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Monday, December 14, 2009

DXing The Shortest Days


It's that time of the year again when the days are the shortest and the nights the longest. There are barely 10 hours of daylight here in southwestern Arizona, as the sun is rising at 0724L and setting at 1722L. D-layer absorption during daytime hours is at the lowest this time of year. Today, at the noon hour, I went on a little mini-DXpedition to a nearby hilltop which gave me a 360 degree view. I started DXing at 1130 local time and continued till about 1230 local.

Radios used were the Tecsun PL-600 and the unassisted truck radio. The Tecsun PL-600 was assisted with the 24-inch box loop. Here are the highlights:

660 KHz, 1130L, KTNN, Window Rock, AZ. 50KW (truck radio). Medium strength, but easy. 327 miles.

740 KHz, 1135L, KBRT, Avalon, CA (Catalina Island, "26 miles across the sea"). 10KW (PL-600 and truck radio). Strong on the truck radio and overriding KCBS, San Francisco. 239 miles.

760 KHz, 1145L, KKZN, Thornton, CO. 50KW (PL-600). 675 miles at the noon hour! Progressive Talk Radio. Signal was in and out, weaker and underneath San Diego's 50KW powerhouse KFMB. I was able to partially null KFMB using the box loop, which made the difference. Great daytime DX.


1090 KHz, 1221L, XEPRS, Rosarito, Baja California, Mexico. 50KW (PL-600). Weak, but readable, peaking to medium at times. This is Baja's XX Sports Radio, broadcasting in English to San Diego from an appreciable distance down the Baja peninsula. Studios are reportedly in San Diego. 186 miles.

1120 KHz, 1210L, XEMX, Mexicali, Baja California, Mexico. 400 watts (PL-600 and truck radio). Broadcasting oldies. 100.9 miles. Good reception for 400 watts.

Now for the amazing "pipeline" station, which always seems to put some kind of a signal into southwestern Arizona at any time of year:

700 KHz, 1225L, KALL, N. Salt Lake City, UT. 50KW (PL-600 barefoot and truck radio). 514 miles.


KALL is the amazing one, not for distance but for signal strength. Though I have heard this one before during the daytime, this time of year it seems to have a pipeline into the southwest. Signals on the unmodified truck radio were absolutely astounding. Note that the distance here is in excess of 500 miles at the exact center of the daylight period. Shown is the beautiful location of KALL's tower array.

Try some daytime DXing during this time of year, particularly near mid-day. You might be surprised at what you can hear.

Sunday, November 29, 2009

WWL New Orleans Finally Logged


November 25, 2009

WWL-870, New Orleans, LA (50KW) appeared this morning at 0455L (1155 UTC). The signal was weak with much phase distortion, however, it is now finally and positively logged! Received both on the Tecsun PL-600 barefoot and with the 24-inch loop.

A 24-Inch Box Loop On A Budget


Last week I completed construction of the 24-inch box loop. As previously described, the frame is composed of 1 x 2 inch furring strips, notched at their centers, and screwed together to form a cross. Length of each member is 33.9 inches (24 x 1.414). A 36 inch piece of 3/4 x 3/4 inch wood is screwed to one of the cross members to form a pivot, which will rest on the ground, elevating the loop to chair height.

Using a wood file, a wide, flat notch was cut at the end of each member to keep the coil turns in place. Sixteen turns (128 feet) of 20 gauge insulated wire was then close-wound on the frame, secured by small nails at each end.

Earlier this summer I rescued a small AM-band variable tuning capacitor from a very old transistor radio. It will serve as our tuning device. Using vinyl electrical tape, I taped this to the end of one of the cross members. These capacitors are actually two capacitors in one. In a superhet radio, one section tunes the signal and the other section tunes the superhet oscillator at 455 KHz higher than the signal, therefore this second section's capacitance is less, and not usually usable for tuning a wide range. We will use the section with the greater capacitance (the first section mentioned) to tune the loop.

Tuning range of the loop was found to be 530 KHz to about 1400 KHz. A short clip lead is used to short about five turns of the coil to allow tuning to the top (1710 KHz) of the band.


Turning the loop, signal peaking and nulling is fairly sharp. Signal strength increase over a barefoot radio is excellent and better than a 7-inch inductively coupled, tuned loopstick. Local electrical noise pickup is low, but the loop will transfer noise if pointed towards close noise sources. Atmospheric noise pickup is very low, and the signal-to-noise ratio seems markedly better than the tuned ferrite loopstick.

Performance. Inductively coupled to the Tecsun PL-600, signal strengths off the loop are equal to or greater than the 240 foot longwire attached to the Eton E1 last winter here at this location. 500+ mile mid-day DX is routine. KGO-810, San Francisco, CA, and KALL-700, N. Salt Lake City, UT are exceptional during the day using the loop, and are not receivable using the barefoot PL-600.

The 24-inch loop is a good compromise between a small loop and a large one. It is easily transportable. Try building one for yourself.

Friday, November 20, 2009

Fresh Japanese Catch This Morning


Nice signals out of Japan this morning at 0710L (1410 UTC). Caught both JOUB-774, Akita, and JOAK-594, NHK-Tokyo. Audio fair to good on JOUB, and fair to poor on JOAK. This is the first time I have heard readable audio out of JOAK. Both stations received with the Tecsun PL-600 barefoot. Tried to enhance the signals with the tunable loopstick, but no luck, the background noise came up right along with the signals.

Thursday, November 19, 2009

Mid-Week Report


Started building a 24 inch box loop Monday. It is made from 1 x 2 inch furring strip, the cross notched at the center and screwed together. Left is to wind the wire and install the variable capacitor. Am planning to use a small transistor-radio variable cap, due to not having a standard sized one at the moment, though not sure if it will work yet.

Checked for JOUB-774, Akita, Japan three times this week. It has not been in at a strength where audio is recoverable, just a carrier present. Carrier is present on 594 KHz, presumably another Japanese station. The Tecsun PL-600 makes tuning for carriers very easy in SSB mode with the nice BFO knob.

Just at sunrise this morning I caught both KKOH-780, Reno, NV (50KW) and KAZM-780, Sedona, AZ, playing tag with each other for superiority. Not sure of KAZM's power at that time as it was just minutes before sunrise. It runs 250W nighttime and 5KW daytime. WBBM-780, Chicago, IL, was long gone by that time of course.

Strung 180 feet of wire across the property early in the week. Unfortunately, I am right near a power line and the noise on the BCB band is rather objectionable. I think I'll give up on the long wire this winter since I'm in town and go strictly with the loops and tunable loopsticks.

Monday, November 16, 2009

Out West Again


I am in Arizona again, at the little desert town of Quartzsite.

THE TRIP REPORT

Just as the landscape changes incrementally as you cross the country, so does the radio reception. From Rochester, NY, WSM-650 out of Nashville, TN is not receivable during daytime hours. Cross over into Ohio and then head southwest out of Cleveland, and it suddenly appears, weakly at first, then getting stronger as you approach the I-70 cross-country corridor. Astonishingly, it remains readable all the way to St. Louis and into Missouri during daytime hours, where it finally fades to nil.

Spending night one near Spiceland, Indiana, near Indianapolis, the next morning before sunrise the Cuban radio time ticks are quite strong. I tune down to 530 KHz, and there is Radio Enciclopedia, weak, but copyable. Now why do I have so much trouble with this station in Rochester? KOA-850 Denver, CO is also in there, as is WBAP-820 in Dallas, TX. Both are tough catches at home. We proceed west.

