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Old 20-01-2013, 08:54   #16
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Re: Power Supply for SSB in a 24v Boat

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Originally Posted by Nicholson58 View Post
Perhaps you might consider operating the SSB off the engine start battery and plan to run the engine while using the SSB. This might be logical since it uses so much power.

On our boat, the SSB is 30 volts. The boat is 24. We have one of those expensive DC-DC devices but it was there when we bought the boat. I have located this supplier that might interest you. Murata Power Solutions | DC-DC Converter, AC-DC Power Supply, Digital Panel Meter, Inductor, Common Mode Choke and Pulse Transformer | Murata Power Solutions
Yikes, would be hard to hear the SSB with the engine running!

But the generator start battery is an option. With a low-noise 24v-12v charger feeding it off the house bank. I have just calculated the cable size needed -- AWG4 will limit to 3% voltage drop over 30 feet at up to 40 amps. That's not as massive as I thought. I wonder, however, whether 30 foot battery cables will pick up noise?

I am starting to get paranoid about noise -- I have a couple dozen LED light units on board, of all different types. They all have buck regulators, which I see from my ham radio forum reading are prodigious sources of noise
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Old 20-01-2013, 09:14   #17
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Re: Power Supply for SSB in a 24v Boat

I am not into SSB stuff so my comments/questions are somewhat moot. You already own the SSB equipment but is there a reason you elected to go with a DC powered system, one that uses only 12vdc for a power source over one that operates from AC?

Sure, there are conversion losses as a result of processing various different voltages along with DC-AC but my off the cuff guess is operating from 12vdc with huge currents is going to be problematic.

I have both 12 & 24vdc systems on my boat as you have. This upcoming season I intend--- make that hope-- to put the greater loads onto the 24vdc and change my solar connections from 12 to 24vdc. Also I am going to try a cheapo 2.5KW true sinewave inverter offered on Ebay to get my AC.

US Stock 5000W Max 2500W Pure Sine Wave Power Inverter 24VDC 110VAC Power Tools | eBay

The thing that intrigues me is this unit is advertised as being a true sinewave output. Most likely all the heavy internal power switching is done as a sinewave thereby minimizing radiated harmonics. But again, I don't intend to use this for a transmitter.

I do share you concern about noise whether its on the dc line or radiated. I currently have a 1 KW sinwave (Xantrex) inverter operating my refrigerator powered from my 12vdc bank. Unfortunately I also have my marine transceiver connected to the same bank. Not sure if the transceiver has a direct wire back to the batteries but I do know that when the fridge's compressor is on, I get a strong 60Hz hum into the transmitted signal. That is my reason for wanting to separate the heavy loads to 24vdc.

Just my thoughs--

Foggy
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Old 20-01-2013, 09:31   #18
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Re: Power Supply for SSB in a 24v Boat

Well, I've never heard of an AC powered marine HF radio.

I do have a 3kW Victron pure sine wave inverter. It works great when it's not broken
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Old 20-01-2013, 10:27   #19
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Re: Power Supply for SSB in a 24v Boat

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Well, I've never heard of an AC powered marine HF radio.

I do have a 3kW Victron pure sine wave inverter. It works great when it's not broken

Well, like I stated I am not into SSB stuff. But is not SSB land based equipment available with the same frequency coverages? My Summit 8.3cuft fridge is not marine rated either but it works well, has auto defrost and an interior light, all features that a noisy equivalent Norcold lacks. But you're happy, I'm happy
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Old 20-01-2013, 16:03   #20
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Re: Power Supply for SSB in a 24v Boat

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Originally Posted by Dockhead View Post
Yikes, would be hard to hear the SSB with the engine running!

But the generator start battery is an option. With a low-noise 24v-12v charger feeding it off the house bank. I have just calculated the cable size needed -- AWG4 will limit to 3% voltage drop over 30 feet at up to 40 amps. That's not as massive as I thought. I wonder, however, whether 30 foot battery cables will pick up noise?

I am starting to get paranoid about noise -- I have a couple dozen LED light units on board, of all different types. They all have buck regulators, which I see from my ham radio forum reading are prodigious sources of noise
Run a temporary light gauge power feed (say 16 AWG) roughly in the location where the permanent run would go and see how much noise the wiring will actually pick up.

