Radio problems

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Mihai (W4MHI)

Aug 27, 2022, 6:06:41 PM8/27/22
to Issaquah Amateur Radio Club

I have some problems with my ICOM-7300 and I need your input here, about what do you think it is the problem.
Scenario: Setup WSJTX (digital) on the radio. Setup the power to 10W. Press button "Tune". The SWR/Power meter shows the power around 10W. Increase power. The Power meter shows power increasing.
This is normal behavior, verified on 2 radios.

The problem: Same setup (WSJTX, same antenna, same power meter). Power at 10W. Power meter at 10W. Increase to 20W, power meter to 20W. Increase to 30W. Power meter 20W. Increase to 100W, power meter 20W. Another thing is the radio gets reset if the power is over 50W and tuning is more than 5s.
So no matter what is the power, it never goes over 20W. Same behavior with 50 ohms load.

My guess is the final is defective (no surprise here after the stunts on Field Day).
Please advice, thoughts, comments.

Thank you and 73!
Mihai (W4MHI)

Derek Chauran

Aug 27, 2022, 6:08:49 PM8/27/22
What does your ALC meter look like when transmitting and what is the drive level in wsjt-x?
From: <> on behalf of Mihai (W4MHI) <>
Sent: Saturday, August 27, 2022 3:06:40 PM
To: Issaquah Amateur Radio Club <>
Subject: [IARC] Radio problems
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Mihai Manolache

Aug 27, 2022, 6:59:02 PM8/27/22
Why this matter? With different radio, same setup, the behavior is correct. 
In thic case ALC shouldn't have any influence. 
I will take a look as I didn't pay attention to it. 


Sent from my Verizon, Samsung Galaxy smartphone

Derek Chauran

Aug 27, 2022, 7:03:03 PM8/27/22
Alc meter is a good way to see if you are providing enough audio drive to a 7300. Different rigs require different audio drive levels to make full power.

From: <> on behalf of Mihai Manolache <>
Sent: Saturday, August 27, 2022 3:58:58 PM
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Bruce Helbert

Aug 27, 2022, 7:59:03 PM8/27/22
Power input12VDC Problem?

Powerpole pins ca get pushed out. Bad connection on PP socket?  
Switching power supply getting RF feedback.  Floating ground?  

Radio reseting is kind of a clue.  

Blown final would probably be zero output.  Bad connection in final circuit could be. 

de KG7OI

On Aug 27, 2022, at 16:03, Derek Chauran <> wrote:

Rod Johnson

Aug 27, 2022, 8:37:50 PM8/27/22
I tend to agree Derek, in principle.
  I find measuring output in SSB mode is sometimes problematic.
  It is somewhat difficult to provide a stable audio input. .
  It is definitely a requirement to have a good power source, as Bruce suggested.  We are pretty sure that was an issue with your Field Day setup, but I think that you solved that problem. Having a way to measure the input voltage to the radio, under load, will prove the repair.
   If possible, try measuring power output in CW mode.  That at least will confirm the radio RF amp is doing it's job.
   If you get the full rated power out in CW mode, then you start looking for variables in the SSB related circuitry, as Derek suggested.
   ALSO,  the September VHF contest is the weekend of Sept 10,11.
   There should be many stations on the FT8 frequencies.
   Rod J

Mihai M.

Aug 27, 2022, 9:10:13 PM8/27/22
The issue is the power and the ground as Bruce suggested.
Thank you Derek for the ALC verification. I see the same values for the 3 radios. Interestingly enough they are all ICOM :)

Rod, I feared I did something wrong at Field Day. I found the HAM hobby is more and more challenging and all settings that ICOM/Yaesu/Kenwood, (not mentioning about chinese radios that are coming very aggressive on the market,) are sometimes confusing. Reading a manual of 500 pages will not get you better HAM, in my opinion. Basic things like you and Bruce mentioned, power, grounding, antenna matching, are the main issues an operator confronts each day.

Today was DOL (Day Of Learning) for me. I separated a lot of devices that are not suitable for HAM and I found some friends answering to may hail.

Thank you very much all for not sending the ICOM 7300 to service!

73 and big hugs :)
Mihai (W4MHI)

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Thank you,

Aug 27, 2022, 10:14:51 PM8/27/22

I have an IC-7300, too.

Enlightening discussion.

Separately, I was testing my new IC-705 with Bob today.  Mixed results.

Again: antennas and grounding are crucial in understanding the failures.



Gil Drynan

Aug 28, 2022, 9:45:02 AM8/28/22

I too have an IC-7300. Just a reminder that you can input of the power
supply 12v by going to menu and meter and check the 12v section.

gil W7GIL
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