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Old 22-10-2010, 20:18   #1
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SSB ICOM 802 Noise

I have a ICOM 802 installed elsewhere by a boat builder but they did not do a great job and my boat is not in thier area. It has too much noise and I need help in trying to solve the problem.
So far I have taken it away form the marina and the noise continued.
I have turned off all other electrical devices and turn on each individually. There may be more noise with the radar on but most of the noise stayed.
I have my Ham general license but know very little and have very little experience.
I am going to try to work on it when I go up to winterize the boat. I would love some step wise help on what to do first and then what next.
RDW
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Old 22-10-2010, 20:31   #2
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Things like an inverter, solar panel regulator especially an MPPT can do it.

Is it quiet at night but not during the day?

If so, the solar regulator would be an obvious choice.

LED lighting can make noise if they employ a decent regulator circuit.

Refrigeration electronics are also a big noise maker.

Do you have an alarm system? Another possibility.

Even cellphones might be the source. Hold one near a portable AM radio and you'll hear the type of noise they make.

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Old 22-10-2010, 20:39   #3
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After working through the above mentioned sources, the noise continues then look at "Line Isolators" by Radio Works - The RADIO WORKS
I installed one after a recommendation from a HAM workshop and it made a significant difference.
- - Noise on a SSB is also caused by atmospheric and solar activity and just the nature of the SSB radio. There is a reason they are referred to as "ear busters."
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Old 22-10-2010, 21:10   #4
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I have to turn off my refridge and inverter to use the SSB. (ICOM 802)
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Old 23-10-2010, 08:17   #5
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There are plenty of things to buy on the power side and the antenna side to filter RFI. There is also DSP filtering in the set if it has it. Best first is to isolate the source one by one, and also validate the position of your rig and antenna.
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Old 23-10-2010, 08:34   #6
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Good observations and recommendations above. I would just add the following:

1. Noise is not likely related to the 802. Any radio would likely be hearing the same noise (RFI).

2. RFI can be extremely difficult to find and eliminate, even for very experienced radio folks. You have to work at it methodically. The steps outlined above are good ones.

3. In addition to those mentioned above, there are several things to check:

a) the power line to the radio. Power should be taken DIRECTLY from the house batteries, with appropriate fusing near the batteries on both the positive and negative cables. It should be a minimum of AWG6 cable for one-way runs up to about 20', and AWG4 or even AWG2 for longer runs.

Note: this is important not only to get full voltage to the radio, but to help eliminate RFI both ways...from the radio to other instruments on board, and from other equipment on board to the radio. Going thru a DC panel is NOT a good idea.

b) use of RG-214 coax between the radio and the tuner....this is double-shielded coax which is the same size as RG-213....also helps reduce RFI.

c) the RF ground system should NOT be tied to any other ground system on the boat (DC, bonding, or lightning). It should be entirely independent.

d) inasfar as possible, run ground system and antenna system wires away from other electrical wires on the boat.

These steps are IN ADDITION to others mentioned above, but can be implemented in any convenient order.

Bill
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Old 23-10-2010, 09:37   #7
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This is the second recent thread on noise from an ICOM M802. As noise is a subjective thing I wonder if folks are giving consideration to the following:

As Bill implies RF noise is ever present in the ether. Just turn off the squelch on your VHF. On HF radio's with their much greater frequency range, a wider range & type of noise will be heard - always - RFI.

If you can prove that your radio is significantly worse than another radio in the same approximate location & frequency range then sure, start looking on board for sources of "local" noise. Anything else is just chasing your tail.

Remember RF gain will have a significant effect on background noise as well as the signal you wish to hear. This needs to be balanced against AGC.
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Old 23-10-2010, 09:49   #8
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btrayfors - nice recommendations.

