14 October 2011

kaito an-200 mediumwave antenna review

The AN-200 tunable passive loop antenna for mediumwave is manufactured by Tecsun, and sold under the Grundig and Kaito brands in the United States. It has an impressive appearance, with red wires wrapped around a clear plastic loop about 9 inches in diameter, and a black plastic arched base. So, is it just for show, or does it deliver better mediumwave reception?

As traditional mediumwave DXing is increasingly threatened by HD (hybrid digital)/IBOC (in band on channel) broadcasting, I'm looking for ways to get more out of this hobby in the near term. I purchased a Kaito AN-200 antenna to use via inductive coupling with my portable receivers. This is the first external AM antenna I've ever owned or even used, so I can't compare its performance with other similar products.

The item

Out of the box, this thing looks cool. The exposed red wire wrapped around the clear plastic ring has a nice, simple appearance and a bold red color for the wire.

The black plastic base and the clear plastic loop wobble as if not solidly connected. Since it's in this condition as a brand new item, I'm concerned that it will eventually fall apart. The antenna gets moved around during normal usage, and perhaps stowed when not needed. Durability of a product like this is a necessity, and the product I received does not inspire confidence.

The wrapped wire fits into a groove on the outside of the clear ring. In some places, the wire looks bent, scuffed, and not evenly distributed. My unit certainly does not resemble the glamor shots I have seen on eBay. I don't know how much functional difference it makes when I gently push the wires into visually-pleasing conformance, but this action provides the aforementioned aesthetic enhancement. However, there's enough slack in the line that the problem of disorderly, overlapping wire returns after a short time.



As for the tuning selector, it's a loose plastic knob with a barely discernible pointer on it. Fortunately, the pointer doesn't make a difference. Just turn the thing and listen to the results. The knob has a range of about a half turn. It's possible to just pull the wobbly knob off and turn the potentiometer directly, although the wobbly knob acts as a cover for the potentiometer to shield it from debris.

Overall, the construction and durability is poor. This is such a simple design that only neglect and inferior components could cause problems. Extra care with the design could have resulted in a wire that stays snug. Tighter coupling between the base and the loop would make me believe that this unit would last a long time, but that remains to be seen.

Test preparation

For calibration purposes, I used my digitally-tuned Eton E5 (which I often use for mediumwave DXing without an external antenna). To test the signal strength improvement of the AN-200 antenna, I used my Tecsun R-9012 radio (which is very similar to the Tecsun R-911 / Kaito WRX-911). Both radios were powered with new alkaline batteries.

Daytime reception tests

My daytime tests of the AN-200 took place between roughly 11am and 6pm local time.

Daytime performance of the AN-200 impressed me. Stations from great distances aren't audible via skywave propagation during the day, so the objective is to find some weak signals without the help of an external antenna, and use the AN-200 to make the signals usable.

On the E5, I tuned to 580 kHz (KMJ; Fresno, CA; 50 kW) and heard a faint signal among the noise. I tuned the R-9012 so I could tell that it was on the same frequency, but could not hear the weak signal sufficiently through the noise. I tuned the AN-200 which was along the left side of the R-9012, and KMJ's signal literally jumped right out of the background noise to sound as good as a local station. That was a dramatic boost in signal strength, and now I can easily hear this station during the day.



Another test involved 650 kHz (KSTE; Rancho Cordova, CA; 21 kW). At a distance of about 120 miles away and a weaker transmitter, this station came through weakly on the E5. I was able to find the frequency on the R-9012 without the AN-200, and the AN-200 boosted the signal to a usable level. This signal was noisy, though, so I wouldn't have enjoyed spending a lot of time listening to that station.

840 kHz (KMPH; Modesto, CA; 5 kW) is about 80 miles away, and during the day, my listening location is in the fringe reception zone according to the radio-locator coverage map. This is an example of when I had to use the AN-200 to pull in the signal on my E5 reference radio, and the R-9012 was able to receive the station but not loud enough to use.

With the E5 and the AN-200 during a later daytime session, the radio was tuned to 840 kHz but picked up KCBS on 740 kHz by tuning the AN-200 down. The KCBS signal came through loud and clear. So, the inductive-coupled antenna can apparently tune the radio.

Nighttime reception tests

My nighttime tests of the AN-200 took place between roughly 8pm and 11pm local time.

For my first nighttime test, I tuned to 840 kHz (KMPH; Modesto, CA; 5 kW) with my diminutive Tecsun R-9012 radio. The signal was weak, noisy, and not illuminating the radio's "Tune" LED. Also, this is a frequency where I often hear overlapping traffic advisory transmitters at night. With the radio held in front of the AN-200, I whipped through the antenna's tuning knob range a couple times. I saw the tune LED come on, and I heard a dramatic increase in the signal strength. Cool! The best results were achieved with the radio six inches or less from the base of the antenna.

Results with my Eton E5 were a bit different. The E5 already had a usable signal for KMPH on 840 kHz, even with the local/dx switch in the local position. But the signal strength meter wasn't showing anything, without involving the AN-200. Moving the E5 close to the base of the antenna caused the signal strength meter to reach the half-way mark.

