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Minimal Antennas and Grounds
Make it cheap, simple and effective

By: Daniel Grunberg (ce369@FreeNet.Carleton.CA)
Date: Aug 8, 1996
Original source: Usenet's

Modern shortwave receivers, particularly modern portables, tend to be very sensitive. Modern shortwave receivers most often are intolerant of overly strong signals, even strong signals well away from the frequency being tuned. For example, a local, strong MW station might overload your receiver's front-end. The result could be images all over the SW bands, or it could be an apparent lowering of the receiver's gain.
Therefore, the best, and least costly, antenna is the least antenna that can receive what you want to receive.
I'd try the following in turn, and stop when I was satisfied with the reception I was getting.

1. The receiver's built-in antenna.

2. Some copper wire.
Up to twenty feet of wire (insulated or not) strung up as high as is convenient, inside the house. Radio Shack has a reel-up wire for this purpose (278-1374), which easily can be taken down and stored when not in use. Ask about Radio Shack's return policy, in case it doesn't work for you.

3. Grounding the receiver and using antenna 1 or antenna 2 (above).
The following grounding methods may increase the received signal-to-noise level, but they will not necessarily protect you, your house, your property, or your receiver from lightening.
Almost any sort of external ground may help.
Improvised, less-than-ideal, external ground connections have been known markedly to increase signal-to-noise ratios.

If your receiver has an external antenna connector, an external ground connection usually may be made via the sleeve of the connector's mating plug (see illustration below). Inserting the plug into the receiver's antenna connector will disconnect the receiver's antenna from the receiver's front-end. A clip lead, from the appropriate lug on the plug to the base of the whip antenna, can be used to reestablish a connection to the receiver's whip antenna.

||__________||0 <--- to rcvr front-end
||     ^
     to rcvr

You can try to eliminate the the clip lead from the plug to the whip antenna by cutting the antenna plug. What remains of the long part near the wire terminals (which were not drawn on the left part of the figure below) should be long enough to makes a non-intermittent ground connection when it is inserted into the radio's antenna jack, but should not be long enough to operate the antenna jack's switch and disconnect the antenna.
The following figure shows what I mean.
The figure is not to scale, so no dimensions should be inferred from it. [Actually, since I haven't tried cutting a plug, I don't know what the dimensions should be.]
||______                    ____
||______                    ____||0 
||   ^                        ^
    insert                 throw   
    this part              this part
    in receiver's          away
    antenna jack

The best way to ground your reciever is to connect its ground to a ground rod (Radio Shack has them, but I don't know the catalog number) driven into damp soil, as near to the receiver as possible.
The next best external ground connection is to a ground clamp mounted on a metal *cold* water line. Ground clamps and ground rods often can be found in the electrical supply section of your local hardware store.
Less satisfactory external ground connections may be made (in the USA anyway) to a #10-24x1.5" screw or a #10-32x1.5" screw that you have pushed into the small round ground-pin on a 120 VAC outlet.
Don't use the wall outlet ground unless you know exactly what you are doing and you have verified that the outlet has been wired correctly.

The diagram below is meant to represent a 120-VAC, 60-Hz, grounded outlet like those used in all but the oldest house wiring in the USA. The outlet has two parallel openings. Although the parallel openings are of roughly the same size, it can be seen that one of the parallel openings, the one shown on your left in the diagram, is slightly longer than the other one. The outlet has a third opening, the lowest one on the diagram, that is shaped differently and is smaller than the other two.

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