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"What's New" Reviews
MT® 2001

Please mention you saw it in Monitoring Times!

2001 Reviews: AOR TDF370 Multimedia Digital Terminal Blonder Tongue Spectrum Analyzer / Emerson Universal Multi-System Video Converter / Flight Explorer Personal Edition / Hamtronics LNK-WB Wideband Preamplifier /MFJ-616 Speech Intelligibility Enhancer / PAR AM Broadcast Filter/ PAR MON-3 VHF/UHF AntennaSGS SG-2020 HF Transceiver / WiNRADiO AX-31B Planar Antenna / WRTH 2001Yaesu VR-5000 Scan Fix

Index to all scanner reviews by Bob Parnass

2000 Reviews

1999 Reviews

1998 Reviews

Index to Reviews 1994-2001

MFJ-616 Speech Intelligibility Enhancer

          Like Many of us, Martin Jue, the man behind MFJ Enterprises, noticed his hearing becoming less acute with age. While a simple, agile, audio filter could help him distinguish desirable audio from the din of muffled noise on his radios, each ear had its own requirements. Realizing that he wasn't alone with this problem, he went to work designing a filter with separate left/right audio contouring.


Martin further discovered in his research which parts of the audio spectrum are more important to intelligibility than others; these became his rolloff edges for the adjustable filters.


The new MFJ-616 allows left/right amplitude balancing between dual 3-watt amplifiers and can drive external stereo speakers (including computer multimedia units) as well as headphones. A dual input allows selection from two audio sources. The unit is very easy to use, and operates from a 12 VDC source (not supplied). Input impedance is nominally 500 ohms (line input), and for those with profound hearing loss, there is an internal solder pad allowing headphone audio boost above that normally provided.


Our Test


The all-analog circuit features an equalizer bank of four separate frequency-contouring controls, centered at 300, 600, 1200, and 2400 Hz. Manual experimentation of the controls allows attenuation or boost of up to 12 dB from center (flat) position. This provides de-emphasis of the low frequencies that constitute a minimum of speech intelligibility, emphasis for those of us with high-frequency loss, and comfort-contouring of the mid frequencies.


While the 616 calls for medium impedance (500 ohm) line input, we found that direct connection to a low-impedance earphone/speaker jack on a receiver or scanner worked just fine. Purists may opt to add an external resistive pad to normalize the load.


A convenient pushbutton bypass switch allows instant comparison of equalization settings to non-compensated signals to determine the effectiveness of the controls.


We found the MFJ-616 Speech Intelligibility Enhancer not only easy to use, but doubly useful: Not only is it quite effective in compensating for hearing loss, but it also optimizes desired audio amidst the din of interference on the noisy radio spectrum.

 WRTH 2001 review

by Gayle Van Horn


 World Radio TV Handbook has recently released its 55th edition, and as last year, it has been met with a mixture of pleasure and consternation by radio hobbyists. The 2001 edition has increased its page count to 656 pages, reportedly as a result of reader feedback and ongoing updates, and in order to address evolving changes within the hobby.


Readers have come to depend upon the WRTH's respected, objective chapter on Receiver Reviews that includes scanners, PC radios, and table-top receivers. Home-brew and antenna enthusiasts will most likely find Antennas and Analysers for the SWL helpful, while George Jacobs' HF Broadcast Reception chapter predicts 2001 will be another good year--with less interference!


Propagation, the number one prerequisite for DX, is featured in a most helpful feature, Introduction To Propagation Theory. If you are confused by the importance of the ionosphere, troposphere, and radio propagation mechanisms, this is an excellent no-nonsense explanation.


In another chapter, take a tour of BBC's Monitoring Service in Caversham and find out just what has been going on in their listening room for decades.


Unfortunately, many on-going complaints by hobbyists still remain unaddressed, especially concerning the National Radio section. As one DXer commented, "errors reported for years still remain untouched." Aussie's report their medium wave section is a mess, while the Russian section has reportedly improved. U.S. mediumwave coverage also receives a thumbs down from many.


Personally, I continue to find their national and international broadcast sections a time-consuming and unnecessary division for the active DXer. Wouldn't it be more advantageous to arrange both national and international information under each county (sorted by continent), instead of constantly shifting to the back of the book?


Despite reports of errors, typos and the lack of corrected data from DXers, I find WRTH a comprehensive guide for national and international radio broadcasting. WRTH continues to offer the listening world a reference manual that should be on every DXer's bookshelf. You can find it at book stores and dealers such as Grove Enterprises (1-800-438-8155 or write PO Box 98, Brasstown, NC 28902) for $24.95 (plus $5.95 shipping from Grove).