Night two is spent in Joplin, Missouri, the extreme southwestern corner of Missouri, just 7 miles from the Oklahoma border. Leaving at 6AM, hopping on the Will Rogers Turnpike after crossing into Oklahoma, I tune to 530 KHz. There, and beaming in like a local this morning, is Radio Enciclopedia again. We are at mid-country now, and I wonder if the west coast is in. Tuning up to 640 KHz, there is KFI, Los Angeles, weak but readable. Nice!

As you pass Oklahoma City and get onto I-40, heading west, long distance daytime DX starts to show. KGNC-710, Amarillo, TX is readable from 40 miles west of Oklahoma City. The land becomes flat as a pancake, and mostly treeless. Passing Amarillo, from the panhandle of Texas, the "Talk Monster", KKOB-770, Albuquerque, NM (50KW) appears, very weak, at a distance of several hundred miles.

At night three I arrived in Tucumcari, NM, and the remainder of the trip was spent camping in the wilds of New Mexico and Arizona. But from this point on, little DXing was done, except to see how far west WWL-870, New Orleans, LA could be heard. Benson, Arizona, 40 miles southeast of Tucson, seemed to be the practical limit, where is was very weak at sunset, while camped on a mountain top about 10 miles north of town. I am going to make a concerted effort this winter to see if it is receivable in Quartzsite (extreme western) Arizona, near the California state line.


LATEST DX

November already. On the Yahoo Ultralight group, I've been reading recently that JOUB, 774 KHz, Akita, Japan has been receivable all the way into Oklahoma for most of October. Last week I decided to have a check of this frequency at sunrise. It was receivable for three of the five days I checked, Nov 8-10, on the Tecsun PL-600. On Nov 10, the signal was strong enough to copy the audio on the Sangean DT-400W barefoot! A nice catch.

WWL-870, New Orleans, LA, is still elusive. One October evening just at sunset I caught WBBM-780, Chicago, IL underneath another station. Chicago is a long way from here, well outside the usual 1200 mile nighttime DX bubble.

Finally, long distance daytime DX is a daily thing. With the tunable loopstick, KKOB-770, Albuquerque, KALL-700, North Las Vegas, NV, and the San Francisco stations KNBR-680, KCBS-740, and KGO-810 are copyable on both the Tecsun PL-600 and Sangean DT-400W. All are in excess of 500 miles except for KKOB.

A day off today, and I might spend it building a box loop! Hope to have more reports soon.

Thursday, October 1, 2009

Arizona Bound


Tomorrow I'll be heading to Arizona for the six month winter season again. This week I've been arranging radios and wire and books in preparation. I'll be taking the new Tecsun PL-600, and the ultralights, but leaving the Eton E1 at home. The box loops may stay at home this year, as they take up a lot of room. Quite possibly I might build a portable box loop while I'm there. Other antenna experimentation is a distinct possibility.

I'll be doing some DXing as I cross the country from New York to Arizona. The next report back here on the blog will be from the Great American Desert, when time permits. At the other end, DXing from southwestern Arizona is always a thrill - super-quiet conditions, lots of open space, minimal IBOC interference, low splatter quotient because the big guns are a long way off, routine 500+ mile daytime DX, and Mexico right in your backyard. Looking forward to the trip, and the new DX excitement it brings!

73 to all!

Sunday, September 27, 2009

DXing The Edge


Out at the edges of the mediumwave broadcast band here in the western hemisphere - that would be 530 KHz and 1700 KHz - channels are thinly populated. US stations don't operate at all on 530 KHz. Here you will find only a few Canadians, a single Cuban, and a small handful of others. At the other end - at 1700 KHz - in the area called the X-Band (1620 KHz - 1710 KHz), the US is sparsely populated at best by only a half-dozen or so stations per channel. These stations generally run 10KW during daylight hours and only 1 kilowatt at night. The relatively low power and far-spaced distances make for some very interesting nighttime DX possibiltities, "sans interference". Let us continue....

The following station lists have been garnered from the FCC lists, the latest (2009) World Radio TV Handbook, and the Internet.

530 KHz

CKHL High Level, Alberta, Canada 1KW/400W (defunct)
CIAO Brampton, Ontario, Canada 1KW/250W
CJFT Fort Erie, Ontario, Canada 250W (defunct)
CIRS Sault Ste Marie, Ontario, Canada 50W (tourist information)
TIRI R. Sinfonola, Cartago, Costa Rica 10KW
R. Enciclopedia, Havana, Cuba 10KW
R. Vision Cristiana International, S. Caicos (Turks & Caicos) 40KW
La Voz de las Madres, Capital Federal, Argentina (power unknown)
R. Republica, San Justo, Argentina 5KW/1KW
HCDC1 530 AM (Radio Iris?), Quito, Ecuador 1KW
FIRS, Stanley, Falkland Islands 15KW

1700 KHz

KBGG Des Moines, IA 10KW/1KW
WEUP Huntsville, AL 10KW/1KW
KVNS Brownsville, TX 8.8KW/880W
KKLF Richardson, TX 10KW/1KW
XEPE (XEKTT) San Diego 1700, Tecate, Baja California Norte, Mexico 10 KW
R. Eternidad, Santo Domingo, Dominican Republic 5KW/1KW (daily, 6AM-7PM, per web site)
R. City (possibly inactive), Partido de Almirante Brown, Argentina
Radio Cristiana Príncipe con Dios, Villa Fiorito, Argentina

1710 KHz

AM 1710, R. Estudio ESBA, Capital Federal, Argentina
OBU4R R. Nuevo Tiempo, Huancayo, Peru


So back to the DXing. Two nights ago I couldn't sleep. I found myself wide awake at 3AM. In the middle of the night I fired up the Tecsun PL-600 receiver and parked it on 1700 KHz and waited. Conditions were good. The Kp-index was at 0 or 1, very low. In one hour I had logged three stations and a possible fourth.

Loggings for Sep 26, 2009:

1700 KHz, 0715 UTC, KBGG, Des Moines, IA. 1KW 814 miles. ESPN, sports talk. Local Des Moines ads.
1700 KHz, 0732 UTC, KVNS, Brownsville, TX. 880W 1621 miles. Positive ID at the 30 minute news break.
1700 KHz, 0750 UTC, WEUP, Huntsville, AL. 1KW 741 miles. Positive ID.

And a possible fourth?
1700 KHz, 0755 UTC, KKLF, Richardson, TX. 1KW 1227 miles. Ads for the Richardson/Dallas area.

In between, I tried a couple of other frequencies:

1600 KHz, 0738 UTC, WAAM, Ann Arbor, MI. 5KW 309 miles.
1710 KHz, 0745 UTC, ????, Spanish music. Weak, and in and out of the noise.

What's this? Oh, now this is interesting. The only stations documented to be on 1710 KHz are in South America - Argentina and Peru. Could it be?


The next morning, September 27, on my way to the coffee shop at 6AM I turn on the truck radio. Fading up out of the noise between 5:55AM and 6:05AM is some nice Spanish music. No ID at the top of hour, though. For fleeting seconds, here and there, it fades in, weak, but readable. Remember what I said about the greyline in a previous post? I check the greyline map for this time frame sometime later in the day. Perfect conditions - a nice greyline path to Argentina and Peru at 6AM! Perhaps one of these was the station I heard? I will keep trying.


