated Continuous Wave) MHz (MegaHertz) MW (MediumWave) PLL (Phase Locked Loop) RTTY(Radio TeleTYpe) SSB (Single SideBand) SWL (ShortWave Listening) USB (Upper SideBand) UTC (Universal Time: by atomic clocks Coordinated to track GMT) VFO (Variable Frequency Oscillator) VHF (Very High Frequencies) Terminology Amplitude Modulation: A technique that multiplexes audio frequencies onto the upper side of a carrier to produce the USB, and a mirror image of the audio frequencies beneath the carrier to produce the LSB. The resulting AM signal is also known as Double Sideband (DSB). BALUN: A device used with to match a BALanced antenna, like a dipole, to an UNbalanced feedline, such as coaxial cable. Beat Frequency Oscillator: A receiver circuit that generates a signal to emulate the carrier missing in CW, FSK, RTTY & SSB signals, and so enable intelligible reception. Carrier: a radio signal transmitted at constant strength & frequency that serves as the reference tuning frequency of the transmission. Continuous Wave: a radio signal transmitted at constant frequency & strength except when interrupted to send messages by Morse code. DXing: listening to distant stations (D=distant, X=transmitter) Exalted Carrier Single Sideband: a reception technique in which the BFO is used to insert a carrier over the received carrier of a signal. Frequency Step: The frequency increment for tuning or scanning. Hertz: cycles per second ( cps - c/s ) Ionosphere: a region in the upper atmosphere where free electrons and ions abound sufficiently to backscatter shortwave photons so that they skip back to earth, instead of just continuing out into space. Kilo: 1,000. Longwave: Radio signals from 30 to 300 kHz in frequency, although this term is often used to mean any radio signal lower than 500 kHz. Lower Sideband: The sideband lower in frequency than the transmitter's carrier. Mediumwave: Radio signals from 300 to 3000 kHz (3 MHz) although this term is often limited to mean a radio signal in the MW broadcast band (at a minimum 530 to 1600 kHz). Mega: 1,000,000. Shortwave: Radio signals between 3 and 30 MHz although this term is often used to include radio signals as low as 1610 kHz. Sideband: That part of the radio signal above or below the carrier frequency that directly corresponds to the original audio frequencies at the transmitter's input (USB), or inversely corresponds in the form of a mirror image (LSB). Single Sideband: A modulation technique that suppresses one sideband entirely and the carrier to varying degrees, leaving the remaining sideband essentially unchanged. Synchronous Detection: A demodulation technique that improves the reception of AM signals. Ironically, there is no 'AM' radio on the market that incorporates this feature. Found on many SW portables from Sony, and on most modern desktop receivers. You will want it if you spend much time listening to music. For listening to voice broadcasts under poor reception conditions, ECSS can give results as good, if not better. Upper Sideband: The sideband higher in frequency than the carrier of a transmission. Very High Frequencies: The radio frequencies from 30 to 300 MHz. The FM broadcast band is found here. _________________________________________________________________ [X] Appendix This intro is intended for those who know nothing about shortwave radios, such as those who are wondering about using one on the same basis as using any ordinary AM/FM radio. It is intended for those who are not technically inclined or hobby-oriented (e.g. modifying or monitoring). It is more of a guide to help someone decide whether a shortwave radio is a useful means of acquiring information to justify the purchase of a new radio that is on the market, particularly at the low end, such as portables and car radios. Copies of this intro are distributed semi-annually to rec.answers, news.answers & radio-related newsgroups on usenet and fidonet (ncf.sigs.radio-tv.shortwave, etc.), and is to be on file at: ftp://rtfm.mit.edu/pub/faqs/radio/shortwave-radios-intro ----------------------------------------------------------------- Last-modified: 20.xii.MMII Previous version modified: 5.xii.MMII .