Emerson Universal Multi-System Video Converter

By Ken Reitz KS4ZR



History is filled with weird anecdotes of engineering oddities. And, while we may be inclined to believe that in our modern computer dominated world we are all in agreement as to engineering standards, we don’t have to look far to find proof of the opposite. Even the precise world of computer engineering struggles with Mac and PC standard deviations. Two decades ago it was VHS versusBeta, and thirty years ago it was eight track cartridge versus cassette. A reasonable person might expect that the best engineered system wins, but, a reasonable person is always shocked to find that isn’t true.


Consider the world of color television. In the U.S., as television progressed in the1940s, there were so many incompatible standards for television broadcasting that an industry-wide organization was formed in 1948 to set, once and for all, a television broadcast standard. The organization was the National Television System Committee and the American standard would be forever known by the Committee’s acronym: NTSC. Nearly a decade later the French had improved upon the NTSC standard with its own Sequential Color A Memoire or SECAM. Four years after that the British had a go at improving things and developed its system known as Phase Alternating Line or PAL. Now, these “improvements” were not exactly earth shaking in their differences, but the differences made it so that none were compatible with any other.


Following a confusing pattern of adoption, all countries around the world have opted for one of the three systems. As a result PAL is used in Britain as well as much of Africa; France uses SECAM; many eastern European countries including Russia also use SECAM; Latin America uses a patchwork quilt of all three including three variations on PAL; the U.S., Canada and Mexico use NTSC as do Nicaragua, Cuba and the Philippines.


Emerson’s Video Converter in Action


Before the introduction of Emerson’s Universal Multi-System Video Converter the only ways to convert PAL to NTSC or vice versa was to use a multi-standard video monitor/TV set or a multi-standard VCR. Both are traditionally more expensive than their less talented counterparts and force the user to lug around another big piece of electronic gear. The Emerson converter really helps in that department because it’s barely bigger than a video cassette, weighs in at just one pound, and the design couldn’t be simpler.


The back panel has an RCA video input jack, into which the source video is plugged, and an RCA video output jack which takes the converted signal to your PAL or NTSC TV set. The unit is set up to automatically detect the type of video received, but you can manually change the input with an Auto/Manual switch. An LED on the front panel indicates which input you chose. Another LED lights on the front to indicate the type of video received.


For the unit to work properly you must take the video from any source (satellite receiver, camcorder, laser disc or VCR) via the familiar yellow, white and red RCA jacks. The yellow jack is video out and the other two are for left and right audio. There are no coax connections. For proper reception and to get both video and audio you must use a VCR or TV set equipped with the three RCA jacks.


The Emerson converter is most useful for people on overseas assignment who don’t want to have to buy new TVs or VCRs and for satellite hobbyists who want to be able to watch international transmissions. These transmissions are occasionally found in both C and Ku-band and most frequently are sporting events being back-hauled to England. The Emerson converter will work with both analog and digital satellite receivers.


What this product won’t do is allow you to play a PAL recorded video tape in an NTSC VCR; the conversion is done with the output signal of the video device. If you want to watch PAL format videos you’ll have to use a PAL VCR.


The Emerson Universal Multi-System Video Converter (model #EVC1575) retails for $219.95 and is available from Skyvision at 800-500-9275 or visit their web site at


SGS SG-2020 HF Transceiver


By Bob Grove



      The price is right, and it's easy to operate. So how does the SG-2020 transceiver work? We recently tested this 12 volt-powered HF SSB/CW rig on the air and found it very straightforward to use.


      Receiving 400 kHz through 29.7 MHz continuously and transmitting at 20 watts PEP (adjustable 0-20 W) on all ham bands within that range, this microprocessor-controlled transceiver measures only 6"W x 2.75"H x 7.25"D and weighs a mere 2.5 pounds. The microphone is included in the purchase price.


      The backlit LCD displays frequencies to 100 Hz (2 Hz tuning steps) and tuning stability is 10 ppm. CW, USB, and LSB modes may be selected for any frequency. The 40-channel memory can work in simplex or semi-duplex, with fast 10 millisecond T/R break-in. The fully-adjustable iambic "A" mode keyer operates under microprocessor control from 5-50 wpm.


      Receiver sensitivity is 0.3 microvolts for 6 dB S/N, with a third-order intercept point of +1.8 dBm. A noise blanker is selectable and RF gain is controllable. Receiver current is a mere 300 mA. Even at full transmit power, current consumption is less than 3 amps for 20W CW, dropping to a mere 0.8A for SSB. A common LED light bar reveals transmit power and received signal strengths. SWR and battery voltage is metered as well.


      The RF speech processor employs VOGAD baseband processing and RF clipping. Split, RIT, and XIT features are included and the audio bandpass is tunable from 100-2700 Hz.



