SSB Current Draw - Both Transmit and Receive

[tedcoats]

Hi All,
I am investigating installing a SSB set on my boat - a Roberts 36' in steel.
I am Ham qualified so could use either Marine or Ham radio provided it can access both sets of bands. Icom radios dominate these marine forums, but seem to have pretty high current draw compared with some other sets, Codan for example, both receiving and transmitting.

Since minimising power usage is a never-ending goal, I wondered if any on this forum have any recommendations of radios which are efficient for power usage and therefore have modest requirements?

Requirements for the radio are for email and weather data transfer,in addition to the usual voice - nets for example.

Cheers
Ted Coats

[model 10]

Are you sure about the power draw of the ICOM? I only notice something like .2 volts drop using our ssb. Of course during tx it is worse but how long does that go on? While our Pactor modem is connected it is more but unless it's a very long email it does not amount to much.
For us, it's my beer in the fridge that uses to much power not the HF radio.

[tedcoats]

Guy,
I agree the refrigeration uses a lot of power - and we pay a fair bit of attention to the efficiency of fridges and freezers. Not much corresponding attention has been paid to the efficiency of SSB except:
http://www.charlespreston.net/batter...-Operation.pdf
I had a technical guy raise a set of questions about efficiency differences across radios and I realised that I was assuming equivalent efficiencies across brands when that clearly is not the case.
Not only am I questioning efficiency - but also output when input voltage drops below the 13.8 volt spec for many radios - a voltage only likely to be achieved with an engine running...
Still saying no case to answer?
Cheers
Ted

[transmitterdan]

Ted,

You may have to ask some owners to report their SSB receiver current draw while on receive. The M802 says 3A with audio at max which I assume means receiving some voice. That isn't typical so it is probably less when just listening to silence. Transmit power is usually insignificant in terms of watt-hours so I would not worry about that part. Anyway transmit power is a variable due to antenna variances and frequency so not easy to predict.

Most good SSB units work over a range of voltages. Icom says the M802 is 13.6 +/-15%. I believe this is for full specified performance. But it will still function at lower voltages. How much lower I don't know. Beware of high voltage conditions such as battery equalization. Many radios use capacitors that will be destroyed by voltages above about 16V.

Also, be aware that some/most SSB radios draw 12V power all the time they are connected to the battery. This is to keep the crystal oven warm so the frequency is accurate as soon as the unit is switched on. Only opening the circuit breaker or fuse will stop this power drain. Typical draw is <100mA but that may be significant in some installations.

[Paul L]

SSB units are not like VHFs, you don't have them on unless you are using them. The duty cycle for daily use is very low. And the duty cycle for Tx, where most of the juice is consumed, is way low. I think there's a lot bigger fish to be concerned about.

[SoonerSailor]

Receive current amongst marine and ham HF transceivers will vary from about 1 amp (Elecraft K3) up to 2 or 3 amps. If low current draw during prolonged periods of receive is important, I would suggest a portable SW radio that runs on 12V, or one of the QRP ham radios that may draw as little as 200 mA.

On transmit, you can pretty much assume that they will all draw about 22 amps when transmitting at 100 watts or 30 amps at 150 watts in Pactor 1 mode or CW. In SSB (voice) or Pactor 2,3, or 4, current draw will be somewhat less. Running at lower watt outputs will reduce current draw too, but current draw will not fall as fast as the power output.

73
Chip

[skipmac]

Hi Ted

Several excellent discussions on Ham and marine SSB radios on the forum. One recommendation, if you only want to receive marine HF bands then any good ham radio would be fine. However if you want to transmit on marine bands, while most ham radios can be opened up to transmit on all frequencies it isn't the best idea. For a detailed discussion on this and HF radio on boats in general you might want to read this thread.

http://www.cruisersforum.com/forums/...sb-121982.html

To understand why marine radios are recommended for transmitting on marine bands read post #42 by ka4wja.

