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Old 30-04-2014, 18:34   #16
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Re: SSB Current draw - both transmit and receive

Not sure why some of my post above is in blue, nor why the videos posted twice, nor why my attempts at editing these things are unsuccessful...

Sorry about all of that!

Fair winds...

John
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Old 02-05-2014, 02:48   #17
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Re: SSB Current draw - both transmit and receive

Quote:
Originally Posted by tedcoats View Post

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
You could save some power by using something like a degen 1103 ssb receiver for weatherfax instead of the main rig.



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Old 04-05-2014, 16:11   #18
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Re: SSB Current Draw - Both Transmit and Receive

Ted,
It's been a week....and we've given you the answers you seek....
SSB Current Draw - Both Transmit and Receive
Just wondering if this helped???

Fair winds..

John
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Old 04-05-2014, 16:28   #19
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Re: SSB Current Draw - Both Transmit and Receive

John you posted some great references in the major difference between an HF Ham radio vs a Marine certified unit with DSC. Since I have Fleet Broadband with 505# EPIRB's, PLB's, integrated AIS class B transponder as well as dual VHF marine stations with integrated DSC I choose to use my ICOM IC7000 as a ham only transceiver and maritime receiver only. I can adjust my output power from as little as 5 watts to 100 watts on SSB. SSB uses AB1 as it's mode of semi linear operation. I draw between 20 to 25 amps on peaks with the speech compressor on and at full output.
I have never had a condition where my battery bank has fallen below 11.5VDC the ICOM operated fine at the lower voltage and remained fairly linear.
73 Bill
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Old 04-05-2014, 16:36   #20
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Re: SSB Current Draw - Both Transmit and Receive

Hi John,
Sorry about the lack of attention to your very comprehensive reply...
And right now I can't respond with similar comprehensiveness except to say that I am very grateful for your input, and from what I have been able to read, am in total agreement. I am Ham qualified - but only recently - so have most of the options available to me....
Will be able to sit down and properly reply within 24 hours.

Cheers
Ted
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Old 05-05-2014, 11:14   #21
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Re: SSB Current Draw - Both Transmit and Receive

Bill,
The IC-7000 is not a bad radio, and I'm glad it is working well for you....(it is a better radio than its predecessor, the IC-706 series radios....and certainly does have a better PA...but it's a far cry from a type-certified maritime transceiver)


And, I don't wish to argue over semantics...but...
Quote:
Originally Posted by Billylll View Post
I choose to use my ICOM IC7000 as a ham only transceiver and maritime receiver only. I can adjust my output power from as little as 5 watts to 100 watts on SSB. SSB uses AB1 as it's mode of semi linear operation. I draw between 20 to 25 amps on peaks with the speech compressor on and at full output.
I have never had a condition where my battery bank has fallen below 11.5VDC the ICOM operated fine at the lower voltage and remained fairly linear.
Operating the IC-7000 at 11.5vdc (or even at 12.0vdc), and trying to get more than 10 - 20 watts output, is certainly NOT going to be running it's PA anywhere near "linear"...(sorry to say, but true...)
Now, I'm not saying that it won't work....but just that the transmit purity suffers significantly with fairly high transmit IMD products...

Not trying to quibble here....just saying that just because it transmits a signal, and you have been able to use the radio, does not in fact mean that it's signal is clean, nor even that it is recommended (not even for the ham radio bands, and certainly not for the maritime bands!)
(remember that until distortion products are truly horrific and/or the radios osc become unstable, many will not notice these transmitter issues on-frequency, but rather they are outside of your transmitter passband, causing interference to others....)
Not to mention the ALC-overshoot and IMD "pops" that Icom still hasn't gotten rid of in most of their ham transceivers...


{And, while some RF design engineers will argue whether there actually are solid-state Class AB1 amps....the facts are that most modern ham transceivers almost always have a Class B PA (no matter what the marketing guys cajole someone to write)....and with negative feedback, they do work surprisingly well for most modes that typically require "linear" amplification (such as SSB Voice)...}



You may find some of these pages helpful...

Understanding Amplifier Operating €œClasses€ | Analog content from Electronic Design

CB Amplifiers Converted to Ham
(an RF design engineer write about various amplifier classes)

understanding power,RF power and transmit interaction
SSCA Forum € View topic - understanding power,RF power and transmit interaction

SERIOUS HAM SSB SETUP ON THE CHEAP
SSCA Forum € View topic - SERIOUS HAM SSB SETUP ON THE CHEAP

Maintaining SSB Friendly Voltage
SSCA Forum € View topic - Maintaining SSB Friendly Voltage

SSB Transmit Issues
SSCA Forum € View topic - SSB Transmit Issues



Again, no worries here.....
I'm glad that the IC-7000 is doing what you need it to do....
Fair winds...

John
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Old 05-05-2014, 11:19   #22
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Re: SSB Current Draw - Both Transmit and Receive

Ted,
No worries here....take your time...
I just wanted to make sure that you saw the info...(what 'ya do with it, is up to you...)

Fair winds..

