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....
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
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...
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!!!
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
, 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
Icom M-802 DSC-Distress Signaling, what really happens!
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
4) Also, you didn't mention exactly what you require e-mail connectivity while at sea, for???
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...
Originally Posted by tedcoats
Requirements for the radio are for email and weather data transfer,in addition to the usual voice - nets for example.
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
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...
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
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...
(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!!)
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...
There are other reasons that it is not a very good idea....
Originally Posted by tedcoats
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.
- 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....
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!!
s/v Annie Laurie