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Old 26-04-2012, 22:23   #1
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side band rookie

Ok, I bought a used ic-m700 w/at120 tuner. I powered the radio direct to the batts w#10 wire. I grounded the radio w/3"copper strap to a keel bolt (iron keel) I grounded the tuner to a through hull. I have a #8 feed wire going to the antenna lead - about 6-7' - to an insulated 3/16''SS cable jumper wire -10' -hooked on to my open wire antenna (3/16ss cable) attached with ss cable clamps. I get the time ticks on 10000 & 15000. I hear some ham bs on 44131, I heard a weather report from down around the Panama canal (weak) I heard the CG hourly on 13xxx weak & garbled. The weather was raining - middle of the day. The tuner sounds like its working, etc.
I just cant raise any local ship traffic or anything else. I programed the freq's that are in the manual.
Seems like it should hear better than this. When I get back (at the cabin trout fishing now) I'll hook up an swr and check that.
Is there something I'm missing??
I recieve static, code, all kinds of racket across all modes & freq's - doesnt seem like there are any dead channels anywhere -but what do I know?? I'm a retired fisherman - that means I know how to get into trouble with radios!
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Old 26-04-2012, 22:45   #2
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Re: side band rookie

The radio does not need to be grounded except as part of the DC power circuit. The tuner would probably be better hooked up to your iron keel with copper strapping though a through hull is supposed to work. Read the manual and find out how to get the radio to display the SWR reading on transmit. The SWR should be below 2.0 and preferably below 1.0. The radio self limits output as a function of SWR mismatch. It starts seriously cutting back with an SWR above 2.O and attenuates the output to a lesser extent below that SWR reading. If the SWR i not close to 1.0, your tuner isn't doing it's job probably because of the ground

Recieve capabilities are little affected by the tuner. The tuner primarily works on transmit. You should be running coax from your radio to your tuner. The tuner should be as close to the antenna as possible. Unshielded #10 insulated wire should be fine from the tuner to the antenna which I assume is your insulated backstay. The effective length of the antenna is all the wire from you antenna tuner to the insulator at the top of your backstay.
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Old 26-04-2012, 23:06   #3
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Re: side band rookie

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The radio does not need to be grounded except as part of the DC power circuit. The tuner would probably be better hooked up to your iron keel with copper strapping though a through hull is supposed to work. Read the manual and find out how to get the radio to display the SWR reading on transmit. The SWR should be below 2.0 and preferably below 1.0. The radio self limits output as a function of SWR mismatch. It starts seriously cutting back with an SWR above 2.O and attenuates the output to a lesser extent below that SWR reading. If the SWR i not close to 1.0, your tuner isn't doing it's job probably because of the ground

Recieve capabilities are little affected by the tuner. The tuner primarily works on transmit. You should be running coax from your radio to your tuner. The tuner should be as close to the antenna as possible. Unshielded #10 insulated wire should be fine from the tuner to the antenna which I assume is your insulated backstay. The effective length of the antenna is all the wire from you antenna tuner to the insulator at the top of your backstay.
I have rg213 coax from radio to tuner. I temp connected copper strap from through hull to keel bolt - made no difference. The radio has a ground lug on the back that is hooked to keel by copper strap. All connections are clean and tight. Antenna lead is #8 shielded wire hooked to insulated open wire cable approx 40' long - 10 feet of which is vertical jumper wire hooked to open wire diagonal antenna that is between mizzen & main - entire length of ant is 48-50 long. There is no swr meter on this radio but I have a 200 watt meter that I can hook up to test with.
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Old 26-04-2012, 23:21   #4
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Re: side band rookie

The Icom ham radios have a setting that displays SWR. Would seem that the marine radio would also. Might want to look through the manual and see if it's mentioned.

The marine raidos are designed to be user proof so may not have any way for the operator to check the SWR through one of the display settings. If that's the case, find an interested ham operator and they will probably have an SWR meter that they can lend you.
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Old 26-04-2012, 23:33   #5
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Re: side band rookie

No problem - I have one. One correction - I mentioned that my antenna feed line was shielded - I meant insulated. My lead wire is about 7' long - I cant get the tuner any closer than that.
The book mentions the use of a counterpoise - such as a copper pipe or tank but doesnt get an more specific than that. It would be easy enough to add a cable to the water tank.
I thought a counterpoise was used to take the place of earth ground??
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Old 27-04-2012, 06:16   #6
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Re: side band rookie

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Recieve capabilities are little affected by the tuner. The tuner primarily works on transmit.
This is incorrect. Receive capabilities can be significantly improved by the tuner. A good example is in receiving weatherfax transmissions. While you cannot "tune up" directly on a fax frequency, tuning on a frequency near the fax frequency can very significantly improve reception. Reception does not "require" tuning as transmit does, but it can significantly improve reception for sure. Any ham who is used to using manual tuner's can tell you that. Rotating that tuning dial just a little bit can be the difference between receiving a signal and not hearing it at all.

Geoduck, all that "racket" you are hearing is a good thing. You are receiving well. HF SSB receivers are wide open to atmospheric noise which is prevalent across the HF bands. Pull that coax connector while receiving and most of that noise will disappear. Noise can be managed well on a marine SSB by using the RF Gain control if it has one. Ham radio's have this as well as many other user controlled filtering options.

Eric
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Old 27-04-2012, 07:17   #7
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Re: side band rookie

Hi. This whole subject might be more art than science.
I have seen installations that theoretically never should work, but worked extremely well. I have also seen "Perfect" installations that just never cut it.