It's also important to point out that the sweet spot is a very narrow range of the antenna's tuning knob. On the one hand, the half-revolution range of the knob allows traversing the whole range quickly, but on the other hand, it means that fine-tuning is laborious. The back and forth tuning adjustments aren't too difficult for one station, but it becomes an issue when trying to log lots of stations.

Another evening test was with 660 kHz. I was worried about 660 kHz being a usable frequency for signal strength tests, because 680 kHz hosts KNBR, a local 50 kW sports station with plenty of bandwidth to spare. But I found the signal properly isolated on the little Tecsun. Given the heavy fading and the chanting I heard on this frequency, I guessed it was the Navajo Nation station (KTNN; Window Rock, AZ; 50 kW). Without the AN-200, this signal was only occasionally fading in above the noise level. The antenna brought in a stronger signal on the R-9012, and was pulsing the "Tune" LED in time with the signal fading. I also heard a clear "Navajo Nation" identification.

Here's a tougher test. 1000 kHz (KOMO; Seattle, WA; 50 kW) next to 1010 kHz (KIQI; San Francisco, CA; 10 kW day/0.5 kW night). KIQI is in Spanish; KOMO is in English. I tuned the R-9012 to where its signal was the strongest, and where I didn't hear interference from the adjacent frequency. While sweeping the antenna's tuning knob, however, it only amplified the adjacent frequency and didn't boost the signal from KOMO. I will point out though in the AN-200's defense that the experience was not the same on the Eton E5. The E5 didn't get a boost of KIQI while tuned to 1000 kHz, so this particular instance revealed poor mediumwave selectivity on the R-9012.

A somewhat weak signal on 1070 kHz (KNX; Los Angeles, CA; 50 kW) seemed like another good place for testing, but the R-9012 was barely able to find it on the left side of a really strong signal on 1100 kHz (KFAX; San Francisco, CA; 50 kW).

On 1200 kHz (KYAA; Soquel, CA; 25 kW day/10 kW night), the station hardly comes in for me during the day, comes blaring in during twilight, and then is reduced to the audio equivalent of rubble later at night. This is one case where the AN-200 provided a nice signal boost to the E5 during my nighttime tests. Without the antenna, the R-9012 wouldn't have a chance with this signal.

Tips

With the R-9012, I found that the best improvement was possible by pointing the top of the radio at the base of the AN-200. This behavior depends on how each particular radio is constructed, whether the radio contains a ferrite bar antenna, and where the ferrite bar is located.

Trying to boost a weak signal next to a strong first-adjacent station was difficult in my experience, and the radio's selectivity plays a factor. If you're trying to boost a weak signal that is right next to a stronger signal, the AN-200 will work best on radios with excellent mediumwave selectivity or selectable bandwidths.

Ideally, you point the antenna at the station you want to receive, and stations not facing the antenna are nulled. I'm not experienced enough at this yet to say how well this antenna does it. One experience was trying to log KMIK (Phoenix, AZ) on 1580 kHz, where there was a strong signal from KBLA in Santa Monica, CA. For me, KMIK is just a few degrees towards the east from KBLA. Two 50 kilowatt flamethrowers on the same frequency, 360 miles apart. They have directional transmissions at night, but I'm glad I don't want to listen to either station on a regular basis.

A brief diversion

I laid the antenna down on my carpet and took a rather dark photo, and submitted the photo to the "Amazon Remembers" service. The Amazon Remembers service is human-powered through their Mechanical Turk service. The item was incorrectly identified by an unknown person as a "Smooth ring door knocker - flat black iron".

Conclusion

Was it worth the expense? Is it producing the stated benefits? Do I recommend this product?

This was a good lesson for the fact that upgrading one piece of equipment exposes flaws in other pieces of equipment. The Tecsun R-9012 has poor mediumwave selectivity which becomes evident when using an external antenna such as the AN-200. The external antenna was working correctly and effectively.

Using the AN-200 is really easy, at least with the inductive coupling method that I used. When you find the sweet spot for a signal with the antenna tuning knob, you know. The signal gets louder and sometimes clearer, and if your radio uses a tuning LED or a signal strength meter, you'll likely observe the change in signal strength. But focus on what you hear, not what you see.

This product provides me with a clear benefit that aligns exactly with why I purchased it. My AN-200 antenna appears to be poorly constructed and is not durable enough to last for many years as I'd like. The very simple design also suggests that this product is easily replicated by those with the knowledge, capability, and materials.

3 comments:

gkinsman said...

Hello,

I have a Tecsun AN-200 antenna, which is basically the same item with the Tecsun name. The loop is solidly connected to the base; there is no wobble. The wires are not loose or overlapping.

Regards,
Gary

gkinsman said...

One more thing. The performance of my AN-200 is about the same as my Terk Advantage, which also has a 9" loop.

-Gary

gkinsman said...

You might find the article "Using Passive Loop Antennas" to be useful. It contains lots of good information and tips. It's the seventh document on this web page:

http://www.dxer.ca/file-area/cat_view/87-ultra-light-radio-files-area/97-ulr-antennas?start=10