Icom: ICOM 7300 PO (Power meter) only shows what its set for not true output

[Retroradio]

So, what I have found is whatever I set the power output to in settings is what the onboard meter says. If it set it at 30Watts thats what it shows etc... no variance.
This is contradicted by my outboard meter which gives the true output.
Useing the built in Tuner it would be logical to assume that the meter would give a true representation...
What is the use of this meter on the screen? Or have I missed something?

 

[AK9R]

If you connect the output of an IC-7300 through a calibrated power meter to a 50 ohm dummy load with the internal tuner bypassed and set the power level to 30 (which has no units, it's just a scale from 0 to 100), does the radio transmit at 30 watts in a full-duty cycle mode? This assumes that the power supply is capable of providing the radio's full rated transmit current at the rated voltage with no voltage drops in the power cable.

 

[Hit_Factor]

So, what I have found is whatever I set the power output to in settings is what the onboard meter says. If it set it at 30Watts thats what it shows etc... no variance.
This is contradicted by my outboard meter which gives the true output.
Useing the built in Tuner it would be logical to assume that the meter would give a true representation...
What is the use of this meter on the screen? Or have I missed something?

I think there is something else, but I don't know what it is.
Generally my output power is set at 100%. Occasionally, I see output is not 100% due to operator error. So I don't think it's directly tied to the setting. I guess that's a use for the power meter, to tell me when I'm wrong.

 

[KC8ESL]

Ok, so we need more information here. Are you testing your theory using CW? Is your meter reading average or PEP? DO you have a 50ohm load on the output of that meter?

If you're using SSB, your meter should be reading "PEP" and only when you say words like "HOOOOOOLA" will the meter move to max deflection of whatever power output your radio is set to.

If you're using CW, again you can use "PEP", but in this case it is either "on" or "off", no 50% here. Full modulation (power level that you have set the radio to) or nothing at all.

 

[alcahuete]

Icom has said themselves that due to variations in radios, it is impossible for that meter to represent actual output power. For example, my 7610 puts out 130w on most bands. 100% would not indicate the correct power, and 50% would be 65w, not 50, etc. As a percentage, I find it to be extremely accurate. I drive my amp with the radio set anywhere from 30-35% on the Icom meter, and that gives me an almost exact 40-45w drive. It is almost exact, to the watt. So as long as you know what your radio is actually putting out, you can use the percentage to come to a pretty good calculation.

I suppose what they could/should do is measure actual output power in watts and show that on the display. No reason they couldn't.

 

[Retroradio]

So this is what I found. I am assuming this is normal so no issue. Thoughts?

SSB, Peak on meter, 50 Ohm load.
Power set 100, Radio meter 100, external meter 60
.................. 75..........................75.......................... 30
...................50..........................50...........................15
...................40..........................40.......................... 10
...................30..........................30.............................7
...................20..........................20.............................4

The onboard power meter shows what the power was set at...but does not show what is really going out.
I am not expecting 100 watts. The best I can get is 40 to 60 with 50 being the a average based of mic/comp setting vocally. A tone gives 80 Watts.
I have never seen a 100 watt radio give more than 60-80 watts anyway.
I really like this radio and its a great performer I just found the meter odd.

 

[KE5MC]

As you have found mic/comp using SSB has variability that confuses the issue. Use CW or FM mode to understand RF power out without the interference modulation brings. Your testing points likely will be more 'aligned', but don't expect them to be equal.

 

[Retroradio]

I did a tone as a quick check on the 100watt setting and got a internal meter reading of 100 Watts external reading of 80 Watts. I will do the same spread and post the results.
I did the SSB as suggested and am primarily a SSB user so I defaulted to that.
Still the onboard meter is reading with a tone what the power is set for and not the actual reading.

 

[AK9R]

I use the RTTY mode on these modern radios when testing power output. Put the radio into RTTY mode, press the Transmit button, and the radio transmits a carrier at whatever power level you have set the radio for. Trying to use SSB and injecting a tone just confuses the matter and keying the radio in CW often requires an external control of some sort.