R. Enciclopedia, Havana, Cuba, still eludes me on 530 KHz. I hear Spanish on this frequency occasionally, but no positive ID yet. CIAO, Brampton, Ontario, Canada dominates as it is just across Lake Ontario from this location. And it will not totally null in the receiver, not in the evening or early morning. I am also hunting for XEPE San Diego 1700, a 10KW station I hear routinely when I am wintering in southwestern Arizona. One day it will make the trip all the way to New York.

DXing the edges of the mediumwave band can be fun. Give it a try.

Saturday, September 19, 2009

Calculations For The MW DXer

Two calculations are imperative to the mediumwave DXer.

1. Sunrise/sunset time for the distant station.



Signal enhancement occurs during sunrise and sunset times, both at the home location and the distant location. Seasoned DXers know this. Knowing when to listen is all-important. But when is sunrise and sunset at the distant station? Latitude and longitude for the station must be known for the calculation. These are available from the FCC database in a previous post, and other locations on the web. Also, and obviously, you must know the time of year: day and month, since sunrise and sunset times change day by day.

2. Distance to the received station.



Sometimes more an interesting statistic than anything else, distance helps somewhat in judging how good the DX is, and makes for an interesting fact in the station log. Again, latitude and longitude for the station must be known for the calculation as well as your own latitude and longitude. So, how can we calculate these? Luckily, both can be had freely on the web.

Probably the most accurate sunrise/sunset calculation on the web is the one presented by NOAA, The National Oceanic And Atmospheric Administration:

NOAA Sunrise/Sunset Calculation

The FCC also has a sunrise/sunset calculator, since it is in the business of policing its radio stations on daylight, nighttime, and critical hours activities:

FCC Sunrise/Sunset Calculation

See NOAA again for a nice distance calculator:

NOAA Distance Calculator

If you get into field strength calculations (see my series on this), you need a distance calculator that also returns the bearing of one latitude-longitude to another. The FCC has a great one.

FCC Latitude-Longitude Distance Calculator

And another interesting distance calculator which has been out on the web for a long time, though spartan, by Chris Michels:

Chris Michels Distance Calculator

Distance can be calculated in statute miles, kilometers, or nautical miles.

Two factors weigh heavily in DXing MW stations: think "Greyline" and "Solar Kp-Index".



Solar Kp-index is an index of geomagnetic activity. Kp-indices of 5 or greater indicate storm-level geomagnetic activity, and geomagnetic storms are not good for great DXing. Geomagnetic storms have been associated with satellite surface charging and increased atmospheric drag. For good mediumwave propagation, think Kp-indices of 2 or less. 1 or 0 is even better, and you will hear the difference on your receiver on a good night. NOAA has a great site which predicts the solar Kp-index over the next three days:

NOAA Kp-Index 3-Day Forecast

It is also presented in graphical form here, a site I refer to often:

NOAA Kp-Index 3-Day Forecast (Graphic)

In the graphic, check out the time period on September 18 from 0600 - 1200 UTC. A very low Kp-index. Conditions were great. These data are made available through the cooperation of the Geological Survey of Canada (GSC) and the US Geological Survey.

More information can be had about the solar Kp-index here:

NOAA Solar Kp-Index Information



Now, how about that Greyline? The line that separates day and night is called the terminator. It is also referred to as the "grey line" and the "twilight zone." It is a fuzzy line due to our atmosphere bending sunlight, separating day and night, and usually lasts some 30 to 45 minutes after sunset or before sunrise. Stations or receivers at sunrise or sunset and in the terminator zone will exhibit enhanced propagation characteristics through the nighttime path. It's easy to know when we ourselves are in this zone, harder to know when the distant station is. Use the sunrise/sunset calculator to figure the sunrise/sunset times for the station of interest. Watch for the "pipeline effect". That is when both you and the distant station are in the greyline - you have continuous greyline between you. Signals can be greatly enhanced during these times.

To see where the realtime greyline is right now, check out these sites on the web:

Greyline#1 - www.fourmilab.ch
Greyline#2 - www.fourmilab.ch
Greyline#3 - www.die.net/earth
Greyline#4 - www.daylightmap.com

More information can be had about the greyline on the wikipedia.org web site.



And now for a program plug. DX Atlas, a program developed for amateur radio operators, has a wonderful mapping ability to display the current greyline for your location, or for any other time of year. This program by Alex Shovkoplyas, VE3NEA, is outstanding. It even has the ability to create ionospheric maps, useful for the shortwave spectrum. DX Atlas is shareware, and requires registration and purchase after 30 days.

A Brick No More


And the Eton E1 crisis has been resolved, at least so far. "gkinsman" responded to the previous post about my E1 problems and suggested a fix he saw in the Yahoo Eton E1 group. Something about a "stuck light switch". Well, after fiddling with the light switch on the E1, it suddenly sprang to life. And, it is working on battery power again, too. Seems to be stuck in Timer mode for the moment, but I think I can resolve that. A big "THANKS" to "gkinsman" for the tip!

I stick by my late comment, though, "This will be the last portable radio I spend $400 on". Too much money for a portable. But it's great having the E1 back in working order.

Friday, September 18, 2009

The $400 Brick


Someone once said that life is all about constantly "saying goodbye". Well, goodbye fair Eton E1. You were a great receiver while you lasted. Am I frustrated? You bet I'm frustrated.

Note: Problem resolved! See this post.

I hadn't turned this receiver on for about three weeks. Yesterday I thought I'd take it outside and check the WCBS AM signal strength out of New York City (265 miles), as Fall conditions here are dramatically improving and I heard this station on the anemic car radio at mid-day. Mistake. I should have left the E1 on the shelf and me in my innocent, ignorant bliss.

I turned the unit on. It came to life. Spun the tuning dial down to 880 KHz. Drat - splatter from local signal swamper WYSL. The usual. I hit the bandwidth button to switch down to a narrower bandwidth. What's this? The button is ineffective. What the....so are all the other buttons surrounding the display. I check the lock function to see if maybe the radio's controls somehow got locked. No. Not locked. Grim becomes grimmer.

Power off. Power on. Same thing. Reset the processor. Power on. Same thing. Check batteries. Batteries okay. I give up. I'll charge the batteries anyway, overnight, and try again in the morning.

Enter this morning. Batteries charged. Pop them into the radio. Hit the power button. Nothing. Not even the clock. Reset the processor. Nothing. I hunt for the A/C wall adapter. There it is. Plug it in. The display lights up. I have a clock. Perhaps? I press the power button. Nothing. Nothing. Nothing.

I will think about this for a day or two. Too bad, I was thinking about selling this radio because I rarely use it anymore. Now it is worthless. Get it fixed? I doubt it. It's out of warranty. It is just more than a year old. I'm not sure I even want it at this point.

This will be the last portable radio I spend $400 on. If I have $400 to burn again (unlikely), I will add another $200 to it and get a tabletop. Too bad, really. The E1 was every good a receiver as my old Drake SW-8 which is what it was designed after. The AM-sync was unmatched. Excellent sensitivity and selectivity. Passband tuning. Dynamite software control. Horrible display, though. Dark, like a cheap LCD weather station from K-Mart. And a reputation for display problems. Live and learn.

More on this another time if the E1 miraculously resuscitates itself. But I doubt it will. Maybe I'll open the case and have a look at the power button in a day or two. My $400 brick, and my last.

