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Old 04-12-2007, 20:12   #16
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There are some gems and some very misleading statements in several of the above posts. And, some red herrings.

1. As Rick said, there are good reasons for having BOTH a ham and a marine SSB aboard these days. I won't elaborate here, for sake of brevity; there are posts on the SSCA board which make the case.

2. Virtually ALL SSB radios aboard small vessels these days -- ham or marine -- are powered by 12 volts. The discussion about 115VAC power supplies and generators is a red herring. It's almost never involved.

3. Marine rigs, in general, are more tolerant of low input voltages than are, e.g., many ham rigs. Once input voltage drops -- for whatever reason -- below a threshold level for that particular radio it begins to behave erratically or to just quit. Typically, an HF set will begin "FM-ing", or distorting the voice signal. Most ham rigs are designed to operate at voltages normally found in cars, i.e., 13.6 or 13.8 volts (with the motor running); they're happy with voltages plus or minus 10%, but not much more. Marine rigs generally have 15% or more tolerance.

4. Some ham rigs are very good in this respect, and will operate down to voltages as low as will marine rigs. And, there are good solutions, like the W4RRY booster which delivers 13.6 volts to the radio with battery voltages as low as about 11 VDC. I've used this wonderful little device on my boat for a couple of years now. See, e.g., Gallery :: W4RRY Leo's Battery Booster

5. The discussion about voltage drop is interesting, but not complete. Yes, quality fuses have lower voltage drops than do bi-metal circuit breakers. And, fuses provide better protection for the radio than do circuit breakers. And, they are more reliable (less prone to failure). Still, circuit breakers may be OK in addition to fuses, since the amount of voltage drop at the typical loads presented by a SSB radio are very small. Usually, the prime culprits in voltage drop occurrences is inadequate size wiring and poor connections, not fuses and circuit breakers.

6. As Rick said, fuses or circuit breakers belong NEAR THE BATTERY. And, contrary to what Rick said, one isn't enough. You need to fuse BOTH the positive and the negative leads to a SSB radio.

7. The discussion re: fixed and variable PEP levels is ...well...misleading (I'm trying to be nice). Both marine and ham radios use similar PEP levels...generally between 100 and 150 watts...and in most cases the user can choose to reduce the output power (many commercial radios have a LOW-MED-HIGH power setting, while many ham rigs have a continuously variable RF power level adjustment). Mostly, users don't touch these....the radios operate at their rated output levels most of the time.

Bill
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Old 05-12-2007, 16:58   #17
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The real world of SSB installations

Many marine and HAM rigs are rated to operate (meet spec) with input voltages down to 11.6, 11.7 V. Many of these rigs that I have tested meet specs down to 11.0 V (but don't count on it).

Many installation problems have been traced to wiring the rigs via the customary installed dc distribution panel that has a breaker for the rig, and a main dc breaker for the panel and then another breaker or fuse from a house battery, also with a switch in-line with the battery and fuse.

HAM rigs operating at rated PEP may draw 20A. It does not matter that the current is a peak value or not because the IR drops in the typical dc panel installation mentioned DO cause a significant drop at these current peaks and, although one might complain that the ship's wiring is marginal or undersized for this, that does not ameloriate the problem of time degradation of all the intermediate connections in the current loop (don't forget ground) which ALSO includes power and ground drops due to things like bilge pumps cutting in. As a result it is recommended, IN GENERAL, to not use the ship's normal dc panel and distribution system (including the ground dc distribution system. Instead, wire the rig directly to a battery using approved wiring and fuses (yeah, one is supposed to put a fuse in the ground side of the rig not for personal safety but supposedly for the safety of the rig and coax).

Regardless, it is a rare installation that uses the ships dc panel that delivers a good terminal voltage to the rig at peak power. Keep in mind here that to meet spec for the rig with a somewhat depleted "house" battery driving it you essentially have NO voltage burden budget left over for the panel distribution wiring losses! This is my point. It doesn't matter that most of the time everything seems O.K. As an engineer I design to spec, not to what seems O.K., average, or most of the time.

As Bill suggests, it could be a good idea to use a buck/boost switcher supply to feed the rig. Make sure that the noise spec is good;not to degrade Rx S/N ratio across the band(s), and that it truly will deliver 20A peak outut current without sagging drive voltage.
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Old 05-12-2007, 17:11   #18
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Absolutely agree with Rick about wiring SSB sets -- ham and marine -- directly to the battery, using appropriate fusing devices on both positive and negative leads. I do this routinely, even with booster devices available. The distribution panels and breakers and wiring in typical installations aboard boats are insufficient for SSB needs AND....as important...introduce unwanted noise into the receiver and RF back into the panels.

