How exactly does a car antenna work anyway? When you get that annoying background buzz in the radio speakers of your antique or classic vehicle..., how do you determine if that buzz is coming from the radio itself, or from the antenna, and once you figure that out, how do you fix the problem?
Most late model radios and modern antennas are a cut and dried event. For this class, I am talking about the factory radios and antennas found on cars of the 1940's through the 1970's.
Many of us want to keep our original radios and have them restored. but it is no fun if the radio does not work as it is supposed to once it is back in the vehicle.
First a little history. The "stick" or "fish pole" antenna that all of us from the "older" generation know best, first appeared on cars around 1937 about the same time that all metal roofs became popular with car makers. Before 1937 the roof insert of most cars were made up of wooden bows with the headliner tacked to chicken wire that was nailed to the wooden bows.
In the early days automakers used the chicken wire in the roof insert as the radio antenna. By attaching a shielded wire to the chicken wire in the roof insert then routing it over along side of the windshield post, the auto manufacturer could advertise the car as being "wired for radio".
A cool custom trick during the 1940's era was to use the side mount spare as a radio antenna. All you had to do was insulate the metal parts of the car body from spare rim. Next, up attach a shielded wire to the spare tire rim. The tire rim then became the radio antenna. If you had dual side mounts, you could have dual radio antennas. How cool was that!
During the 50's if you were really, really, sneaky, you could insulate the trunk hinges and attach the antenna wire to the trunk lid. Then the entire trunk lid became the car antenna. Who would ever suspect that the entire trunk lid was your car antenna?
No matter what part of your car becomes the antenna, the "antenna" must be tuned to your radio and the lead-in wire must be well grounded at both ends just as if you were using a conventional stick antenna. If you have a poor ground or a loose connection, you radio is gonna have poor reception... guaranteed.
If you are getting a lot of ignition noise in your radio, the first place you should look is the antenna. There are only two ways engine noise can get into your radio, from the battery powered "hot" wire, and from the antenna. The obvious way is through the hot wire but most radio manufacturers took care of that by installing noise filters inside of the radio.
So how do you determine if it is the radio, or antenna that is at fault? It's simple...just tune in the radio on AM band to the noisiest spot (which is usually on the upper 1400 kc part of the dial). Now reach down and unplug the radio antenna from the radio. If the noise disappears or is greatly reduced, you have found the source of your radio noise…the antenna. In most all cases, the cause of engine noise in the radio is the result of a poor ground at the antenna end of the cable.
Some of us (we know who we are) never had any radio problems until we painted our car. That is because we spent more time and effort than the factory did priming and painting places that were never painted at the factory. Among the places we painted was underneath side of the fender where the antenna base mounts to the fender. Because paint is an insulator, the antenna is no longer grounded, at the antenna base. No ground, No Elvis. Simple, as that.
To make your radio work again as it did before you need to restore the metal to metal contact on the underneath side of the fender. A tooth washer will help insure that you have a good solid metal to metal ground connection on the underneath side of the fender. While you are tuning up things, you might as well trim the antenna to the radio and the car body.
Antenna Trim Adjustment...
The antenna trim adjustment has a big effect on how well your radio works and how many stations your radio will receive. The trim adjustment also helps to determine if the stations will fade in and out during your favorite song.
The Trim Screw Location Of a 1957 Chevy Car Radio
The Trim Screw Location On The Outside Cover of The Radio
Adjusting the trim is simple and many of the radios built after 1960 have a thumb screw so no tools are required. To adjust the trim tune the radio to a weak station at the top of the AM band (usually around 1400 kc) then turn the trim thumbscrew in and out until the station is the loudest. Next, gently tighten the thumbscrew and you are done.
On earlier radios, the trim screw adjusts with a small flat, screwdriver. The owner's manual will show you where the trim screw is hiding. On some early radios I have found them hidden behind the volume knob. They were pretty sneaky when it came to hiding the trim screws in the early days.
One, final thing. The round ball on top of the metal car antenna is there for what purpose? A) protection from the sharp end. B) a decoration. C) static- discharge?
If you said static discharge, you are correct! While you are driving down the road static discharge builds up and collects on your radio antenna. Without the ball on top of the antenna the static will continue to collect until eventually it forms a visible ball of static sparks known as a "corona discharge" in radio speak. This static discharge will travel through your radio antenna wire causing that annoying popping sound you hear through the speakers on a dry cold night.
Oh, I know someone will ask…the Conelrad symbols, (the little triangles that appeared on car radio dials during the duck and cover days of the early 1950's...) they first appeared on Studebaker and Chrysler vehicles beginning in 1954. Ford included them beginning in 1955 as did Hudson and Mercury. GM and Packard included them starting in 1956. They were there to tell you where to tune your radio in case of a national emergency, like a nuclear attack.
Now you know the basics of how a radio and the antenna are designed to work. Some simple adjustments will keep you and your radio in tune and singing to Elvis and Hank Williams. Enjoy!!
Psst...Wanna Buy A Tucker Car Radio...?
Preston Tucker had every intention of putting his cars into production. His goal was to produce 100,000 cars his first year. As was standard practice in the industry Preston ordered materials, especially long lead items, well ahead of scheduled production. Motorola was the company selected to manufacture the radios for the Tucker cars. Motorola geared up and made upwards of 10,000 Tucker Radios in anticipation of a brisk sales year.
As we all know, only 51 Tucker cars were built and all 51 were equipped with radios. So the burning question...what happened to all of those extra radios...?
In the early 1950's the assets of the Tucker Car Company were liquidated. The McGee Radio Company of Kansas City Missouri bought the entire inventory of nearly 10,000 leftover Tucker Radios for the modest sum of a dollar each. They began selling the radios as aftermarket add-on radios new in the box with antenna for $20.00 each.
Then in 1955 the car manufacturers switched to 12-volt electrical systems, thus making the McGee radio kits nearly obsolete (with just a few hundred sold via mail order), as all of the Tucker radios were 6-volt radios. Sales of the Tucker radios slowed to a trickle. With hundreds of radios still stored in their warehouse in Kansas City, a fire erupted and the entire warehouse was completely destroyed, including the balance of the Tucker Radios.
Many people assume that the Tucker Radios are quite rare. But we know every car that Tucker built... all 51 of them, came with a radio. So clearly there are way more spare Tucker radios left than there are Tucker cars to install them into.
Some projects are just doomed from the start and do not get better as time goes on, but instead go from bad to worse. When your next project seems doomed and you think it can't get any worse...just remember the Tucker radios. There is always a project somewhere, worse off than yours...
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