Wednesday, September 16, 2009

Three Helpful Web Sites For The MW DXer


Mediumwave DXers can be a pretty technical bunch. I know I am one in that crowd. I like to know "Why", "When", and "How". And mostly just "When, and is it Possible"? That is, in terms of receivable stations and the various possibilities thereof. Three web sites exist that can tell us some interesting technical things about the stations we want to receive.


Radio-Locator is probably the one I use the most. My favorite chunk of information available on this site are the antenna pattern/coverage maps. Type the call sign of the station you are interested in and up comes a page with a lot of information about the station. Click the coverage link on that page and see the predicted coverage drawn on a map. Stations with different day and night (and critical hours) antenna patterns have separate maps showing each coverage pattern. You can even click a latitude/longitude link which generates a Google map of the transmitter site.

Radio-Locator has three other great features for general station searching. A US state search allows you to search for stations by state. A format search allows you to search stations by format. A city/zipcode search allows you to locate stations by city or zipcode. There is also a Canadian station search page similar to the US state search. Radio-Locator also includes many Mexican stations in its database, searchable by call sign.


Next, V-Soft Communications owned by Doug Vernier, supplies software products for the communications world. Its important contribution to MW DXers is its Zip Code Signal pages. Type your zip code in the box and click the Find Stations button, and back comes a page listing all stations in your area with a signal strength of 50dBu or greater (display is in millivolts per meter - mV/m - for AM). Each station is linked so that a click on the station call sign takes you to the FCC page describing its facility - another wealth of information. Zip Code Signal also has a reverse look-up feature. Type the station call sign into another box, click the Find Zip Codes button, and a page is returned that shows all nearby zip codes where that station puts in a signal strength of 50dBu or greater (again, in mV/m for AM). Neat stuff.


Last, the FCC to the rescue. One of the most, if not THE most, comprehensive US station lists on the 'net comes from the US Federal Communications Commission. The FCC maintains a database of all US AM, FM, Travelers Information Stations (TIS), and many Canadian and Mexican stations. Information includes geographic coordinates of all transmitter sites, station power, owner, antenna type, and more. The FCC's AM Query web page will extract the information you desire from its official database records and present it in a readable format.

Give these three sites a look when you have a chance. I think you will find them as useful as I do.

Tuesday, September 15, 2009

The 42-Inch Passive Loop


The 12-Inch Passive Loop, constructed earlier, is great for its portability. It sits very nicely on a small garden table. Unfortunately, its signal gain is not much better than a tuned ferrite stick of moderate length. For the next project I considered building an 18-inch or 24-inch, but I rejected the idea outright - not a big enough improvement for the cost and effort to construct them. For real signal grabbing power, the loop size must be increased to 36 inches or more. 42 inches seemed like a good compromise between a 3 and 4 foot loop.

I prefer working with wood here, as I have a lot of scrap available and a nice table saw for cutting whatever size I want. How long to make the cross members, you ask? The formula is quite simple.


Multiply the side length of any loop by the square root of 2 (1.414). So, taking the side length of 42 x 1.414 we get a cross member length of 59.388 inches. I located a nice piece of 1/4 inch pine that was two inches wide, and cut two pieces 59 inches long. It is lightweight and strong enough to support the wires without bending. Each piece was notched halfway through at the middle and fitted together. Next I cut an 8 x 8 inch piece of 1/8 inch veneer and screwed it to the center to sturdy-up the cross and hold the members at right angles. No glue was used on this project at all.


A 42-inch loop is a fair-sized piece of hardware. How do we rotate it? It certainly won't sit on a garden table. I had a 36 inch piece of 1/4 inch steel rod lying about and the idea occurred to me that it might somehow be attached to the loop and pushed into the ground to serve as a pivot. I cut a 27 inch length of 1 x 2 furring strip and screwed it to the center support plate so that it bisected one of the sides. It extends about one inch past the coil edge. Carefully, I then drilled a 1/4 inch hole into the end of this furring strip, about three inches deep to accept my steel rod. As shown, the loop can now be pushed into soft soil and it will rotate freely.


Now to construct a mount for the tuning mechanism. On the 12-inch loop it hardly mattered and I mounted the variable capacitor through the center support plate. On a loop of this size, the tuning mechanism needs to be out at the end of one of the members where the loop ends terminate. I had some scrap 1/8 inch plexiglass, so I cut a small rectangular piece and mounted a 365 pf variable capacitor and an SO-239 coax receptacle through it. The SO-239 coax connector will be left unwired, to be used at a future time for the termination of a one-turn coupling coil. I then screwed the plexiglass to the edge of one of the two cross members nearest the rotating arm.


The 42-inch loop requires 9 turns of wire, 126 feet total. I had 100 feet of white, 20 gauge solid insulated wire, so to that I soldered a scrap of 20 gauge black wire that was lying around. This is why you see two different colors of wire in the photographs. Small wire nails hammered into the ends of the cross members serve as starting and ending pins for the coil. At the end of each of the four cross members I filed notches 3/16 inch apart to properly space the loop turns. When the coil was wound and secured, I then soldered the ends to the variable capacitor.

Signal strength on this loop is phenomenal, and exponentially better than the 12-inch loop. Nulling and peaking are both fairly sharp. The base tuning range of the loop is approximately 520 KHz to 1500 KHz, too narrow to cover the entire mediumwave band. A short jumper wire with clips at each end was fashioned to short-circuit one turn of the loop. This changes the tuning range to approximately 650 KHz to 1750 KHz. The loop couples well to my ultralights and the Tecsun PL-600, and often a radio only needs to be one or two feet away for improvement. Pushed into the ground and ready for rotation, the tuning panel is perfectly accessible from lawn chair height.

All-in-all, this has been a very worthwhile project. Though this sized loop would be cumbersome to carry in a small car, it performs very nicely in a backyard environment and can be stored flatly on a wall in the garage. Sometime in your DXing life try building one of these larger loops. You will be amazed at their performance.

Thursday, September 10, 2009

Empires Of Light


Okay - not radio - but electricity, for without electricity we would not have our beloved radio. Here is what promises to be a great book which documents the race to see who would electrify the world first - Nikola Tesla, Thomas Edison, or George Westinghouse.

From Publisher's Weekly - Author Jill Jones "details the rise and fall of the three visionaries who harnessed electricity, while also offering a critique of corporate greed. Her tale emphasizes the "War of the Electric Currents," in which Thomas Edison sought to defend the primacy of his direct current electrical system against George Westinghouse's higher-voltage and more broadly applicable alternating current system. Nikola Tesla, the somewhat kooky Serbian genius (and former Edison man), joined the fray on Westinghouse's side with his AC induction motor."

I purchased this book from Borders last week. This one will be on the top of the reading stack for the Arizona trip this year.

See the Edward Morris review-

http://www.bookpage.com/0308bp/nonfiction/empires_of_light.html

Wednesday, September 9, 2009

The 4-Inch Tunable Ferrite Bar


This summer I've been searching the flea market for transistor radios and radios otherwise having ferrite loopstick rods or bars. The occasional portable or tabletop transistor radio is to be found, sometimes at a cheap-enough price. Most use ferrite rods or bars for their antenna, though the maximum length found is usually not more than 4 inches.