Our Test


      We were fortunate to find a European DX contest going on 20 and 15 meters, an ideal way to test the QRP transceiver. Using a GAP vertical antenna, we were generally clobbered by the high-powered contesters at 20 watts USB, while our 100-watt "big rig" consistently made it through. But on clear frequencies, satisfactory QSOs were readily accomplished, with stations giving us good signal reports for both strength and audio.


      We did find the radio extremely sensitive to power supply voltages; only one of three AC power supplies rated at 12 VDC would activate the radio. Other users have reported the same phenomenon, indicating that it needs more than the minimum voltage called for in the manual to operate the rig.


      A characteristic reported by other SGC owners is a somewhat chirpy CW note on transmitting, but we didn't try this mode. We did find the built-in speaker perfectly intelligible and adequately loud on all reception modes given the small size of the case.



The Bottom Line


      At under $700, with as many features as this little rig has, it's an unusual value in today's amateur radio market and makes a fine QRP take-along rig for backpacking, mobiling, or camping.


      The SG-2020 carries a list price of $675 and is available from SGC Inc., SGC Building, 13737 SE 26th St., Bellevue, WA 98005. Phone (800) 259-7331 or visit their website at



WiNRADiO AX-31B Planar Antenna

By Bob Grove



WiNRADiO, an Australian company famous for innovative computer-hosted receiving products, has just released their AX-31B active VHF/UHF antenna. Although designed primarily for their own receiver line, the antenna works just as well on any VHF/UHF scanner or other receiver. It is not capable of transmitting.


The planar (flat plate design) enables the 8.5” x 11.5” board to be hung on a wall, or even on a window. A six-foot length of RG-58/U cable terminated with a BNC connector leads the signals to a nearby radio.


Architecturally, the layout incorporates a log-periodic dipole array (LPDA) antenna design etched on both sides of a fiberglass circuit board; an integral, solid-state preamp is part of the same board. The antenna is impedance-matched to the input of the amplifier by an RF transformer.


Powered by the 9-volt battery, the amplifier’s 25 mA current drain assures continuous operation of many hours before replacement is necessary; a super-bright LED will remind you that it’s still turned on! A simple modification, the addition of a resistor, enables the antenna to be powered remotely from an AC adaptor through the coaxial cable.


Claiming a 230-1400 MHz frequency range, we discovered that the unit actually works quite well over a much wider swath of spectrum. Gain is advertised as 20 dB, dropping off as the unit is utilized outside its advertised bandwidth. Technically inclined readers will be relieved to know that the third order intercept point is a healthy 25 dBm, protecting it from generating intermod under most signal receiving conditions.


While the specs show an antenna forward gain of 6 dBi, the small dimensions of the LPDA elements limit its directional response to the higher end of its bandwidth. At lower frequencies it is essentially omnidirectional.


Since the AX-31B is not intended for outdoor use, it’s only fair to compare it with other indoor antennas. We selected a Uniden BC3000XLT hand-held scanner, its factory rubber duckie antenna, and a Condor whip for our test. A synopsis of observations at my indoor location, along with an indication of the best antenna at each sample frequency(*), can be found in Table 1.


The Bottom Line:


We are eternally in search of the perfect antenna: small, wideband, potent, and immune to interference. It doesn’t exist. Signal capture is a function of element size and placement, and active (amplified) antennas require power, generate noise, and are subject to overload problems like intermodulation and desensitization.


But the AX-31B has its niche. Exhibiting decent gain, acceptable noise figure, and high overload immunity, it works well in the upper VHF/UHF land mobile frequencies, and its low profile invites unobtrusive placement next to a wall or window.


It can even be used in a pinch for upper shortwave frequencies -- as low as 15-20 MHz or so -- but doesn’t work much better than a few feet of wire randomly run around the room, and it is just as vulnerable to interior electrical interference from appliances, electronic accessories, and power lines.


Nonetheless, for the new genre of wideband scanners which tune down into the shortwave frequencies, the AX-31B offers significant improvement over the factory-supplied whip, and since those scanners commonly have just one antenna port, the AX-31B can be that one antenna.


While a good rubber duckie like the Condor may work just as well on some frequencies, it is not always convenient to set the radio where the whip works best. By experimentation, the AX-31B can be located at an optimum spot for reception and the cable run to the monitoring position.


There is no substitute for an efficient outdoor antenna. But there are cases where such an installation is impractical or even impossible. Given its few limitations, the AX-31B is a welcome addition to the cadre of listening tools.


The WiNRADiO AX-31B planar antenna is available for $129.95 plus shipping from most WiNRADiO dealers, including Grove Enterprises  (PO Box 98, Brasstown, NC 28902; 1-800-438-8155 or visit



Table 1: A Comparison of Indoor Antennas


NOTE: Results will vary with signal direction and propagation, placement and polarization of the antenna, and location of the installation. Directivity is present at the higher frequencies only, becoming omnidirectional (nondirectional) lower, and will be influenced by nearby metal masses.