My habit, is to ground the radio to the tuner to the counterpoise always, because the RG213 screen will be carrying the counterpoise of the power sent down the coax. The PL259's are notorious for not working well if they are not perfectly fitted. So, you can do this as a T or an L or a triangle but, the tuner must connect to the radio and both to the keel. Using foil is the correct way because of skin effect, a solid copper bar would only conduct on its air surface at RF frequencies (Think AC house wiring at 30,000 cylces not 60)
One thing to check with the 700, is that the NEG fuse is not blown, the radio will continue to work with it blown, but the neg from the battery will come to the radio via the grounding, and it should not.

One correction, there is no such thing as "Ham BS" its all really important stuff.

Over...
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Old 27-04-2012, 08:36   #8
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Re: side band rookie

[QUOTE=sy_gilana;939872]Hi. This whole subject might be more art than science.
I have seen installations that theoretically never should work, but worked extremely well. I have also seen "Perfect" installations that just never cut it.

My habit, is to ground the radio to the tuner to the counterpoise always, because the RG213 screen will be carrying the counterpoise of the power sent down the coax. The PL259's are notorious for not working well if they are not perfectly fitted. So, you can do this as a T or an L or a triangle but, the tuner must connect to the radio and both to the keel. Using foil is the correct way because of skin effect, a solid copper bar would only conduct on its air surface at RF frequencies (Think AC house wiring at 30,000 cylces not 60)
One thing to check with the 700, is that the NEG fuse is not blown, the radio will continue to work with it blown, but the neg from the battery will come to the radio via the grounding, and it should not.

Ok, I'll have to check the fuse - never thought of that. I will install more copper straps from the tuner to the keel so that will tie the tuner and the radio to the same earth ground - that should cover it.
I was just a little concerned that I couldnt pick up some locall ship traffic but maybe they all were asleep at the wheel that day. I'll have to get away from the dock and see what happens.
I have to disagree about the 'ham bs' statement - I was a ham when I was a kid - It was alot of BS then and it still is! After all, I'm an old commercial fisherman and I KNOW BS WHEN I HEAR IT!! (I always thought I was quite good at it myself!) "No BullShip, No Bullship, No Bullship - this is the Eastwind - you pick me up, ok?"
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Old 27-04-2012, 12:01   #9
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Re: side band rookie

Counterpoise is the proper terminology rather than ground. A radio 'ground' is not the same thing as an electrical circuit ground. My counterpoise is two strips of copper strap strap down each side of the boat under the deck. The tuner isn't connected to anything else and works fine.
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Old 28-04-2012, 08:12   #10
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Re: side band rookie

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Counterpoise is the proper terminology rather than ground. A radio 'ground' is not the same thing as an electrical circuit ground. My counterpoise is two strips of copper strap strap down each side of the boat under the deck. The tuner isn't connected to anything else and works fine.
Thanks for that info - I'm getting a higher education here on this forum! Sooner or later, I'll have it all figured out - maybe.
I see that the KISS ground/counterpoise is nothing more than a measured length of wire, stuffed inside a plastic pipe/hose with a coax connector on it. I think I read 66' of wire folded into 3' lengths - something like that - and everyone seems to like them. Go figure.
I saw on the internet where some guy took one apart to see what makes it tick - very basic for sure - all anyone needs to know is the length of wire to make one.
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Old 28-04-2012, 09:55   #11
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Re: side band rookie

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The SWR should be below 2.0 and preferably below 1.0.
I get consistently 1.0 and thought that was the "best".
How far below can you get...?

Does it matter if my plate under the hull is covered with barnacles or slime?
(In other words, does it make a difference to clean it..?)

No ICOM, but a 10 year old SEA 235 R.
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Old 28-04-2012, 10:13   #12
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Re: side band rookie

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I get consistently 1.0 and thought that was the "best".
How far below can you get...?

Does it matter if my plate under the hull is covered with barnacles or slime?
(In other words, does it make a difference to clean it..?)

No ICOM, but a 10 year old SEA 235 R.
There's no "below 1". An SWR of 1:1 would be a perfect 50-ohm match.

Corrosion and/or growth on the plate can affect RF grounding somewhat. That's why the "scintered plates" become less than useful after a few months. Anyway, there's practically no reason to use them, when there are lots of other good solutions.

Nothing wrong with a 10-year old SEA235. Good radio.

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Old 28-04-2012, 11:42   #13
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Re: side band rookie

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There's no "below 1". An SWR of 1:1 would be a perfect 50-ohm match
That is what I thought as well, but somebody else mentioned:

Quote:
The SWR should be below 2.0 and preferably below 1.0.
Quote:
Anyway, there's practically no reason to use them, when there are lots of other good solutions.
When I installed my system 10 years ago it was higly recommended,
what is the modern solutions?

Quote:
Nothing wrong with a 10-year old SEA235. Good radio.
Yeah, I have been happy with it, never had any problems and I get the occasional long range radio-check, severeal times between Florida and Lima, Peru and once from Florida to Stockholm Radio, but it was very week.
Normally I use the radio for phone patches when anchored in remote Bahamas and needing to call somebody in the US. Been happy with WLO over the years, the price now is $0.99 per minutte..whereas ATT using their International plan and roaming charges $1.99 per minutte in the Bahamas.
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Old 28-04-2012, 11:52   #14
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Re: side band rookie

One correction, there is no such thing as "Ham BS" its all really important stuff.

Hah! Now THAT is funny!
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Old 28-04-2012, 18:53   #15
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Re: side band rookie

Geo-
I would wonder if you aren't suffering from a skip zone.
Skip zone - Wikipedia, the free encyclopedia
or better
NVIS Army Field Manual 24-18 Appx M see section M2, note that your local communications on HF radio can "fail" at only 2 miles out from your location. I'm not saying this is the problem--just be advised that HF often works better for long distances than it does for "just over the horizon".

Not knowing what "local" is to you...just tossing this in for consideration.
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