John
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Old 05-05-2014, 11:32   #23
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Re: SSB Current Draw - Both Transmit and Receive

Thanks John, no arguments from me. Most of the amplifiers I work with are class A but that's in the commercial world.
73 Bill
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Old 15-01-2015, 13:27   #24
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Re: SSB Current Draw - Both Transmit and Receive

Sorry to resurrect a 7 month old thread....but, I have some additional info...


Working with a ham radio manufacturer who is looking into improving their transceiver's transmit IMD, he mentioned that it seems the M-802 used a fair amount more power than typical "100-watt" ham rigs did, and asked me if I had the current draw figures (which I did for the most part, but I went ahead and did a new round of tests..)

Here are the Icom M-802 current draw figures (normal production run tolerances might be reflected in other M-802's having minor variations on different bands/freqs, but overall these should be very close for all M-802's...)

The stand-by and receive current draw...
Under stand-by, radio turned off, the TCXO draws about 100-110ma (~0.1amps), and on receive w/ audio, in all modes, it draws about 2.1 amps....all at 13.7vdc


My M-802 is run off a large (1125 A/H) battery bank, charged via a large solar array....and early this morning the battery voltage was 13.7vdc....a short run of 2ga wire powers the radio, with typ. max voltage drop of about 2%...giving me about 13.3-13.4vdc at the radio this morning, at the max current draw of 29.4 amps...


So, here are the overall current draws of the radio on the various bands (subtract 2.1 amps, the current draw in receive, for transmitter-only current draw), at approx. 140-150 watts output...

The zero-signal, mic-keyed but no modulation, current draw was 5.4 to 5.5 amps on all bands, 160m - 10m...


Band ```` SSB-whistle````` FSK Carrier (PACTOR-I)
160m````` 25.6amps`````` 25.6amps
80m ``````28.7 ````````` 28.7
40m ``````25.6`````````` 25.6
20m ``````28.7``````````28.8
17m```````24.7 `````````24.6
15m```````29.3 ``````````29.4
12m ``````24.4```````````24.3
10m ``````24.6``````````` 24.5


PACTOR-II is an approx. 50% duty-cycle mode, so "average" current draw in PACTOR-II would be about half of the FSK PACTOR-I figures....and PACTOR-III's duty-cycle varies from ~ 30% to ~65% (depending on speed), so your "average" current draw in P3, will be 30% - 65% of the FSK PACTOR-I figures...

(FYI, the M-802 is spec'd at 30 amps, max current draw @ 13.6vdc....and all of these figures are about typical for a 150-watt marine HF transceiver....and yes, that is more than your typical "100-watt" HF ham rig...)


All measurements were done near the radio, with a fairly new Klein clamp-on meter (which has proven to be within 0.1 amps of other meters I have tested it against), at ambient temp of about 70*F....with battery voltage of 13.7vdc, and voltage at radio of approx. 13.3-13.4vdc under full current draw of ~ 29amps...

So, when people tell 'ya that you need to figure on 30 amps of current draw from a Marine SSB radio, they are correct....judge and size your wiring run accordingly...



I hope this helps...



Fair winds to all....


John, KA4WJA
s/v Annie Laurie, WDB6927
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Old 15-01-2015, 20:45   #25
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SSB Current Draw - Both Transmit and Receive

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Old 15-01-2015, 20:52   #26
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Re: SSB Current Draw - Both Transmit and Receive

John's point is a good one. You would be amazed at how even 0.5V drop will affect the audio quality (IMD) of SSB transmitters. Unlike VHF FM, SSB requires very high linearity and a moving DC supply can cause a lot of distortion. While the average current draw is proportional to loudness the peak current is still needed. I am often surprised at how a soft spoken voice can have peaks just as high as a loud voice.
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Old 15-01-2015, 21:09   #27
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Re: SSB Current Draw - Both Transmit and Receive

Uh, Vivid, I learned about single-side-band modulation 45 years ago...and have been using it on-land/at-sea, on maritime and ham bands for over 40 years....

And, am well aware of marine "SSB", etc....

The point here is that wire size, terminals, etc. need to be sized for the 30 amp current draw and low voltage drop (3%, or less)....

And, while SSB radio "average" current draw is typically 25% - 35% of peak, for average speech, w/o any speech processing / compression, it is typically 50% - 65% with speech processing / compression...

Also, if you look at the figures, you'll see that even without any output at all (no talking at all), the radio is still drawing > 5 amps....

With most using speech processing / compression, the "average" current draw by most M-802's is about 15 - 18 amps under normal voice transmit, with peak current draw of 28 - 30 amps....
Quote:
Originally Posted by Vivid View Post
But remember that on SSB voice you are only transmitting while actually talking, so even at full power you are running a fraction of full output in terms of energy and drawing current proportionally.
I think if you read some of my other posts, etc. you'll see that the only reason I posted this info was for the folks asking about it, not trying to say that the "radio uses a lot of power" (it doesn't), but that it DOES draws a lot of current, and things need to be sized correctly....






And, yes, while this is true...most do not "reduce power after connected"....except for the facts that the "average power" is of course less in PACTOR-II and PACTOR-III, which you'll use after connecting....
Quote:
Originally Posted by Vivid View Post
Also remember that Pactor II and III work amazingly well at very low RF power once the connection is established.