27.185 (CB) Undetectable Some signals *Much stronger
49.845 (Baby monitor)  Undetectable   Good, some hiss   *Full quieting
88.1 (FM broadcast)  Trace Good, some hiss   *Full quieting

88.5 (FM  broadcast)

Undetectable Undetectable   *Receivable

109.8 (Airport VOR)  

(Equal) (Equal) (Equal)

151.550 (VHF hi)   

*Good, some hiss   *Good, some hiss   Weaker

162.400 (NOAA weather) 

Readable, hiss *Full quieting    *Full quieting    
171.025 (IFLOWS)  Very weak *Full quieting  *Full quieting
407.225 (Mil trunking) Very weak Undetectable *Moderately strong
411.550 (Hydrotelemetry) Strong, some hiss Strong, some hiss  *Full quieting
453.075 (UHF mobile)  Weak   Weak   *Full quieting
462.750 (UHF mobile) (Equal)    
475.050 (UHF carrier)  Undetectable  Undetectable  *Receivable
499.750 (UHF TV) Noisy      Noisy     *Full quieting
855.7375 (UHF trunking)   (Equal)    
864.7375 (UHF trunking)   (Equal)    
996.000 (VOR)  (Equal)    
1090.000 (Aircraft DME)  Weak, receivable  *Receivable  Undetectable 


PAR AM Broadcast Filter



Strong-signal interference not only plagues scanner and shortwave listeners, but medium wave, tropical band, and 160 meter ham operators as well. Now PAR Electronics has come to the rescue with their new BCST-HPF AM broadcast filter.


As the product code suggests, this is a high-pass filter designed to attenuate medium-wave AM broadcast signals; it is inserted in line with the antenna cable. Equipped with SO-239 bulkhead connectors, it’s ready for attachment to PL-259-equipped coax.


With a razor-sharp cutoff at 1.8 MHz, the high-pass filter has an incredibly low 3 dB attenuation at 1.8 MHz, but a steep 50-80 dB swath is taken out of the medium-wave broadcast band and below. AM broadcasters don’t stand a chance of causing problems with this filter! A handy toggle switch allows the filter to be bypassed entirely.


Does it Work?


You bet! We were bothered by a spurious intermod product right in the middle of the 160 meter ham band coming from two local powerhouse broadcasters. A flip of the switch and it was gone, with nothing remaining but pure, unattenuated 160 meter signals! A low-pass filter BCST-LPF is also available.






Other than a new receiver, nothing seems to spark more interest among radio addicts than a new antenna! And PAR’s new MON-3 is worthy of the attention. Using heavy-gauge aluminum elements and stainless steel screws, washers, and nuts, the MON-3 comes as a kit, requiring 15-30 minutes set aside for assembly. Only pliers are required.


Claiming 50-ohm-impedance center frequencies in the 144-174, 430-470, and 800-900 MHz bands, the MON-3 actually receives well outside those bands.


Test Results  


One of the nicest antennas we’ve seen in quite a while is the AOR DA3000 discone, reviewed last year in MT. Since it was still in place in our test fixture, we decided to compare the two. Numbers indicate S units of signals received on an Icom R8500 test receiver.


FREQ. MHz  DA3000 MON-3
27.185 6.5       7


0       2.5
72.745  6 5
88.1 3 6


9.5 8
144.390 5.5 5
152.91  trace 4
154.465  5 5
162.4  4.5 5
171.025    7   7
253.55  (trace)   (trace)
406.175 same  full quieting, no S reading
411.550 weak, no S reading Very weak, no S reading
453.4 3.5  2
462.775  9  9+10 dB
499.7375 5    3
864.7375  (trace)  full quieting, no S reading
880.320  9    9
996.0125  good   (trace)


Considering variables such as different cables and lengths, slight pattern differences, and time delays between switching out the antennas, we considered their performance to be very similar. A user would be hard pressed to choose between one or the other based upon signal reception.


For further information and pricing on these products, contact Par Electronics, Inc. PO Box 645 Glenville, NC 28736-0645. Voice: 828-743-1338 Fax: 828-743-1219 Email



Hamtronics LNK-WB Wideband Preamplifier



It's a universal myth that the best way to hear weak signals is by adding a preamplifier to the antenna line. Preamps almost invariably aggravate reception by increasing front-end-overload problems like intermodulation ("intermod"), recognized by the mixed sounds on several frequencies.


With scanners, intermod often includes the beeping garble of digital paging transmitters, or the voice sounds from two different communications transmissions. The interference frequently contains the music of a local FM broadcaster as well. On shortwave, a common malady resulting from over-amplification is a constant background din of sounds from a myriad broadcasters and strong utility signals.