An old Japanese transistor radio from the early 1970s was procured early in the summer from the flea market. It did not work. Though I tried, I never was able to get it to work, but it had a nice 4-inch ferrite bar in it with intact coil. The miniature variable capacitor was sturdy and in good shape too, and it had a perfect little plastic clip which could be used to attach the capacitor to the bar. I decided to put the two together and make my own miniature "Q-Stick", so I disassembled the radio, removing these parts.


You see the result in the accompanying photos. The variable capacitor and clip were mounted to the bar, then the coil wire ends were soldered to the variable capacitor. Tuning is fairly sharp, particularly at the high end of the band, and I found it tunes the entire mediumwave broadcast band without problem. The resulting assembly can then be placed or held near a radio containing a loopstick antenna. The signal picked up by the tunable bar is inductively coupled to the radio's internal loopstick, increasing signal strength. Rotating the tunable ferrite bar produces a sharp null just like rotating the radio itself, and used in combination with the radio's nulling ability can produce some interesting results. My ultralights all have very short loopstick antennas, generally not much longer than 2-inches, so the 4-Inch Tunable Ferrite Bar does improve signal pickup quite dramatically on these units.

So, if you have an old transistor radio around that doesn't work anymore, don't throw it away. You might be able to make your own tunable antenna accessory.

Monday, September 7, 2009

Are Sunspots Disappearing (Forever)?


An interesting article appeared September 3, 2009 on the NASA Science web site asking this very question.

"Personally, I'm betting that sunspots are coming back," says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, "there is some evidence that they won't."

"Sunspot magnetic fields are dropping by about 50 gauss per year," says Penn. "If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015."

Check out this interesting article.

http://science.nasa.gov/headlines/y2009/03sep_sunspots.htm?list1066443

Sunday, September 6, 2009

Favorite Frequencies?


Favorite frequencies? Seems like a silly question, "What are your favorite frequencies?" MW DXers are interested in any new, interesting, or rare DX, regardless of frequency. But many times, and more often than not, I find myself hanging out on certain same frequencies every night to see what might pop out underneath the usual pickings.

Here in Avon, New York, 20 miles south of Rochester, current evenings at sunset and beyond I am listening on 630 KHz for that big WMAL fade down (50KW, Washington, DC) to see what shows up underneath. Canada is well represented on this frequency, but there is a lot of weak US stuff underneath, many under 100 watts nighttime power. This is where the nulling proficiency and sensitivity of your radio is really tested.

850 KHz is another frequency I am checking now. WKNR, Cleveland, OH (4.7KW) usually dominates, and WKGE out of Johnstown, PA (10KW) broadcasting a baseball game, and WEEI, Boston, MA (50KW). But a few weeks ago I heard KOA, Denver, CO (50KW) fade up when the sun set at the Denver end. Who knows what else will appear in time?

1620 KHz is another favorite. One day I will catch WDHP out of Frederiksted, Virgin Islands (1KW) over the other weak offerings on this frequency. One day.


I am always checking the 570 KHz and 870 KHz Cuban frequencies for the Radio Reloj time ticks. In recent days last week good Cuban audio has been received on these two frequencies at 0600 local time. This is a good propagation indicator for the southern US like the Gulf Coast, and further into Florida or the Caribbean. The Cubans can be quite strong at times. Now that summer is dying and the Fall MW DX season is upon us, WWL, 870 KHz, New Orleans, LA (50KW) has been a power house here lately both in the evening and early mornings. Almost always underneath are the Cuban time ticks fading up and down.

The X-Band is always fun too, 1620-1710 KHz. 1630 KHz, another favorite, can be counted on most evenings to bring me KCJJ out of Iowa City, IA (1KW). They are often broadcasting a sports event. I have had WRDW from Augusta, GA (1KW) fade up and ID for me on occasion. However, I am looking for the elusive KKGM, Ft. Worth, TX (1KW) to appear.

820 KHz is another interesting frequency. It is sparsely populated, and a lot of what is there is low power. That is, all except for WBAP, Ft. Worth, TX (50KW). It will appear one of these days if I can get past WWLZ and WNYC, both New York stations, low power, but dominating. But I am always checking.

Those are some of my favorite frequencies of late. How about you?

Thursday, August 27, 2009

The IBOC Mess In North America


NOW FOR A RANT.

"Bacon frying in a pan", that's what the co-channel interference sounds like when you are 10-20 KHz from one of Ibiquity Digital Corporation's AM HD Radio-equipped stations. At nighttime in the northeast part of the US, a veritable RF storm of digital hash appears across the entire AM broadcast band precluding reception of many distant stations. What a mess.


IN-BAND, ON-CHANNEL?

Huh? I'm not sure why they call it "In-Band, On-Channel" - it most certainly is NOT "On-Channel". The 15 KHz digital sidebands either side of the main carrier bleed fully beyond the adjacent AM channel center and into that adjacent station's far sideband. No filter, on any receiver, regardless of bandwidth, can reject it. In order to provide room for these expanded sidebands superimposing digital information on top of analog audio, stations also have had to narrow their audio response to an absolute 5 KHz maximum, further reducing standard analog audio quality. Adherence to strict technical standards is now an absolute imperative, both in the transmitter, modulation technique, and antenna or you have an even worse interference problem. And we all know radio stations often fail in this area of strict adherence. This, currently, is what the FCC calls "Hybrid" digital operation, the precursor to going fully digital at some future date.


ENTER MONEY AND BIG BUSINESS

Now on to money and big-business, which seems to fuel today's society more than ever. Have you ever seen the licensing agreement that radio stations must capitulate to in order to broadcast under Ibiquity Digital Corporation's patents? Well, here it is:

http://www.ibiquity.com/i/Licensing_%20Fact_%20Sheet_2009.pdf

Here's the meat of it, and what the radio station must agree to if they wish to broadcast IBOC HD Radio:

1. The agreement is perpetual. You are handcuffed to Ibiquity, your provider and benefactor, forever.

2. Pay a one time fee of $25,000 to Ibiquity for rights to broadcast the Main Audio Channel. A station now pays a private, for-profit company for the right to broadcast its main signal.

3. Revenue sharing (part of your profit goes to Ibiquity). Pay 3% of incremental net revenue derived from any supplemental audio services made possible with HD Radio technology (a minimum of $1,000 per year per audio channel).

4. More revenue sharing (more of your profit goes to Ibiquity). Pay 3% of incremental net revenue derived from transmission of Auxilliary Data (Secondary and Tertiary digital data not associated with the Main Channel Primary Data).

5. Pay me again. Software upgrades to the existing HD Radio system must be licensed by paying an extra annual fee or the prevailing rate at the time of increase.


ENTER THE GOVERNMENT

And sad to say, the US Government (in name of the FCC) acts as a money-funneling agent for Ibiquity in their authorization of Ibiquity as the sole supplier of HD Radio technology. Call it monopoly if you wish. Yeah, yeah, I know - so Ibiquity has the patents on this technology. So what. Money, money, money, and more money. What ever happened to the PUBLIC INTEREST?

THE BIG DELAY

One more thing. Did you know that HD Radio is delayed by several seconds because of the technical encoding requirements? The figure most often seen is 8 seconds. No more taking the radio to the ballgame and listening to the commentator instead of the stadium announcer. No more listening to your favorite radio announcer describing the game while you watch it on TV.

SOME INTERESTING INFORMATION

As of this writing, some 289 stations broadcast in HD on the AM band in the US. Recently the FCC has added a link to their web page which provides a list of them:

http://www.fcc.gov/mb/audio/digital/index.html

Click on the "AM" link on the page. The FM list is also available by clicking on the "FM" link.

