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Old 13-02-2010, 13:28   #1
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SSB Antenna Question

I have recently purchased an SSB receiver. Receiver only. The intent is to enable myself to become familiar with SSB, and to listen to the various Carribean nets and get weather fax. My question is what is the best and simplest answer for an antenna, and does it need to be grounded. The receiver I have is a Realistic DX 302. It had good reports on some of the ham sights, and besides that it looks good. Currently I am just using the little telescopic antenna that comes with the receiver, but results are less than satisfactory. Is it necessary to use a ground with even the little telescopic antenna, and what is a better solution for an antenna.
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Old 13-02-2010, 14:24   #2
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I would start with a horizontal long wire as high as you can get it off the ground and between whatever you have. Wire size does not matter except for the physical strength of the wire. I think the NEC does have a requirement of #14 but you can use almost anything that you can find. Insulated ends.

Lots of good stuff on the interrnet. Hams are famous for cheap!


Experimenting with various setups will teach you a lot about radio and that’s a good thing if you are going to eventually use Marine HF onboard.

Yes, a ground, even to receive. The house ground on the ac circuits will work.

Um Saudade
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Old 13-02-2010, 18:14   #3
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An RFground is not critical for receiving, though it might help. If you are going to run an antenna outside, you really need a lightning arrestor with a ground rod for safety purposes.

You might get away with a wire strung around the ceiling of your room, but that puts the antenna close to all the sources of RF interference in the house.
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Old 13-02-2010, 21:48   #4
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Quote:
Originally Posted by SoonerSailor View Post
If you are going to run an antenna outside, you really need a lightning arrestor with a ground rod for safety purposes.
Good advice, but how critical this is depends on where you are and what surrounds your antenna. I have to admit that I haven't used a lightning arrestor in over 30 years, and have been lucky. Of course, my antennas aren't usually all that high, there are usually surrounding trees, and there isn't much lightning where I live. And I've been lucky.
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Old 14-02-2010, 07:41   #5
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A lightning arrestor won't offer much protection from a direct strike, but it can shunt damaging and potentially fatal currents induced in an antenna fro a nearby strike. So even if you think your longwire antenna isn't high enough to get struck, you aren't out of the woods.
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Old 14-02-2010, 07:51   #6
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I use plain wire, perhaps 30' long, up and along the mast. No grounding. NASA unit.

Was able to receive weatherfaxes and listen to Radio International mid-oceans no problem.

b.
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Old 14-02-2010, 16:49   #7
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Lightning is not an issue if equipment is not hooked up! I would rather rely on a total disconnect of equipment than anything that is supposed to shunt thousands of volts around my sensitive equipment.

I have heard and seen too many stories about catastrophic equipment burn out in lightning strikes and I always ask, "How much of this stuff did you need on at the time?"

The sheepish answer is usually, "Very little."

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Old 15-02-2010, 23:23   #8
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I have done everything humanly possible experimenting with antenna's for a HF receiver. All of them were much worse than a simple whip + tuner on a SSB transceiver. I have come to the conclusion that there are only 3 ways to tackle this:

1. Buy a transceiver instead, even if just to listen, but you can tune the antenna.
2. Use an active antenna (expensive)
3. Use a pre-scaler. This works effectively and isn't too expensive but if you're not a HAM or into radio's and stuff it can become a hassle.

I choose option 1 and now have a DDB transceiver and a HAM transceiver.

cheers,
Nick.
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Old 16-02-2010, 15:46   #9
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2. ... active antenna (expensive)
Hi,

I might be off, but we have a little active antena from NASA here,

CHEAP (I think around 40 GBP)

Can't say how good it is.

Cheers,
b
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Old 16-02-2010, 17:09   #10
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I'm a bit baffled by the discussion of ground rods - should we presume you are using the receiver at home on onboard? The latter obviously makes the issue of a ground rod moot.
The efficacy of a receiving antenna is dependent on two fundamental issues:
1. height, and
2. impedance match to the receiver (including resonant length).

Clearly the first issue is greatly assisted by using the mast in whatever fashion you prefer
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Old 16-02-2010, 17:33   #11
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Basic rule: if you receive noise then more antenna or grounding is useless for signal strength.

Also, it sure helps to be away from the city and marina. Even one mile helps.
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Old 17-02-2010, 09:06   #12
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Ok... I see some good and bad advice.

Any antenna is better than NO antenna. But, for a general coverage receiver a longer antenna is better.

Someone said "the wire size" doesn't matter. TECHNICALLY it does matter, but for your purposes he's right (the technical aspects of a 'thicker wire' give you a wider bandwidth of reception. The length determines the FREQUENCY, at which the wire is resonant and receives BEST, the thickness determines the width of frequencies that can be best received... again, for the purpose of just receiving though, it's not important).

Sonnersailor said "rf grounding isn't important for receiving". That's not true either.

A receiver OR transmitter uses a "dipole" antenna best. If you don't have a dipole, most antennas use the grounding system as a counterpoise - basically the other element of a dipole antenna.

(For a technical description of a dipole see http://www.arrl.org/tis/info/pdf/9106023.pdf and if that doesn't work, let me know and I will email you the pdf file)

Noise - is INHERENT in HF reception and you're going to get it no matter where you are. However, as Daddle pointed out, if the noise is being generated at a marina or from electrical systems near by, you're going to have trouble. Some radios have a built in noise blanketer which when switched on which will clip the peak noises.

Single Side Band (SSB) is an Amplitude Modulated mode - so any kind of noise generated by electrical devices will interfere with HF reception. (Technical note: lightning strikes even thousands of miles away are pulses of Electromagnetic energy that will be heard on a receiver. Motors generate exactly the same sort of noise).

So, what this boils down to is simple... use an external antenna.

Use a good ground.
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Old 17-02-2010, 10:57   #13
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I spent many years on the shortwave listening side of the hobby before becoming an Extra class licensed ham, and in my experience with long or random wire antennas, running a wire to a ground did not improve the ability to receive signals. On occasion, it resulted in a slight increase in both signal and atmospheric noise equally, but that didn't result in an increased ability to pick out a signal.

All good receivers have enough sensitivity that atmospheric noise is the limiting factor for receiving HF signals when a reasonable antenna is used. Sometimes the higher frequency bands (those above 15 to 20 mHz) can be an exception - you can experiment to see if a ground is needed or helps, but if you can hear atmospheric noise in your receiver (as opposed to the very low level white noise of your receiver's noise floor) you probably have enough antenna and receiver sensitivity and more signal+noise won't really help.

There is no doubt that an antenna resonant for the frequencies you are interested in, and perhaps a good RF ground when using a random wire antenna, will increase the power delivered to your receiver, but it will increase signal and atmospheric noise equally. This is quite different from the case when trying to transmit, where resonance and grounds can really matter.

The best thing to do is experiment and find out what works best for your needs. In all likelihood, you won't "need" an RF ground, but heck, it doesn't hurt to try it and see if it helps, particularly if your antenna and/or receiver are somewhat deficient.
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Old 17-02-2010, 11:13   #14
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On further thought, I should qualify my position on grounds. Some type of ground or counterpoise is indeed necessary. Typically, that provided by your receiver's connection to its power source does the job with nothing else necessary. Even the metal chassis of the receiver itself can function as a ground and it might well be enough without anything extra. With the original poster's small telescopic whip, a good ground might indeed make a difference.
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Old 21-02-2010, 14:28   #15
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I have been following several threads on how to install an antenna, and have found so many different thoughts, here is a site which has made it all clear, with instructings in plain english, which also works on cats. Rope Antennas, Single Side Band antennas for Sail boats, powerboats, SSB antennas
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