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Old 19-12-2011, 22:46   #31
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Re: general cost of SSB install

Icom 718 illegal to open to commercial (marine) frequencies. Commercial ICOM can legally be opened ro ham but not vice versa.. The manufacturing specs for commercial are tighter than amateur specs. I know lots of people do it

SGC and ICOM have manuals on their websites re grounding for boats.

DC and RF way different on grounding.

Speaking as an amateur, if I were choosing an antenna for a boat for HF, the whip would be my last choice as the back stay or rope is longer and closer to resonant length. This means more watts to the antenna and less absorbed by the antenna tuner. Also more microvolts per length on receive provides better received signal.

I have often wondered why ceramic (egg) insulators couldnt be used to make a vertical sailboat antenna (all right near vertical) or even an 'L' antenna on a ketch. Wire would be either copper or copper clad steel. There are several companies that make both stranded and solid with a waterproof coating that should handle salt air. The egg fails safe if it breaks.

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Old 19-12-2011, 23:25   #32
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Re: general cost of SSB install

It's not illegal to open up a ham radio to broadcast on other than ham frequencies. It's not legal to transmit outside of the Ham frequencies except in an emergency, however. My Ham radio is a safety Item and If I need to yell for help, want to be able to yell loudly and over the broadest range of frequencies.

I've heard from people who ought to know that modern ham rigs are just as frequency stable as the Marine SSB rigs. Would be willing to bet that ICOM ham rigs are using the same frequency production circuits as their marine radios. The 718 is a relatively old radio and at the bottom of the ICOM Ham line so don't know about that radio. You can get a frequency stabilizer for the 718 which I understand is just a heater to make the crystal or whatever generates the signal operate at a constant temperature. The ICOM 7000 and 7200 ham radios are both state of the art and will probably work as built.

Many marine radios will transmit on the Ham frequencies without modification. It may not be convenient to tune around the bands as with a Ham set, however. The marine radios are set up to broadcast on a channel at specific frequencies. No tuning allowed other than switching between the preset channels on the marine bands.
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Old 20-12-2011, 06:21   #33
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Re: general cost of SSB install

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No tuning allowed other than switching between the preset channels on the marine bands.
Some marine radio's including the 802 have a "VFO mode" that allows tuning in 100hz or more increments. With a simple software mod, the M710 can do the same thing.

Marine SSB's are more frequency stable than ham rigs because they utilize OCXO's for the reference ocillator while ham rigs use TCXO's except perhaps for some of the real fancy high dollar ones, I don't know. There is also the issue with spurious emissions. Many ham rigs allow variable speech compression to be turned on/off/adjusted. The very reason the M802 has it's speech compression feature disabled from the factory is because it will not pass certification with it on due to spurious emissions.


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Old 20-12-2011, 06:38   #34
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Quote:
Originally Posted by fairbank56

Some marine radio's including the 802 have a "VFO mode" that allows tuning in 100hz or more increments. With a simple software mod, the M710 can do the same thing.
700pro does the same thing -- no software mods required. I use it to go slightly off frequency for tuning.
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Old 20-12-2011, 07:15   #35
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Quote:
Originally Posted by fairbank56
Marine SSB's are more frequency stable than ham rigs because they utilize OCXO's for the reference ocillator while ham rigs use TCXO's except perhaps for some of the real fancy high dollar ones, I don't know.
Let's see, the 710 spec says freq stability is 10Hz. My cheap Kenwood says 5 ppm. With optional TCXO it becomes 0.5 ppm.

At 8 MHz the 480 has better than 40Hz without, and better than 4Hz with the TCXO. At 16MHz that doubles and the TCXO is still within same spec as the 710. And all that without the oven. The TCXO option is just over $100.- or so.

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Old 20-12-2011, 07:25   #36
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Re: general cost of SSB install

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The only thing disabled on the 802 is the DSP Speech Compression.

All things turned off, can be turned on.
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Old 20-12-2011, 07:57   #37
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Re: general cost of SSB install

Good info.
I have a Icom 802 and am tight on space. Is it ok to install radio vertical?
How important is air space? I will not enclose it.
Thanks
Mike
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Old 20-12-2011, 09:57   #38
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You can mount the main unit any way you want, but it should not be closed up in a small space and the fan and vents should not be obstructed. The radio will be generating somewhere between 25 watts of heat at minimum in receive, and up to around 150 watts of heat in full power transmit. Keep that in mind when choosing your space.