My only question is the size of the power cables which I think may be overkill for the amperage needs of the radio and wasteful of currrent/power as well as costly. Cannot you get by with a cable rated for the distance and power requirements - perhaps just a step higher?
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Old 23-10-2010, 09:54   #9
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Old 23-10-2010, 10:14   #10
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Originally Posted by richardhula View Post
RF noise is ever present in the ether. Just turn off the squelch on your VHF. On HF radio's with their much greater frequency range, a wider range & type of noise will be heard - always - RFI.
The noise you hear on an unsquelched VHF is not RF noise from the ether. It is receiver noise generated entirely from circuitry inside the radio, primarily from shot noise and thermal noise.

The typical background noise you hear on HF is usually just normal atmospheric noise. The inexperienced are always asking why there is so much noise on the SSB. It's the nature of the beast, excluding onboard and very nearby sources of interference that can add greatly to the overall noise level and as stated, can be difficult to trace and alleviate.

Eric
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Old 23-10-2010, 10:20   #11
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Quote:
Originally Posted by fairbank56 View Post
The noise you hear on an unsquelched VHF is not RF noise from the ether. It is receiver noise generated entirely from circuitry inside the radio, primarily from shot noise and thermal noise.

The typical background noise you hear on HF is usually just normal atmospheric noise. The inexperienced are always asking why there is so much noise on the SSB. It's the nature of the beast, excluding onboard and very nearby sources of interference that can add greatly to the overall noise level and as stated, can be difficult to trace and alleviate.

Eric
That's the exact point I was trying to make regarding HF noise.

BTW if VHF noise is only generated as you suggest why do I hear a dramatic change in receiver noise when I disconnect/reconnect VHF antenna cable?
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Old 23-10-2010, 10:25   #12
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My only question is the size of the power cables which I think may be overkill for the amperage needs of the radio and wasteful of currrent/power as well as costly.
Bill's assessment is correct although you could use AWG8 for one-way runs of 10' or less. The larger cable size is to prevent excessive voltage drop but how is the size of the cable a waste of current/power???

Eric
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Old 23-10-2010, 10:32   #13
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BTW if VHF noise is only generated as you suggest why do I hear a dramatic change in receiver noise when I disconnect/reconnect VHF antenna cable?
You don't hear a dramatic change in noise level when doing that unless you have a serious RFI problem. Anyone can do that simple test for themselves to see that I am correct.

Eric
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Old 23-10-2010, 10:36   #14
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Before doing any of the above, you need to understand some fundamentals - there are two causes of noise:
conducted and radiated.
Just like anything else, before you try fixing a problem, it helps to know what is causing it; otherwise, you are wasting your time and money in some cases with things like chokes and cables, grounds, etc.

The problem is that it is not easy to differentiate the causes. On some radios, you can turn the RF gain all the way down, up the AF gain and notice if the noise is present indicative of internal receiver noise which all radios inherently cause. This is only a generality and there are exceptions to the procedure. If you can isolate it as internal noise, the fix is probably beyond most boaters.

Remove the coax to do the same test although this is not as conclusive.

Shutting off everything while running direct radio power to the battery bank can often demonstrate the existence of conducted noise by it's absence in such a test. Again, nearby RF hash can interfere with this test.

The litany can go on here but without knowing more precisely the conditions present, giving a definitive answer is usually going to be misleading and many folks follow some advice to the peril of their wallet and time.
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Old 23-10-2010, 11:04   #15
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Before doing any of the above, you need to understand some fundamentals - there are two causes of noise:
conducted and radiated.
These are not causes of noise, they are just two ways that noise is propagated. My guess is that since the OP says he has very little experience with HF, that he is just hearing normal atmoshperic noise that we all hear on these bands. I can't tell you how many times Iv'e heard from those with little HF experience, why is there so much noise? While there is internal receiver noise generated in our HF radio's, it is totally dominated by environmental (atmospheric) noise by some 30 to 70db so receiver noise never comes into play. VHF is totally different and it is the internal receiver noise that dominates and environmental noise becomes negligible. Except of course, in cases of extreme local RFI.

Eric
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