This was just a "paste" from the info I was asked to provide to the engineer evaluating radios....and I certainly NEVER ever told anyone to be as much of a fanatic as I am...
Quote:
Originally Posted by Vivid View Post
By all means, though, don't skimp on the power wiring. Number 2 wire and (1125 ah batteries) sound a bit over the top,but budgets vary.
Quote:
Originally Posted by Vivid View Post
I get through every day with number 6 and 225, though no doubt the voltage drop is a bit more.
I've made my living in the electronics industry (commercial sat comm and communications), and what I do for my own radio comms (both on-board and at home on land), are not necessarily what I recommend to others....
And, I have never implied that 2 ga and 1100 A/H's was necessary....(sorry that I included that in this posting.....as I wrote, I just pasted this from the e-mail I sent to the radio engineer inquiring about current draw, etc...)




I hope you don't take offense to my clarifying things here....but just wanted you to know that I was never trying to tell anyone that they had to do it my way, just wanted to share the exact current draw numbers and explain why we all (all HF communications professionals) specify installing the system based on 30 amp peak current draw...

fair winds...


John
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Old 16-01-2015, 01:31   #28
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Re: SSB Current Draw - Both Transmit and Receive

My ICOM 718 performed well even with battery voltage below 12v. Used the radio to check in and listen to the Pacific Maritime mobile Net, download gribs and send an email or two a day. Went nearly 12 days in overcast conditions on the sail to Hawaii so limited charging by 260 watts of solar. Battery voltage at the end of 12 days on the 2 6v golf cart batteries wired in series was down to 12v. Got good reports on my signal on the net all the way till the sun came out on the 13th day. My boats pretty low electric usage with LED's for all lights. Did run the AIS, Garmiin 3206 plotter, Raymarine instruments, laptop battery charging and autopilot on standby for the entire trip. No refrigeration. Didn't take note of the radio's current draw but it couldn't have been much.
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Old 16-01-2015, 05:06   #29
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Re: SSB Current Draw - Both Transmit and Receive

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My ICOM 718 performed well even with battery voltage below 12v. Used the radio to check in and listen to the Pacific Maritime mobile Net, download gribs and send an email or two a day..
I wonder how you define "performing well". My mileage is different on this.

I also have a 718 and had the suspicion that it lost much its transmission power when the engine (hence alternator) was off and battery voltage dropped from 13-plus to 12.5 or so.

When I came back home I run a controlled test using an adjustable regulated power supply and Morse code. I found that power output drops by two thirds when supply voltage drops from 13.8V (Icom's spec) to 12.5V. Therefore I concluded that I cannot count on 100W Tx unless I run the engine, which is bad because of that adds noise.

I wonder if anyone has run the same test on an Icom M-802.... I am curious...


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Old 16-01-2015, 07:57   #30
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Re: SSB Current Draw - Both Transmit and Receive

svlamorocha,
Unfortunately this happens with many ham rigs...despite being spec'd at "13.8vdc +/- 10%".....
And while in some rigs it might be protection circuitry built too sensitive, it is a fact that most "12vdc ham rigs" are not designed to run at anything close to 12 volts, and many simply "shut-down" at voltages of 12vdc - 11.9vdc or less...Also, most of these rigs start producing seriously distorted audio (and "fm'ing") with low supply voltages, and unfortunately this is only noticed by a few others, as it usually manifests itself on voice peaks, when current draw is highest (and voltage drop the worse)....
Quote:
Originally Posted by svlamorocha View Post
I also have a 718 and had the suspicion that it lost much its transmission power when the engine (hence alternator) was off and battery voltage dropped from 13-plus to 12.5 or so.

When I came back home I run a controlled test using an adjustable regulated power supply and Morse code. I found that power output drops by two thirds when supply voltage drops from 13.8V (Icom's spec) to 12.5V. Therefore I concluded that I cannot count on 100W Tx unless I run the engine, which is bad because of that adds noise.
But, the real problem that is overlooked (actually unknown by most), are the horrible transmit IMD products produced with low supply voltages, from most HF ham rigs...(this causes splatter across a wide area...and of course this is one reason why many bemoan others trying to use PACTOR in an anchorage when others are trying to copy the weather, etc. as the guy running his rig with too low of voltage is causing serious interference to others....
Take note of what Dan wrote above....





But, here is some good news....Marine SSB Transceivers (those that are FCC Part 80 certified), like the M-802 must meet their design specs throughout their designed voltage range...so, they do NOT suffer from this problem...
The M-802 will meet its specs from 11.5vdc to 15.5vdc...
Quote:
Originally Posted by svlamorocha View Post
I wonder if anyone has run the same test on an Icom M-802.... I am curious..
And, yes I have tested the M-802 at low voltages (12 volts), and it continues to produce its full output, and when listened to off-frequency, produces no discernible splatter....



Again, the IC-718 is a nice entry-level "starter-rig", ham radio....but it (like most other ham rigs) was not really designed for "battery power operation"....



I hope this helps...

Fair winds...

John, KA4WJA
s/v Annie Laurie, WDB6927
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