Be sure you have room to get to all connectors, and be sure your antenna coax doesnt have to make any tight turns. You will want to find out what the minimum recommended turning radius is for the coax you are using to help decide how much space you need to leave between the antenna jacks and any adjacent surface.
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Old 20-12-2011, 10:13   #39
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Originally Posted by SoonerSailor
You can mount the main unit any way you want, but it should not be closed up in a small space and the fan and vents should not be obstructed. The radio will be generating somewhere between 25 watts of heat at minimum in receive, and up to around 150 watts of heat in full power transmit. Keep that in mind when choosing your space.

Be sure you have room to get to all connectors, and be sure your antenna coax doesnt have to make any tight turns. You will want to find out what the minimum recommended turning radius is for the coax you are using to help decide how much space you need to leave between the antenna jacks and any adjacent surface.
I would hope not... It transmits at 150W maximum and should consume about 200W at that point, so heat output is 50W then. A bit more for receive and control circuitry. But the transmits will be so short that it's hard o imagine it could ever lead to problems.

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Old 20-12-2011, 11:43   #40
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Re: general cost of SSB install

The M802 will draw about 30 amps at 13 volts at full power output in a continuous carrier mode like CW, RTTY, or Pactor1. That is almost 400 watts. You send 150 watts out to the tuner/antenna if you have a perfect 1:1 SWR, so you are left with over 200 watts of energy that the M802 circuitryy has to dissipate. Granted cruisers don't do much RTTY - which is a 100% duty mode, or Pactor1 - which is slow and only used at the beginning of a Pactor3 exchange - unless conditions are extremely marginal.

With voice SSB, you won't come close to 150 watts average power output, and even with a Pactor3 send you aren't putting out more than 75 watts as an average over time, but due to the nature of a Class A or AB power amplifier and its supporting circuitry, the unit still consumes about twice as much power as it is putting into the antenna, and what doesn't go out is generated as heat in the unit.

Bottom line: decide how you are going to use your M802 and plan its living space accordingly. And I would recommend conservatively. The cooler your M802 is, the longer its parts should last and the more reliable it will be.
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Old 20-12-2011, 12:25   #41
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For 400W in CW mode you must be leaning on the key by accident?

It's good to err on the safe side of course, but cruisers don't do CW nor RTTY etc. which could be done in class-C btw.

If it gets too warm in the space where the radio is, a small fan can be added that turns on when the radio is turned on.

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Old 20-12-2011, 13:36   #42
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Re: general cost of SSB install

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Originally Posted by PhilE View Post
I have often wondered why ceramic (egg) insulators couldnt be used to make a vertical sailboat antenna (all right near vertical) or even an 'L' antenna on a ketch.
That's what I have for insulators on my backstay antenna.

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Let's see, the 710 spec says freq stability is 10Hz. My cheap Kenwood says 5 ppm. With optional TCXO it becomes 0.5 ppm.

At 8 MHz the 480 has better than 40Hz without, and better than 4Hz with the TCXO. At 16MHz that doubles and the TCXO is still within same spec as the 710.
Apples and oranges. You are applying in-band specs for out-of-band operation.
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Old 20-12-2011, 15:01   #43
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That's what I have for insulators on my backstay antenna.

Apples and oranges. You are applying in-band specs for out-of-band operation.
I'm comparing two fixed frequency, crystal oscillators. All further frequency selection, regardless of band, is done digitally, using PLL circuitry, i.e. perfect. Any deviations are caused by the crystal temperature.

You must be thinking about spurious emissions suppression I guess.

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Old 20-12-2011, 16:14   #44
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Re: general cost of SSB install

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Let's see, the 710 spec says freq stability is 10Hz. My cheap Kenwood says 5 ppm. With optional TCXO it becomes 0.5 ppm.
The frequency stability of the 710 is much better than 10Hz. It is only stated that way because the rules call for it to be 10Hz or better. The 480's spec with the TCXO is .5ppm for -10C to +50C and 1ppm for -20C to +60C. The marine radio must pass rigid certification requirements. It must be within 10hz over a temp range of -30C to +60C and is tested at intervals of 10C throughout the temp range in an environmental chamber and the voltage input is varied from 85% to 115% of nominal voltage. It is tested at low, mid and high frequencies with the high being 27.5Mhz The radio is first "soaked" for 12 hours at -30C without power applied and must be within spec 3 minutes after power is applied. At the low and mid frequencies, the stability over the full temp range was within 2Hz and within 6Hz at 27.5Mhz. I doubt any ham radio with a TCXO would pass these tests to meet certification.

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Old 20-12-2011, 16:22   #45
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Re: general cost of SSB install

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All things turned off, can be turned on.
Ham radio "guru" Gordon West advocates turning it on. The weak average output of the 802 is well known. I have done side by side testing with an M700, M710 and M802 and the difference with the 802's compression on/off is significant.

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