car radio for AM dxing

When I drive around Tucson AZ late at night, KOA Denver 850kHz comes in at levels equaling many of my local stations. I've heard that an automobile radio is good for AM band dxing but I haven't talked to anyone who has done so OUTSIDE of the car.

Has anyone setup such in their home and tried it out? If so what were the results?

Actually, by using the car, you are hopefully able to drive to a location away from those things which cause AM band interference such as computers, florescent lighting, etc. Unfortunately, I think it has gotten harder to escape such things. Even in what may be considered a remote area, you still have possible high tension electric lines and other man-made elements that can create problems on AM. Sometimes even electronic items operating in the car can do this.

sam critter said:

When I drive around Tucson AZ late at night, KOA Denver 850kHz comes in at levels equaling many of my local stations. I've heard that an automobile radio is good for AM band dxing but I haven't talked to anyone who has done so OUTSIDE of the car.

Has anyone setup such in their home and tried it out? If so what were the results?

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The problem that you have setting up a car radio for AM DX'ing is that the AC power in most homes is so severely compromised by conducted noise that it is tough to filter it enough in a 12V supply to get a clean signal.

I tried such a setup with an old Delco car radio from the 60's - which was a time when Delcos were slug- inductor tuned and had an IF bandwidth of 262.5 kHz. They were used with 6 inch whips, and were very good radios! I packaged the whole thing in a nice enclosure, put the 60 inch whip on the side, a power supply in the box, and good speaker. Turned it on expecting great things and was met with severe interference. The only way I could get it to work was with batteries - at first a string of D's, which didn't last very long, finally with a small lead / acid from golf cart. Combined with a switchable charging system, I got very good DX results.

The problem with doing this now is that very few car radios have taken any care at all to be sensitive. AM /FM have been combined with DVD, bluetooth, digital displays, and every other manner of digital technology that is inherently noisy. Designers have no concept of proper methods of bypassing, circuit board layout, shielding, or other techniques to make digital and analog live in peace. So the "solution" is to de-sensitize AM. Even Pioneer did this for a decade, with only the newest models restoring sensitivity in an attempt to get HD- AM to work. I could definitely DX with the latest crop of Pioneers, but I don't think they would compare with Delco's from the 60's.

Some of the radios in the cars of the 1950's were very good. About all they lacked was today's digital dial. I easily remember a Pontiac model car that had a telescoping antenna that probably went close to eight feet or so from the fender. This usually had to be kept down for the most part to avoid damaging it while pulling into a garage. Nice to see the mention of the Delco models. I recall those with the beveled knobs in the Chevrolet Impalas of the 1960's.

Cincinnati Kid said:

Some of the radios in the cars of the 1950's were very good. About all they lacked was today's digital dial.

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....which is actually an advantage if you wish to try for ZIZ in St. Kitts (AM 555) or trans Atlantic or trans Pacific DX!

My Delco on my old '75 Chevy Nova, when I was stationed in Alaska, brought some oddities late nights, like possibly Japan on what had to be AM 774. My favorite catch was on the Delco there---WWL 870!

Of course, those radios didn't go up to 1700 kHz either....

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If I missed it, let me know. The upside of those Delcos is/was that you can take them to areas where there is little electrical noise. The downside is that a typical telescoping whip cannot null out stronger signals that would be separable with a directional antenna such as a loop. Any ideas as to the best way of connecting a loop antenna using a short transmission line and match it to an old Delco and the loop? I tried connecting a short vertical with a one transistor preamp to a 25 foot piece of 300 ohm twinlead terminated with a small loopstick as a load and coupled it to a windshield antenna in the 1970s. It worked fairly well in Northwest Michigan.

I could hear WIND, WMAQ, WGN, WBBM, WAIT, WLS, WCFL, WJJD, WTMJ, WOKY, WJR, WTAC, WFDF, WKMF, WYLO, WILL, WKZO, CFCO, WDBC, WLW, CHYR, WVIC, WSGW, CKLW, WKAR, WKHM, WOAP, WCEN, WOWO, WKNX, WHBL, WERK, and others more than 100 miles away in the daytime just with the short vertical and preamp, with the loading coil inductively coupled to the ferrite rod in a Sony CF Series radio with cassette recorder. It was about 175 miles from the Chicago stations, for all you Chicago DXers out there.

^ 'Cat, I once had a radio in my 1989 Honda Civic, where you could easily detach the Motorola plug in the back. I had (still have) a Select-a-Tenna with a 1/8" jack....I used to run a Motorola F-cable with an F-to-1/8" plug adapter on one end & the Motorola plug on the other. I think there indeed was some directionality about it. Of course, the car was parked and the engine off.

My current car (2010 Kia Soul) has no way to get to the back of the thing without tearing it apart.

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Those Delco car radios from the 60s were the best I ever used for DXing in the car. The telescoping antenna was excellent, but as "SC" pointed out not directional. However, I found if you could position the car a certain way regarding the surrounding structures you could make it directional.

radioman148 said:

Those Delco car radios from the 60s were the best I ever used for DXing in the car. The telescoping antenna was excellent, but as "SC" pointed out not directional. However, I found if you could position the car a certain way regarding the surrounding structures you could make it directional.

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Yes, you can block signals, but it is unpredictable. I used to park on the east side of this Northwest Central Michigan record store called Believe In Music. I could get WTRX Flint on 1330 there, whereas other places I got WHBL Sheboygan on 1330 with slight interference from WTRX. That was one that a loop wouldn't have helped much, as they were about 180 degrees apart. A direction finder would have been good for that situation. Anyone ever use one for DXing? As I recall, no one here did. Perhaps a little too expensive to just DX with, like a Field Strength Meter.