Often, inexperienced hobbyists will be disappointed after adding a wideband preamp only to hear the background noise ("hiss") increase noticeably, another shortcoming of inappropriate additional gain. And wideband amplifiers have considerably higher noise figures than narrow-band amplifiers, somewhat akin to selecting a narrow-bandwidth filter to reduce wideband hiss on a receiver.

            But there are situations in which a preamp can help: rural locations where all signals are low; UHF and microwave bands where distant signals such as satellites are weak; or on antennas ahead of a long, lossy feedline. Another common use for a wideband preamplifier is in a laboratory environment to boost weak signals adequately to be analyzed with test instruments.


If preamps were the ultimate cure-all, professional receiving installations would simply install a marginal antenna and toss a preamplifier in line, but they don't; they design the best antenna they possibly can, and if additional preamplification is necessary, they choose low-noise preamps with only moderate gain, and add plenty of filtering to block frequencies or bands which contribute to strong-signal overload.


Now that we've characterized the appropriate use of a preamp, let's take a look at a good, affordable, wideband preamplifier from a long-time player in the ham radio market, the Hamtronics LNK-WB. Housed in an anodized aluminum case measuring 3-1/2"L x 1-1/2"W x 1-1/4"D, it is affixed with two female, chassis-mount BNC connectors, and a protruding, 24" length of wire to attach +12 to +15 VDC at 10 mA of current. The negative terminal is the metal case.


Inside the box is a single 2SC2369 low-noise, bipolar microwave transistor, a popular part number designed for just this application, and its supportive bias and isolation components. An "idiot" diode is in line to prevent accidental damage from reverse-polarity power connections – as I've done too often myself!


The preamp provides 10-20 dB gain from about 10-500 MHz, gradually decreasing to around 5 dB at 1000 MHz. It cannot be used for transmitting.


Our Test


The LNK-WB was connected between an outdoor log-periodic antenna and an ICOM R8500 receiver to measure received signals.


Without bandpass filtering to remove strong signals from FM broadcasters and paging transmitters, the LNK predictably generated high intermod products, characteristic of small-signal bipolar transistors. Hamtronics warns prospective customers of this on their web site. Bandpass filtering tamed the unit considerably, and its general performance matched the advertised specifications.


With consideration given to its limitations in a strong signal environment, we judge the LNK-WB to be a good value for general purpose, wideband, small-signal amplification. Hamtronics also offers preamplifiers from 24-470 MHz for narrow-band applications


The LNK-WB is available for $59 plus $7 shipping U.S. from Hamtronics, 65 Moul Rd., Hilton, NY 14468-9535. For information, call  (716) 392-9430 or visit their web site at



Yaesu VR-5000 Scan Fix



Yaesu has supplied the following replacement page to the VR-5000 manual correcting the procedure to be followed for doing a programmable memory scan.


Programmable (Band Limit) Memory Scan (PMS)


This feature, a more refined and useful form of VFO scanning, allows you to establish sub-band limits for scanning. This allows you to monitor only a portion of the wide frequency range of the VR-5000, instead of sweeping the entire spectrum from 100 kHz to 2.6 GHz.


Programmable Memory Scan utilizes a pair of frequencies to establish the upper and lower scanning limits within special memories. Here is the procedure for setting up limited band scanning:



1.         Press the [F] key momentarily, then press the [PMS(PMS SET)] key to enable the storage of the frequency pair into a PMS memory.

2.         The cursor will be pointing at the “PMS CH” menu option; press the [ENT(SET)] key.

3.         If you want to program the frequency pair into the currently-selected PMS register (shown on the right edge of the display), proceed to the next step; if you wish to choose a different PMS register, press [ENT(SET)], then use the [q(t)/p(u)] keys to select a different memory register number. Then press [ENT(SET)] to move on to the next step.

4.         Rotate the DIAL knob to set the cursor to the “PMS TAG” menu option.

5.         Press the [ENT(SET)] key to enable the programming of the name tag to the PMS memory. To attach an alpha/numeric name tag to the PMS memory, program the alpha-numeric “label” using the DIAL knob and keypad, as described previously; if you don’t want to label this frequency pair register, press the [ENT(SET)] key again.

6.         When you have complete the creation of the label, press the [ENT(SET)] key.

7.         Now it’s time to set up the band limits. Rotate the DIAL knob to set the cursor to the “START F” menu option, then press the [ENT(SET)] key.

8.         Set the VFO frequency to the Lower sub-band limit, then press the [ENT(SET)] key.If you programmed the frequency using the keypad, press the [ENT(SET)] key again.

9.         Confirm that the cursor is on the “END F” menu, then press the [ENT(SET)] key.

10.       Set the VFO frequency to the Upper sub-band limit, then press the [ENT(SET)] key.If you programmed the frequency using the keypad, press the [ENT(SET)] key again.