Also, supply voltage is critical. The IC-7300 requires 13.8 volts DC (+/- 15%) at 21 amps in order to produce full rated power output. Connect a voltmeter across pins 3 and 4 of the TUNER connector (4-pin Molex connector on back of radio). That will tell you what voltage the radio is seeing. If the voltage measured at the radio doesn't match the voltage at the power supply, then you have a problem with the power wiring. If the voltage at the power supply sags more than about 10% under full transmit load, then you have a problem with your power supply.

 

[bill4long]

All of us having said all that,

75 watts output vs 100 watts is not going to matter. At all. Nobody will be able to tell the difference.

So relax. And forget about it.

Over the years It's been amusing that people are so concerned with every last watt.

 

[Retroradio]

All of us having said all that,

75 watts output vs 100 watts is not going to matter. At all. Nobody will be able to tell the difference.

So relax. And forget about it.

Over the years It's been amusing that people are so concerned with every last watt.

Absolutely except I’m getting 40 to 50 (60 if I basically yell) on a good day. My original post was why does the meter not show the true output and only what the power level is you set it for.

 

[KE5MC]

I don't know the 7300, but possibly there are two displayed version of power. One is what it is set to, like the speed control on your car, the maximum the radio will do. The other is the actual power out a summation of the set power out, mode and modulation level. It might be there is only one RF meter on the display and you can switch it between set and actual. No matter, from a SSB, voice operation point of view with today's poor propagation most of the time set to max power and hope for the best. For persons running digital modes then the power level setting comes into play. No need to run 100w when 30w will get the job done. The other question of why in SSB and 100w setting do I not get 100w 'peak' indications. The answer is complex because the RF actual output is comprised of microphone gain, compression setting, microphone audio bandpass, radio transmit audio bandpass, your voice characteristic and proximity to microphone. It almost guaranteed that if you get consistent 100w peaks others will hear a harsh, raspy and clipped voice. Another point is your external meter having a peak reading mode does not make it so. For peak readings you need a meter that can sample and hold requiring more electronics and $$$ to get the job done correctly. Taking a moment to go back to the last sentence of your previous post... I suspect by design the set RF level is displayed for easy reference during operation. However, I would be surprised that actual could not be displayed too. Understanding that in SSB peak actual will be less than set. Hopefully my early morning ramblings bring some clarity.

 

[Retroradio]

Ramblings not...lol quick and clearly described.
I also suspect that the display is to show what you set it at. If I did not have an external meter then I would no idea what is actually going on. I was hoping that this was user error.....
Your summation of gain, mic settings, voice etc... are critical for this radio in terms of quality and outbound wattage.
I’m a going to redo my list with CW and see, but primarily as a SSB user I find the meter odd.
Also going to verify the power supply Voltage/Amperage as I haven't double checked that.
Albeit I love this radio but will have to make a chart so when I set the power I know what power setting gives me what and can ignore the internal meter. I find this odd.

 

[Fladave]

May I suggest some study materials. A quick view of the IC7300 schematic page PA UNIT (PA-2) page 17 shows the power measurement is taken before the tuner unit. There are no analog adjustments for calibration purposes. The signal names are FORLP and REFLP. There are test points.

https://www.hamradio.co.uk/userfiles/file/IC-7300_Schematic_Diagram.pdf

Coming Soon

Power Measurement with Simple Techniques

5 RF Transmitter Measurements Engineers Should Know

RF transmitters are an essential part of modern communications. Designed and assembled from core RF components, they have different forms and applications.

www.ni.com

I have found ICOM to be very responsive to technical questions from Amateurs at the link pasted below.

Support - Icom America

www.icomamerica.com

Best of luck.

 

[prcguy]

What kind of power meter is the OP using? If its not a true peak reading wattmeter and he is in SSB voice mode then all readings he has taken should be thrown out the window. Many peak reading wattmeters are good and some are crap so just because its "peak reading" doesn't guarantee accuracy in SSB mode.

I have several peak reading meters here with the Bird 43 being a standard and my much more accurate Agilent power meter with calibrated attenuators is what I use to calibrate various wattmeters. My Diawa peak reading is sort of a joke and so are a few others here. I had an old Heathkit that when calibrated it tracked very well in peak mode.

To see if the 7300 power meter and power settings are in the ball park use FM mode, not SSB. My 7300 and 7610 both read very close on percentage of power selected vs actual power out and the internal power meter is close enough to make most people happy. Any particular radio could have a problem or the meter circuit could be broken.