A few years ago I picked up a listenable WWL at night on a stock car radio on M-37 between Caledonia and Grand Rapids. Also, the only night AM bandscan was done on a stock car radio in the middle of a housing complex.

Some of the older car radios were quite good because they had an RF amp. I still have an old 1970 Philco that worked well off a 12 volt battery and short wire. It quit working last year when I pulled it out of the closet; I suppose it's going to be next in line for tinkering / repair.....

Perhaps the only useful thing on some modern car radios for DXers is that they often have mind-crushingly narrow bandwidth. Terrible for music or long-term speech radio, but great for picking out a weak signal adjacent to a stronger one.

The narrow band IF on car radios doesn't bother me, unless it is so narrow that speech is hard to understand, or music has noticeable distortion. There should be a narrow-wide IF switch and circuitry to get the best selectivity and sound quality, whichever you want. That would add cost though.

boombox said:

Some of the older car radios were quite good because they had an RF amp.

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Just about all car radios have tuned RF on both AM and FM. I suspect, though, that tuned RF on AM was deleted to let interference jammers like DVD players work in cars.

The idea of using a car radio outside of the car is nothing new.  I remember reading an article in one of those electronics or mechanics hobby magazines, about 1965, called "Junk the Car, Save the Radio! - Car Radios Outperform AC-DCs".  The article explained how the car radios were better, and showed plans for building a power supply for the radio and a box that would hold both.

Recent car radios that surprised me:

Had a 1997 Ford Crown Victoria, where the trunk of the vehicle served as the AM antenna.  The trunk was a non-magnetic metal (likely aluminum), while the rest of the car was steel.  This was very sensitive on the AM band (for example, I was able to hear a TIS in the X-band from more than 160 miles in the middle of the day).  This DX performance ended the day the alternator had to be replaced, after which a horrible whine came over the band anytime the engine was running.  Another thing about this radio is that the radio signals came in though a telephone jack.  This was unfortunate, as I had built a shortwave converter kit and had no way of installing it in that car.

I also, on occasion, drive a 2007 Toyota Prius.  This radio is also excellent for AM DX (the antenna is typical of today, a rubber whip about a foot long with a helix running inside it). What is really weird about the Prius is that only the AM band comes in well.  On the FM band, things work pretty well when I happen to be parked, but once I start moving, the FM band is hit with interference from the car's electronics.  It is not a problem if you have a very strong FM signal to listen to (thanks to the capture effect), but not good for DXing or rural listening.  The HF (shortwave, 3-30 MHz) spectrum gets completely whacked, as do the 6 meter (50 MHz) and 2 meter (144 MHz) amateur bands.  The noise is worst when slowing down (i.e., then the wheels are charging the traction battery), but there is no such interference to the AM BCB at all.  On the downside, the audio quality is just awful on AM, little bass and no treble at all.

I'll give props to the stock AM/FM/cassette/CD radio in a 2000 Toyota Camry. The inside is likely Clarion but one of the better AM sections I've encountered. It's not wideband but music sounds reasonable compared to Delco plus the sensitivity and selectivity rivals my Superadio II or CCrane. Here's the best part, it has a windshield antenna.

As far as utilizing an AM radio away from a car my best advice is to keep AC power away from the radio. A 12 volt car battery with a small charger to refresh it once in a while is your best friend avoiding interference.

The car battery approach is the best, but if you don't want that, you must certainly avoid switching type power supplies, and look for a LINEAR power supply or even a "brute force" power supply, which contains very few parts, none of which can make the noises which can get in the way of AM reception.

Even then, getting a noise free ground for a car radio can present difficulties.

The remote loop is a good idea. Almost any chunk of coax can be used when a radio has a Motorola plug.
Just wind a few loops at the far (noise-reduced) location, and connect to the inner and outer of the coax.
Then for real fun, put tuned loop around the pickup loop and see amazing dx.

It will even work pretty well even with a twisted pair but coax is better when the run is longer.

I've only ever done this with 1960s to 1980s car radios, but assume any AM car radio would work as well.

radiorob2.0 said:

I'll give props to the stock AM/FM/cassette/CD radio in a 2000 Toyota Camry. The inside is likely Clarion but one of the better AM sections I've encountered. It's not wideband but music sounds reasonable compared to Delco plus the sensitivity and selectivity rivals my Superadio II or CCrane. Here's the best part, it has a windshield antenna.

As far as utilizing an AM radio away from a car my best advice is to keep AC power away from the radio. A 12 volt car battery with a small charger to refresh it once in a while is your best friend avoiding interference.

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I had good results with the 1986 Camry car radio - full AM stereo. It was a bit soft on sensitivitiy, but was wideband and music sounded really good. FM was not very good on it. I ended up swapping it out for a Pioneer Supertuner when AM music stations all switched to talk.

2004 Honda Accord - stock radio/cd changer. Insanely sensitive and quite selective.

One example: traveling south on I-81, usually lose WSLQ/Roanoke around MM +/- 40 in any other car. Honda carried it much further - around MM 5 the side channel interference on 99.3 finally killed it. For a few minuntes there I thought I'd make the Tennessee line.

Quite stout with AM as well. No externally visible antenna, I honestly have no idea where it is.

Interesting observation about my car radio in my 2002 Saturn.

Back when I went to Daytona Beach to do some daytime AM DXIng, it didn't pick up a trace of any signal on 880 when I listened in the parking lot but on my Sangean PR-D5 near the beach (without the loop), I could hear a faint WZAB with what I think was likely WCBS behind it.

But here in Tampa, my Sangean PR-D5 can barely pick up 740 WORL Orlando during the day but it has a listenable signal on my car radio.

Weird.