[btrayfors]

Choosing a ham radio or marine radio to put aboard based on the (miniscule) differences in receive current draw is a fools errand....don't waste your time.

Current draw on transmit is dependent mostly on the rated output power....a 100-watt rig draws about 20A on voice peaks or CW; a 150-watt class rig draws 30A on voice peaks or CW.

To be legal, you need an FCC-certificated marine SSB for use on the marine bands.

One caution: all marine SSBs have a pretty wide voltage input tolerance, and will work with the typically low battery voltages often found on cruising boats. All ham radios are NOT so tolerant. They will begin FM-ing with low voltage or will cut out entirely (like the Icom IC-706 ... one of the least tolerant rigs out there). If you're going to use a ham radio, it's often a good idea to get a DC-to-DC voltage booster -- there are several on the market.

Bill
WA6CCA

[Sailor_Hutch]

Originally Posted by tedcoats

Hi All,
I am investigating installing a SSB set on my boat - a Roberts 36' in steel.
I am Ham qualified so could use either Marine or Ham radio provided it can access both sets of bands. Icom radios dominate these marine forums, but seem to have pretty high current draw compared with some other sets, Codan for example, both receiving and transmitting.

Since minimising power usage is a never-ending goal, I wondered if any on this forum have any recommendations of radios which are efficient for power usage and therefore have modest requirements?

Requirements for the radio are for email and weather data transfer,in addition to the usual voice - nets for example.

Cheers
Ted Coats

The Ten Tec people were pioneers in low power radios since the seventies. They made some marine radios as well, and they're still in business. Not sure if they have a current unit that would be good on a boat, but worth a check IMO...

[denverd0n]

Just to summarize the above...

If you want a radio that you can leave on, receiving all the time, then it would be best to buy one of the small, cheap, receivers. Something like the Kaito 1103. The draw will be very little. You don't want to use your big transceiver for this (and, frankly, I don't know why you'd even want any radio left on all the time).

For a transceiver, it will be on such a small amount of time that the difference in current draw between the best and the worst will make almost no practical matter. You should be much more concerned with the features and abilities of the radio than you are with its current draw on receive.

And, as has been said, their current draw on transmit will all be very close. You'll be transmitting even less time than you'll be receiving, so the practical difference will be virtually nill.

Good luck.

[continuouswave]

In single side band transmission, the amplification of the signal from low level to full transmitter power must be (should be) done by linear amplifiers. Amplifiers that are linear--another way of saying low distortion--are usually not as efficient at converting their input power into radio frequency power as non-linear amplifiers. You can figure about 50-percent efficiency, at best, for a linear amplifier. So a 100-Watt output SSB transmitter will tend to need to run about 200-Watts DC input in the final stage.

[crui1948]

Originally Posted by tedcoats

Icom radios dominate these marine forums, but seem to have pretty high current draw compared with some other sets, Codan for example, both receiving and transmitting.

There are some explications for the higher current consumtion in marine radios:
- less distortion requires class A linear amplifier
- less frequency drift requires a thermal control oven

But I understand you compared ICOM and Codan radios.
Can you figure out some data?
I am aware that the ICOM M801 has a build in DC/DC converter allowing to operate the radio to lower voltage than 13,8 Volt +/- 10%.
So you can Tx without a running motor.
Thanks for more details, Willy

[leftbrainstuff]

I don't see the high current draw on either of my two icoms. One ssb and one ham.

For these type of radios you need good power supply and good electrical and ground connections.

Sent from my GT-I9300 using Cruisers Sailing Forum mobile app

[leftbrainstuff]

Your transmit duty cycle will be low so amp hour demands aren't usually an issue.

Sent from my GT-I9300 using Cruisers Sailing Forum mobile app

[ka4wja]

Ted,
1) I've got accurate, real-world current draw numbers for you....(but after you read the rest of what I write, you'll understand why everyone mentioned that your HF radio's electrical efficiency is a rather moot point...)