The receiver is the noise sensitive part and only needs an amp or so and to run.

If OK, go ahead with permanent heavy gauge wiring as this is really the most elegant solution.
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Old 21-01-2013, 07:30   #21
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Re: Power Supply for SSB in a 24v Boat

I am offered a 24v-12v converter from Alfatronix which is supposed to produce output noise according to this specification:

<50mV pk-pk at continuous load. Meets CISPR25 and VDE0879-3

Is that quiet enough? It's a switch-mode converter, but they say it's free from RFI emissions.

It's rated for 24 amps continuous and 30 amps for 2 minutes out of 8. Should be ok for voice, but I'm worried that might not be enough if I transmit continuously while using Pactor.

Here is the data sheet: http://www.farnell.com/datasheets/25962.pdf


This would be the simplest installation. Still considering using the generator start battery, but worried about the long power leads picking up noise (should I be worried?).

The other variant would be something like a LiFePo motorcycle battery, 20 amp/hours or so, with a low-noise 24v-12v charger. That version has a big advantage of no voltage drop under load; also could run the radio straight from the battery with no outside power for fair periods of time if I wanted to. Could be an advantage in noise -- could in fact shut the entire electrical system of the boat down if I have some really important conversation.
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Old 21-01-2013, 07:47   #22
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Re: Power Supply for SSB in a 24v Boat

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Originally Posted by Dockhead View Post
This would be the simplest installation. Still considering using the generator start battery, but worried about the long power leads picking up noise (should I be worried?).
Other clever folks knowledge of this would be interesting, but on my ham rig all the noise seems to be airborne. I'm not sure how much noise can get into the radio via the power leads, anyone care to comment?
I've tried mine off a battery not connected to anything else and the worst culprits, fridge and mains charger, were no different.
One of these little radios, DEGEN DE1103 Digital AM/FM/LW SSB Radio Receiver (Gray) | eBay canbe useful to track down rf noise, and they're a great little radio for the price as well.

Good luck
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Old 21-01-2013, 15:18   #23
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Re: Power Supply for SSB in a 24v Boat

Dockhead,
1) I understand now....
Quote:
Originally Posted by Dockhead View Post
Yes, Option A is the difference between about $5000 and, in my case, $1000 including antenna tuner and latest Pactor USB
BTW, getting an M-802, AT-140, and PACTOR modem for $1000 is not just a great deal, but it is a "steal"!!!







2) As for you other options....
Quote:
Originally Posted by Dockhead View Post
I think using existing 12v banks is no good because of distance (probably 10 meter cables).

I don't want to 12v tap my 24v bank - I know it works, but I just hate the idea.

That leaves, I think:

1. DC-DC converter. IF I can find one with our RFI noise, this is the best option, I think.

OR

2. Separate battery charged by a 24v to 12v three stage charger like the Mastervolt Magic. I don't like this as much due to weight, space and complexity, but it is relatively cheap and should be noise-free. I have a place to put a battery box next to where the radio will be installed, but I would rather use the precious space for something else. Also, separate batt with charger will eat a lot more power.
I personally like your idea #2...(or even doing this using your existing 12vdc battery...)


-- Looking at the option of using your existing 12vdc battery, charged via a 24v to 12v charger, yes the current draw of the M-802 (and hence the voltage drop in the 12vdc power wiring), is the main negative issue here....and with a 10 meter run (20 meters round-trip) you'd need 2awg wiring in order to reduce voltage drop to 3% or less....and this would not only be expensive, but may be a pain in the a** to run that wiring....
So, perhaps finding a location to mount the M-802 transceiver closer to the battery...

-- Or your idea #2 of using another (smaller?) battery closer to the M-802, is really the best overall approach here....

-- To be clear, either of these ideas (your idea #2 or using your existing 12vdc batteries with the same 24-12 charger), allows use of the M-802 without using anything else on-board.....no engine, no dc-dc converter, etc....even if your 24-12 charger fails.....AND, should the 24v-12v charger present some unwanted RFI, it is simple to install an on/off "cut-off switch" on the 24vdc input to the 24v - 12v charger, to completely eliminate any troublesome RFI when using the M-802....