Here's another useful page which attempts to document all AM IBOC stations, and stays fairly current:

http://topazdesigns.com/iboc/station-list.html

If you dislike IBOC, be sure to check out the Stop IBOC web site:

http://www.stopiboc.com/

An interesting article on Ibiquity's web site on technical requirements:

http://www.ibiquity.com/i/pdfs/Conversion_Requirements.pdf

And Ibiquity's licensing FAQ page:

http://www.ibiquity.com/broadcasters/licensing

Some other links:

http://hdradiofarce.blogspot.com/
http://radiomagonline.com/digital_radio/eye_iboc/

CONCLUSION

Let's hope from a radio enthusiast and DXer's standpoint that IBOC eventually fails when radio stations give up on the technology. Some have started to do that.

Tuesday, August 25, 2009

Sangean DT-400W Mini Review



The Sangean DT-400W is a dream receiver. Let me explain what I mean by this. If I had had one of these little radios when I was a teenage kid in the early 1960s I would have been in heaven. Digital tuning. It receives AM and FM frequencies, though no shortwave. It receives the Weather band. Good sensitivity. Fair but acceptable selectivity. Shirt pocket sized, and ten times better than the Japanese transistor radios of the day. And today, almost the perfect ultralight. I ordered mine from PROVANTAGE.COM for $49.58 plus shipping.

The DT-400W is the size of a pack of cigarettes, only thinner. It is in a vertical format, as were the transistor radios of many years ago. Audio is crisp, and very enjoyable. It has no external antenna, save the loopstick at the bottom of the radio for the MW band.

Two AA batteries are required. Battery life is fair, though nowhere near the Kaito WRX911. I use a pair of 2500 mAH NIMH rechargeables.

Tuning is accomplished with up and down arrow buttons. 19 memory positions are present for saving your favorite channels. A drawback I find is that you cannot tune out of a memory channel as the memory function is part of the carousel band switching method: AM-FM-MEMORY. You must switch back to the AM or FM band before you can tune again.

Sensitivity is good, and better than most ultralights. I find the selectivity only fair, but about the same as most small ultralights. In a dense RF environment, you may have some channel bleed on adjacent frequencies. The new DSP ultralights promise better selectivity, but so far have not shown better sensitivity. I find its nulling capabilities on the MW band also excellent.

Lack of an FM or Weather band antenna has been overcome by having the radio's circuitry couple to the headphone lead-in when headphones are connected. A short wire is also supplied with a headphone type plug on one end to act as an antenna if you are using the speaker.

The DT-400W comes with a nice belt clip which you can attach to the back. Volume control is a traditional wheel at the top. A switch is also at the top which will give DBB bass boost to the radio. A lock switch is at the right side which will prevent the radio from changing settings or tuning should you bump it.

Power button is at the top as well, and a quick press turns the radio on and sets a 90 minute timer. The radio will turn off after 90 minutes in case you fall asleep. Holding the power button down for an extra second will void this "feature". The dial has a nice, warm yellow backlight which comes on for a few seconds if the controls are touched.

The DT-400W couples to a passive loop fairly well, though not as well as some ultralights. Coupling needs to be quite close. Remember the loopstick is at the bottom of the radio.

Though not a cheap buy at a $50-dollar bill, the DT-400W lives up to my expectations very nicely. When I want a small portable unit to take with me, I usually grab it versus the other radios I have. Very nice, indeed.

Sunday, August 23, 2009

Kaito WRX911 Mini Review



I've had the Kaito WRX911 ultralight for a couple of months now since ordering it from JR.com. What a fantastic receiver for the price - $16.99 plus shipping! I bought the black one. It is slightly larger than a pack of cigarettes and about as thick.

The WRX911 is an analog set with slide rule tuning dial. Mediumwave AM, FM, and shortwave bands are included. The dial is tight, I can find almost no slack in it - very good for such a small, inexpensive radio. The tuning knob is sized large enough to get a good grip on, a little larger than the tuning wheel of the Sony SRF-59. Tuning is still touchy, though not as touchy as the SRF-59. Shortwave tuning range is 4.6 - 22 MHz. It is a very quiet receiver, being analog.

The radio uses two AA sized batteries. With headphones, battery usage is almost nil. A fellow owner claims upwards of 400 hours battery life. Batteries do not come with the unit. Included with the radio are a pair of earbuds and a cloth carrying case with drawstring.



The WRX911 uses a ferrite loopstick antenna for the MW band. Contrary to the wildly-enthusiastic reports of superb nulling ability, mine was only so-so out of the box and I questioned why. I noticed some interaction with the telescoping whip on the MW band, so I opened the case and had a look. Naturally, the whip has a short jumper which connects it to the circuit board. Tracing the circuit path, it seems to also connect somehow to one end of the loopstick wiring. The MW sensitivity is increased a little with this connection to the whip, but this severely compromises the nulling ability. Mostly I bought the WRX911 for MW reception anyway, so using a soldering iron, I unsoldered this connection (see photo) and taped off the wire, and rechecked. The nulling ability improved dramatically and is now as good as noted by others. And I no longer receive Radio Poland (on shortwave) at the high end of the MW band! Note that unsoldering this wire gives you no reception possibility on shortwave or FM.

Sensitivity with the antenna mod is still fair, though a little down from before. The radio's sensitivity is less than the Sangean DT-400W but easily brought up to acceptable with a small loop or external tuned ferrite rod like a Q-Stick. I have a homemade 4-inch tunable ferrite bar which does a nice job in coupling to the WRX911. Coupling to a passive loop is good. Currently I use both 12 inch and 42 inch loops here. Reception on the 42 inch is phenomenal.

Selectivity on the WRX911 is fairly good, a world of difference better than the Sony SRF-M37V, and perhaps on a rough par with the Sangean DT-400W.

The radio has a separate on/off switch from the volume control. I find it easy to forget and leave it on. I think it would be better had they incorporated it into the volume control.

For $16.99, how can you go wrong with this radio? Cheap fun. Get one before they are gone.

Saturday, August 22, 2009

The 12-Inch Passive Loop


Now on to some projects I've been working on here this summer.

Haven't built a passive loop in many years, probably since way back in the 1970s, so thought I'd get back into it. The first is a 12-inch loop (12 inches per side). Now where do I find 100+ feet of wire? Who wants to buy wire? Not me.

I had a 20 foot length of 6-conductor, solid, twisted-pair telephone wire in a box in the cellar. The cover can be stripped with a razor blade or Xacto-Knife if you work carefully. In 15 minutes I had it complete. Take each pair of wires, tighten them up in an electric drill motor chuck, tie the other end to a door knob, and unwind them. Now you have 120 feet of nice, 24 gauge insulated wire of different colors.

I then spliced and soldered the lengths together. The wooden form consists of two 1/2 x 4 x 17 inch hardwood pieces formed into a cross by notching and gluing. The 4-inch width makes it sit up nicely all by itself. I then cut a small, 4 x 4 inch piece of thin wood veneer and nailed it to the center of the cross for support and a mount for the variable capacitor.