Originally Posted by tedcoats

I am investigating installing a SSB set on my boat -
Since minimising power usage is a never-ending goal, I wondered if any on this forum have any recommendations of radios which are efficient for power usage and therefore have modest requirements?

The Icom M-802 MF/HF-DSC-SSB Marine Transceiver is currently the only affordable option for cruisers/voyagers....it sells for about $1800 USD....
http://www.docksideradio.com/Icom%20SSB%20Radios.htm

Here are my measured M-802 current draws from a few years ago...

Normal SSB RX / Max Vol = 2.1 amps
Normal SSB RX / Avg Vol = 2.0 amps
DSC Watch Mode / bright display = 1.9 amps
DSC Watch Mode / dim displat = 1.8 amps
Turned OFF / Standby = 0.10amps - 0.12amps (~ 100 - 120ma)

(you can see that the thermal device on the TCXO uses very little power)

On transmit the M-802 draws approx. 25 - 26amps PEAK (at 150 watts PEP output), and significantly less than that AVERAGE (approx. 7-8amps w/o speech compression, and 12 - 15 amps w/ speech compression On...)
You understand that the actual power used by an SSB transmitter varies quite a bit, depending on the voice, etc...
Normal SSB transmissions without any speech processing, are typically 25% - 30% duty-cycle....and with speech processing, about 50% - 55%....
And, FYI....the Icom M-802 has 3 selectable power levels (20w, 60w, and 150w), which allows you to further reduce your HF radio power consumption during transmitting, should you desire to do so....


And, regarding power output with reduced voltage..

Originally Posted by tedcoats

Not only am I questioning efficiency - but also output when input voltage drops below the 13.8 volt spec for many radios

Not only will the Icom M-802 output its full power (150 watts) with voltages as low as 11.5vdc, it will still meet all of its rated specs at that voltage (actually from 11.5 thru to 15.5 volts)...
This is a VERY important criteria, meeting all of its specs at these voltages...as most ham radios (almost all that I've come across in the past 40 years), CANNOT do this, as most of them start distorting badly as the voltage AT THE BACK OF THE RADIO, under transmit (when the voltage drop is high), falls below 12.5 volts, and most start "fm'ing" as voltages near 12 volts, and many just shut down the transmitter at this point, or at voltages between 11.5 to 12vdc....
(yes, some of the "older" ham radios, such as the Atlas 210-x, Drake TR-7, etc. are actually good performers here and do not suffer from this malady....but 35 - 40 year old radios are not really good to recommend to sailors!!! But, I still use my two TR-7''s at home....)

Here are a few pictures of my Nav Station (and my shack on-shore)...











And, other pictures/articles here...
http://www.c470.jerodisys.com/470pix/foto_bot.htm




2) Regarding your "radio requirements", you didn't mention where you are at, nor where you are planning on cruising/voyaging...
But regardless, the Icom M-802 will serve you well....

For LOTS of details on this radio, how-to properly/optimally use it, and even lots of info on HF communications in general...Please have a look at this thread, and watch the videos!!!
http://www.cruisersforum.com/forums/f13/icom-m-802-instr-videos-basic-adv-and-live-dsc-distress-call-114734.html

An hour (or at most, two) per day of receiving and a few minutes of transmitting, is typically all that you'd need to do....and all that most, except for the confirmed "radio nuts" like me, use their HF radios each day...
Figure about 2 A/H per day (for each hour of receiving), and about 1 A/H per day (for every 5 minutes of transmitting)....and this adds up to be about 3 - 4 A/H per day of total power consumption from your Icom M-802, which is a VERY small amount of power used, and a VERY small thing to worry about!!
(this is typically only 2% - 3% of your average cruising boat's daily average power usage at anchor....and typically 2% or less, than the average cruising boat's daily average power usage when underway / at sea....if you were to find a radio that is even significantly more power efficient, you'd only be saving at best 1 A/H per day...)

Also, remember that the Icom M-802 has 3 selectable power levels (20w, 60w, and 150w), which allows you to further reduce your HF radio power consumption during transmitting, should you desire to do so....