So, while it took us some time to get there....
I do think we have come upon a solution!!!




3) As for RFI, it is almost always "radiated" noise that is picked-up by your M-802's antenna.....RFI ingress from dc power wires is VERY rare (I've never seen it on-board, and only once when at a shore station)....
But, if RFI is generated by systems on-board, such as inverters, chargers, refrigeration compressors, etc....it is made significantly worse when that RFI is radiated by the wiring coming out of that device.....
So, IF you do have RFI from something on-board causing you reception problems, reducing the length of wiring on those devices, AND adding ferrite beads on those wires as close to the RFI-generating device as possible, will be the best way to reduce/eliminate the RFI....



4) As for other questions about your M-802 installation / set-up, I'd be happy to help....(as I have ~ 40 years experience in HF comms at sea and on land, have run my own electronics company for ~30 years, and have taught many seminars on radio propagation, antenna system design, alt energy, etc...)
First off, have a look at some of these threads....
SSCA Forum &bull; View topic - A Few SSB Install Questions
SSCA Forum &bull; View topic - Tips for using an HF-SSB Radio (mostly for newcomers)
SSCA Forum &bull; View topic - KISS-SSB Counterpoise
SSCA Forum &bull; View topic - HF Radio Freqs, summertime Atlantic crossing, offshore Net..

ssb freqs



5) To be clear here, HF radio communications and radio wave propagation, radio/antenna design and installation (including antenna counterpoises), etc. are all very well understood science and engineering.....
Contrary to what many write, there is no "art" involved in most of this....
(although there is some "art" involved in the human operations of the radio, there is no art involved in the proper design, engineering, and installation of these things.....and many of the basics have been studied/written about for many, many years....some references still used go back to the 1930's....after all electrons do flow the same now as they did decades before I was born!!!


Here are my Top 5 Tips in brief...
a) read some books about radios, antennas, hf communications, etc....where you will learn a GREAT deal, and where you will not be mislead by "internet discussion board" mis-information....
b) make sure you have a short, low-loss, hi-current 12vdc power connection for your radio, direct to the batteries....
c) have a low-inductance direct sea water connection from your antenna tuner grd lug....
d) reduce on-board generated RFI, and use ferrites beads...etc....
e) listen on-the-air / learn the easy and proper operating procedures....

If you take the above tips to heart, and follow them, you'll be happy with your marine HF radio system....



I do hope all the above helps...

Fair winds...

John
s/v Annie Laurie
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Old 21-01-2013, 15:46   #24
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Re: Power Supply for SSB in a 24v Boat

One more idea. Before I was aware of LiFePO4 battery's ability to not sag under heavy loads, and was still using lead acid, I just used two power supplies run off the inverter. One for the HF radio rated at 30 amps, and the other for the solid state amp rated at 75 amps. Any kind of long wire run just wasn't working running the two, so I decided to loose some efficiency in conversion. This way the voltage to the radio didn't sag due to the amp draw of the linear amplifier.
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Old 22-01-2013, 08:24   #25
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Re: Power Supply for SSB in a 24v Boat

Quote:
Originally Posted by ka4wja View Post
Dockhead,
1) I understand now....
BTW, getting an M-802, AT-140, and PACTOR modem for $1000 is not just a great deal, but it is a "steal"!!!







2) As for you other options....
I personally like your idea #2...(or even doing this using your existing 12vdc battery...)


-- Looking at the option of using your existing 12vdc battery, charged via a 24v to 12v charger, yes the current draw of the M-802 (and hence the voltage drop in the 12vdc power wiring), is the main negative issue here....and with a 10 meter run (20 meters round-trip) you'd need 2awg wiring in order to reduce voltage drop to 3% or less....and this would not only be expensive, but may be a pain in the a** to run that wiring....
So, perhaps finding a location to mount the M-802 transceiver closer to the battery...

-- Or your idea #2 of using another (smaller?) battery closer to the M-802, is really the best overall approach here....