I didn't bother filing spacing notches for the wires, choosing to wind the coil in a close-wound fashion. Small wire nails in appropriate places make nice anchors for the wire. 26 turns of wire were wound around the form. My variable capacitor is a 250 pf unit, so a few extra turns were called for. Normally you wouldn't need 26 turns for a 365 pf unit. This loop tunes from about 510 KHz to 1500 KHz or so. A small jumper wire, about 4 inches in length with alligator clips on either end, is used to clip off a couple of turns of the loop to get the tuning range up to 1710 KHz.

Sensitivity of the loop is good, better than a 4-inch tuned ferrite rod placed next to your ULR. Nulling is sharp. Best thing about this loop is that it is extremely portable and can be set on a small garden table next to your chair. New York City, about 265 miles from here, is not generally receivable under daytime circumstances. Using this loop, stations like WFAN-660, WABC-770, and WCBS-880, all 50KW, are adequately above the noise level and are comfortably received using headphones.

Thursday, August 20, 2009

Signor Marconi's Magic Box


Took this book to Arizona last winter to read. And what a great read it was. Learn the history of radio and how it developed through the efforts of Marconi himself, constantly striving for greater and greater distances of transmission, using larger and larger antennas and transmitters. If you love radio like I do, you will love this book.

Here's the Kirk McElhearn review-

http://www.techsoc.com/marconi.htm

Available from amazon.com-

http://www.amazon.com/Signor-Marconis-Magic-Box-Remarkable/dp/0306812754

Saturday, August 15, 2009

Tecsun PL-600 Review And Schematics

       -With Comparisons To The Kaito 1103
       -And a slant towards medium wave reception

       -by RADIO-TIMETRAVELLER

       Purchased From: www.amazon.com
       US Distributor: Kaito Electronics
       Price: $79.99 + shipping

       Serial#: 20090220

Arrival

My new radio arrived from the Kaito distributor in California after a one week UPS trek across country. The PL-600 and accessories themselves were in a box of their own inside the shipping box which was stuffed with Chinese newspapers - I had no doubt that this Tecsun had come straight out of China! Adequate it seems, as everything arrived in good shape. Lots of Chinese writing all over the radio box, English as well, this ought to be interesting!

The PL-600 is available in three colors - a medium grey, silver, and black. Kaito sent me a grey one, though the Amazon ad depicted a black unit. Good enough.

Accessories

The PL-600 comes with a nice accessory package. Inside was an extremely nice foldover velcro travel case, external antenna wire wound on a spool (including mini connector and curtain clip), earbuds, 4 NiMH batteries (1000mAH), a 6 volt wall-wart AC adapter (for 110V), and manuals.

Manuals

Yes, manuals. Both English and Chinese manuals were included. The Chinese manual has many graphics depicting the use of the controls, and even some of the textual balloons are in English, though 99.9% of the manual is Chinese of course. The English manual is mostly a textual explanation of radio operations with a few pertinent graphics on pages 3 and 4. The Chinese manual contains a lot of numerical specifications that are not presented in the English manual.

Setup

The radio requires 4 AA batteries. Battery level is displayed on the screen, and is accurate for either NiMH batteries (~1.2 volts) or standard alkalines (~1.5 volts). When you set up the radio, you tell it through a system set code whether you are using alkalines or NiMH. The NiMH batteries are chargeable right in the radio using the AC adaptor. You can even set up the charge rate too. Charging automatically shuts off when finished. Excellent. The radio came preset for NiMH batteries.

The radio was also preset for North America, in that the medium wave (MW) broadcast band split was already set up for 10KHz. The long wave band (100KHz - 520KHz) was already activated too (the LW band on this radio is activated/deactivated by setting a system set code).

No other setup was required.

Quality and Ergonomics

The PL-600 build and fit quality is good, about the same as the Kaito 1103. The telescoping whip antenna seems a little cheaper in quality. My top section was slightly bent the first time it was pulled out, but easily straightened. It is the same length as the whip on the 1103, though not chromed as much.

Buttons are square on this radio, and give a nice solid click when pressed. Lettering is next to each button (usually above or below), not on the button itself, so it can't be worn off by repeated pressing of the button. Good thinking. Keypad is laid out very well. Very intuitive. Ergonomically, this radio is a near masterpiece. You hardly need the manual to learn how to use it.

A front-firing, round speaker is to the left, nearly 3 inches across. The left side of the radio has an external antenna jack, a three-position attenuator switch, a two-position tone switch (favoring treble or bass), a headphone jack, and a power jack for the AC adapter (6 volts, center pin is negative, by the way).

Three knobs are on the right side of the radio. They are tuning, volume, and BFO (used for tuning SSB). The BFO has a center detent, a nice feature.

On the back of the radio is a flip stand for elevating the PL-600 if set on a flat surface. The PL-600 also comes with a hand strap.

The LCD Display

The display is clear and easy to read, contrast is good (better than other reviews seem to have indicated). Backlight is yellow with a faint greenish tint to it. I like it, as it seems more natural and warm. It is 1000% more readable than my Eton E1, which was five times the price. The clock shows all the time, and in 24 hour format, hours and minutes only, no seconds. Two timers are available which can activate the radio for up to 90 minutes.

The PL-600 also has a nice 5-section signal strength bar, with 5 hash marks per section. I find it reads a little high, but it is an admirable effort at showing signal strength. It does catch your attention, much more so than the tiny Kaito 1103 signal strength bar.

The BFO

The BFO covers a little more than 2 KHz either side of the tuned carrier, wider than the Kaito 1103. The BFO at detent was close to but not exactly zeroed on the carrier frequencies of the MW stations I checked (perhaps ~500Hz off). It is touchy to adjust when attempting to tune an AM station using the ECSS method, but no touchier than tuning a Sony SRF-59! I will call it okay for a small portable - at least it has a real knob to grip and a wide range.

I find the recovered audio weak when tuning AM stations in the ECSS mode, so I probably won't use this technique much on this receiver. The BFO works well for normal CW or SSB though, and is fun and easy to tune in stations operating in these modes. It also works well for detecting weak carriers on the MW band.

Antennas

The PL-600 employs a ferrite antenna (4" in length) for the LW and MW band frequencies (up to 1710 KHz). Signal nulling is excellent, and slightly better than my Kaito 1103. It is probably the best signal nulling radio I own, including the ultralights. Its null is very distinct, where the 1103's seems broader and a fraction less deep. It's peak also has more of a sharpness to it which I don't notice in the 1103. It couples well to a passive loop, though not as well as the 1103. Coupling distance needs to be closer than the 1103, and the sweet spot is about two inches down from the top of the radio on the back side.

Shortwave and FM employ the telescoping whip antenna. An external antenna jack is at the left side of the radio, usable for shortwave and FM, defeating the whip.

Attenuator Switch

The attenuator switch (Local, Normal, DX) works for shortwave and FM only. Beware - the manual errs in stating it works for AM and shortwave only. It does not work for AM, unfortunately. While tuning shortwave, I found the attenuator switch attenuated signals too heavily even in the "Normal" position, so I left it in the "DX" position at all times. It seems to work okay on the FM band.

Sensitivity

Sensitivity of the PL-600 is good. On the MW band it is just slightly down from my Kaito 1103 across the band. Judging by ear on a weak station at noise level, I would figure it to be some 3-6 dB down from the 1103 at worst. For example, a signal barely above the noise level on the PL-600 which is 50% copyable (by voice intelligibility) will be just at the threshold of 100% copyable on the 1103. Used as your primary receiver, the slightly less sensitivity of the PL-600 on MW becomes a moot point if combined with a signal enhancing agent like a Q-Stick or even a small tunable passive loop.