 

[jwt873]

I wouldn't trust measuring SSB peaks even with a peak reading meter. The output is completely dependent on the audio input.

As pcrguy suggests.. Use FM mode. This method will give you a nice constant carrier to measure.

One thing. I don't know how old your 7300 is, but Icom's power line fuse holders are notorious for building up resistance. When that happens you get a voltage drop and your radio starts seeing less than 13.8 Volts. I have an IC-7600 and periodically see my output power start to decrease. When that happens, I pull the fuses and clean the prongs. That always restores the power.

I just had to do that a few days ago when I saw my power drooping down to 70 Watts.

 

[prcguy]

When I get a new radio I cut the power cord at the fuse holder and install Anderson Power Poles and rely on a higher quality fuse or circuit breaker upstream. And I don't subscribe to a fuse in the negative lead giving more voltage drop.

One thing. I don't know how old your 7300 is, but Icom's power line fuse holders are notorious for building up resistance. When that happens you get a voltage drop and your radio starts seeing less than 13.8 Volts. I have an IC-7600 and periodically see my output power start to decrease. When that happens, I pull the fuses and clean the prongs. That always restores the power.

I just had to do that a few days ago when I saw my power drooping down to 70 Watts.

 

[jwt873]

When I get a new radio I cut the power cord at the fuse holder and install Anderson Power Poles and rely on a higher quality fuse or circuit breaker upstream. And I don't subscribe to a fuse in the negative lead giving more voltage drop.

I keep meaning to do that.. I've got no excuse putting it off with all the quality home time I've been having these days

 

[KE5MC]

Ramblings not...lol quick and clearly described.
I also suspect that the display is to show what you set it at. If I did not have an external meter then I would no idea what is actually going on. I was hoping that this was user error.....
Your summation of gain, mic settings, voice etc... are critical for this radio in terms of quality and outbound wattage.
I’m a going to redo my list with CW and see, but primarily as a SSB user I find the meter odd.
Also going to verify the power supply Voltage/Amperage as I haven't double checked that.
Albeit I love this radio but will have to make a chart so when I set the power I know what power setting gives me what and can ignore the internal meter. I find this odd.

Retroradio,
The internet is a great place,"sometimes". I took a look at the 7300 manual to get a better understand and forgive me if some of what follows you already know. Upper right corner of the display is a display 'button' for RF POWER and one of the knobs will get you from 0% to 100%. Effectively for a 100 watt radio you are setting power in watts. Expect some variance in measured power when you get to modes not effected by modulation input. Not a bad idea to establish a baseline for the radio RF performance, excluding the antenna system for this test. With the antenna system in place checking bands at frequency end-points and middle for SWR and recording is another good baseline. Expect weather (rain/snow) to have some effect on SWR and a retune by the tuner needed. Once things dry out then it should be back to near the original value.
Below the frequency display is you multi-function bar-graph display and looking for Po to be displayed from the rotation list selection. In SSB it will move from zero (no audio) on the left up scale to the right depending on the strength (peak) of you voice at any moment in time.
I know you want to focus on power and use the external meter. We can come back to the power 'thing' in a year and I'm betting you will have a different perspective. Go for power... I do want to point out about the meter, that Icom has built a 'system' with all the hardware and software bits to make it work as best as they know how. I would trust the internal meter because of the integration with the radio. The external meter to me is just about relative RF power indicator. I'll include a picture of my RF indicator a repurposed Radio Shack Field Strength/SWR meter. Modified to increase sensitivity without added electronics and a number scale, used only in F.S. mode.
The 7300 meter is displaying the way it should in SSB, nothing odd about it. If for you the oddity is the difference between internal and external metering I would trust the internal meter. Too many unknowns with the external meter for absolute readings and trust.
Have a great holiday during this difficult time and enjoy the hobby and learning along the way.

 

[Retroradio]

Granted and once again well written. I am familiar with how to set the levels and transverse the menus.
I have tried 2 different meters with the same result.
I have set the radio up as per the balancing act between ALC/Comp/Mic gain.
On CW I get a full 100watt deflection on the external meter when set the internal Power is set at 100 watts and the internal meter shows I00 watts.
On SSB I get 40 Watts deflection on the external meter when the internal power is set for 100 watts and the internal meter reads 100.
this leads me to questiuon the internal meter.