-- To be clear, either of these ideas (your idea #2 or using your existing 12vdc batteries with the same 24-12 charger), allows use of the M-802 without using anything else on-board.....no engine, no dc-dc converter, etc....even if your 24-12 charger fails.....AND, should the 24v-12v charger present some unwanted RFI, it is simple to install an on/off "cut-off switch" on the 24vdc input to the 24v - 12v charger, to completely eliminate any troublesome RFI when using the M-802....


So, while it took us some time to get there....
I do think we have come upon a solution!!!




3) As for RFI, it is almost always "radiated" noise that is picked-up by your M-802's antenna.....RFI ingress from dc power wires is VERY rare (I've never seen it on-board, and only once when at a shore station)....
But, if RFI is generated by systems on-board, such as inverters, chargers, refrigeration compressors, etc....it is made significantly worse when that RFI is radiated by the wiring coming out of that device.....
So, IF you do have RFI from something on-board causing you reception problems, reducing the length of wiring on those devices, AND adding ferrite beads on those wires as close to the RFI-generating device as possible, will be the best way to reduce/eliminate the RFI....



4) As for other questions about your M-802 installation / set-up, I'd be happy to help....(as I have ~ 40 years experience in HF comms at sea and on land, have run my own electronics company for ~30 years, and have taught many seminars on radio propagation, antenna system design, alt energy, etc...)
First off, have a look at some of these threads....
SSCA Forum &bull; View topic - A Few SSB Install Questions
SSCA Forum &bull; View topic - Tips for using an HF-SSB Radio (mostly for newcomers)
SSCA Forum &bull; View topic - KISS-SSB Counterpoise
SSCA Forum &bull; View topic - HF Radio Freqs, summertime Atlantic crossing, offshore Net..

ssb freqs



5) To be clear here, HF radio communications and radio wave propagation, radio/antenna design and installation (including antenna counterpoises), etc. are all very well understood science and engineering.....
Contrary to what many write, there is no "art" involved in most of this....
(although there is some "art" involved in the human operations of the radio, there is no art involved in the proper design, engineering, and installation of these things.....and many of the basics have been studied/written about for many, many years....some references still used go back to the 1930's....after all electrons do flow the same now as they did decades before I was born!!!


Here are my Top 5 Tips in brief...
a) read some books about radios, antennas, hf communications, etc....where you will learn a GREAT deal, and where you will not be mislead by "internet discussion board" mis-information....
b) make sure you have a short, low-loss, hi-current 12vdc power connection for your radio, direct to the batteries....
c) have a low-inductance direct sea water connection from your antenna tuner grd lug....
d) reduce on-board generated RFI, and use ferrites beads...etc....
e) listen on-the-air / learn the easy and proper operating procedures....

If you take the above tips to heart, and follow them, you'll be happy with your marine HF radio system....



I do hope all the above helps...

Fair winds...

John
s/v Annie Laurie
Thanks; extremely helpful advice!!!

I have given up on the simple converter -- too much voltage drop at 30 amps unless I buy a huge massive one, and that already defeats the purpose of avoiding heavy cables or a separate battery.

The next simplest solution would be using the generator start battery. I think it's 4AWG cables I would need, and that's maybe not the end of the world for 10 meters of run (maybe a bit less). I would have to change the battery -- it's a plain truck starting battery now -- for something like a 110amp/hour Varta hobby battery, but that's not that expensive and about time to replace that batt anyway. Then add a 24v-12v charger and probably a battery monitor. I guess it will cost me $500 altogether, which is acceptable to me if it's a good solution.

A plus here is that I'm sharing the battery with generator start function, which reduces the number of banks on board.

Only problem, I guess, is the voltage drop over long cables and lead-acid battery. Violating the rule of having big cables as short as possible to the radio.

So in that respect I guess the dedicated LiFePo motorcycle battery is better -- shorter cables and no voltage drop in the batt. Maybe worth losing volume to the batt (but this one will be pretty small and quite light). The batt will be more expensive but I will save money on the cables. I guess the cost will be about the same.

Yeah, I guess this is the right way to do it. Now to find LiFePo batts in the UK.