11.       Rotate the DIAL knob to set the cursor to the “END” menu option, then press the [ENT(SET)] key.

12.       Confirm that the cursor is on the “WRITE” menu option, press the [ENT(SET)] key.

13.       The PMS memory programming process for this register is now completed.


Note: 50 PMS memories are available. You therefore can set upper and lower operation limits on a number of bands, if you like. Each PMS memory register, remember, stores both the lower and upper frequency limits.


Operation (Current PMS Register)

1.         Press the [PMS(PMS SET)] key to initiate PMS scanning in an upward direction.

2.         If the scanner encounters a signal strong enough to open the squelch, the scanner will halt and pause on that frequency. Scanning will resume according to the protocol you selected in the previous discussion.

3.         To change to a different PMS frequency pair, press the numerical keys on the keypad corresponding to the PMS register you wish to use. For example, if you are on PMS register “00” and wish to use PMS register “03,” press [0] + [3] while PMS scanning is engaged. Scanning will begin on the new register without further action.

4.         To reverse the direction of the scan (i.e. toward a lower frequency, instead of a higher frequency), turn the DIAL knob one click in the counter-clock direction or press the [q(t)] key momentarily while the VR-5000 is scanning. To revert to scanning toward a higher frequency once more, rotate the DIAL knob one click clockwise or press the [p(u)] key momentarily.

5.         Press the [V/M(MW)] key to disable the PMS scanner, and return to VFO mode.

Flight Explorer Personal Edition


By Ian Doyle


For US aviation hobbyists or for those whose interest lies in HF, you may be interested in Flight Explorer Personal Edition. This is a fabulous product which enables listeners to track real-time aircraft flight-planned to/from the USA and certain transoceanic routes to/from the USA. Flight Explorer has been in existence for a number of years and, for just a small subscription fee, it enables the individual to access information usually available only to airlines.


Flight Explorer will run on a “reasonably fast PC” using a standard internet connection (dial up or dedicated). The aircraft data is provided from the Flight Explorer (FE) data center and will provide the user with a real-time graphical image of aircraft currently flying at any altitude over the US (Including Alaska and Hawaii), and US “tracked” aircraft over parts of Mexico, Canada and the Atlantic and Pacific Oceans.


Registering is easy via a secure signup from the Flight Explorer Personal Edition section of Avweb ( After registering, you can download the client software and once payment has cleared you will be sent the install code for the software. Once installed, you will be able to fully access the web page and use the product proper via the user selected ID and password.


Two versions of the software are available; the one for which most monitors opt is Personal Edition, which costs USD $9.95 per month for 10 hours usage, charged monthly to your credit card. This should be adequate for most hobbyists. If, however, you are feeling flush, there is a $250 Professional Edition which encompasses a number of enhancements aimed at the corporate airline or professional user; it has a variety of additional features as well as unlimited connect time.


Using Flight Explorer


Once you have an account and user ID, and you have successfully run the set-up programs and logged onto the site, what can you expect? Well, this is truly an Aladdin’s cave of treasures. Flight Explorer will allow the user to monitor any aircraft which is flight planned in or out of the USA.


As a large percentage of HF aviation listening is done over the Atlantic Ocean, Northern Canada, The Caribbean and South America, the advantages of access to a package like this are obvious. Being able to see graphically what you can hear increases the interest enormously.


When you first log on to the site you will see a picture of the world with every aircraft lodged with the centre represented as a dot. It is, however, possible to click and drag on a particular area, for example, the Caribbean. So if we're listening to the HF Caribbean Net and want to identify a particular aircraft that is providing a position report on HF, simply right click on the aircraft icon and then click “Properties.” The aircraft type, airline, position, height, speed arr/dest airport will all be displayed. If you “tag” an aircraft, this information will be retained as the aircraft moves across the screen.


We may, of course, actually hear an aircraft and wish to interrogate the flight details. Press the horizontal aircraft icon in the top right of the screen; this will clear the screen in readiness for our query. Now press the “Quick Filter Option” and key in the flight number heard. If this is flight planned into or out of the USA it will appear as a dot on the main screen. Ensure that the aircraft you are monitoring does actually correspond to the one are that you can see visually on screen; otherwise the aircraft  may not appear, because of being outside the interrogated range.


Numerous other search/filter options are available in this mode. You can input Flight Numbers, Aircraft Types, or Airport Codes; all aircraft currently in the air with a live flight plan to or from the USA will appear. Again, you must remember to clear the screen after each query. It is also possible to overlay the latitude and longitude coordinates, which is particularly useful over the North Atlantic, Canada and Pacific Area.


One word of caution; in some cases of transoceanic routes beyond radar range, the data provided can appear up to 40 minutes old, as only the last reporting point is provided. Hence, the reason the picture over the North Atlantic consists of rows of dots in vertical groupings. Despite this limitation there are still numerous advantages in using the software.  