On FM, the PL-600 is about the same sensitivity as the 1103. A cursory check was done on several weak stations, and strength was identical in all cases.

Sensitivity on the shortwave bands is so close I can't tell a difference. A few extra feet of wire clipped to the whip greatly enhances shortwave signal strength.

Tuning

In tuning the radio, no chuffing or dropout is apparent, and tuning is very smooth. Two tuning speeds are available, slow and fast, selectable by pressing a button on the front of the radio. In the fast speed, the radio tunes in 9 or 10 KHz increments on the MW band using the tuning dial or up and down buttons, 5 KHz on the shortwave bands, and 100 KHz on the FM band. Fast speed tunes through the LW band in 9 KHz increments. In the slow speed, the radio tunes in 1 KHz increments on the LW band, MW band and shortwave, and 10 KHz on the FM band.

Direct entry tuning couldn't be easier, and is the best on any radio I have used lately, including the Eton E1 and my old Drake SW-8. Simply punch in the frequency and the radio tunes to it - no pressing an "Enter" key, or period "." key twice, etc. It does in fact have an "Enter" key, however it is generally only needed on the FM band for MHz operations if you choose not to enter the trailing zeroes. Also, general band selection can be done by the "carousel" method. There is a button which takes you through LW-MW-FM, and another button that carousels you through the shortwave bands.

Scanning

Scanning is simple. Simply press and hold the "Up" or "Down" tuning button for a couple of seconds and the radio will scan in that direction through the current band. The PL-600 has a special function called Automatic Tuning Scan (ATS), which will scan both the MW and FM bands for receivable stations. Those found are saved in the P0 (Page 0) memory bank. Up to 100 can be saved. Simply press and hold the LW-MW-FM button and the ATS scan starts. A very nice feature.

Filters

Two filter widths are available for LW, MW and shortwave - wide and narrow, most likely 6 KHz and 4 KHz. The English manual does not specify the filter widths, although I am fairly certain the narrow filter is a 4 KHz one.

I tested both against strong local channels on the MW band. Both radios have front-end overload tendencies in an extremely strong signal area, and at my location I have one problem station: a 20KW transmitter at 4.9 miles distance. Both radios suffer mild overload and desense with the 20KW station at full daytime (20KW) power in the wide filter setting, though dramatically less in the narrow filter setting. This is not a defect in either radio at signals of this magnitude with standard filtering (non-DSP), considering their price point. My problem station drops its power to 500 watts at night, so further testing was done at that time.

Continuing on after dark, the wide filter feels slightly wider than my Kaito 1103, and a little extra slop-over is heard on the PL-600 at +/-10 KHz either side of a strong station. The PL-600 wide filter setting introduces a bit of treble hiss into the audio, more than the 1103. This is natural of its own right, regardless of the radio, though I attribute this on the PL-600 to the audio curve tending much more towards the treble end of the spectrum than the 1103.

The narrow filter is very close in performance to the 1103's. Adjacent channel slop is minimal on strong stations and about the same as the 1103. In an additional bonus, I found the narrow filter on the PL-600 to be lengths ahead in audio intelligibility as opposed to the 1103's. To me, the 1103's narrow filter sounds muffled. Not so on the PL-600. Signals are crisp and intelligible like tube sets used to be. Old timers will remember this sound, almost a feeling of being out there in the "ether", a third-dimensional feeling. Which brings us to audio....

Audio

Audio seems to be the sticking point for most critics of this radio. The complaints I have read indicate that it sounds harsh or distorted. It definitely tends towards the treble end of the spectrum, both with the wide and narrow filters, which is not to the taste of many people. I found YouTube to be a great source when prescreening a radio for purchase, as you can not only SEE, but HEAR it in actual use.

So check out the video reviews on YouTube. They give you a pretty good idea of the audio quality. Some will like it and some will not. I actually like my audio a bit harsh, skewed to the treble side. I think it aids in intelligibility with identifying DX. Many sets have too much injected bass, which muddies the signal. I always felt the renowned Sony 2010 was the worst offender here - great audio in the wide filter position, but total unintelligible mush in the narrow position, like someone speaking through a pillow. Why have a narrow filter if the audio is so unintelligible it's not usable? Another tip - use headphones. Audio is always better in headphones.

Lastly, the PL-600 does not incorporate a Line-Out jack, where the Kaito 1103 does. This would have been helpful.

Images

Both the PL-600 and the Kaito 1103 do have some image problems (what radio in this price range doesn't?). I found my PL-600 images to be about the same number and strength as my 1103 on each filter setting. A good way to tell? Tune your radio down in the long wave area between 100 KHz and 520 KHz and look for AM broadcast band signals 2 times (2X) the IF frequency down (910 KHz for the PL-600, and 900 KHz for the 1103). Another good place to check for images is in the 60 meter shortwave broadcast band, 4750 KHz - 5100 KHz. Strong stations in the 49 meter band (5750 KHz - 6200 KHz) will produce images here, at 900 or 910 KHz lower. Both radios show problems in this band as well.

Signal Spurs

In a quick check of the MW band, I found a couple of signal spurs on the PL-600, showing up as weak heterodynes. One was at 550 KHz, which was probably a weak image combination with another local AM powerhouse station at 1460 KHz. The Kaito 1103 had a nice image of this station at 560 KHz, with full but weak audio. No image audio of this station was apparent on the PL-600 at 550 KHz, just the weak heterodyne, which by the way was nullable, another indication it is image-related.

Noise Immunity

The PL-600 seems less noise-prone than the Kaito 1103. In that, I mean it has less susceptibility in reproducing household RFI noise than the 1103. I can take both radios to a particular part of the house plagued with RFI from computers, switching supplies, lighting, etc., and the 1103 is always markedly noisier. The PL-600's LCD display is also quite a bit cleaner than the 1103. Moving your hand close to the 1103's display produces a tremendous amount of hash. Not so with the PL-600.

Memory

The PL-600 has 600 memories, divided into ten pages of 50 each, and one page of 100. Even this can be modified when you set up the radio. I've never been one much for using memory on radios, preferring to tune. But memory operation couldn't be simpler, and is very intuitive. Tune the station, press the Memory button, select the memory slot#, press Memory button again to store a frequency. You can even copy a memory location into another one, a nice feature. Recall is even easier.

Summation

I find the Tecsun PL-600 to be a marvelous radio for the price, and one I will keep. It is a strong contender against the Kaito 1103 in performance/price range, stronger than any other I know at this time, and definitely worth the $79.99 asking price. Realize it is near half the asking price of a Grundig G5 or a Sony SW7600GR, and 95% as able. Though the audio might be considered a little harsh depending on taste, it is adequately sensitive, selective, and has great nulling and peaking ability on medium wave. It has terrific ergonomics and software, 600 memories, and adequate filters - specifically the narrow filter having excellent audio recovery (particularly apparent in headphones). It has two tuning speeds, a well-designed BFO, a main tuning knob including up and down tuning buttons, a real volume control, a bright (with backlight) easy to read display, and a well-supplied accessory package. It will make a great substitute for my ailing 1103, and a great spotting radio for MW band DX.

In my travels about the 'net this week, I've discovered the schematics for the PL-600. I've uploaded them to my file sharing service for your perusal.

PL-600 schematic: http://www.box.net/shared/viigcmuxl4