A question: Am I right in thinking that when using Sailmail over Pactor, or other data comms over HF, that I will be transmitting continuously over long periods of time? Using maximum power? This is important to know, in order to size the components correctly. Voice only would be a fairly light duty cycle, where transmitting is concerned, and so much less demanding from a power point of view.
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Old 22-01-2013, 11:32   #26
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Re: Power Supply for SSB in a 24v Boat

Dockhead,
You're welcome...
(I'm at a client's office, and don't have my references with me....so I may be a bit "general" in my recommends this morning...)




Quote:
Originally Posted by Dockhead View Post
The next simplest solution would be using the generator start battery. I think it's 4AWG cables I would need, and that's maybe not the end of the world for 10 meters of run (maybe a bit less).
1) For 30 amps thru 10m of cable (20m round trip) to allow a max 3% voltage drop, you'd typically need 2awg wire....although I suspect that the M-802 would still work okay with a bit more voltage drop if using 4awg wire...the shorter the run of wire here, the better!!






Quote:
Originally Posted by Dockhead View Post
I would have to change the battery -- it's a plain truck starting battery now -- for something like a 110amp/hour Varta hobby battery, but that's not that expensive and about time to replace that batt anyway. Then add a 24v-12v charger and probably a battery monitor. I guess it will cost me $500 altogether, which is acceptable to me if it's a good solution.
2) Sounds like a good plan....although I'm not sure a battery monitor is necessary here, that's up to you....
If it were me (and I got a steal on a 12vdc radio), this is the way I'd go....
Call this "Plan A"




Quote:
Originally Posted by Dockhead View Post
A plus here is that I'm sharing the battery with generator start function, which reduces the number of banks on board.
Only problem, I guess, is the voltage drop over long cables and lead-acid battery. Violating the rule of having big cables as short as possible to the radio.
So in that respect I guess the dedicated LiFePo motorcycle battery is better -- shorter cables and no voltage drop in the batt. Maybe worth losing volume to the batt (but this one will be pretty small and quite light). The batt will be more expensive but I will save money on the cables. I guess the cost will be about the same.
Yeah, I guess this is the right way to do it. Now to find LiFePo batts in the UK.
3) If "Plan A" isn't do-able, then I'd call this idea "Plan B"....
Even though they do exhibit low voltage drop when drawing current, I'd try it with a simple AGM....as I'm not sure there is any reason to look for a lithium battery here.... as a mid-sized battery CLOSE to the radio (<2' of wire) will give you less voltage drop....perhaps a deep-cycle group 24 AGM, next to the radio...charged by the 24volt bank thru a 24v-12v charger....
Call this "Plan B"...






Quote:
Originally Posted by Dockhead View Post
A question: Am I right in thinking that when using Sailmail over Pactor, or other data comms over HF, that I will be transmitting continuously over long periods of time? Using maximum power? This is important to know, in order to size the components correctly. Voice only would be a fairly light duty cycle, where transmitting is concerned, and so much less demanding from a power point of view.
4) Before you even get to PACTOR, understand that the current draw (and voltage drop) when using SSB-Voice is also VERY important, and the voltage drop should be minimized in order for the radio to output a clean, non-distorted signal....
Here it is the voltage drop in the wiring that makes the biggest difference, as SSB-Voice has a very low average-to-peak ratio.....so "voltage sag" of the battery, while important, is a secondary factor here....

For 100% duty-cycle modes, such as FSK/PSK/PACTOR, both the voltage drop in the wires and voltage sag of the battery effect things...
BUT....
But, if you have a 24v-12v charger hooked-up (even a low-current unit), the 12vdc battery will probably be providing a fairly high voltage (>12.5volts even under load), so here again the voltage drop in the wires from the 12vdc battery to the transceiver are going to be the primary factor....
(and here again, you see why I'd not spend the $$$/effort on a lithium battery solution....)


As for long periods of time and at max power???
The answers sort-of depend on a few variables that I'd don't know....not the least of which are these two primary ones....
a) radio propagation conditions at the time..
b) e-mail / file size....

If you read over the sailmail primer, you'll see that the "power" used by the radio will depend on whether you're in PACTOR II or PACTOR III, and somewhat on what "mode" of PACTROR III....
SailMail
SailMail Primer
Setting Drive Levels

But, in general, you'll be using an "average power" of about 2/3 of maximum when in PACTOR-II or PACTOR-III transmission....(a pure FSK/PACTOR-I transmission would be 100% power, drawing approx. 30 amps....and this is used by the SCS modem to initially contact a sailmail station...)