Although not relevant to the UK, various overlays can also be added with the additional of beacons, navaids, airways and ATC sectors within the USA. This is useful for monitoring the Caribbean area, where, sadly, aircraft serials do not appear.


Another very useful feature is the “Flight List Look Up.” A list of all tracked aircraft in the system will be displayed, showing aircraft ID, origin, destination, aircraft type, altitude, speed, departure time, ETA, or status for each aircraft. The list can be sorted by any of the criteria just by clicking on the title bar.


Once again, this is a superb product and is bound to be of tremendous interest to the serious HF monitor with an interest in aircraft. Although there has been much criticism of the Internet, there seems little doubt that technology that would have been unthinkable five years ago is now a reality, I feel sure that many readers would agree that such developments will only enhance the future of radio monitoring and the general radio listener!


Editor's Note: This review originally appeared in Shortwave Magazine. The author, based in the UK, uses Flight Explorer to monitor international flights while listening to HF communications. However, the program covers overland flights as well, and anyone  can tune in to tower communications at a large U.S. airport via internet-streamed audio while watching the planes arrive on their screen. Jean Baker also reported on Flight Explorer in Plane Talk, June 2001.


The Spectrum Analyzer as a Receiver 


By Bob Grove


Those of us who hunger for gadgets occasionally come across equipment intended for another use and wonder whether it would work for our applications. Such a device is the spectrum analyzer, a highly-useful instrument for the electronics professional.


Spectrum analyzers paint a visual display of busy frequencies across their screens. Some even have audio recovery so that modulated signals can be monitored audibly as well as detected and measured visually.


But how do spectrum analyzers compare with dedicated communications receiver and scanners? After all, spectrum analyzers are considerably more expensive, so shouldn’t they work just as well for listening?


The short answer is no. Spectrum analyzers do have receivers in them as a primary subsystem, but their performance falls far short of that of communications receivers and even inexpensive scanners in terms of signal reception. Let’s see why.


The Blonder Tongue BTSA-8558C


As a case in point, let’s examine the specifications and performance of a very nice, low-cost spectrum analyzer, the BTSA-8558C, manufactured by a noted TV test equipment company, Blonder Tongue Laboratories.


Intended for benchtop, mobile, and field applications, the 8558C is loaded with features. Its slim profile (10-1/2”W x 3”H  x 16”D), unusually-light weight (9-1/2 lb. including battery), and universal power supply (AC, 12 VDC, and internal batteries) invite portability.


A bright, green-trace, 3” CRT displays signals visually; a smoke-grey dust cover may be left over the face plate for dust and impact protection, or hinged upward for access to the controls. A small, thermostatically-controlled fan automatically cools internal temperatures. 


The 8558C has a continuous frequency range of 100 kHz-1020 MHz; demodulates AM and FM signals so that they can be monitored with its internal speaker; incorporates several selectivity bandwidths; may be set to display as much as the entire 1000 MHz at one time or just a few kHz; has a 4-digit frequency display; and can be powered by AC, DC, or its own internal battery for nearly an hour.


The spectrum analyzer comes with an AC adaptor/charger, light shield for the CRT screen, canvas carrying back, BNC adaptors, and a protective transparent panel cover. Available options include a noise generator, interchangeable power pack, audio/video generator, reflectometer bridge, and cigarette-lighter power adaptor.


But we must not lose focus on the fact that this is not a communications receiver; it is a test instrument designed for specific applications, not for listening to signals. For serious sleuthing for elusive, weak communications signals, or continuous monitoring of their modulated contents, a low-cost spectrum analyzer just won’t hack it.


Blonder Tongue lists several recommended applications in the instruction manual: RF product design and production testing, signal analysis, interference compliance and detection, technical measurements in the broadcasting industry, and security/surveillance. And for these applications, the 8558C works well.


But as a receiver, we need to examine the specs a little closer.


First of all, sensitivity is not near that of a communications receiver or scanner; while we can add a preamplifier to boost the sensitivity, the 8558C has a third-order intermodulation figure of only  -65 dB, promoting strong-signal overload in a busy RF environment. In the absence of automatic gain control (AGC), a manual, 8-position attenuator is adjusted, as is a three-position toggle switch for both the display and recovered audio.  


While the 8558C has a digital frequency readout, its best resolution is a wide 100 kHz; and because of its voltage-controlled oscillator system, the readout is not accurate and the signal drifts. This is acceptable for wideband video and aural broadcasting signals, but voice communications bandwidths are ten times narrower. No SSB mode is provided, but the drift would make sideband detection intolerable.


Selectivity of the 8558C may be set as 30, 300, and 3000 kHz (that’s 3 MHz!); VHF/UHF voice channels are typically spaced 12.5-15 kHz or even closer. With communications receivers boasting voice/data  filter selectivities of 3-15 kHz, and filter shape factors of a sharp 2:1 or 3:1, the 8558C’s 14:1 means that if two or more adjacent signals transmit simultaneously, the strongest signal wins; the others are covered up.