3) You mention "radio requirements", but you did not mention DSC...
MF/HF-DSC-SSB radios are an almost "requirement" these days, and I'm not sure you understand this (as you also mention using a ham radio, none of which have DSC capability, let alone are even certified for use on the maritime bands)

For more than 15 years (since Jan 1999) there has been NO Voice Radio Watchkeeping requirement for vessels at sea (nor for coast stations), but there IS a DSC-Radio Watchkeeping requirement for all SOLAS vessels and coast stations....(this both VHF-DSC and MF/HF-DSC)

The only affordable MF/HF-DSC-SSB Maritime transceiver is the Icom M-802....selling for approx. $1800 USD....(the comparable Furuno or Sailor/Thrane units are as much as 4 - 6 times the price!)

If you desire / need to call another vessel (or shore station, other than the USCG), for assistance (weather, information, medical advice, navigational information, fuel, water, food, etc. etc.) or in the event of Distress (MayDay), the only way to signal other vessels (beyond VHF-DSC range), or shore stations is by use of MF/HF-DSC signaling....

If you think that there would never be a need for that (since you may be thinking that an EPIRB takes care of the distress signaling requirement), you may wish to read further....(do a search and read over these threads...)

EPIRB Activation? What happens/How to improve rescue odds
http://www.ssca.org/forum/viewtopic.php?f=5&t=15457

Icom M-802 DSC-Distress Signaling, what really happens!
http://www.ssca.org/forum/viewtopic.php?f=5&t=16705


Here's one of the videos....this one dealing with sending a DSC-Distress

Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call
http://www.ssca.org/forum/viewtopic.php?f=5&t=16779

http://www.cruisersforum.com/forums/f13/icom-m-802-instr-videos-basic-adv-and-live-dsc-distress-call-114734.html





4) Also, you didn't mention exactly what you require e-mail connectivity while at sea, for???

Originally Posted by tedcoats

Requirements for the radio are for email and weather data transfer,in addition to the usual voice - nets for example.

a) Many cruisers/voyagers find Wi-Fi and cellular/3G/4G connectivity when in port to suffice for all their e-mail (and internet) needs, and they find no need for e-mail when at sea and/or in remote areas...

Also, I assume that by "weather data transfer", you are referring to access to weather info/forecasts for ocean sailing and when in remote locales???
For a great deal of information / detail (and plenty of links) about obtaining some of the best weather info/forecasts available, please have a look at these threads (where you'll find almost all the info you'd ever need)...

Offshore / Hi-Seas Weather data / forecasts
http://www.ssca.org/forum/viewtopic.php?f=5&t=13712

http://www.cruisersforum.com/forums/f13/obtaining-accurate-offshore-hi-seas-weather-data-forecasts-while-at-sea-103555.html#post1232682

http://www.cruisersforum.com/forums/f13/obtaining-accurate-offshore-hi-seas-weather-data-forecasts-while-at-sea-103555-2.html#post1235615



b) As for HF Nets / Cruiser's Nets / etc..
An Icom M-802 will serve you well for BOTH maritime and ham nets....
Here is just a small sampling of nets...
http://www.docksideradio.com/Cruising%20Nets.htm

http://www.docksideradio.com/HF%20Distress%20&%20Watchkeeping%20Skd.htm

http://www.docksideradio.com/east_coast.htm

http://www.docksideradio.com/west_coast.htm



c) Regarding ham radio use of the Icom M-802 Marine transceiver...it is an excellent choice for the cruising ham!!!