So, if you figure on about 20-25 amps max when transmitting a PACTOR signal, you should be fine with your system design....(sailmail recommends setting your modem drive levels so that you are drawing approx. 25 amps in FSK/PACTOR-I and approx. 15 amps in PSK/PACTOR-II/III....)

And also remember that most cruisers are not usually "sending" large files or lengthy e-mails, but rather are sending fairly short requests, and are "receiving" longer e-mails / files....
So, "how long" you're transmitting will depend on what you are sending....
(I can't imagine you'd be transmitting more than one or two minutes straight...and probably a lot less...)

For some further information on "getting weather", etc. have a look here...
SSCA Forum &bull; View topic - Offshore / Hi-Seas Weather data / forecasts

And again, if you haven't read the sailmail primer, please do so....and print it out....as you will learn quite a bit from it....




I hope this helps.....maybe more later...

Fair winds...

John
s/v Annie Laurie
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Old 22-01-2013, 13:19   #27
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Re: Power Supply for SSB in a 24v Boat

Certainly the ideal is to have power cabling from battery to the transceiver such that there is no more than 3% voltage drop at maximum load at the load end. There may be situations where cable of quite large enough diameter is not available or practical for the desired run. In that instance, you can put a voltage booster at the load end of the run. Such a device will maintain the 12V, 13V, or 14V (whatever you set it to) output even if the input voltage sags because of voltage drop from the battery. These are well designed and tested units. They will help to a point - obviously if the power cable from the battery to the voltage booster is seriously undersized you could get into some some hot cable issues, but if you are trying to correct something like a 10% or 15% voltage drop over a long cable run they can solve your problem.

You can find such devices sold by TGElectronics and also MFJ. I'm sure there are others.

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Old 23-01-2013, 08:36   #28
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Re: Power Supply for SSB in a 24v Boat

For what might be a less expensive 24V to 12V convertor, contact TGElectronics. They don't show them on their web store, but the site does say they have them. Might be cheaper than the $500 Newmar solution.

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Old 23-01-2013, 08:51   #29
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Re: Power Supply for SSB in a 24v Boat

Thanks, everyone, for all this useful input.

It's a tough question still. I think I have kind of settled on a dedicated battery next to the radio, especially if I can find a suitable LiFePO4 one. This is lighter and smaller than lead acid (I am jealous of the precious space it will take up in my nav table area), and has the huge advantage of no voltage sag during intense discharge.

I will charge this with a 24-12 DC to DC battery charger. Victron makes a 25 amp one, which is almost enough obviate the battery, but I am afraid that the voltage will sag a lot with a converter (10% voltage drop is typical when you near their capacity limits) plus voltage drop of the 24v supply, and plus the risk of its being noisy.

Additional advantages of a dedicated battery are that I have failsafe power for comms in case of disaster (I think I'll connect my VHF to this battery as well), and also I can switch off the battery charger or indeed shut down the entire boat electrical system, in case I need to eliminate all noise on board, and still be able to use the radio.

If this turns out to be impractical, then I think plan "B" will be to substitute a new 110 amp/hour leisure battery for my existing generator start battery and run AWG4 cables to the radio. Install DC-DC battery charger and battery monitor (I want to keep an eye on the condition of the battery since I need to be able to start my genset with it). And hope I don't pick up noise through the power cables, and hope that there is not too much voltage sag.

That's still preliminary -- not final. Still thinking about it, and still grateful for advice.
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Old 23-01-2013, 08:59   #30
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Location: Camden, ME
Boat: A Thistle and a Hallberg-Rassy 36
Posts: 661
Re: Power Supply for SSB in a 24v Boat

Dockhead -

You have good reasons for using a separate dedicated battery, but if a 24v to 12v convertor is located close to your radio, you should see almost no voltage drop with a well designed unit even at rated current output.
My only concern would be RFI from the convertor, and I don't know about their 24v to 12v convertors, but some of the TGE 12V boost regulators have an RF sense feature such that they are active only on transmit, but shut down on receive to eliminate any possibility of RFI.

Chip
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