Bill
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Old 05-12-2007, 17:24   #19
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Although an interesting read, none of the above few posts (discussing voltage) is relevant to the issue(s) brought up in terms of the ambient noise floor from radiated or conducted noise sources. I have no problem that we got off-topic but didn't want others to infer any of this will help their noise problems.
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Old 25-01-2009, 07:17   #20
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S/V Illusion

I had the same problem when I came into the marina I am in right now. Very dissapointing compared with the wonderful calm and low noise level I get when I am at anchor. After trying everything you did, I found that indeed, there was nothing I could do about it.

I have been told that MFJ makes a noise filter that can weed out these types of signals. You could also try some of the external DSP devices and speakers that are out there.

I have two rigs aboard, an ICOM M700PRO marine SSB and a Yaesu FT-857D amateur transceiver. The DSP on the 857 is pretty good...no amount of working with that or RF gain eliminated the noise (one regular pulse, in particular).

What I ended up doing:

Resigned to the fact that I could not enjoy my ham radio hobby very much in the marina, I took my portable rig (the 857) and made a temporary set up with a simple wire dipole antenna, that I could use at the homes of friends and family.

Experiment with different types of antenna's. As you know, some antenna's can have nulls in certain paths, some may be higher or lower gain. By chance, I tried a simple long wire antenna run horizontally. That seemed to work better, though of course this was a lower gain antenna.

What really worked was the departure of the offending boat. Things seem much quieter now...so I can only assume it was the BIG yacht nearby with its plasma screen TV's and all high end electronics and heat/ac systems that ran continuously.

At any rate. A few of ideas:

1. You could try some of the filtering products out there.
2. Get a portable rig and set up shop somewhere else (your home?)
3. Anchor out more often.
4. Try some different antenna's, even if they are less efficient and lower gain. Or perhaps even a yagi, higher gain, directional antenna.
5. Enjoy 2m for a while

Anyway...just my 0.02, no expert.

best

John
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Old 26-01-2009, 20:25   #21
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I think that is a great idea David, go help that guy! You can pull while he listens.

Without listening to the noise, It is hard to tell if you have only one source or many. Lots of good suggestions. If it would be from the power company, you could complain to the local company, but my expierence is that they mostly ignore complaints. The FCC doesn't have the money or people to inforce their own regulations. I've been fighting the electric company here in Ok City for twelve (12) years and although they have done some work on occasion (eye wash), they never have fixed the problem. The ARRL (American Radio Relay League) has a good book on RF interference. www.arrl.org
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Old 26-01-2009, 21:59   #22
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Noise and the marina environment

We've been in a lot of marinas over the years, and nearly all of them have sported high noise levels. I have been as aggravated as any of you by this, but have only taken any action when it was truly unbearable. Then I've roamed the docks with a portable Sony "shortwave" rx tuned to the frequencies in question (mostly the 40 metre band). Usually one finds that the noise is kinda general... no specific source identifiable. But sometimes a real villain is found. Without wanting to sound biased, they have usually been motor yachts. One particular item that has been identified as a big-time noise radiator is 24-12 volt dc to dc converters which are common on larger MYs (24 volt house systems and cheaper 12 volt accessories). I have had some luck getting their owners to turn these items off when they are not aboard -- a little tact helps here !

Another common villain is newer Danfos 12 volt compressors (these are found in many fridge systems like Adler-Barbour, etc). They seem to have a microprocessor in their "black box" which radiates noise that sounds sorta like CW, and comes on whenever the compressor starts up. I've not had much luck in convincing folks to turn their fridges off, tho'!

Noisy power lines, light fixtures and motors abound in marinas, just as they do in landlubber environments, and there is bugger-all to do about them as far as I know... except get the hell out of the marina, which of course is what we all should be doing!

Another factor interfering with good communications is the attenuation of signal strength, both incoming and outgoing, which is due, I think, to parasitic absorbtion in all the masts and rigging surrounding your boat. We have done informal tests by getting signal reports just before and just after leaving a marina. Not too scientific, but we've typically gained 2 or 3 S-units by simply getting outta Dodge.

One last noise source that rears its ugly head is the over-the-horizon radars operated by several nations' militaries. Known colloquially as the "woodpecker",these blast huge quantities of RF over vast distances and covering wide frequency ranges. In the western Pacific we often get signal levels of S9+20dB on 40 metres, which is devastating to say the least. Buggers...

Wish there was a good solution... I'd be glad to hear of any successful interventions!!!

Cheers and 73's

Jim N9GFT/VK4GFT
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Old 11-01-2010, 16:33   #23
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Fuse in negative lead

Can someone please explain why (technical reason) a fuse is "necessary" in the negative lead? I have read often that an SSB, but no other equipment, should have a fuse in the negative lead but none of the technical reasons hold up.
thanks, phil, No Ka Oi.
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Old 14-01-2010, 16:40   #24
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SSB negative lead fuse

Because the external coaxial connector is common with the chassis and negative power lead of the transceiver a fuse is placed in the negative lead to prevent burning up the power lead should a source be connected to an antenna or tuner fed by the coax.
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