Have a look here at this thread, where you'll find many details....
Icom M-802 use on the Ham Radio Bands
http://www.ssca.org/forum/viewtopic.php?f=5&t=13712

And, here is one of the videos that I referred to earlier, which shows the use of the M-802's "VFO Mode" on the ham radio bands...

http://www.sailmail.com/
http://www.sailmail.com/smprimer.htm
(if you are actually in need of e-mail at sea and will be installing a PACTOR modem, please read the Sailmail Primer, it will teach you all you'll need to know about Sailmail!!!)

d) If you are running a business from on-board and/or require e-mail connectivity when out at sea and/or in remote areas...you're probably going to be looking at Sailmail and use an SCS PACTOR-IV modem....(yes, it is a pricey thing....but for e-mail connectivity when offshore and in remote areas, it is one of the best approaches....bottom line: Sailmail and PACTOR work and work well!!)


http://www.docksideradio.com/Pricing%20&%20Ordering.htm
http://www.docksideradio.com/Icom%20SSB%20Radios.htm

Remember that Sailmail limits you to 90 minutes of connection time per week....which means an average of about 12 - 13 minutes per day....a minute or so of transmitting and 10 minutes of receiving daily, would be also be a VERY small amount of power consumption...

As for the details of your radio's power consumption when using a PACTOR modem, most of what you're likely to be doing is receiving, with only some transmitting...
And, even though your initial connection is with PACTOR-I, this is typically only a few seconds of full-power 100% duty-cycle FSK (PACTOR-I is FSK, like SITOR)...and then you're going to be using PACTOR-II, PACTOR-III, or PACTOR-IV...
PACTOR-II is actually approx. a 50% duty-cycle mode (about what an SSB transmission is with speech processing)...
PACTOR-III's and IV's duty-cycle varies, depending on connection quality (link s/n), with stronger signals being a very light duty-cycle of about 30%...and under very bad conditions, a duty-cycle of about 60%....

So as you see, the power consumption even when using a PACTOR modem is quite small....and here again hardly worth any concern...






5) Ted, if you are "ham qualified", you should understand that you CANNOT use a "ham radio" on the marine bands (except in case of distress/MayDay)
There are many reasons for this...
Not the least of which are:
a) --- It is illegal..
b) --- The "ham radios" have serious transmit spectral purity and distortion product problems, that cause harmful interference as well as reduced intelligibility on-air...
c) --- NO "ham radio" has DSC capability...

Originally Posted by tedcoats

Hi All,
I am investigating installing a SSB set on my boat - a Roberts 36' in steel.
I am Ham qualified so could use either Marine or Ham radio provided it can access both sets of bands.

There are other reasons that it is not a very good idea....
- Most "ham radios" are less reliable...
- Most "ham radios" are less "user friendly"...
- Most "ham radios" have serious transmit functionality issues when operated on battery power (serious increases in distortion products and worse transmit spectral purity....AND many of then just quick working, once the voltage supplied to the back of the radio, during transmit, falls to 12 volts and below....)
- The list goes on and on....but the most important points are above in "a", "b", and "c"...


If you wish to actually SEE what is meant by significantly worse spectral purity and distortion products, here are a few postings with images/pictures showing these differences (and much text explaining everything)...
These 5 posts here (all different), highlight some of the importance differences in transmit spectral purity and distortion products between HF "ham" radios, and marine HF transceivers....

http://www.cruisersforum.com/forums/f13/icom-725-switch-to-ssb-115358.html#post1390840

http://www.cruisersforum.com/forums/f13/icom-725-switch-to-ssb-115358.html#post1391886

http://www.cruisersforum.com/forums/f13/icom-725-switch-to-ssb-115358.html#post1393953

http://www.cruisersforum.com/forums/f13/icom-725-switch-to-ssb-115358.html#post1393963

http://www.cruisersforum.com/forums/f13/icom-725-switch-to-ssb-115358.html#post1394200

Look at them all, as they are all different...




Okay, there is more....but I think you get the "gist"...
Worrying about "power efficiency" of your HF radio is a rather moot effort....and you're almost certainly going to be installing an Icom M-802....
...If you read all the above, including all the threads/posts referenced, and all the links provided in those threads, and watch the videos, you're going to know more about Marine HF communications than probably 90% of the other cruisers out there!!!



I do hope this helps....but, if you are confused by some of my ramblings, please ask for clarifications!!

Fair winds..

John
s/v Annie Laurie