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Standardized AM radio connector

K

KTN Corp

FM has the F-connector, but on most surround system receivers, it involves clipping two wires into the receiver to connect the included AM loop antenna. It doesn't seem very consumer friendly since there is no direction to see which wire should be connected to which clip. The Belling-Lee connector seems to be suited for this task but it's not used. Any ideas why there hasn't been a connector for MW (and maybe including LW and SW) antennas?
 
In the FM world there is much more of a standardized idea of what a receiving antenna is, looks like, "acts like" electrically.

In the AM world... or in the world of long wave and medium wave, the format of antennas is all over the place. A big long wire stretched from the window to a tall tree. A loop of wire with several turns around a supporting frame. A little whip like a car radio. And the "transmission line" that may be used to get from the actual antenna in the attic or outside the building can have various formats.

The beauty of that A.M. connectors on your radio is that if you do your homework and figure out what kind of antenna would work best for you, then you will understand how it should hook up to your radio and those two little connectors give you maximum flexibility.

I sometimes think they are a bit of window dressing. I used to connect external AM antennas to radios "back in the day" with pretty good results. Today's radios... even with clips for the purpose, seem to be a bit "antenna agnostic". But maybe I just haven't done my homework. ;D
 
Since I have one nice tunable AM loop and a few different radios, I've added female RCA plugs to the tuners AM antenna clips/screws and put a male RCA plug on the antenna. I haven't noticed any reduction in signal quality when doing this and it makes swapping the antenna a lot easier.
 
The polarity of those little loop antennas doesn't matter. They have much less inductance than previous AM antennas, and the tuning capacitance is inside the IC. Most people don't even hook up the AM antennas that come with receivers, etc. because they never listen to AM. So the AM sections are effectively disabled.

I have found that if I make a frame out of two yardsticks and string a single turn of wire around it, then lightly twist the ends together back to the AM antenna inputs, most AM sections these days are plenty hot - you can get some amazing reception.
 
I gave in and bought several Pomona 4969 BNC adapters, cut the wires kinda' short, and dedicated one to each AM receiver:

http://www.pomonaelectronics.com/pdf/4969_4970.pdf

If in doubt, try ohm'ing out the antenna connections on the radio, to see which is grounded (if either), and mark the "hot" connection.
 
rbrucecarter5 said:
The polarity of those little loop antennas doesn't matter.
Click to expand...

Yeah I know, but some of those receivers i have seen in the store have color-coded ends on those two clips; the top being light gray or almost white and the bottom being medium/dark gray or solid gray. It gives the average consumer a false impression that there is a tip and a ring or a live and neutral connection.

Clipping wire connections don't look as finished as a plug (such as the Belling-Lee connector) would. It connotes sloppy design or lackluster effort in manufacture and is pretty hard to install. It takes some aptitude to make sure the stripped areas are all the way in the clip or enough wire was stripped beforehand.

I think the Belling-Lee connector ended up being used in European TV sets because radio sets used the existing connection and all that was needed for TV service was to replace the radio antenna with a TV antenna, but use the same wiring.
 
I've found that a number of the newer AM receivers can be pretty easily overloaded when connected to anything more than those little plastic loop antennas they sometimes come with. If they have built-in ferrite antenna in them, I usually set my Grundig AN200 loop next to them and tune it up. That does about as good as anything. Last I looked, they were being put on clearance at Radio Shack for $14.97
 
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