Audio is derived by slope detection; this means that AM signals come in well, but FM is distorted, requiring off-center tuning which reduces sensitivity further.  And you can’t sweep visually and monitor aurally at the same time. The procedure is to tune through the panorama of frequencies on the screen, centering an interesting signal spike, then stepping the span switch down to “0” which engages the audio recovery, but deactivates the sweep.


But there is considerable response lag between switching the span switch from visual sweep to audio recovery -- some 4-5 seconds, then more lag between the turning of the tuning knobs and the response of the circuitry -- another two or three seconds, imbuing a “rubbery” feel to the fine tuning procedure.


A one-inch tuning knob traverses the entire 1 GHz of spectrum in just eight turns; a separate fine-tuning knob permits touching up after the coarse frequency is set.



The Bottom Line


Next to multimeters and oscilloscopes, spectrum analyzers are the most versatile pieces of test equipment at the technician’s disposal. But they are test instruments, not communications receivers or scanners. Provided you know how to use them, they are invaluable for tuning up receivers and transmitters, making antenna adjustments, trouble-shooting defective equipment, aligning satellite systems, and technical surveillance countermeasures (TSCM), the professional term for “debugging” or “sweeping” for surreptitious listening devices.


If a radio transmitter is operating anywhere in the frequency range that the spectrum analyzer is capable of tuning, it can be found in a snap. Even spectrum-hopping and spread spectrum can be seen on the scope when properly adjusted. And for determining the presence of unknown agencies, licensees, or non-licensees on the air, a spectrum analyzer can’t be beat.


The versatile BTSA 8558C lists at only $3295 and is available from Grove Enterprises (PO Box 98, Brasstown, NC 28902; 800-438-8155 or


AOR TDF370 Multimedia Digital Terminal

By Bob Grove



Seldom have we come across an affordable device with so many modes and applications for receiving and transmitting as this new AOR accessory. Operable either as a stand-alone device, or in conjunction with a PC for control, the TDF370 has a tactile membrane keypad and back-lightable LCD display. The two-line display shows encoder/decoder settings in the first line, and up to 16 characters for the message in the second line. The unit may be powered by an optional AC adaptor (9 to 15 volts, regulated preferred), or by four AA alkaline cells (not included).


A built-in speaker allows temporary monitoring of the signal for tuning purposes, but an external speaker is recommended for listening. A pair of ear buds is included for monitoring simulated stereo through the earphone jack; while quite usable, we used a padded, stereo headset. And now let's have a look at all those functions:


A fast Fourier transform (FFT) digital filter scrubs the desired audio contents of a signal clean from background noise.


Simulated stereo lets the desired signal -- voice or CW -- "hang in the center of your head," away from the interfering left- and right-channel background interference. Simulated stereo, although not new to communications, works well in the TDF370. While plenty of filtering is available to further cleanse the signal from interference, the stereo effect alone isolates the desired audio dramatically.


Separate bandpass and adaptive filters do a remarkable job in separating signals from interference. The pushbutton functions work in conjunction with a two-level key for adjusting frequency centers and bandwidths. An automatic notch function is also selectable.


An eight-frequency-band microphone equalizer custom-contours the voice characteristics of your mike and and cancels background noise for optimum audio. This is a multiple-application benefit for hams, CBers, public safety and commercial two-way radio users, broadcasting, and public address.


PSK31 (BPSK and QPSK packet) and RTTY (170/425/850 Hz shift radioteletype) signals may be both monitored off the air and displayed on an LCD, as well as generated when the unit is connected to a transceiver and computer. Tuning is effectively accomplished using only the LEDs on the unit's panel.


A digital audio recorder permits the storage of up to 102 seconds of received or transmitted audio -- any mode -- in eight memory slots for playback. Since the circuit constantly monitors streaming audio, the activation of the recorder includes six prior seconds of audio so that no information is lost during the slow response time of the operator. Clever idea.


Slow scan TV (9600 bps at 56.7 kHz) is supported by the unit, but requires optional software and a computer for viewing images.


The TDF370 comes with stereo ear buds, computer serial cable, shielded audio cable terminated in 1/8" (3.5 mm) mini plugs, stereo connectors for custom I/O attachment, 8-pin mike connectors, a DC power cord for connection to a recommended regulated supply, and a complete, illustrated manual.


The Bottom Line


All in all, we were very impressed with the capabilities of this welcome accessory. Functions were carefully laid out with an excellent selection of options. The keyboard is easy to use, as are the two rotary controls. Best of all, the sound quality of recovered audio is excellent.


The TDF-370 is available for under $300 from AOR dealers.



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